FIXED CROSS-RAIL MILLING MACHINE MILLING ATITOMOB1LE CASTINGS
FOUNDRY WORK
A Practical Handbook on Standard Foundry Practice,
Including Hand and Machine Molding; Cast
Iron, Malleable Iron, Steel, and Brass
Castings; Foundry Manage-
ment; Etc.
REVISED BY
BURTON L. GRAY
INSTRUCTOR IN FOUNDRY PRACTICE, WORCESTER POLYTECHNIC INSTITUTE
MEMBER, FOUNDRYMEN’s ASSOCIATION
ILLUSTRATED
AMERICAN TECHNICAL SOCIETY
CHICAGO
1927
OcL\. 1 ^r
Gr-n^f
'C, & \ '~y\<2. €. V
%
r
Copyright, 1916, 1918, 1920, 1923
BY
AMERICAN TECHNICAL SOCIETY
COPYRIGHTED IN GREAT BRITAIN
ALL RIGHTS RESERVED
179992
INTRODUCTION
HE making of a metal casting seems like a very simple opera-
tion—given a pattern, a flask, a supply of molding sand, and
some molten metal; presto! it is done — but a little study de¬
velops the fact that there are few industries where more depends
upon shop kinks and the many other essential things which make
up a broad knowledge of a distinct trade than in foundry work.
The industry, as such, is as old as our knowledge of brass and iron,
the former having been made into castings from earliest times.
Casting methods, however, have partaken of the general mechanical
development of the last few years and today there is no com¬
parison as to the quality of castings, the complexity of the patterns
cast, and the speed of manufacture, with the work of a few years ago.
<1 In this article the methods of hand molding have been carefully
discussed, including the many questions of pattern construction
which are more or less closely associated with foundry work. The
presentation also includes the uses of the various types of molding
machines, which have become so papular within the last few years.
Malleable iron practice has now become well standardized and this
type of casting, particularly for small work requiring much dupli¬
cation, is very important. An excellent discussion of steel castings
is particularly pertinent as this type of casting is fast displacing
drop forgings for many classes of work.
<1 Altogether the article represents a well-rounded and thoroughly
up-to-date discussion of this important subject. The original author
and the reviser, both men of broad experience, have combined to
give the reader the benefit of their knowledge and it is the hope of
the publishers that the book will be found instructive and interest¬
ing to the practical foundry man as well as to the general reader.
Siw
CONTENTS
Molding practice.. .
Main branches..
Molding equipment
Classes
Molding sand. .
Core sand
Graphite
Charcoal
Sea coal
Distinction
Fire clay
Parting dusts. .
Core binders. . .
1
1
3
Q
o
5, 6
6
7
7
7
7
7
8
9
Tools 9
Flasks 9
Shovel 12
Rammers 13
Finishing tools 14
Clamps 17
Molding processes 18
Sand mixture 18
Sifting 19
Ramming 20
Gating 24
Shrinkage heads 2G
Pressure in molds 27
Common defects in castings 31
Typical molding problems 31
Flat joint 32
Coping out 35
Sand match 36
Split-pattern molds v 38
Floor bedding 42
Open mold 45
CONTENTS
PAGE
Core work 46
Materials 46
Equipment 48
Conditions of use 50
Methods of making 53
Cylindrical cores 58
Setting chaplets 60
Projecting cores 60
Hanging cores 61
Bottom-anchored cores 61
Duplicating castings 66
Practical requisites in hand molding 66
Use of molding machines 67
Dry-sand work 89
Characteristic features 89
Molding engine cylinder 89
Making barrel core 92
Loam molding 94
Rigging 94
Materials 97
Principles of work 99
Simple mold 102
Intricate mold 104
Casting operations 109
Furnace parts 109
Blast 112
Running a heat 116
Foundry ladles 118
Pouring. 119
Chemical analysis 123
Calculation of mixture 124
Fuel 126
Sand mixing 127
Cleaning castings 131
Steel work 136
Present development 136
Processes 136
Characteristics of metal. .. . : 136
CONTENTS
PAGE
Steel molds 137
Facing mixtures 137
Packing 139
Cores 141
Steel castings 141
Running a heat 141
Setting up molds 143
Cleaning castings 144
Annealing 144
Malleable practice 145
Comparative characteristics of metal 145
Testing 146
Production processes 148
Molding methods 149
Methods of melting 152
Iron mixture 156
Variation from gray-iron practice 159
Cleaning castings 160
Annealing 161
Finishing 167
Brass work 167
Metals 168
Mixtures 170
Production 171
Molding materials 171
Equipment 172
Examples of work 175
Melting 176
Cleaning 181
Shop management 182
Governing factors 182
Molding divisions 184
Materials 186
Handling systems 186
Cleaning department 187
Performance 188
Accident prevention 189
Checking 190
Keep’s mechanical analysis 190
Arbitration-bar tests 191
FOUNDRY WORK
PART I
MOLDING PRACTICE
Introductory. Foundry work is the name applied to that
branch of engineering which deals with melting metal and pouring
it in liquid form into sand molds to shape it into castings of all
descriptions.
In the manufacture of modern machinery three classes of
castings are employed, each one having its individual physical
properties, such as strength, toughness, durability, etc. These
castings are as follows: gray iron; copper alloys, i.e., brass, bronze,
etc.; and mild steel. By far the greatest number of castings made
are of gray iron, that is, iron which may be machined directly as it
comes from the mold without any further heat treatment.
The main purpose of this book is to explain the underlying prin¬
ciples involved in making molds for gray-iron castings, and the mix¬
ing and melting of the metals for such castings. The articles on
Malleable Cast Iron as well as the articles on Brass Founding and
Steel Casting emphasize only those features of the methods used
which differ from gray-iron foundry practice. The article on Shop
Management is intended to set students thinking on this subject;
because the whole trend of modern shop practice is toward special¬
ization and system in handling every department of the work, in
order to increase efficiency and reduce cost.
DIVISIONS OF IRON MOLDING
Main Branches. There are four main branches in gray iron
molding: (1) green-sand work; (2) core work; (3) dry-sand molding;
and (4) loam work.
Green-Sand Molding. The cheapest quickest method of form¬
ing the general run of castings is by green-sand molding. Damp
molding sand is rammed over the pattern, and suitable flasks are
used for handling the mold. 'When the pattern is withdrawn the
2
FOUNDRY WORK
mold is finished, and the metal is poured while the efficiency of the
mold is still retained by reason of this dampness. The mold may be
poured as soon as made; and in case of necessity it may be held over
a day or more depending upon its size. If the sand dries out, the
mold should not be poured.
Core Making. Core making supplements molding. It deals
with the construction of separate shapes in sand which form holes,
cavities, or pockets, in the castings. Such shapes are called cores.
They are held firmly in position by the sand of the mold itself or by
the use of chaplets. Core sand is of a different composition from
molding sand. It is shaped in wooden molds called core boxes. All
cores are baked in an oven before they can be used. The whole
detail of their construction is so different from that of a mold, that
core making is a distinct trade—a trade, however, that is generally
considered a stepping stone to that of molding. Boys usually begin
to serve their time in the core shop.
Dry-Sand Molding. Dry-sand molding is the term applied to
that class of work where a flask is used, but a layer of core sand mix¬
ture is used as a facing next to the pattern and the joint, and the
entire mold is baked before pouring. This drives off all moisture
and gives hard clean surfaces to shape the iron. It is used where
heavy work having considerable detail is to be cast, or where the
rush of metal or the bulk of it might injure a mold of green sand.
Dry-sand molds are usually made up one day, baked over night, and
assembled and cast the next day.
Loam I York. Loam work is the term applied to molds built of
bricks carried on heavy iron plates. The facing is put on the bricks
in the form of mortar and shaped by sweeps or patterns depending
upon the design of the piece to be cast. All parts of the mold are
baked, rendering the surfaces hard and clean. After being assem¬
bled, these brick molds must be rammed up on the outside with green
sand in a pit or casing to prevent their bursting out under the casting
pressure. Simple molds can be made up one day, assembled, rammed
up and poured the next, but it usually takes 3 or 4 days and some¬
times as many weeks to turn out a casting.
Loam work is used for the heaviest class of iron castings for
which, on account of the limited number wanted, or the simplicity of
the shape, it would not pay to make complete patterns and use a
FOUNDRY WORK
3
flask. In some cases the intricacy of the design makes a pattern
necessary, and size alone excludes the use of sand and flasks.
Selection of Method. No hard and fast rules exist for the selec¬
tion of the method by which a piece will be molded. Especially
with large work, the question whether it shall be put up in green
sand, dry sand, or loam, often depends upon local shop conditions.
The point to consider is: How can the best casting for the purpose
be made for the least money, considering the facilities at hand to
work with?
MOLDING EQUIPMENT
MATERIALS
Before taking up the making of molds, let us consider briefly
the materials used, where they are obtained, and what is their
particular service in the mold. Also we shall describe the principal
tools used by the molder in working up these materials into molds.
Classes. There are three general classes of materials for mold¬
ing kept in stock in the foundry, as tabulated herewith:
Molding Materials
Sands
Facings
Miscellaneous
Molding sands
Light
Medium
Strong
Free sands
Sharp or Fire
Beach sand
Graphite
Charcoal
Sea coal
Fire clay
Parting dust
Burnt sand
’Charcoal
Partainol
Core binders
Sands
Quality. All sands are formed by the breaking up of rocks due
to the action of natural forces, such as frost, wind, rain, and the
action of water.
Fragments of rocks on the mountain sides, broken off by action
of frost are washed into mountain streams by rainfall. Here they
grind against each other and pieces thus chipped off are carried by
the rush of the current down into the rivers. Tumbled along by the
rapid current of the upper river, the sand will finally be deposited
where the stream flows more gently through the low land stretches
4
FOUNDRY WORK
TABLE I
Proportions of Elements in Sands
Elements
Eire
Sand
(per cent)
Molding Sands
Core
Sand
(per cent)
Iron Work
Brass
Light
(per cent)
Medium
(per cent)
Heavy
(per cent)
Light
(per cent)
(a) Silica
.SiO,
98.04
82.21
85.85
88.40
78.80
85.50
Alumina (clay). . .
AL.Oa
1.40
9.48
8.37
0.30
7.89
2.05
Iron oxide
Fe«03
.00
4.25
2.32
2.00
5.45
.85
Lime oxide
.Cat)
.20
.50
.78
.50
(b) Lime carbonate. . CaCOs
.08
.29
1.40
2.05
Magnesia
. MgO
.io
.32
.81
.50
1.18
4.27
Soda
JN a2()
.09
.10
.13
.04
Potash
.K,()
.05
.03
.09
.04
Combined water. .
TLO
.14
2.04
1.08
1.73
3.80
2.00
Organic matter.. . .
.28
.15
.04
.04
1.00
Specific gravity. . .
2.592
2.052
2.045
2.030
2.040
Degree of fineness.
85
00
40
95
1
below the hills. Here the slight agitation tends to cause the finer
sand and the clay to settle lower and lower down in the bed. Thus
we find beds that have been formed in ages past; possibly with a top
soil formed over them, so long have they been deposited. But on
removing this top soil we find gravel or coarse sand on top; this
merges into finer sand and this again finally into a bed of clay.
Rocks, however, are very complex in their composition, and
sands contain most of the elements of the rocks of which they are
fragments. For this reason molding sands in different parts of the
United States vary considerably.
A good molding sand first of all, should be refractory, that is,
capable of withstanding the heat of molten metal. It should be
porous to allow the escape of gases from the mold. It should have
a certain amount of clay to give it bond or strength, and should have
an even grain. All of these properties will vary according to the
class of work for which the sand is used.
Elements. The two important chemical elements in such sands
are silica, which is the heat-resisting element, and alumina, or clay,
which gives the bond. Other elements which are found in the mold¬
ing sands are oxide of iron, oxide of lime, lime carbonate, soda potash,
combined water, etc. The analyses shown in Table I, made by
FOUNDRY WORK
h
W. G. Scott, give an idea of the proportions of these elements in the
different foundry sands.
Silica alone is a fire-resisting element, but it has no bond. These
other elements help in forming the bond. But under heat, silica
combines and fuses with them, forming silicates. These silicates
melt at a much lower temperature than does free silica. Therefore
with sands carrying much limestone in their make up, or with those
containing much oxide of iron, soda potash, etc., the molten iron will
burn in more, making it more difficult to clean the casings.
The limestone combinations also go to pieces under heat, tending
to make the sand crumble, which may result in dirty castings.
The proportions given in Table I must not. be considered as
absolutely fixed, for no two samples of sand, even from the same bed,
v ill analyze exactly alike. The table is instructive, however,
because it indicates the reasons why the different sands are especially
adapted to the use to which they are put in practice.
Fire Sand. Such sand is used in the daubing mixture for repair¬
ing inside of cupola and ladles, and should be in the highest degree
refractory, and should contain as little matter as possible that would
tend to make it fuse or melt.
Light Molding Sand. This sand is used for castings such as
stove plate, etc., which may have very finely carved detail on their
surfaces, but are thin. The sand should be very fine to bring out
this detail; it must be strong, i.e., high in clay, so that the mold will
retain every detail as the metal rushes in. On the other hand, the
work will cool so quickly that after the initial escape of the air and
steam there will be very little gas to come off through the sand.
Medium Sand. Sand of this grade is used in bench work and
light floor work, for making machinery castings having from to
2-inch sections. These will have less fine detail, so the sand may be
coarser than in the previous case. The bond should still be fairly
strong to preserve the shape of the mold, but the tendency of the
large proportion of clay to choke the vent will be offset by the larger
size of the grain. This vent must be provided for because the metal
will remain hot in the mold for a longer time and will cause gases to
form during the whole of its cooling period.
Heavy Sand. This grade of sand is used for the largest iron
castings. Here the sand must be high in silica and the grain coarse,
6
FOUNDRY WORK
because the heat of the molten metal must be resisted by the sand,
and gases must be carried off through the sand for a very long time
after pouring. The amount of bond or clay must be small or it will
cause the sand to cake and choke these gases. The detail is gener¬
ally so large that the lack of bond is compensated for by the use of
gaggers, nails, etc. The coarse grain is rendered smooth on the
mold surface by careful slicking.
Core Sand. Core sand, often almost entirely surrounded by
metal, must be quite refractory but have very little clay bond.
This bond would make the sand cake, choking the vent, and render
it difficult of removal from a cavity when cleaning the casting.
Compared with medium molding sand, it shows higher in silica,
although having less than half the proportion of alumina.
Free Sands. Sands having practically no clay in them are
called free sands. Of these there are two kinds in use: river sands,
and beach sands.
River Sand. The grains of river sand retain the sharp frac¬
tured appearance of chipped rock, and these little sharp grains help
much in making a strong core because the sharp angular grains
interlock one with another. River sand is used on the larger
core work.
Beach Sand. Beach sand is considerably used in coast sections
because it is relatively inexpensive, but its grains are all rounded
smooth by the incessant action of the waves. It will pack together
only as will so many minute marbles. For this reason it is used
only for small cores.
Facings
Function. Foundry facing is the term given to materials
applied to or mixed with the sand which comes in contact with
the melted metal. The object is to give a smooth surface to the
casting. They accomplish this in two ways: (1) by filling in the
pores between the sand, thus giving a smooth surface to the mold
face before the metal is poured; and (2) by burning very slowly
under the heat of the metal, forming a thin film of gas between the
sand and iron during the cooling process. This prevents the iron
burning into the sand and causes the sand to separate from the
casting when cold.
FOUNDRY WORK
7
Different forms of carbon are used for this purpose because
carbon will glow and give off gases, but it will not melt. The prin¬
cipal facings are graphite, charcoal, and sea coal.
Graphite. Graphite is a mineral form of carbon. It is mined
from the earth and shipped in lumps which are blacker than coal
and are soft and greasy like a lump of clay. The purest graphite
comes from the Island of Ceylon, India. There are several beds,
however, in the coal fields of North America.
Charcoal. Charcoal is a vegetable form of carbon. It is made
by forming a shapely pile of wood, covering this over with earth and
sod, with the exception of four small openings at the bottom and one
at the top. The pile is set on fire and the wood smoulders for days.
This burns off the gases from the wood, leaving the fibrous structure
charred but not consumed. Charcoal burning is done in the lumber¬
ing districts. The charcoal for foundry facings should be made
from hard wood.
Sea Coal. Although sea coal contains a high per cent of car¬
bon, it is less pure than the other facings and gives off much more
gas. Sea coal is made from the screenings from the soft-coal
breakers. The coal should be carefully selected by the manu¬
facturer and be free from slate and very low in sulphur.
Distinction. All facings are manufactured by putting the
raw materials through a series of crushers, tumbling mills, or old-
fashioned burr stone mills, and then screening them. The finest
facings are bolted much as flour is.
In the shop the molder distinguishes between facings or black¬
ings, and facing sand. Blacking consists of graphite or charcoal,
and is applied to the finished surface of a mold or core. Facing sand
is the name given to a mixture of new sand, old sand, and sea coal,
which in the heavier classes of work forms the first layer of sand next
the pattern.
The use of the different facings will be clearly seen from the
tabulation on page 8.
Miscellaneous Materials
Fire Clay. Fire clay comes from the same source that sand
does. It is almost pure oxide of alumina, which is separated out
from the sand by a combination of the chemical action of the waters
of the streams. Fire clay has traces of the other impurities men-
8
FOUNDRY WORK
Characteristics of Facings
Material
Uses
Action |
Charcoal
Good facing for light molds; dusted
on from bag after pattern is drawn.
Mixed with molasses water for
wash for small cores and dry-sand
work.
Mixed with some graphite and clay
wash for blacking for heavy dry-sand
and loam work; slicked over with
tools.
May be used as a parting dust on
joint of bench molds.
Burns at low enough
temperature to be effec¬
tive before thin work
cools.
Resists moisture; pre¬
vents sand surfaces from
sticking together.
Graphite
Good facing for bench molds; dusted
on from bag; good for medium and
heavy green-sand work. Applied with
camel’s hair brush, and slicked over
with tools.
As heavy blacking for dry-sand and
loam work, used as above.
Good on heavier green
sand because it is more
refractory than char¬
coal, but still forms gas
enough to keep metal
from burning into sand.
1
Sea Coal
Mixed with facing sand in propor¬
tions from 1:6 to 1:12. See section on
Molding.
Helps to force vents
through sand when mold
is first poured, and pre¬
vents strong sand of the
facing from caking, be¬
cause it continues to
throw off gas after cast¬
ing has solidified.
tioned in the analysis of molding sands. It is found in the lowest
strata of the deposit beds. It is used to mix with fire sand in the
proportion of 1 to 4 as the daubing mixture for cupola and ladles.
Clay wash is a mixture of fire clay and water. The test for
mixing it is to dip the finger into the wash and then withdraw it,
whereupon there should be an even film of clay deposited on the
finger. Clay wash is used as the basis of heavy blackings. It is
used as follows: for wetting crossbars of flasks; for breaks in sand
where a repair is to be made; to wet up the dry edges of ladle linings
when repairing with fresh daubing mixture; in fact, any place where
a strong bond is required at some particular spot.
Parting Dusts. Parting sands or parting dusts must contain no
bond. They are used to throw on to the damp surfaces of molds
which must separate one from another. They prevent these sur¬
faces formed of high bond sands from sticking to each other.
FOUNDRY WORK
9
The cheapest parting sand, and by far the most commonly used,
is obtained by putting some burnt core sand, from the cleaning shed,
through a fine sieve.
Beach sand is also used as a parting sand, but the rounded
nature of its grain weakens the molding sands more than does burnt
core sand.
Charcoal facing dusted from a bag makes an excellent parting
dust on fine work.
A dust manufactured expressly for the purpose and called “Par-
tainol” is the most perfect material for fine work. This is applied
from a dust bag. It is not only useful for sand joints, but is a great
help if there is a deep lift on a pattern where the sand is liable to
stick, or for a troublesome box in the core room.
Core Binders. Although the materials for this purpose—flour,
rosin, oil, etc.—are on the purchasing list of the general foundry
buyer, for the purposes of this article they will be explained in detail
under Core Work.
TOOLS
Under this heading only the hand tools and equipment used by
the molder in putting up his mold are described. The mechanical
appliances for reducing labor are described in a later section.
Flasks. To use sand economically for molds, sets of open frames
called flasks are used. Flasks consist of two or more such boxes.
The lower box is called the drag or noicel, the upper box is called the
cope. If there are intermediate parts to the flask they are called
cheeks. Flasks are fitted with pins and sockets so that they will
always register.
Snap Flask. For small castings the molds are rammed up on
benches or projecting brackets. Such work is termed bench work and
the flasks are usually what are known as snap flasks. They range in
size from 9 by 12 inches to 18 by 20 inches. As is seen in Fig. 1,
these flasks hinge on one corner and have catches on the diagonal
corner. The advantage of the snap flask is that any number of
molds may be put up with but one flask, and the flask removed as
each mold is completed. There are several good snap flasks to be
had on the market. Many foundries, however, make up tlieir own.
Each size of flask should have at least one smooth straight board
called the mold board, the size of outside dimensions of the flask.
10
FOUNDRY WORK
Rough boards or bottom boards of same size should he provided,
one for each mold that will be put up in a day.
Boards for snap work are made of from §- to 1-inch stuff, and
should have two stiff cleats, as shown in Fig. 2, to hold them straight.
Wood Flash. For
heavier castings where the
molds are made on the
floor, box flasks are used
made of wood or iron.
In the jobbing shop,
wood flasks are more
economical, as they can
more readily be altered to
fit a variety of patterns,
while in a foundry turn¬
ing out a regular line of
castings, iron flasks pay because they require less repair.
Wooden flasks of necessity receive hard usage in the shop and
grow weaker each time they are used. They will burn more or less
each heat; they receive rough usage when the mold is shaken out; and
often the flasks must be stored where they are exposed to all kinds of
weather. It is economy, therefore, to build wooden flasks heavier
than would be necessary if they were always to be used in their new
condition.
Fig. 3 shows the construction of a typical wooden flask; the sides
project to form lifting handles; the ends are gained in to the sides.
Through bolts, in addition to the nailing, hold the sides firmly. A
detail of the pin is shown at A,
and at B is a cast-iron rocker
useful on flasks over 4 by 5 feet,
to facilitate lifting and rolling
over. The cleats make it a simple
matter to alter crossbars. The
crossbars should be not over 8
inches on centers. For more than 3-foot spans they should have short
crossbars through the middle connecting the long ones. In flasks 4
feet and over there should be one or more iron crossbars and a f-inch
through bolt with good washers to clamp the sides firmly to them.
FOUNDRY WORK
11
TABLE II
Sizes of Wooden Flasks
Material
Flask Sizes
Sizes
Arrangement
(6 inches deep)
Sides
(inches)
Cross¬
bars
(inches)
Short
Cross¬
bars
(rows)
Iron
Cross¬
bars
(number)
Up to 24 by 24 in.
18 in. to 24 in. wide up to 5 ft. long
1J2
2
1
1
1
24 in. to 36 in. wide up to 6 ft. long
23 £
IK
1
2
36 in. to 48 in. wide up to 7 ft. long
3
134
2
2
Note. For each additional 6-inch depth of cope or drag add 25 per cent to the thick¬
ness given.
Table II shows thickness of stuff for sides and crossbars for
average sizes of jobbing flasks.
Illustrative Example. Find thickness of sides and bars in a
flask 30 by 48 inches.
By referring to Table II, it is noted that for lengths on the sides
over 2 feet and under 5 feet the thickness of sides should be 2 inches.
Similarly, for widths of flask of over 24 inches and under 36 inches,
the thickness of crossbars should be 1| inches.
12
FOUNDRY WORK
Iron Flask. In Fig. 4 is shown the construction of a large iron
flask suitable for dry-sand work. The pieces of the flask are usually
cast in open sand from a skeleton pattern, all holes cored in. The
crossbars are cast in the same way; they have a slot in the flange
instead of holes to facilitate adjusting them. Trunnions and rockers
are sometimes cast on the sides in a core instead of being made
separate and bolted on. Holes for pins are usually drilled through
the joint flange. For pins, short iron bars are used temporarily in
Fig. 4. Iron Flask
closing. The thickness of metal varies from £ inch to 1£ inches,
according to size of flask.
In F ig. 5 is shown a typical form of. iron flask used on some
molding machines. The boxes are cast in one piece. The handles
serve as lugs for the closing pins. Only one pin is fixed on each box.
This makes the boxes interchangeable and capable of being used for
either cope or drag.
Shovel. For cutting and handling loose sand the molder uses
a shovel with flat blade, as in Fig. 6, for it is often more convenient
to let the sand slide off of the side of the shovel than off of the end.
FOUNDRY WORK
13
This is especially true when shoveling sand into bench molds or
molding-machine flasks.
Sieve. The foundry sieve or riddle, Fig. 7, is used to break up
and remove lumps, shot iron,
nails, etc., from the sand
placed next the pattern or
joint. Sieves should have
oak rims with brass or
galvanized-iron wire cloth.
In ordering, the diameter
of rim and the number of
meshes to the inch of the
woven wire is given. Good
• n ,i • p i Fig. 5. Flask for Molding Machine
sizes tor the iron foundry
are 16 inches to 18 inches diameter, No. 8 to 12 on bench work,
No. 4 to 8 on floor work.
Rammers. Rammers are used for evenly
and quickly packing the sand in the flask. One
end is in the shape of a dull wedge, called the
peen end, the other is round and flat called the
butt end. Of the rammers shown in Fig. 8, a is
the type used on bench work; b is a floor rammer
having cast heads and wooden shaft; c shows a
rammer made up in the foundry by casting the
Fig. 6. Flat Blade
Shovel
heads on the ends of an iron bar; cl shows a small peen cast on a
short rod—this is convenient for getting into corners or pockets on
floor work.
14
FOUNDRY WORK
Pneumatic Type. In shops equipped with compressed air a
pneumatic rammer, as shown in Fig. 9, is sometimes used to butt
off large flasks, and for ramming loam molds in pits.
Finishing Tools. Holders* tools are designed for shaping and
slicking the joint surfaces of a mold and for finishing the faces of the
mold itself. Excepting the trowels, they are forged in one piece
from steel. The trowels have steel blades and short round handles
which fit conveniently into the grasp of the hand. All of the tools
are ground slightly crowning on the bottom, and they are rocked
just a little as they are worked back and forth over the sand to pre¬
vent the forward edge cutting into the surface of the mold.
Of the sixty or more combinations of shapes on the market,
the few illustrated represent the ones most commonly used in job¬
bing shops.
FOUNDRY WORK
15
Trowels. Trowels, Fig. 10, are used for shaping and smoothing
the larger surfaces of a mold. The square trowel a is convenient for
working up into a square corner, and the finishing trowels b and c
are more for coping out and finishing along the curved edges of a
pattern. Trowels are measured by the width and length of blade.
Slicks. Slicks are designated by the shape of the blade and the
wddth of the widest blade. In Fig. 11, a is a heart and leaf; b is a
Fig. 12. Lifters
leaf and spoon; c is a heart and square; and d is a spoon and bead.
These are in sizes of 1 inch to If inches. They are used for repairing
and slicking small surfaces.
Lifters. Fig. 12 showrs lifters used to clean and finish the
bottom and sides of deep narrow openings; a is a floor lifter, made in
16
FOUNDRY WORK
Cd)
Fig. 13. Square Corner Slicks
Fig. 14. Floor Swab
sizes from §- by 10-inch to 1- by 20-inch; b is a bench lifter, the
sizes of which vary from ^ inch to f inch wide.
Corner Slicks. Fig. 13
shows at a and b inside and
outside square-corner slicks,
made in sizes of 1 to 3 inches;
c is a half-round corner,
widths 1 inch to 2| inches;
and d is a pipe slick made 1
inch to 2 inches. This style
of tool is mainly used on dry
sand and loam work.
Swabs. Swabs are used
to moisten the edges of the
sand about a pattern before
drawing it from the mold.
This foundry swab is a dan¬
gerous though useful tool.
Its danger lies in the too free
use of water around the mold, which may result in blow¬
holes. A good swab for bench work is made by fasten¬
ing a piece of sponge, about double the size of an egg, to
a goose quill or even a pointed hardwood stick. The
point will act as a guide and the water may be made
to run or simply drop from the point by varying the
pressure on the sponge.
Floor swabs, Fig. 14, are made from hemp fiber.
They should have a good body of fiber shaped to a
point, and should be made about 12 inches or 14 inches
long. They will take up considerable water and deliver
it from the tip of the point. In heavy work the swab
is trailed lightly over the sand like a long bristled brush.
Vent Rods. Vent wires are used to pierce small
Fig. 15. Vent holes through the sand connecting the mold cavity with
the outside air. For bench work a knitting needle is the
most convenient thing to use. It should have a short hardwood
handle or cast ball on one end. Select a needle as small as possible,
so long as it will not bend when using it.
FOUNDRY WORK
17
Heavy vent rods are best made, as shown in Fig. 15, of a spring
steel from inch to \ inch with the pointed end enlarged a little
to give clearance for the body of the
rod when run deep into the sand.
Draw Sticks. Draw sticks are
used to rap and draw patterns
from the sand. In Fig. 16 are shown
three kinds: a is a small pointed rod
| inch to f inch in size, which gets
its hold by simply driving it into
the wood of the pattern; b is a wood
screw welded to an eye for conven¬
ience; c is an eye rod with ma¬
chine-screw thread, which requires
a metal plate let into the pattern.
The plate is called a rapping plate
and is made with separate holes
not threaded, into which a pointed
rapping bar is placed when rapping
the pattern, thus preserving the
threads used for the drawbar.
Clamps. In pouring, the parts
of a mold must be clamped by
some method to prevent the pres¬
sure of the liquid metal from sep¬
arating them, causing a run-out. For light work a weight such as
shown in Fig. 17 is the most convenient. This is simply a plate of
cast iron 1 inch to 1§ inches thick, with a cross-shaped opening
cast in it to give considerable
liberty in placing the runner in
the mold. The weights are
from 15 to 40 pounds, accord¬
ing to size of flasks.
Floor flasks are fastened
with clamps made of cast iron
which are tightened by prying them on to a hardwood wedge. In
Fig. 18 is shown how the wedge may first be entered and how the
clamping bar is used to firmly clamp the flask. For iron flasks
18
FOUNDRY WORK
Clamp Wed/jQ
Fig. 18. Illustrating Method of Clamping
used in dry-sand work the clamps are very short, as only the flanges
are clamped together, as may be seen in Fig. 4. In that connection
iron wedges are used instead of wood. Often the iron bottom board
is clamped on and the joint
flanges bolted together before
pouring.
MOLDING PROCESSES
PRINCIPLES OF GREEN-
SAND MOLDINGj
Good Work. There are
certain principles underlying
iron molding which hold good
in all classes of founding,
and a practical understand¬
ing of these principles is necessary for good work in any line.
Aside from the fact that generally a mold is wanted which takes
the least possible time to put up, three things aimed at in green¬
sand work are: (1) a sound casting, which is free from internal
imperfections, such as blow holes, porous spots, shrinkage cracks,
etc.; (2) a clean casting, which is free from dirt, such as slag, sand,
etc.; and (3) a smooth casting, having a uniform surface free from
scabs, buckles, cold-shuts, or swells.
Sand Mixture. The natural sands best adapted to obtain
these results have already been dealt with. The methods of adding
new sands vary with different classes of work. For light work the
entire heap should be kept in good condition by adding a little new
sand every day, for the light castings do not burn out the sand to
a great extent.
On heavier work of 50 pounds and upward, the proportion of
sand next the pattern is so small compared with that used simply
to fill the flask, that it does not pay to keep the entire heap strong
enough for actual facing. The heap should be freshened occasionally
with a cheap molding sand, but for that portion of the mold which
forms the joint surface, and especially that which comes in contact
with the metal, a facing sand should be used.
The range of new sand in facing mixtures on a 10-part basis,
with sea coal in addition, is as tabulated herewith:
FOUNDRY WORK
19
Proportions of Facing Mixtures
(Basis of 10 Parts)
Sand
Sea Coal
(additional part)
New
Old
Free
3—6
6—2
1—2
1 1
6 8
These proportions, and the thickness of the layer of facing sand,
vary with the weight of metal in the casting. Too much new sand
tends to choke the vent and to cause sand to cake; too little new
sand renders facing liable to cut or scab. Too much sea coal makes
sand brittle and more difficult to work, and also gives off too much
gas which is liable to cause blowholes in casting. Not enough
sea coal allows the sand to cake, making cleaning difficult.
Tempering and Cutting. To prepare foundry sand for making
a mold, it must be tempered and cut through. This is now usually
done by laborers. To temper the sand, throw water over the heap
in the form of a sheet by giving a peculiar backward swing to the
pail as the water leaves it. Then cut the pile through, a shovelful
at a time, letting the air through the sand and breaking up the lumps.
This moistens the clay in the sand, making it adhesive and puts
the pile in the best condition for working.
To test the temper, give one squeeze to a handful of sand.
An excess of water will at once be detected by the soggy feeling
of the sand. Now hold the egg-shaped lump between thumb and
finger of each hand and break it in the middle. The edges of the
break should remain firm and not crumble. Too much moisture
will make excess of steam in the mold, causing blowholes. Not
enough moisture renders sand weak and apt to wash or cut.
Bearing in mind the nature of the materials we have to work
with, we must now study the important operations involved in
making a sand mold.
Sifting. The sand next to the joint and over the pattern
should be sifted. The thickness of this layer of sifted sand varies
from about f inch for light work to 2 inches on very heavy work.
The fineness of the sieve used depends upon the class of work. No.
1G or 12 would be used for small name plates, stove plate, etc., while
20
FOUNDRY WORK
No. 8 or 6 is good for general machinery work. On floor work,
from 4 to 6 inches of sand back of the facing should be riddled through
a No. 4 sieve to ensure more even ramming and venting.
Ramming. The object of ramming is to make the sand hang
into the flask and to support the walls of the mold against the flow
and pressure of the metal. The knack of ramming just right only
Fig. 19. Setting Gaggers
comes with continued practice and comparison of results. Hard
ramming closes up the vent, causing blowholes. Iron will not
“lay” into a hard surface. Soft ramming leaves a weak mold sur¬
face, and the flow of the metal as it enters the mold washes or cuts
the sand, leaving a scab on one part of the casting and sand holes
on another. A mold rammed too soft tends to swell under the
pressure of the liquid metal, making the casting larger than the
FOUNDRY WORK
21
pattern or leaving an unsightly lump on the casting. The bottom
parts of a mold, being under greater casting pressure, must be
rammed somewhat harder than the upper portions. The joint
also should be packed firmly, as it is exposed to more handling than
any other part.
Gaggers. Crossbars are put in the cope to make it possible
to lift the sand with the cope without excessively hard ramming.
As an additional support for the cope sand on large work there are
Fig. 20. Chaplets
used gaggers, which are L-shaped pieces of iron made from wrought
or cast iron of from -j^-inch to §-inch square section.
The force of sand pressing against the long leg of the gagger
holds it in place and the short leg supports the sand about it. There¬
fore the gagger will hold best when the long leg is placed tight against
the crossbar and is plumb. The long leg of the gagger should not
project above the level of the cope, as there is much danger of striking
it and breaking in the mold after the flask is closed. In Fig. 19
are shown the right and wrong ways of setting gaggers.
Use of Chaplets. Chaplets should be used to support parts
of cores which cannot be entirely secured by their prints which are
held in the sand of the mold. In Fig. 20 are shown the three prin¬
cipal forms of chaplets used, and how they are set in the mold;
a is a stem chaplet; b is a double-headed or stud chaplet; and c is
a form, of chaplet made up of strip metal.
22
FOUNDRY WORK
That portion of the chaplets which is to be bedded in metal
is tinned to preserve it from rusting, because rusty iron will cause
liquid metal to blow. For small cores nails are often employed
for this purpose, but only new ones should be used. With the stem
chaplets the tails must be cut off when the casting is cleaned—the
stud chaplet becomes entirely embedded in the metal. There are
now manufactured and on the market many different styles of
chaplets. In selecting the size and form for a given purpose the head
of the chaplet should be large enough to support the weight of the
core without crushing into the
sand and thin enough to fuse
into the liquid metal. The stem
must be small enough to fuse
well to the metal and stiff enough,
when hot, not to bend under its
load.
Venting. In the section on
Sands reference has already been
made to gases which must be
taken off from a mold when it is
poured. There are three forms
of these: (1) air, with which the
mold cavity is filled before pour¬
ing; (2) steam, formed by the
action of the hot metal against
the damp sand during the pour¬
ing process; and (3) gases formed
while the casting is cooling, from
chemical reactions within the liquid metal and from the burning
of organic matter, facings, core binder, etc., in the sands of the
mold. It is of the greatest importance that these gases pass off
quickly and as completely as possible. If they do not find free
escape through the mold they are forced back into the liquid
metal, making it boil or blow. This may blow the metal out
through risers and runners, or simply form numerous little bubble-
shaped cavities in the casting, called blowholes. These often form
just below the skin of the casting and are not discovered until
the piece is partially finished.
FOUNDRY WORK
23
Various Systevis. One cannot depend entirely upon the
porosity of the molding sands, but must provide channels or vents
for the escape of these gases. For light work a free use of the vent
wire through the sand in the cope will answer all purposes.
On castings of medium weight, besides venting with the wire,
risers are placed directly on the casting or just off to one side as
shown in Figs. 19 and 21. These are left open when the mold is
poured and provide mainly for the escape of the air from the mold.
Heavy castings that will take time to cool, and thus keep
facings burning for a long time after the mold is poured, require
venting on sides and bottom as
well as top. Fig. 21 shows side
vents aaaa connecting with the
air through the channel bbb cut
along joint and risers ccc passing
through the cope. At the bottom
the vents connect with cross-vents
dd run from side to side between
the bottom board and edge of
flask. Fig. 22 shows a mold
bedded in the floor; the side or
down vents connect at the top, as
in previous examples, and at the
bottom with a cinder bed about
2 inches thick, rammed over
entire bottom of pit. The gases find escape from this cinder bed
through a large gas pipe.
Action During Pouring. In pouring, the gas from vents should
be lighted as soon as may be. The burning at the mouths of vents
helps to draw the gases from below and also keeps the poisonous
gas out of the shop.
It is customary to keep risers closed with small cover plates
when large castings are being poured so that the air in the mold
will be compressed as the metal rises in the mold. This helps
sustain the walls of the mold and forces the vents clear so that they
will act more quickly when the mold is full. These covers are
removed occasionally to watch the progress of pouring, and are
entirely removed when the metal enters the risers.
24
FOUNDRY WORK
Gating. Gating is the term applied to the methods of forming
openings and channels in the sand by which liquid metal may
enter the mold cavity. The terms sprues and runners are also
used in the same connection in some shops.
Functions of Parts. There are practically three parts to all
gates: pouring basin; runners; and gate, as seen in Fig. 21. The
runner is formed by a wooden gate plug made for the purpose. The
pouring basin is shaped by hand on top of the cope, and the gate
proper is cut along the joint surface by means of a gate cutteT.
In all cases the gate section should be smaller than any other part
so that, when pouring, the runner and basin may be quickly flooded;
also that the gate when cold will break off close to the casting and
lessen the work of cleaning.
The object of gating is to fill the mold
cavity with clean metal—to fill it quickly,
and while filling, to create as little dis¬
turbance as possible in the metal.
The impurities in liquid metal are
lighter than the metal itself, and they
always rise to the top when the melted
metal is at rest or nearly so. Advantage
is taken of this important property
to accomplish the first of the objects
mentioned.
Fig 23 shows a good type of gate
to use on light work. .For reasons given,
the point a should have the smallest sectional area. This section
should be wider than it is deep as shown at b, because the hot iron
necessary for light wrork runs very fluid.
The runner should not be more than f to f inch in diameter.
The pouring basin should be made deepest at point c, and slant
upward crossing the runner. When pouring, the stream from the
ladle should enter at c, flood the basin at once, and keep it in this
condition. The current of the metal will then tend to hold back
the slag, allowing clean metal to flow down the runner.
Skimming Gate. When particularly clean castings of medium
weight are required, some form of skimming gate should be used.
Fig. 24 illustrates one of several practical forms. They all depend
/
/
7
I
*\
\
\
c
FOUNDRY WORK
25
for their efficiency upon the principle cited. In the illustration,
a is the pouring basin' -and runner, b is a good sized riser placed
about 3 or 4 inches from a, and c is a channel cut in the cope joint,
connecting these two. The gate d should be cut in the drag side
of the joint, just under the riser but at a right angle with the
direction of c. The metal rushing down the runner is checked by
the small size of the gate and so washes any dirt or slag up into
the large riser b. The level of metal in this riser must be sustained
n hy sufficiently rapid pouring
until the mold is filled.
In bench work and floor
work, the greatest care must
be used to have all parts of
the gate absolutely free from
loose sand or facing which
would wash into the mold
with the first flood of metal.
On heavy wTork special
skimming gates are not used,
for the capacity of the pour¬
ing basin is very much
greater than that of the run¬
ners which can be quickly
flooded and thus retain the
slag. Besides this, large
risers are set at the sides
or directly upon the casting, to receive any loose sand or facing
that washes up as the mold is being filled. Fig. 22 illustrates
this type.
Important Conditions. As regards the filling of the mold
quickly and quietly, these two conditions are closely allied. The
shape and thickness of the casting are the important factors in
determining the number and position of the gates. Aside from
the fact that the gate should never be heavier than the part of the
casting to 'which it attaches, the actual size of the gate opening
is something that the molder must learn from experience.
In arranging gates with regard to the shape of the pattern,
the following points should be borne in mind: Place gates where
d-
Fig. 24. Skimming Gate
26
FOUNDRY WORK
\L
the natural flow of the metal will tend to fill the mold quickly.
Usually gate on the lighter sections of the casting. Select such
points on the casting that the gates may be
broken and ground off with least trouble—the
greater the number of castings to be handled,
the more important this point becomes. A
study of the molding problems given will illus¬
trate this point.
Provide enough gates to fill all parts of
the mold with metal of uniform temperature.
This depends upon the thickness of the work,
as is illustrated in Fig. 25 by two molds having
the same shape at the joints but of different
thicknesses. In thin castings the metal tends
to chill quickly, so it must be well distrib¬
uted. In this illustration, a is a plate \ inch
thick, and should have several gates. |A piece
having the same diameter but heavier, would
run better from one gate as at b, while if a bush¬
ing of this diameter is required, the best results
would be obtained by gating near the bottom, as in
Fig. 22. For running work at the bottom as shown
in Fig. 22, the gate piece b is separate from the run¬
ner, and is slicked into the mold after the pattern
is drawn. The runner r should extend below
the level of the gate to receive the force of the
first fall of metal, which otherwise would tend
to cut the sand of the gate.
Shrinkage Heads. Melted metal shrinks
as it cools, and this process begins from the
moment the mold is filled. The surfaces
next to the damp sand are the first to solidify,
and they draw to themselves the more fluid
metal from the interior. This process goes
on until the whole casting has solidified.
This shrinkage causes the grain in the middle
to be coarse and sometimes even open or porous.
The lower parts of a casting are under the pressure or weight
Fig. 26. Sinking
of Casting
FOUNDRY WORK
27
of all the metal above, and so resist these shrinkage strains. The
top parts, however, require the pressure of liquid metal in gates
or risers to sustain them until they have hardened sufficiently to
hold their shape, or they will sink as indicated by the section, Fig. 2b.
Risers, mentioned in connection with securing clean metal, are also
required on heavy pieces to prevent this distortion and to give sound
metal. When used in this way they are called shrinkage heads
or feeders. They should be G or 8 inches in diameter, so as to keep
the iron liquid as long as possible, and should have a neck 2 or 3
inches in diameter, to
reduce the labor required
to break them from the
casting in cleaning. To
prevent the metal in
this neck from freez¬
ing, an iron feeding
rod is inserted, as in
Fig. 27, and is churned
slowly up and down.
This insures fluid metal
reaching the interior. As
the level in the feeder low¬
ers, hot metal should be
added from a hand ladle.
Pressure in Molds.
The subject of the pres¬
sure of liquid iron men¬
tioned repeatedly in the
foregoing pages, must be
dealt with by themolder, in weighting his copes, strengthening flasks,
securing cores, etc., and most frequently in connection with the first-
of these.
Natural Laws. Molten iron acts in accordance with the same
natural laws that govern all liquids—as, for example, water (see
Mechanics, Part II); iron, however, is 7.2 times heavier than water.
The two laws applicable in foundry work are these: (1) Liquids
always seek their own level; (2) pressure in liquids is exerted in every
direction.
A
c
Fig. 2S. Illustrating Pressure of Liquids in Molds
28
FOUNDRY WORK
Pressure-Head Example. Applying the first law, if we have
two columns of liquid iron connected at the bottom, they would
just balance each other. For convenience we shall leave out of our
calculations the upward pressure on the gates in the following
examples, for in practical work they need seldom be taken into
account.
In A, Fig. 28, suppose these columns stand 6 inches above
the joint bd, and that the column cd, has an area of 1 square inch.
In B, suppose the area of the right-hand column cdcf is 5 times
the area of column cd. In both cases the level with top of runner
a will be maintained. The depth of the cavity below the joint
bdf makes no difference in main¬
taining these levels. The weight
of one cubic inch of iron, .26
pound, is taken as the basis of
all calculations.
Now if we close the column
cd at cl, as in C, it is clear that
it would require the actual
weight of that column to balance
the lifting pressure of the surface
d, or 6X.26X1 = 1.56 pounds.
And if the larger area df is closed
over, as in D, it takes 5 times
this weight to resist the pressure
exerted upon it by the runner,
or 6X.26X5 = 7.8 pounds. If the pattern projected 2 inches into
the cope, the height of the runner above the surface acting
against the cope would be 4 inches, and the pressure to be overcome
would be equal to the weight of cghe, or 4 X .26 X 5 = 5.2 pounds.
The important factors, then, are: height of runner; and area
of mold which presses against the cope. We can therefore state
a rule: To calculate the upward pressure of molten iron, multiply
the depth in inches by the weight of one cubic inch of iron (.26), and
multiply this product by the area in square inches upon which the
pressure acts.
Pressure-Distribution Example. Applying the second law cited,
the strains on sides and bottom of molds and upon cores is explained.
Fig. 29. Diagram Showing Analysis of
Liquid Pressure
FOUNDRY WORK
29
By the rule just stated we first find the pressure per square
inch at any given level by multiplying the depth by .20, and it is
obvious that this pressure increases, the lower in the mold a point
is taken.
In Fig. 29, the pressure at a equals hX.26. This also acts
against the sides at ee. The pressure at b is h' X .26, and is exerted
sidewise and downward. The pressure at c is h"X.26. This
point, being half way between the levels a and b, represents the
average sidewise or lateral pressure on all of the sides.
If this mold, then, is 11 inches square and 9 inches deep, with the
pouring basin 6 inches above the joint, we have the following con¬
ditions:
Area of a = 121 sq. in.
Area of 6 = 121 sq. in.
Area of c (one side) = 99 sq. in.
Area of four sides =396 sq. in.
Height of /i =6 in.; pressure head = 1.56 lb. per sq. in.
Height of h' =15 in.; pressure head = 3.90 lb. per sq. in.
Height of h" = 10| in.; pressure head = 2.73 lb. per sq. in.
Multiplying these together, we have the pressures on the various
faces as follows:
Upward pressure on a = 188.76 lb.
Total pressure on side c = 270.27 lb.
Total pressure on four sides = 10S1.08 lb.
Total downward pressure on 5= 471.90 lb.
A study of these figures shows the necessity of well-made flasks
and bottom boards, for these must resist a greater pressure even
than that required to keep the cope from lifting. They also
show clearly why the lower parts of the casting resist the pres¬
sure of the gases more and require firmer ramming then the upper
portions.
Variation of Pressure Head. A difference in the way a pattern
is molded may make a great difference in the weight required on
the cope. Compare A and B, Fig. 30. Supposing this pattern
is cylindrical in shape and with the dimensions as indicated, we would
have the following basis:
30
FOUNDRY WORK
Area of circle a =113.10 sq. in.
Area of circle b = 78.54 sq. in.
Area of ring c'c' (b subtracted from a) = 34.56 sq. in.
Then
Total lift on cope A is 8X.26x113.10 =235.24 lb.
The lift on cope B is 8X.26x34.56= 71.88
+ (8+5) X .26 X 78.54 = 265.46
Total lift on B =337.34 lb.
Fig. 30. Diagram Showing Difference in Pressure on Cope Due to Placing of Pattern
Variation of Pressure Distribution. Fig. 31 is an example
of a core 5 inches square surrounded by 1 inch of metal, with a
runner 6 inches high. We have
here:
Pressure per square inch on a is
7 X-26 = 1.82 lb.
Pressure per square inch on b is
12X.26 = 3.12 lb.
The difference in these pressures
is 1.30 pounds per square inch,
Then for every foot of length in
the core we must balance a lifting
pressure on the bottom of the core
of 5 X 12x3.12 = 187.2 pounds, until
the metal covers surface a, when
it will exert a counteracting down¬
ward pressure, and the strain on the chaplets will be only
5 X12 X 1.30 = 78 pounds.
Pig. 31. Diagram Showing Difference in
Pressure on Top and Bottom
of a Cube
FOUNDRY WORK
31
Common Defects in Castings. Some of the ordinary defects
which the beginner will find on his castings are as follows:
Short Pourings. The amount of metal in the ladle is misjudged
with the result that the mold is not completely filled.
Blou'holes. These come from gases becoming pocketed in
the metal instead of passing off through the sand. This is due
to hard ramming, wet sand, etc.
Cold-Shuts. These form when two streams of metal chill so
much before they meet, that their surfaces will not fuse when forced
against each other, as illustrated in
Fig. 32.
Sand Holes. These come from the
washing of loose sand or excess of facing
into the mold cavity when pouring. They are usually bedded in
the cope side of the casting.
Scabs. Scabs show like small warts or projections on the
surface of the casting. They result from small patches of the
mold face washing off. They may be caused from too much
slicking, which draws the moisture to the surface of the mold,
making the skin flake under the drying effect of the incoming
metal.
Swells. Swells are bulged places on a casting and are due
to soft ramming which leaves the walls of the mold too soft to
withstand the pressure of the liquid metal.
Shrinkage Cracks. These are due to unequal cooling in the
casting. They are sometimes caused by the mold being so firm
that it resists the natural shrinkage of the iron, causing the metal
to pull apart when only partially cold.
Warping. This occurs when these strains cause the casting
to bend or twist, but are not sufficient to actually crack the metal.
TYPICAL MOLDING PROBLEMS
General Precautions. When starting to ram a flask, see that
the sands1 to be used are well cut through and properly tempered.
Select a flask large enough to hold the pattern and have at least
2 inches clear of the flask all around for bench work, and 4 to 8 inches
on floor molds, depending upon the weight of the work to be cast.
See that the flask is strong enough to carry the sand without racking
32
FOUNDRY WORK
ancl that the pins fit. Have the necessary tools at hand, such as
sieve, rammer, slicks, etc.
Jointing. Examine the pattern to be molded to see how it
is drafted and note especially how the parting line runs. That
part of the mold forming the surface between the parts of the flask
is caked the joint, and where it touches the pattern this joint must
be ma i to correspond with the parting dine.
The joint of a mold may be a plane or flat surface, or it may
be an irregular one. When the joint is a flat surface it is formed
entirely by the mold board except with work bedded in the floor;
there it is struck off level with a straightedge. When it is irregular
the drag joint must be coped out for every mold needed, that is,
shaped freehand by the molder before making up the cope; or, by
another method; the shape of the cope
joint is built up first in a match frame with
the cope part of the pattern bedded into it,
and upon this form the drag may be packed
repeatedly, receiving each time the desired
joint surface without further work on the
mohler’s part.
Our first problems in molding illustrate
these three methods of making the joint. It is aimed to give the
directions for making up molds in as concise a form as possible.
The student should refer frequently to the preceding sections and
familiarize himself with the reasons underlying each operation.
Flat Joint. In the small faceplate shown in Fig. 33, all of
the parting line aaa will touch the moldboard, so the joint will be
flat. The draft is all in one direction from the cope side c, there¬
fore all of the pattern will be in the drag. Use a snap flask for
this piece.
Molding Brag. Place a smooth mold board upon the bench
or brackets. Place the drag with sockets down upon this. Set
the pattern a little to one side of the center to allow for the runner.
Sift sand over this about 1| inches deep. Tuck the sand firmly
around the pattern and the edges of the flask as indicated by the
arrows in Fig. 34, using the fingers of both hands and being careful
not to shift the sand away from the pattern at one point when tucking
at another.
FOUNDRY WORK
33
Fill the drag level full with well-cut sand. With the peen end
of the rammer slanted in the direction of the blows, ram first around
the sides of the flask to ensure the sand hanging in well, as at 1 and
2 in Fig. 35. Next carefully direct the rammer around the pattern,
as at 3, 4, and 5. Do not strike eloserTham 1 inch to the pattern
with the end of the rammer.
Shifting the rammer to a vertical position, ram back a forth
across the flask in both directions, being especially careful not to
strike the pattern nor to ram too
hard immediately over it. The
student must judge by feeling when
this course is properly rammed.
Now fill the drag heaping full of
sand. Use the butt end of the
rammer around the edges of the
flask first, then work in toward the middle until the sand is packed
smooth over the top. With a straightedge strike off the surplus
sand to a level with the bottom of flask. Take a handful of sand
and throw an even layer about | inch deep over the bottom of the
mold. On this loose sand press the bottom board, rubbing it slightly
back and forth to make it set well. With a hand at each end, grip
the board firmly to the drag and roll it over. Remove the mold
board and slick over the joint surface with the trowel. Dust part¬
ing sand over this joint (burnt core
sand is good on this work), but
blow it carefully off of the exposed
part of the pattern.
Set the wooden runner or gate
plug about 2 inches from the pat¬
tern, as shown in Fig. 23, page 24.
In snap work the runner should come as near the middle of the
mold as possible, to lessen the danger of breaking the sides,
and to allow the weight to ' be placed squarely on top of
the mold.
Molding Cope. Set the cope on the drag and see that the hinges
come at the same corner.
Sift on a layer of sand about 1| inches deep. Tuck firmly
with the fingers about the lower end of the runner and around
With Fingers
Fig. 34. Molding Sand with Fingers
34
FOUNDRY WORK
Fig. 36. Use of Iron Band
the edges of the flask. Fill the cope and proceed with the ramming
the same as for the drag.
Strike off the surplus sand, swinging the striking stick around
the runner so as to leave a fair flat surface of sand. Partially shape
a pouring basin as illustrated
in Fig. 23, with a gate cutter,
before removing the runner.
Draw the runner and finish
the basin with a gate cutter
and gently smooth it up with
the fingers. Carefully moisten
the edges with a swab and
blow it out clean with the
hand bellows.
Lift the cope and repair any imperfections on the mold surface
with the trowel or slicks. See that the sand is firm around the lower
end of the runner. Blow through the runner and all over the joint
to remove all loose parting sand. Slick over the sand which forms
the top surface of the gate, between the runner and the mold.
Having finished the cope, moisten the sand about the edges
of the pattern with a swab. Drive a draw spike into the center
of the pattern and with a mallet or light iron rod, rap the draw
spike .slightly front and back
and crosswise. Continuing a
gentle tapping of the spike,
pull the pattern from the
sand. If any slight break
occurs, repair it with bench
lifter or other convenient
slick. Cut the gate and
smooth it down gently with
the finger; blow the mold out
clean with the bellows. No
facing is needed if the castings
The mold should now be closed and the snap
Fig. 37. Weight in Position
are to be pickled,
flask removed.
Strengthening against Pressure. There are two methods used
to strengthen these molds against the casting pressure. One is
FOUNDRY WORK
35
to use an iron band which will just slip inside of the flask before
the mold is packed, as in Fig. 36. The other is to slide a wooden
slip case over the mold after the snap flask is removed, as in Fig. 37.
In either case the weight, shown in position in Fig. 37, should not
be placed on the mold until pouring time, lest by its continued
pressure it might crush the sand.
Coping Out. The second type of joint surface mentioned above
is illustrated by the method of molding the tailstock clamp shown
in Fig. 38. This is a solid pat¬
tern and rests firmly upon the
mold board on the edges aa,
but the parting line bbb runs
below these edges. The bulk
of the pattern drafts down from
this line and so will be molded
in the drag, while all above it will be shaped in the cope.
To mold the piece, set the pattern on the mold board, planning
to gate into one end. Ram the drag, and roll it over, as described
in the last example. With the blade of the trowel turned up edge¬
wise, scrape away the sand to the depth of the parting line, bringing
the bevel up to the main level of the joint, about 2| inches from the
pattern, as shown at Fig. 39, and slick this surface smooth with the
Fig. 39. Coped-Out Mold
finishing trowel or leaf and spoon. This process is called coping
out. Dust parting sand on the joint thus made. Be careful not to
get too much at the bottom of the coping next the pattern. Pack
the cope, then lift it, and finish the mold as directed.
36
FOUNDRY WORK
Shape of Draft. In coping out, the molder practically shapes
the draft on the sand of the drag. Aim to have the lower edge
of the coping parallel with the main joint for a short distance, and
then spring gradually up to it at
about the angle shown in the sec¬
tion at c, Fig. 40, as this is the
strongest shape for the sand. If
made with an abrupt angle as in d,
the cope sand will tend to wedge
into the cut with the danger of a
drop or break when the cope is
Fig. 40. Angle of Joint lifted
In many cases, more especially in floor work, an abrupt coping
angle may be avoided as follows: Set wooden strips, whose thickness
is equal to the depth of the desired coping, under the edges of the drag
when ramming up the pattern. (Use, for example, the hand wheel
Fig. 41. Molding a Hand Wheel
shown in Pattern Making, Fig. 114.) When the drag is rolled over,
the sand will be level with the top of strips and pattern at aa, Fig. 41.
Remove the strips and strike surplus sand off level with edges of
drag bh, and slick off the joint." Proceed with the cope in the usual
manner. In gating this pattern, and
wheels generally, place a small runner
directly on the hub.
Sand Match. The solid bush¬
ing, Fig. 42, serves to illustrate the
use of a sand match. For exercise
work, use only one pattern.
In practice, however, several small patterns are bedded into
the same match. It is clear that in this pattern the parting line
runs along the center of the cylinder, and to make a safe lift for the
FOUNDRY WORK
37
cope it should follow around the circumference of the ends abc,
as shown by the heavy lines.
The frame for the match is shallow, and of the same size as the
snap flask with which it is used. It is provided with sockets to engage
the pins of the flask. The bottom board is fastened on with screws.
Fill the match with sifted sand rammed hard. Strike off a
flat joint and bed in the pattern. Cope out the ends to the lower
edge of the pattern, as shown in Fig. 43, flaring it well in order to
make a good lift. Slick the whole surface over smooth. Rap and
lift the pattern to test the correctness of the work.
Replace the pattern. Dust on parting sand and ram the drag,
tucking carefully in the pocket at each end. Roll the two over.
Lift off the match, and set it to one side. The pattern remains
Fig. 43. Use of Sand Match
in the drag. Dust on parting sand. Set the runner and ram
the cope as described. When the mold is opened and the pattern
is drawn, it should be set back immediately into the match, ready
for use again.
Usage. On account of economy of construction in the pattern
shop, irregularly shaped work is often made in one piece. The
molder must then decide whether it is cheaper to cope out each
joint or to make up a sand match. Where the number of castings
required is small, or where the pattern is large, it is better to cope
out. But where a number of castings is required it is cheaper
to make up a sand match. For methods of making quantities of
castings and the use of a more permanent match, see the section on
Duplicating Castings.
38
FOUNDRY WORK
In the foregoing the main use of the match was to save time.
It frequently happens that a pattern is so irregular in shape that
it will not lie flat on the board in any position. In this case, a match
is absolutely necessary before the drag can be packed. For large
patterns, the cope box of the flask is used to bed the pattern into instead
of a separate frame. After the drag has been packed upon it and
rolled over, this first cope is dumped, and the box repacked
Fig. 44. Split- and Loose-Piece Patterns
with the necessary gaggers, vents, runners, etc., required for casting.
The first cope is then termed, not a match, but el false cope.
For very light wooden patterns which may or may not have
irregular parting lines, the pattern-maker builds up wooden forms
to support the thin wood while the drag is being packed and to
give the proper joint surface to the sand. This board serves exactly
the same purpose as the sand match and false cope, but it is termed
a follow board. See article on Pattern-Making.
SpIit=Pattern Molds. So far the patterns used have been made
in one piece, but a flat joint is the most economical for the molder,
FOUNDRY WORK
39
when many castings are required. Generally such pieces as bushings,
pipe connections, and symmetrical machine parts are made in halves;
one piece of the pattern remaining in each part of the flask when
the mold is separated. There are many cases, too, where, to make
a flat joint for the mold, the pattern maker can separate one or
more projections so as to have the main part of the pattern in the
drag and to let these loose parts lift off in the cope.
The small punch frame and the gas-engine piston, shown in
Fig. 44, are examples of these two classes of patterns. At A, the
sections through the patterns show the methods of matching them
together. B shows the drag parts of the patterns in position for
molding. At C, is the section
through the mold and the plan of
the drag showing how the gates are
connected. Attention is directed to
the use of the horn sprue—the sprue
pattern is shown at a—by which the
metal enters the mold at the bottom.
If the gate were cut at the joint sur¬
face, there would be danger of cutting
the sand on top of the green-sand
core b as the metal flowed in upon it.
Loose-Piece Mold. It often hap¬
pens that bosses or projections are
required on a casting at right angles Fig. 45. strengthening Mold with
to the main draft lines of the pattern Iron Rod
and below the joint surface. Examples of such cases are shown
in Pattern-Making. In molding such work, care must be taken
that the overhanging portion of sand shall be strong enough to
support itself. Where the projection is deep, the mold should be
strengthened by nails or rods, as shown in Fig. 45. These should be
wet with clay wash and set into the sand, when the mold is rammed.
Use of Green-Sand Core. Some work has projections on it
which lie above or below the parting line in such a way that it cannot
be molded by either of the foregoing methods. Examining the
patterns for some of this work, we find two entire parting lines with
the pattern made to separate between the two. Such patterns
require between the drag and cope an intermediate body of sand,
40
FOUNDRY WORK
from the top and bottom of which the two parts may be drawn
In small work, as illustrated by the groove pulley, this inter¬
mediate form is held in place by the sand joint of the cope anc
drag, and is termed a grcen-sand core. The method of molding
Fig. 46. Section of Mold
such a piece is given in Pattern-Making, Part I. To provide for
pouring the casting, a runner should be placed on the hub of the
first part packed C, Fig. 46, which shows a section of the mold before
either part of the pattern has been removed. When the flask is
rolled over to remove the final part C of the pattern, the runner is
on top ready for pouring.
Fig. 47. Part Section of Mold Showing
Use of Core-Lifting Ring
Fig. 48. Pattern Shown in Fig. 47
with Mold Complete
Core-Lifting Ring. Another method used does away with
rolling the entire flask. A core-lifting ring is first cast slightly larger
in diameter than the flange of the sheave, and having such a section
as shown in a, Fig. 47. The ring is set in position in the middle
of the inverted drag, the pattern is held central inside of the ring
by the recess in the mold board. Pack the drag, roll over, and
remove the mold board. Tuck the green core all around and
FOUNDRY WORK
4]
Fig. 49. Casting for Ten-Inch
Nozzle
slick off the top joint of the core. Pack the cope in the usual way,
lift it off, and draw the cope pattern. Now, by means of lugs cast
on this lifting ring, the green core may
be lifted off of the drag pattern, allowing
it to be removed. Replace the ring and
close the cope; and the mold is com¬
plete, as shown in section, Fig. 48.
Three-Part Mold. In larger work,
where the parting planes are farther
apart, this intermediate body of sand
is carried in a cheek part of the flask,
and we speak of it as three-part work.
Fig. 49 shows a casting for a 10-
inch nozzle, the mold for which illus¬
trates this class of work. Here the pattern is separated just
above the fillet of the curved flange. Fig. 50 gives a view of the
mold, showing the way
the joint is formed.
This casting should
be made on the floor.
Select a square flask, 4
inches on a side larger
than the diameter of
the flanges. The cheek
should be as high as that
part of the pattern which
is molded in it. There
should be two projecting
bars on opposite sides
of the cheek to support
the sand, and crossbars
in both drag and cope.
These should be well wet with clay wash before using the boxes.
Set the pattern centrally inside the cheek, and place a runner
stick just the height of the pattern in one corner of this box. On
account of the depth of the cheek, the sand must be rammed in
two courses. Sift enough facing sand into the box to cover the
joint and 5 inches up around the pattern to a depth of about 1|-
42
FOUNDRY WORK
inches, tucking about the pattern with the fingers. Fill in about 5
inches of loose sand and before ramming tuck around the ends of
the side bars, compressing the sand between the finger tips, having
a hand on each side of the bar, as illustrated in Fig. 51. Now use
the peen end of the floor rammer in the same general way as the
hand rammer is used in bench molding. Guide the rammer around
the sides of the flask and bars first, then direct it toward the bottom
edges of the pattern. As the sand gradually feels properly packed
at this level, direct the blows higher and higher up. Proceed in this
way to within about 1 inch of the drag joint. Make this joint by
ramming in sifted facing sand, being careful to tuck it firmly under¬
neath the flange. Cope this joint to the
shape of the curved flange.
Dust on parting sand. Place the
drag in position and ram it up in the
usual way, only using facing sand next
the joint and pattern. Place six long
gaggers to strengthen the sand which
forms the inside of the casting. Clamp
the drag to the cheek and roll them over.
Test, repair, and dust parting sand on
the joint. Try the cope. The bars
should clear the pattern and joint by
about 1 inch. Set the cope runner about 2 inches to one side of the
cheek runner and set the riser in the corner opposite. Sift on facing
sand and tuck well with the fingers under the crossbars. Shovel
in well-cut sand and finish packing the cope. Form a pouring
basin, and vent well. Lift the cope. Draw the pattern from the
cheek. Join the runners on the cope joint and connect the mold
with the riser. Lift the cheek and repair it. Draw the drag pat¬
tern. All of the mold surfaces should have black lead facing brushed
over them with a camel’s hair brush, and this facing slicked over.
Cut a gate on the drag joint. Close the cheek on the drag.
Close the cope on the cheek, and the mold is ready for clamping.
Floor Bedding. Owing to the development of the electric crane,
there is much large work now rammed in iron flasks and rolled over,
which was formerly always bedded in the floor. This method is still
much used in jobbing shops to avoid making a complete large flask.
Fig. 51. Tucking Sand under Bars
FOUNDRY WORK
43
The mold shown in Fig. 52 illustrates the principal operations
involved. The casting is a flask section for a special steel-ingot mold,
and in design is simply a heavy plate braced on one side by flanges
and ribs of equal thickness. For convenience in ramming between
the flanges, portions of the top plate of the pattern are left loose,
as seen in Fig. 53.
Pit. Dig the pit for the mold 10 inches larger on each side
than the pattern, and about 6 inches deeper. Having screened
some hard cinders through a No. 2 riddle, cover the bottom of the
44
FOUNDRY WORK
These Pieces Loose
Fig. 53. Bedded-In Work
pit with them to a depth of 3 inches. Ram these over with a butt
rammer, and at one end set a piece of large gas pipe. Put a piece
of waste on the top of this to prevent its getting choked with sand.
Ram a 3-inch course of sand over the cinder bed and strike it off
level at the depth of the
pattern from the floor
line. Sift facing sand
over this where the pat¬
tern will rest; set the pat¬
tern, and with a sledge,
seat it until it rests level.
Remove the pattern and
with the fingers test the firmness of packing all over the mold.
Vent these faces through to the cinder bed, and cover the vent
holes with a |-inch course of facing sand. Now replace the pat¬
tern, and bed it home by a few more blows of the sledge. The
top of the pattern should now be level and flush with the floor
line. Seat the runner sticks, and, to prevent the sand on the bottom
of the runners from cutting, drive 10-penny nails about f inch apart
into this surface until the heads are flush. Ram the outside of the
mold the same as if in a flask, and strike a joint on top. Ram
green sand between the inside
webs of the pattern, and
strike off at the proper
height with a short stick a,
Fig. 54. Drive long rods 3
inches apart into these piers
to pass through to solid sand
below the cinder bed.
Vent all around the pat¬
tern, outside and inside,
through to the cinder bed.
On top of the inside piers
cover these vent holes with facing sand, ram, and slick to finish;
then cover with the loose pieces of the pattern.
Cope. Try the cope and stake it in place; set the risers and vent
the plugs. Ram the cope, slicking off level for about 2 inches around
the top of the risers, to receive a small iron cover.
FOUNDRY WORK
45
Lift the cope, repair, and face with graphite. Draw the pattern
with the crane and finish the mold. Connect the outer vent holes
by a channel with the vent plug. From the end of each core
print bbbb, Fig. 53, vent through to the cinder bed, and set the cores.
Close the cope. Set the runner box against the side of the cope
and build a pouring basin with its bottom level with the top of
the risers.
In weighting, great care must be exercised not to strain the cope.
Place blocking upon the top ends of cope. Across these lay iron
beams which will be stiff enough to support the load, and pile weights
Fig. 55. Leveling a Bed for Open Sand Wrork
on these, as shown in Fig. 52. Now wedge under the beams to the
crossbars of the cope at necessary points.
Open Mold. There is a large class of foundry rigging, such as
loam plates, crossbars, and sides to iron flasks, which may be cast
in open molds. As there is no head of metal, the beds must be
rammed only hard enough to support the actual weight of the metal,
or it will boil. To insure uniform thickness in the casting, the bed
must be absolutely level.
Drive four stakes aaaa, as shown in Fig. 55, and rest the guide
boards A A on the top of these. By using a spirit level bb, make
46
FOUNDRY WORK
these level, and bring them to the same height by testing with the
straightedge B.
The space between the guide boards A A should be filled with
well-cut sand even with their tops dd. Sift sand over the entire
surface. Strike this sand off f inch higher than the guides, by
placing a gagger under each end of the straightedge, as it is drawn
over them. Tamp this extra sand to a level with the guides by
rapping it down writh the edge of the cross-straightedge, and the bed
will be as shown in Fig. 56. We can now proceed to build up
Pouring
Ba'sin
'OyerP/oiA/ iy. v':V; .
Fig. 56. Open Sand Mold
to a segment of pattern, or with a sledge drive a pattern into this
surface.
The pouring basin should drain itself at the level of the top of
mold, and an overflow may be cut on one edge to drain the casting
to any desired thickness.
CORE WORK
Reference has been made in the first part of this article, under
Divisions of Iron Molding, to the general difference between core
work and green-sand wrork. This, and the section on Sands, the
reader should review carefully.
Dry-Sand Cores
Materials. Sand. Here, as in green-sand molding, the prin¬
cipal material used is a refractory sand. In molding sand, however,
FOUNDRY WORK
47
the alumina or clay forms a natural bond in the sand. To meet
the necessary requirements of cores we must use a naturally free
sand as a base, and give it bond by adding some form of organic
matter as a binder, then bake the core.
Binders. The most common binders are the following four
materials: Ordinary wheat flour is an almost universal material
for use as a core binder. Every one is familiar with its action when
moistened and baked. The hard vegetable gum rosin—a by¬
product of the manufacture of turpentine—for use as a core binder,
should be reduced to a powder. It melts under the heat of the oven,
flows between the grains of sand, and upon cooling binds them
firmly together. Linseed oil, made from flaxseed, acts in a way
similar to rosin; a small proportion of oil together with some flour
makes a very strong core. Glue, which is obtained from animal
hoofs and from fish stock, is also used to some extent as a core
binder. It should be dissolved in water before mixing with
the sand.
Tempering. A weak molasses water is used for tempering the
sand for small cores; and on the larger work the same purpose is
served by clay wash. There are many patent combinations of the
above or similar materials put on the market as core compounds.
There are two classes of these: dry compounds, and liquid com¬
pounds. The advantages claimed for them is that they are more
economical—(1) because a smaller proportion of the compounds
is sufficient to obtain the desired results; and (2) because a large
proportion of the sand may be used over and over again.
Reinforcement. Among other necessary core-room supplies are:
annealed iron wire No. 6 to No. 16, and round bar iron in sizes 3-inch,
f-inch, ^-inch, f-inch, and f-inch, which are cut to length as needed,
and are bedded in the core sand to strengthen the core, as will
be demonstrated later.
Venting. A supply of clean cinders must be available also for
venting larger cores. Small wax tapers make good vents for crooked
cores. There is also a patented wax vent for sale on the market.
Facing. As before stated, charcoal with some graphite is the
principal facing material used on cores. It is always applied in liquid
form by dipping the core or by using a flat brush having extra
long bristles.
48
FOUNDRY WORK
Equipment. General Tools. The general tools of the core room
are similar to those already mentioned. A piece of iron rod very
often replaces the regular rammer on account of the small size
of the opening into which sand must be packed.
The trowel is the most common slick, because most of the sur¬
faces which require slicking are flat ones formed by striking off
after packing the box. Except in the largest work, the entire face
of the core is not slicked over,
so a variety small slicks is
not needed.
A spraying can, shown in
Fig. 57, is used for spraying
molasses water over small cores.
Fill the can two-thirds full and
blow into the mouthpiece.
Small cores are made up
on a flat bench, the sand being in a small pile at the back.
Larger boxes are rammed up on horses or on the floor, as is most
convenient.
Baking. After being made up, cores are baked on core plates.
The smaller plates are cast perfectly flat. Plates over 18 inches
long are strengthened by ribs cast about 1 inch from the edge,
as shown in Fig. 5S; this keeps the plate from warping, and admits
of its being picked up readily from a flat bench top or shelf.
Ovens are built with reference to the size of the cores to be baked.
A good type of small oven is illustrated in Fig. 59. It can be run
very economically with either
coal or coke, and bakes cores
up to 2 inches in diameter
within half an hour. Each
shelf is fastened to its own
door, and, when open for receiving or removing cores, a door at
the back of the shelf closes the opening. This prevents a waste
of heat.
Fig. 60 shows the section through an oven suitable for the largest
work, including dry-sand and loam molds. The fire box A is situated
in one corner at the back; its whole top opens into the oven. At
the floor level diagonally opposite is the flue B for conducting the
Fig. 5S. Core Plate
FOUNDRY WORK
49
Fig. 59. Small Core Oven
S'
50
FOUNDRY WORK
waste heat to the stack C. The entire front of the oven may be
opened by raising the sheet-steel door. Two tracks side by side
131
m
accommodate cars upon which heavy work is run into the oven.
Fig. 61 showTs a good form of cast-iron car. The wheels are designed
on the roller principle to make it easier to start the
car when heavily loaded.
For medium work smaller ovens of this type
are used. Racks similar to the one shown in
Fig. 62 may be bolted on the sides, arranged
to hold the ends of the core plates; and the car
may carry a line of double racks to increase the
capacity of the oven.
Conditions of Use. As mentioned before,
cores form those parts of a mold which are to be
nearly or entirely surrounded by metal; in other
words, such parts as would be in danger of breaking
or require too much work to be constructed in
green sand. The object, then, in making cores is
to insure a better casting and to reduce costs.
Cores are held in position by means of core
prints (see Pattern-Making). The main weight
of the core is supported by these prints and
through them all vent must be taken off and all
sand removed in cleaning. Therefore, cores must
be stronger than green sand, because, whether large
or small, they must stand handling while being
set and must not cut or break during pouring.
Fig. 62. Rack They require greater porosity than green sand
because their vent area is limited and their composition contains
more gas forming material. Furthermore, cores must lose all their
FOUNDRY WORK
51
bond by the time the casting is cold, so that the sand may be easily
removed no matter how small the available opening.
These conditions are obtained by using a coarse free sand and
a binder. To give additional strength when necessary, iron wire
or rods, or cast-iron core arbors are bedded in the core. These
serve the same purpose in a core that the flask does in green¬
sand work.
Binder. The action of the binder enables the sand to retain
its shape when the box is removed, and renders the core hard and
strong when baked. In the mold the intense heat of the metal
gradually burns out the organic matter or binder, leaving the
core without bond. In this condition, the sand may readily be
removed.
Too much binder tends to make the core sag out of shape before
baking, and blow when metal strikes it; that is, give off more gas
than the vents can carry away. With too little binder the sand
does not bake hard, and cuts when the mold is poured.
The effectiveness of all binders, especially flour, depends upon
their thorough mixing with the sand. The especial value of rosin
and oil lies in the fact that by melting under the oven heat they
form a more perfect bond with the sand.
Many intricate cores are now made with an oil mixture, without
using rods or wires, which formerly were considered absolutely
necessary for strength. Such cores must be well supported when
green, must be thoroughly baked, and handled with much care until
they are cold.
Core-Sand Mixture. No universal mixture for core sand can
be given, as sands vary so much in different localities. The mixtures,
as shown on the following page, illustrate approximate proportions.
In preparing core sand, the different ingredients should be
measured out, thoroughly mixed, and sifted while dry. Temper the
mixture a little damper than molding sand. Too much moisture
makes the sand stick to the box. Not enough makes it hard to
work and gives a crumbly surface if dried.
Facing. Blacking for light work should include one cup of
molasses to a pail of water, into which is worked powdered charcoal
until an even black coating is deposited upon the finger when dipped
into the blacking and out again.
52
FOUNDRY WORK
Core Mixtures
Materials
Small Cores
(parts)
Large Cores
(parts)
Intricate
Smaller Cores
(parts)
Beach sand
10
15
15
Fire sand
15
Molding sand
5
Sharp fire sand
s
Strong loamv sand
2
Flour
1
H
1
2
Rosin
2
Oil
1
Tempering means
Molasses water
Clay wash
Molasses water
For heavy blacking there should be used about 2 parts charcoal
and 1 graphite, mixed into thick clay wash.
Miscellaneous. In finishing small cores, they should be sprayed
with weak molasses water while green, then well baked and removed
from the oven. When cool enough to handle, they are dipped into
the blacking; then put back in the oven until this facing has dried.
For large cores the blacking is applied with a brush before baking.
All cores should be baked as soon as made, for air-drying causes
the surface to crumble.
Cores must not be set in a mold while they are hot, or the mold
will sweat, that is, beads of moisture will form on the inside faces.
This would make the mold blow when poured.
A core should be rammed evenly and somewhat harder than a
mold. Too hard ramming will make the sand stick in the box,
besides giving trouble in casting. Too light ramming makes a
weak core.
From the very nature of cores, the matter of venting them is
very important and often calls for much ingenuity on the part of
the core maker.
For simple straight work a good sized vent wire is run through
before the box is removed. Half cores have their vents cut in each
half before pasting together. Cinders are rammed in the center
of large cores connecting through the prints, with the mold vents.
For crooked cores, wax ventc are rammed in the center—the wax
melts away into the sand when the cores are baked, leaving smooth
even holes. This is illustrated in one of the following examples. '
FOUNDRY WORK
53
Methods of Making. The examples here given serve to illus¬
trate the principal methods used in making cores.
Small Cylindrical Core. The simplest form of core is one which
can be rammed up and baked as made by simply removing the box.
Short bolt-hole cores, etc., are made in this way, as shown in Fig. 63.
Fig. 63. Short Bolt-Hole Core3
Set the box on a flat bench top. Hold the two halves together
by the clamp A. Ram the hole full of core sand by the use of a
small rod. Slick off the top; run a good sized vent wire through
the middle of the core. Remove the clamp. Set the box onto
the core plate, rap the sides, and carefully draw them back from
the core.
Symmetrical Shapes. Larger cylindrical cores, up to about
\\ inches diameter, are rammed in a complete box also, only they
are rolled out on their sides, as shown in Fig. 64. This, however,
tends to make a flat place on the side, from the weight of the sand
supported on this narrow surface.
For this reason cylindrical cores of large diameter, and many
symmetrical shapes, are
made in half boxes. See
Pattern-Making, Figs.
110, 208, 213, and 219.
Such boxes are rammed
from the open side.
V\ires are bedded when
necessary about in the middle of the half core. The fingers and
the handle of a trowel are often used to ram the sand, and with
the blade of the trowel the sand is struck off and slicked to the level
of the top of the box.
Y hen baked, two half cores are held with their flat sides together,
and any slight unevenness in the joint removed by a gentle rubbing
Fig. 64. Large Cylindrical Cores
54
FOUNDRY WORK
motion. A vent channel is then scraped centrally on each half.
Paste, made of flour and molasses water, is applied around the edges
and the two halves pressed firmly together; care is taken to see
that they register all around. The core should then be placed in
the oven to dry out the paste. When pasting cores of 6-inch diam¬
eter and over, it is well to bind the halves at each end with a single
wrap of small wire.
Proper Seating. Wherever possible, core boxes should be made
with their widest opening exposed for packing the core, and designed
so that the core may rest, while being baked, on the flat surface
formed by striking off at this opening.
Core plates will sometimes become warped. When a core would
be spoiled by resting it directly upon such a plate, the unevenness is
overcome by sifting upon the plate a thin bed of molding sand and
seating the core on this.
Crooked Shapes. All cores cannot be made with a flat surface
for baking, as illustrated by a port core, the box for which is shown
in Pattern-Making, Fig. 251. This core must be rolled over on a
bed of sand. Using an oil mixture, ram the core carefully, bedding
into it several wax vents. These should start near the end which
will touch the main cylinder core and lead out of the end which
will enter the chest core. To get this crooked core on a plate for
baking, a wooden frame is roughly nailed together, which is large
enough to slip over the core box when the loose pieces have been
drawn off of the cqre, as shown in A, Fig. 65.
The space on top of the core is now filled with molding sand,
rammed just enough to support the weight of the core. The edges
of the frame project above the highest points of the core and form
guides for striking off this sand and seating a core plate, as at B,
FOUNDRY WORK
55
Fig. 65. Box, frame, and plate are now firmly clamped and rolled
over, and the frame and box removed, leaving the core well bedded
on the plate ready for the oven, as at C.
In manufacturing plants quantities of cores are often required
which cannot be baked on a flat plate. To save the time and material
necessary to roll each core onto a bed of sand, metal boxes are made,
Pattern-Making, Figs. 233 and 234, and the core is baked in
one part of the box. Only one casting is required of the larger
portion of the box. The smaller part is duplicated for every core
required for the day’s
mold.
Rod Reinforcing.
Mention has been made
of the use of wires for
strengthening small
cores. In making larger
ones, there is a greater
weight of sand to cause
strain in handling the
core, and proportionately
greater casting strain.
To resist these stresses
a systematic network of
rods is bedded in the core
while being rammed, as
shown in the sectional
viewq Fig. 66. Heavy
bars aabb extend the length of the core to give the main stiffness.
Smaller cross-rods rest on these at the bottom and top, and with
the small vertical rods tie the whole core together.
At even distances from each end lifting hooks c are placed.
Cross-rods through the lower eyes of these hooks bring all the strain
of the lift on the long heavy core rods. The holes in the top of the
cores where the lifting hooks are exposed, are stopped off when the
core is in the mold, by moistening the sides of the holes with oil
and filling up with green sand.
Cinders are packed in the middles of such cores. They aid
in drying the core. They furnish good vent, and they allow the sand
a c a
Fig. 66. Network of Rods in Cores
.56
FOUNDRY WORK
to give when the casting shrinks, thus relieving the strain on th(
metal itself.
Use of Arbors. For the largest class of cores for green-sand
work, cast-iron core arbors are used, of which a very satisfactory
type is shown in Fig. 67. This
consists of a series of light rings, A,
carried on a cast-iron beam, B. The
rings are of about ^-inch metal cast
in open sand and set about 8 inches
on centers, and may be wedged to
the beam. The beam has a hole at
each end for lifting the core.
This skeleton is made up and
tried in the box before the work of ramming the core is begun. It
is then removed and given a coat of thick clay wash. A layer of
core sand is first lightly rammed over the inside of the box, and
the core arbor seated into this. The full thickness of core-sand
facing is then firmly rammed, and the entire center filled with well-
packed cinders. Vents through the facing at both ends provide for
the escape of gases from these
cinders.
Sweeping. Often, when but
one or two large cores are wanted,
the cost of making a box is saved
by sweeping up the core. This
is illustrated in the pipe core
shown in Fig. 68.
The pattern-maker gets out
2 core boards and 1 sweep. The
boards are made by simply nail¬
ing together 3 thicknesses of
f-inch stuff, with the grain of the
middle piece crossing that of the
others to prevent warping. The
outer edges of the boards have the exact curve of the outside of
the pipe pattern, and at the ends is tacked a half section of the
core, shown at aa. One sweep does for both boards. The curve
is cut the exact half section of the core. The edge b equals the
Fig. 67. Sections Showing Use of Cast-
Iron Core Arbor
FOUNDRY WORK
57
thickness of metal in the casting, and the stop c acts as a guide
along the outer edge of the board.
In making up this core, a thin layer of core sand is spread on
the board and the outline of the core swept. On this the rods with
their lifting hooks are bedded, and the vent cinders are carefully
laid along the middle. The whole general shape is then rammed
up in core sand larger than required, and by using the sweep it is
brought to exact size. The core is then slicked off, blackened,
and baked while still on the board. When both halves are dried,
they are pasted together, the same as with smaller work. To
prevent breaking the lower half when turning it over to paste, it
is rolled over on a pile of heap sand.
Core Machines. For making stock cores, round or square,
several styles of core machines have been put on the market within
the last few years, of which the one illustrated in Fig. 69, is a good
representative. This is arranged to be driven by hand or by power.
The core sand is placed in the hopper, and by means of a horizontal
worm at the bottom it is forced through a nozzle under just the
right pressure to pack the core firmly. A clean-cut vent hole is
left in the middle of each core. As the core is forced from the
nozzle it is received on a corrugated sheet-steel plate, which is moved
58
FOUNDRY WORK
along to the next groove when the core has run to the full length
of the plate.
The advantage of the machine is that with it an apprentice
boy can produce a true, smooth, perfectly vented core, in very much
less time than could possibly be done by hand-ramming.
Setting Cores
Cylindrical Cores. Plain Fitting. Among the following exam¬
ples showing typical ways of setting and securing cores in molds
and of connecting vents, the bolt-hole core, shown at A, Fig. 70,
illustrates the simplest form of core to set. Only a drag print is
necessary; the flat top of the core should just touch the cope surface
of the mold. The level may be tested by a straight stick or by
sighting across the joint. If the core is too long, one end may be
filed off a little, if too short, a little sand may be filled into the bot¬
tom of the print. For longer cores, especially hub cores, a taper
print is placed on the cope side of the pattern, and the same taper
is given to the end of the core; this guides it to the exact center
when the mold is closed. Numerous examples are shown in Pattern-
Making. The exact length of the core should be obtained from
the pattern with a pair of calipers, as shown in Fig. 71. One
point of the calipers should then be placed on the taper end of
the core, and the print filled in, or the core shortened in case of
variation from the right length. It is well to make a vent hole
from the center of each print before setting the core.
With pattern and core boxes properly made, little difficulty
should be experienced in setting small horizontal cores for hollow
bushings, pipe connections, etc. (See Pattern-Making, Figs. 110,
FOUNDRY WORK
59
203, and 210.) The core must fit the print or a poor casting will
result. The sand supporting the prints must be tucked firmly
enough to withstand the lifting pressure on the core. A scratch
Fig. 72. Supported Body Core
with the point of the trowel along the joint surface from the end
of the print to the edge of the flask, will usually take care of
the vent.
For larger cores of this character crossbars made to fit snug
against the core print are nailed in both drag and cope. See aaaa,
Fig. 72. These hold the core absolutely firm. The spaces bb in
the cope, are not packed until the core is set, when it is a simple
matter to ram these spaces and take off an air vent directly from
the center of the core.
Holes beloiv Joint Level. There are two methods of coring
holes below the level of the joint. One is shown clearly in Fig. 73.
60
FOUNDRY WORK
r
G
virnfTTr-
[Fig. 74. Gage for Setting Chaplets
A stock core is set in the bottom of the prints; a wooden template,
shown at b and b', is set over the core, and the print a is then
packed with molding sand, or stopped off, as it is termed.
The other method is shown at B and B', Fig. 70. Here that part
of the core which will shape the hole through the casting, is
formed on the end of a core which
exactly fills the print. A single oper¬
ation sets the core and stops off the
print. For this reason this method
is used where a large number of
such holes are to be cored.
Setting Chaplets. In setting
chaplets, the height of the lower
one may be tested with a rule, with a straightedge rested on the
prints, or by a gage similar to that shown in Fig. 74. A small boss
is usually formed by pressing the trowel handle into the mold where
the chaplet is to go.
The cope chaplet is not fastened until the mold is closed, then
the stem can be properly wedged down under a oar clamped across
the top of the mold.
Projecting Cores. Balanced Type. In work where a hole
must project well into the casting, but .not all the way through it,
a balanced core is often used. Such a case is illustrated by the
rammer head, Fig. 75. When making this core, let the vent extend
through the entire length, then stop up the vent at the small end
with a bit of clay after the core
rVent . . . . J
is baked.
It is not always practicable
to enlarge the print as shown
here, but when possible, it reduces
the length of print necessary to
balance the projecting end and
ensures accurate depth to the
hole.
Heavy Form. Heavy projecting cores must be supported by
chaplets, as illustrated in Fig. 76. Vents may be taken off through
a channel and air riser as explained in the section on Venting. Fig. 77
shows the shape of the print on the pattern for this mold at a, the
Fig.
Small Balanced Core
FOUNDRY WORK
61
pockets formed by the core are
position of the gate.
Hanging Cores. A core is
lift for the cope. Suitable wire
shown at bb, and c indicates the
frequently used to avoid a deep
hangers, shown at a, Fig. 78, are
bedded in the core when it is
- made. In setting the core, small
annealed wire about No. 20 or
Fig. 76. Large Balanced Core
Fig. 77. Shape of Print on Pattern for
Projecting Core
No. 24 gage is looped through the hangers, passed through small
holes made in the cope, and fastened with a granny twist over an
iron bar on top. This bar should bear on the sides of the cope and
the core be brought up snug in its print by wedging under its ends.
The rigging need only be strong enough to support the weight of the
core, for the pressure of metal will force this core firmly into its
print with little danger of
shifting it. For heavy cores,
a lifting eye, as previously
illustrated in Fig. 66, takes
the place of the wire hanger,
and the core is hung by means
of a hooked rod with a nut on
the end. As shown in Fig. 79,
this rod passes through a long
washer which bears on a pair
of rails, or similar stiff rigging.
Bottom=Anchored Cores.
Where possible, the placing of
cores in the bottom of molds should be avoided, for in this position,
being much lighter than molten iron, they must be secured against
a pressure tending to float or lift them. This pressure is propor¬
tionate to their depth below the pouring basin. But the metal
Wire
Fig. 78. Section Showing Use of Wire Hangers
62
FOUNDRY WORK
at the bottom of a mold is cleaner and more sound than that at
the top. Therefore, planer beds, large faceplates, and pieces of
this character are usually cast face downward, making it necessary
to anchor the T-slot cores in the
bottom of the mold.
In some cases, such cores
may be held down by driving
nails so that their heads project
somewhat over the ends of the
core, as shown in Fig. 80. If
this method is not strong enough,
pointed anchors, with a foot on
one end, are run through a hole
in the core, and are carefully
driven into the bottom board, as
shown in Fig. 81. Where the
work is bedded into the floor, a
plank must be set to receive these
anchors just below the cinder
"bed. As in the case of lifting eyes, the holes in the core, into
which the foot on the anchor is driven, are smeared with oil and
stopped off with green sand.
?ig. 79. Section Showing Use of Lifting Eye
for Heavy Cores
Joint Line
Hold Cores in Place
Green=Sand Cores
Expediency in Use. Many times the jobbing foundry may
find it expedient, where patterns and core boxes are furnished by
the customer, to make certain changes which will reduce the cost
of production; for, unhappily, the patterns furnished sometimes
FOUNDRY WORK
63
show a great desire on the part of the pattern-maker to produce
the patterns cheaply, without making due allowance for difficulties
encountered in the foundry.
Typical Instance. The practice of substituting green-sand
cores for dry sand has many possibilities. As an example, consider
the case of a flange and spigot pipe 72 inches long and 6 inches
inside diameter. The pattern furnished was satisfactory, as was
the half-core box, until it was found that the number to be made
each day was gradually increasing and the number of half cores
64
FOUNDRY WORK
to- be dried was seriously interfering with the production of the
regular cores required. It was decided by the foundry management
to adopt the use of a green-sand core, and not only relieve the core
ovens, but also effect a considerable saving in core sand and core
FOUNDRY WORK
65
binders. To make a green-sand core it was necessary to make the
core box. The method used was as follows:
First, a half core was made in the original box, and when this
was dried it was placed on a new mold board as shown in Fig. 82.
Over this was placed lagging of the desired thickness for the casting,
as shown in the figure; then over this were placed the loose pieces
Fig. 87. Complete Mold with Green-Sand Core in Position
b to form the ends of the box and part of the hinge c, also forming
a part of hinge on drag half of box, and e and g acting as strength¬
ening ribs.
66
FOUNDRY WORK
With these loose pieces in position the drag was duly rammed
and rolled over, the cope was rammed and the dry-sand core secured
in and lifted off with the cope. The loose pieces were withdrawn
from the drag, and the mold was properly finished; when closed
and poured, this gave a satisfactory casting of the drag half of the
core box. The cope half was made in the same way, the only change
being in the shape of the loose pieces forming the ends as seen
in Fig. 83.
An arbor being required to carry the green sand, it was made
of cast iron, as shown in Fig. 84. To make the green-sand core,
first riddle sand in the drag half of the core box; next place the
arbor as shown in Fig. 83; then fill and carefully tuck the sand under
the flanges on the arbor. The cope is simply filled with sand and
rammed, and both drag and cope are struck off level with the joint.
The two halves are now closed, as shown in Fig. 85, when the cope
may be rolled back to its former position and the core removed
from the drag half of the box by lifting an arbor extending through
the end of the box.
The core should be placed on horses as shown in Fig. 86, so that
it may be repaired if necessary and blackened. Fig. 87 shows the
complete mold with green-sand core in position.
In this way a satisfactory core box was made without heavy
expense for patterns, as the foundry carpenter or flask man was able
to produce the loose pieces from a rough sketch furnished by the
foundry foreman.
DUPLICATING CASTINGS
Practical Requisites in Hand Molding. Devising methods for
increasing production and decreasing its cost is one of the important
problems of modern engineering in the foundry as well as elsewhere.
In the jobbing foundry where there is a great variety not only in
the patterns themselves, but in the number of castings called for
from each pattern, the molder makes up a sand match as already
described. On this match he arranges such an assortment of pat¬
terns as will fill his flask, and beds them into place. From a well-
made sand match two or three hundred molds may be made up.
When the desired number of castings is made from one pattern
on the match, that one is removed and another one which fits
in its place is substituted.
FOUNDRY WORK
67
Gated Patterns. For manufacturing purposes thousands of
the same casting may be required, calling for more durable patterns
and match. Metal patterns are made and as many as can be cast
in a flask are soldered to a smoothly finished metal gate pattern.
With a draw screw inserted in this gate, all of the patterns may be
drawn at once. Two steady pins should be screwed and sweated
into the drag side of the gate pattern. These should be of small
round brass rod and should project below the deepest point of the
patterns, for they guide the pattern as it is being drawn and prevent
it from swaying and breaking the edges just as it leaves the sand.
Patterns so arranged are termed gated patterns.
Permanent Match. When such patterns have a flat joint, a
special mold board should be provided, and the patterns stored
on the same board. When the
joint is irregular, a permanent oil
match should be made. Make a
strong hardwood frame the size
of the flask and about 1 inch deep,
with the bottom board arranged
to screw on to the back. Nails
should be driven into the inner
sides hanging parallel to the bot¬
tom board. Measure the quan¬
tity of sand needed to fill this match. Mix thoroughly and, while dry,
put through a fine sieve one-half this quantity of burnt sand, one-half
new molding sand, and about one-fortieth litharge. Temper the
same as molding sand, using boiled linseed oil. Ram up the drag
and joint the mold very carefully. Put on the match frame and
ram up with the above mixture; strike off, and screw on the bottom
board. Remove the drag and allow the match to dry for a day
with the patterns left in it. A coat of shellac when dry improves
the surface. Fig. 88 shows a set of gated patterns bedded in a hard
match.
Use of Molding Machines. Types. Although there are many
styles of molding machines on the market, these may be classified
under four general types as follows: stripping-plate machines;
squeezers; roll overs; and jar or jolt-ramming machines. The
benefits derived from the use of these machines are manifold.
6S
FOUNDRY WORK
Advantages. If no consideration were taken of the increase
in production possible by their use, the improvement in the quality
of castings alone would oftentimes warrant their installation, as
the decrease in cost of machining castings produced by this method
pays good dividends on the investment. The use of unskilled work¬
men on these machines is no small item in their favor.
Stripping-Plate Machine. The stripping-plate machine is best
adapted to that class of work which offers difficulties in drawing
the pattern from the sand.
Fig. 89 shows a pattern for a cast gear mounted on the strip¬
ping-plate machine. It is obvious
that it would require a consider¬
able degree of skill to produce this
class of work by the hand-molding
method. The pedestal base of
the machine has a flat top. The
stripping plate is supported above
tins by a rigid open framework.
Working in guides carried on the
sides of this framework is the draw¬
ing frame, made to rise or descend
by a strong crank and connecting
rod. On top of this drawing frame
and parallel to the stripping plate
is screwed the plate to which the
pattern is fastened. The stripping
plate is cast with an opening which
Fig. 89. Typical Molding Machine
leaves about 1 inch clear all around the pattern. W hen both pat¬
tern and stripping plate are properly set in place, this space is filled
with babbitt metal, this being an easy way to secure a nice fit.
In many cases there may be an interior body of sand to be
supported when the pattern is drawn. To accomplish this stools
are used. A leg screwed into the stool plate supports the stool
at the exact level of the stripping plate. The stool plate is fastened
to the flat top of the machine inside of the box-like framework
which supports the stripping plate, as seen in Fig. 90.
A flask is inverted on the machine, rammed, vented, and struck
off. Movement of the crank lever at the side draws the pattern;
FOUNDRY WORK
G9
and the mold then is removed and set on a level sand floor, tlius doing
away with bottom boards. A second stripping plate and pattern is
used for ramming the cope boxes.
Pulleys are manufactured on molding machines of this type,
as shown by the equipment illustrated in Fig. 91. The rim patterns
Fig. 91. Pulley Molding Machine
have the form of long hollow cylinders and can readily be set for
any desired width of face. The hub carrying the core print separates
70
FOUNDRY WORK
from the spokes, lifts off in the mold, and is drawn by hand. The
arm patterns are so flat and smoothly rounded that the mold is
Fig. 92. Simple Molding Machine or Squeezer
Fig. 93. Match Plate
Courtesy of Tabor Manufacturing Company, Philadelphia, Pennsylvania
easily lifted off of them with little fear of breaking the sand. The
cope and drag molds are both alike for a pulley mold.
FOUNDRY WORK
71
Squeezer. Fig. 92 shows a type of machine known as the hand
squeezer, which only packs the sand. Here the patterns are carried
on two sides of a plate set between the cope and drag, as in Fig. 93.
Both boxes are filled with sifted sand and set on the machine. The
boards are made to follow inside of the flask. The molder’s weight
on the lever compresses the sand.
Fig. 94. Hand Squeezing Machine with Cope and Drag Patterns Attached to Portable Table
Courtesy of Arcade Manufacturing Company, Freeport, Illinois
The sprue is cut by a thin hollow steel tube called a sprue-
cutter, which is pressed through the cope sand by the molder
before separating the flask. In separating the mold the cope
is first lifted from the drag, and the plate is gently rapped and
lifted from the drag. To make a clean lift when parts of the
patterns project in the cope, a second molder raps with an iron
bar between the battens of the bottom board while the cope is
being dra„xi off.
72
FOUNDRY WORK
Such machines are used chiefly on thin work which vents and
solidifies very rapidly—for the outer surfaces of the drag and cope
are apt to be rammed so hard that they might choke the vent on
heavier castings.
A somewhat different style of hand squeezer is shown in Fig. 94,
which shows both cope and drag pattern plates attached to a portable
Fig. 95. Beginning the Operation with Hand Molding Machine. Two Halves of
Flask in Position
Courtesy of Arcade Manufacturing Company, Freeport, Illinois
table. Beginning the operation, the table holding the plates is
turned face up with the two halves of the flask in position as shown
in Fig. 95. After the sand is thrown in the flask and the surplus
scraped off, the bottom boards are placed in position and held by
four clamps. Next, the table is rolled over as in Fig. 96. The
ramming or squeezing operation is accomplished by pulling down
FOUNDRY WORK
73
the long lever at the left of the machine, as shown in Fig. 97. At
this point the clamps holding the cope and the bottom are auto¬
matically released.
Fig. 98 illustrates the method of drawing the patterns. The
lever is slowly lifted with the left hand, while the operator raps the
vibrating pin with a mallet held in the right hand. When the long
Fig. 96. Table Rolled Over Preparatory to Squeezing
Courtesy of Arcade Manufacturing Company, Freeport, Illinois
lever is returned to its upright position, the two halves of the mold
rest on the sliding platform. This is drawn forward in the position
shown in Fig. 99. The mold is then closed, the flask removed,
and the completed mold carried to its position on the floor for pour¬
ing. Snap flasks are best adapted for this style of machine.
Roll Over. The roll-over machine-which is illustrated by Fig. 100,
has the pattern mounted on a wooden match plate as shown at A,
74
FOUNDRY WORK
which when in position to receive flask is resting on pins at BB. The
mold is rammed by hand in the usual manner, the bottom board being
clamped on by a special device to the frame C. The mold is next
rolled over and rests at A. The pattern is withdrawn by the use
of the foot pedal E, the operator meantime rapping the match plate
Fig. 97. Ramming or Squeezing Operation
Courtesy of Arcade Manufacturing Company, Freeport, Illinois
with a wooden maul. This type of machine is best adapted to side
floor work, the grate bar here shown being a good sample.
Poiver Operation. The above-mentioned types show only hand
machines which have been in general use for a considerable period
of time, but the last decade has shown a wonderful change in this
branch of foundry practice; indeed so great is the advance that
FOUNDRY WORK
75
hardly a month passes that there does not appear some new featuer.
The most important advancement, of course, was the adaptation of
power, usually compressed air being resorted to, but more recently
there has been quite a tendency to utilize electricity.
Power Squeezer. Fig. 101 shows compressed air applied to the
squeezer type of molding machine. This machine is designed
Fig. 9S. Drawing the Patterns. Use of Mallet
Courtesy of Arcade Manufacturing Company, Freeport, Illinois
especially for use in molding light snap-flask work in large or small
quantities, and the method of pattern fitting depends upon the
number of castings to be made from one pattern.
A careful study of the line drawing of this machine shown
in Fig. 102 should give a clear understanding of the working parts
of the power squeeze**, the numbered ones being identified as follows:
76
FOUNDRY WORK
Fig. 99. Two Halves of Mold in Open Position
Courtesy of Arcade Manufacturing Company, Freeport, Illinois
1.
Yoke
20.
Counterbalance spring
2.
Left-hand stop for yoke
21.
Adjustment block for spring seat
O
O.
Yoke handle
22.
Adjustment-block set screw
4.
Pressure gage
23.
Trunnion
5.
f-inch air cock
24.
Bracket for lower spring seat
6.
Eye bolt
25.
No. 5 snap oiler
7.
Left-hand strain bar
26.
Trunnion shaft
8.
Right-hand strain bar
27.
Pop throttle-valve lever
9.
Right-hand yoke stop
28.
Valve-lever stud
10.
Platen
29.
Throttle-stop segment
11.
Knee-pad rod
30.
Valve sand guard
12.
Air hose from knee valve to
31.
Valve spring for exhaust
vibrator
32.
Adjustable strain-bar stop
13.
Air hose from knee valve to
33.
Valve body
supply
34.
L hose nipple
14.
Hose guard
35.
Straight hose nipple
15.
Knee pad
36.
Valve bracket
16.
Knee starting valve
37.
Taper pins, trunnion to shaft
17.
Cylinder base
38.
Blow valve
18.
Piston
39.
Blow-valve hose
19.
Piston ring
FOUNDRY WORK
77
Attention is called to the fact that the production of the power
squeezer exeeeds that of the hand squeezer by 15 to 30 per cent.
For description of various ways of mounting patterns, see Pattern-
Making.
Power Poll-Over. A power roll-over power-draft machine is
shown in Fig. 103. This is designed to handle side floor work,
Fig. 100. Roll-Over Molding Machine with Pattern Withdrawn
Courtesy of Tabor Manufacturing Company, Philadelphia, Pennsylvania
and has a straight draft of 8 inches and sufficient power to roll over
a weight of 1000 pounds. It will be noted that as in the hand roll¬
over the patterns are mounted on wooden match plates, the small
expense of which makes this style of machine very effective in job¬
bing shops where but few castings are made from a pattern at a time.
In Fig. 104 is shown the latest type of this machine with the
flask shown in position ready for bar ramming. Fig. 105 shows the
78
FOUNDRY WORK
mold partly rolled over; the mold rolled over and partly with¬
drawn is shown in Fig. 106. The view given in Fig. 107 shows the
finished mold on one side and the pattern back in place.
The working parts of the above machine are shown in Fig. 108,
and are as follows:
1. Roll-over frame
2. Air cylinder
3. Link
4. Wedge leveling device
5. Adjustable support for leveling device
6. Operating valve and lever
7. Vibrator
The plunger is made hollow and acts as an oil tank into which
air under pressure is admitted when the machine is to be operated.
When air pressure is admitted to the plunger, the oil is forced through
Fig. 101. 10-Inch Squeezer Operated by Compressed Air
Courtesy of Tabor Manufacturing Company, Philadelphia, Pennsylvania
FOUNDRY WORK
79
a port into the cylinder, causing the plunger to rise and by means
of its link connections to roll over the mold which is deposited on
the leveling device. After the flask has been undamped air is
again admitted to the plunger, causing the pattern to be drawn
vertically the full draft of the machine, at which point the link
connections cause the roll-over frame to return to its initial position
ready to receive another flask.
Jolt-Ramming Machine. The jar or jolt-ramming machine is
used for all classes of work from light work up to the largest floor
work made in green sand, the limit being only the capacity of the
80
FOUNDRY WORK
machine itself, which varies from a few hundred pounds to many
thousands of pounds. Large engine beds are a good example of the
castings produced on the heavy-duty machines.
Fig. 103. Power Roll-Over, Power Draft Molding Machine with 12-Inch Straight Draft
CotLrtesy of Tabor Manufacturing Company, Philadelphia, Pennsylvania
Fig. 104. Latest Type of Tabor Molding Machine with Flask Ready for Ramming
Patterns mounted on heavy wooden match plates are used in
the manner hereafter described. The flask is first placed on the drag
FOUNDRY WORK
81
half of the pattern board, and the flask filled with sand. By the
use of an upset, usually about 4 inches deep, it is possible to heap
sufficient sand on the flask to insure its being filled after the ramming
has taken place. The flask must be securely clamped to the pattern
plate, when both may be listed by the traveling crane and placed
on the table of the jarring machine, which in the heavy-duty machines
is on the foundry-floor level; the working parts of the machine being
below and resting on a rigid concrete foundation. Here, air under
Fig. 105. Machine with Mold Partly Rolled Over
Courtesy of Tabor Manufacturing Company, Philadelphia, Pennsylvania
pressure is allowed to enter the cylinder, and, acting on the plunger,
which in turn lifts the table usually about 4 inches, when the air
is suddenly exhausted, allows the table to drop heavily on the
anvil. The number of blows required to pack the sand must be
determined by experience. The time required to ram the largest
mold is but a small fraction of that consumed by hand-ramming.
Fig. 109 is an illustration of one of the simplest styles of this type
of machine. Fig. 110 shows the working parts of the same machine.
82
FOUNDRY WORK
Fig. 106. Mold Completely Rolled Over and Partly Withdrawn
Courtesy of Tabor Manufacturing Company, Philadelphia, Pennsylvania
Fig. 107. Finished Mold on One Side and Pattern in Place
Courtesy of Tabor Manufacturing Company, Philadelphia, Pennsylvania
FOUNDRY WORK
83
Fig. 108. Diagram of Working Parts of the Tabor Molding Machine
Fig. 109. Simple Type of Jolt-Ramming Machine
Courtesy of American Molding Machine Company, Terre Haute, Indiana
A quite distinct style of jolt machine, called an electropneumatic
jolt-ramming machine, is shown in Fig. Ill, the unique feature
being the motor-driven compressor without a clutch, spring, cam,
84
FOUNDRY WORK
Fig. 111. Krause Electropneumatic Jolt Rammer
Courtesy of Vulcan Engineering Sales Company, Chicago, Illinois
Fig. 112. Section of Krause Jolt Rammer Showing Transmission and Unique Compressor
86
FOUNDRY WORK
or valve. A very little study of Fig. 112 should make clear its
radical features.
Automatic Squeezer. Fig. 113 illustrates an automatic molding
machine of the squeezer type. The operator places the flask and
bottom board in position, then by simply pressing on the starting
lever the filling of the flask with sand, the ramming and the drawing
of the pattern is completely automatic and accomplished in about
Fig. 113. Automatic Molding Machine of the Squeezer Type
Courtesy of Berkshire Manufacturing Company, Cleveland, Ohio
eight seconds or some six or seven hundred molds per day. This
machine is best adapted to the production of small duplicate work
such as small pipe fittings.
Roller-Ramming Machine. The very distinctive type of mold¬
ing machine shown in Fig. 114 is known as the roller-ramming
machine. It is best adapted to long work of comparatively thin
cross-section, of which a cornice section would be a good example.
This class of work could not be produced readily on any of the
FOUNDRY WORK
87
previously mentioned types of machines. Fig. 115 is a detailed
drawing of Fig. 114.
The success of any and all molding machines depends on the
intelligent selection of the type best suited for the work in hand.
Fig. 114. Moldar Roller-Ramming Machine in Ooeration
Courtesy oj Rich-n Browne and Donald, Maspeth, New York
Fig. 115. Plan and Elevation of Moldar Roller-Hamming Machine
FOUNDRY WORK
89
DRY=SAND WORK
Characteristic Features. This branch of molding becomes
a separate trade in shops where the work is done continually. The
dry-sand molder must use the same precautions as the green-sand
molder in setting gates and risers, and in fastening his sand with
crossbars and gaggers. At the same time, he works with a core-
sand mixture next his patterns and backs this with a coarse molding
sand, so that he must combine the skill and judgment of both the
green-sand molder and the core maker. The venting of dry-sand
work must be ample, as in the case of cores, but it is simpler than
in core work, because the core mixture surrounds the casting so that
vents may be taken off in all directions.
Iron flasks are used, generally provided with trunnions to
facilitate turning. The facing mixture is the same as that used
for making large cores, as discussed in the section on Core Work;
the remainder of the flask is packed with the same sand after it has
been used. The patterns are made and used the same as with green
sand, only they should be brushed over with linseed, crude-oil,
or other heavy oil, before ramming. In some shops oil is brushed
over the joint before parting sand is thrown on. After the pattern
is drawn, the mold is finished by applying a heavy coat of good black
wash. When the sand has absorbed the moisture so that all glisten
has disappeared, this blacking is slicked over. Great care must
be exercised in this operation, for too much slicking will draw the
moisture to the surface again and result in scabs on the casting.
Molding Engine Cylinder. Engine cylinders are a representative
line of work for dry sand. Consider a simple type of cylinder,
such as shown in Pattern-Making, Fig. 244, to have a bore of from
16 to 26 inches, and with the exhaust-outlet flange placed above
the center of the cylinder. To facilitate setting the cores, the pat¬
tern may be split through the steam chest. The flange just men¬
tioned should be molded in the drag, and should be made loose
and draw in the opposite direction from the main pattern. The
cylinder core should be made on a barrel, as will be explained later,
and the mold poured on end to insure sound metal and to reduce
the casting strain on the port cores. The flask is made with a
round opening in one end to allow the core to project through it.
This opening is larger than the diameter of the core to allow for
90
FOUNDRY WORK
gates and risers. There must be another opening at the side of
the flask adjacent to the steam-chest core to provide for fastening
these cores. Iron plates serve for flask boards and there should
be a hole in the drag plate in line with the exhaust core to allow for
renting and fastening its end.
One-half of Fig. 116 shows the end view of the flask. The
other half shows a section through the middle of the completed mold.
Here A is the hollow cylinder core, B is the chest core, C the live-
steam core hung in the cope, and D the exhaust core. The flask
is packed in a manner similar to green sand.
Use of Cover-Core. The method of molding the exhaust
flange, however, has not previously been explained. To do this,
proceed packing the drag until the pattern is covered. Tuck the
facing carefully underneath the flange, setting in rods as in core work,
to strengthen the overhanging portions. Make a flat joint, FG.
at the level of the top of the flange, then carefully fit over the print
of the flange the cover-core E, and fix its position with nails driven
into the joint at its corners. Now remove the cover-core, draw
the flange, and finish that part of the mold with black wash and
slicking. When this is accomplished, replace the cover-core, place
a short piece of pipe over its central vent, and finish ramming the
drag. This method may be used in many cases, both in dry-sand
FOUNDRY WORK
91
and in green-sand work where a small detail of the casting require?
a separate joint surface.
A sectional plan looking down on the drag is shown in Fig. 117.
When the mold has been properly finished and baked, the drag is
brought from the oven and set on a pair of stout horses. The
cylinder core is first set in place, then the exhaust core is set in its
drag print and held close to the cylinder core, while the port and
chest cores, previously pasted and fastened, are lowered into the
chest print. The chest print is cut a little long at aa, to allow its
core to be drawn back slightly, while the exhaust core is entered
into its place between the port cores. Then all of the cores are set
forward into position, the chaplets bb set, the space aa tightly packed
again, and the anchor bolts cc placed in position and made fast.
92
FOUNDRY WORK
The drag print of the exhaust core is made fast from underneath
the drag plate. When all the cores have been firmly fastened,
the cope is closed on, and the two boxes clamped at the flanges
and set up on end. The runner R and the riser S were cut and
finished before baking; the basins must be built in green sand after
the mold is closed.
Making Barrel Core. Loam is used here for the outer shell
of the core. It is probably the simplest job in which a loam mix¬
ture is employed, and is made by a core maker more frequently
than by the higher paid loam molder. Barrel cores are used where
the core is long and can best be supported at the ends only; for
example, in gas and water pipes and cylinder work.
Loam. Loam is a facing mixture, of the consistency of mortar,
applied to the face of the core or mold. It contains fire sand with
a bond of strong porous molding sand moistened with a thick clay
wash. A small proportion of organic matter in the shape of horse
manure is put in to aid the bond and to leave the crust of loam more
fragile by burning out as the casting cools. Proportions of the
mixture will vary according to locality, but the principles already
cited hold here as with other molding compounds. With too much
bond the loam works easier but tends to choke the vents when
casting. With not enough it is weak and is liable to break, cut,
or crumble under strain. A typical mixture is as follows:
Loam Mixtures
Material
Mixed by Hand
(parts)
Mixed by Mu i
(parts)
Fire sand
10
10
Strong coarse molding sand
4
3
Horse manure
U
2
Temper
Thick clay wash
Thick clay wash
The advantages of loam cores are that they are lighter, cheaper
to make, and carry off the gases faster than do dry-sand cores.
Method. The method is as follows: A piece of pipe about
3 inches smaller than the outside diameter of the core is selected
to form the center. The pipe is perforated with a large number
of holes. If the pipe is more than 3 or 4 inches in diameter, centers
FOUNDRY WORK
93
or trunnions are riveted in the ends to serve as bearings. The pipe
is arranged to revolve freely on a pair of iron horses, as shown in
Fig. 118. A crank handle is attached by which the pipe may be
turned. A couple of wraps of hay rope are first given around one
end of the pipe, and the loose end is pinned flat by a nail run under
these strands. Tight wrapping is then continued to the other end
of the pipe, where the rope is fastened in a similar manner and cut
off. Hay rope should be made of long wisps tightly twisted. Sizes
vary from f to 1 inch. Where only a small amount of hay rope
is used, it is bought ready made. Foundries using large quantities
are equipped with one or more machines built especially for making
this rope.
The first coat of loam is rubbed on with the hands, then well
pressed in with the flat side of a board as the barrel is slowly revolved.
When this has set, the core board A is placed in position, and the
roughing coat worked on to the core to within about f inch of
finished size. The core is now dried in the oven. Placing the core
again on the standards, the finishing coat of slip is applied with the
core board while the core is still hot. The diameter is tested with
calipers and brought to required size by slight adjustment of the
sweep board A. When the core has been built to size, move the
loam back from the edge of the board A, then withdraw the board
while the barrel is still in motion.
94
FOUNDRY WORK
Slip. Slip or skinning loam is made by thinning regular loam
as it is rubbed through a No. 8 sieve. The heat of the core is usually
sufficient to dry this slip coat enough so that black wash may be
brushed on and slicked, as in dry-sand work, before running the-
core into the oven again for its final baking.
The service of the hay rope on a barrel core is twofold: it fur¬
nishes a surface over the smooth metal of the barrel to which loam
will adhere; and it is elastic enough to give as the casting shrinks
around the core. The hay slowly burns out after the casting has
set, and this frees the barrel so that it cart easily be withdrawn and
used again.
LOAM MOLDING
Skill Required. The loam molder requires the greatest all-
around skill in the whole range of foundry work. He must know all
the tricks of the core room and dry-sand shop, and most of those in
green sand. Added to all this he must have a practical working
knowledge of the principles of drawing and must possess to a large
degree the foresight of the designer.
In order to save time and lumber in the pattern shop, only a set
of sweeps is provided if the mold is simple, and these, with blue
prints of the piece wanted, are all the molder has to work from. In
intricate work, such as a modern Corliss cylinder, a skeleton pattern
carrying the steam chests, etc., in accurate position is made, and in
some very crooked work a pattern is furnished complete. As a rule,
however, the loam molder must rely upon his own skill and ingenuity
for the best method of constructing each detail of the work.
Rigging* The equipment for the loam floor varies in different
shops. In Fig. 119 are shown the essential features of an equipment
for sweeping-up circular forms.
Spindle. The spindle a should be large enough not to spring
when being used, and long enough to conveniently clear the highest
mold. A piece of 2-inch shafting is a handy size, for with it the sweeps
may be made uniformly 1 inch less than the required diameter and
placed snug to the spindle when set up, and the correct size of mold
is ensured. This spindle should revolve smoothly in a step b. The
step shown may be set at any convenient place on the floor. It has
a long taper bearing, as shown in section A, capable of holding a 5-foot
spindle without need of any top bearing. The three arms serve to
FOUNDRY WORK
95
make the step set firmly, and upon them any plate may be readily
leveled up. Where a tall spindle is used, the spindle socket is more
shallow; the step may be cast without arms and be bedded in the
floor. The top of the spindle is steadied by the bracket c. This
must carry a bearing box so designed that the spindle may be readily
set in position or removed. And the bracket must swing back out of
the way when any parts of the mold are to be handled by the crane.
Sweeps. The sweeps are attached by means of the sweep arm d.
The detail B shows one method of clamping the sweep arm to the
spindle by using a key. The arm is offset so that one face hangs in
line with the center of the spindle. Bolting the face side of the sweep
to this brings the working edge in a true radial plane. Sweeps are
usually made from pine about 1| inches thick. The working edge
is cut to the exact contour of the form to be swept, and then is
beveled so that the edge actually sweeping the surface is only about
f inch. For very accurate work or when sweeps are to be much used,
the edge is faced with thin strap iron to prevent wear.
Plates. We have seen that the walls of green- and dry-sand
molds are supported by sand packed into flasks and that these flasks
may be lifted, turned up sideways, or rolled completely over to suit
FOUNDRY WORK
9e
the convenience of the workman. The facing which forms the wall
of a loam mold is supported by brickwork built upon flat plates of
cast iron, and laid in a weak mortar of mud. From the nature of their
construction, therefore, these molds must always be kept perpen¬
dicular when being handled. The parts may be raised, lowered, or
moved in any direction horizontally, but they must not be tipped or
rolled over.
The plates are cast in open sand molds, as illustrated in Fig. 56.
Two methods are employed to provide for handling them by the crane;
Fig. 120. Laying-Up Loam Work
either lugs are cast on the edges of the plates, as in C, D, and E,
Fig. 119, or wrought staples are cast in the-plates, as shown in B,
Fig. 120, or in the crown plate of the main cylinder core, Fig. 123.
Three typical plates for a loam job are shown in Fig. 119.
C is the building plate; it should be at least IS or 20 inches larger
than the largest diameter of the casting to be made, and thick enough
to support the weight of the entire mold without springing. D shows
a cope ring; its inside diameter should clear the casting 2 inches
on all sides. The face should be 8 to 12 inches wide, depending upon
FOUNDRY WORK
97
the height of the mold. E shows a cover plate; its diameter equals
the outside diameter of the brickwork on that part of the mold which
it covers. Here the loam facing is placed directly on the iron, and
must be supported when the plate stands vertically or is turned com¬
pletely over as in C, Fig. 122. To hold the loam in this way, fingers
or stickers are cast on these plates. This is accomplished by simply
printing the end of a tapered stick into the bed of the open mold which
Fig. 121. Steps in Sweeping Up Type Mold
shapes the plates. These sticker plates are often used for a purpose
similar to the core E, Fig. 116, and shape the outer face of a picked-
out flange. This is illustrated in D, Fig. 122.
Materials. Brick. Common red brick is best for making loam
molds, Figs. 120 to 123. It should be free from glaze and have a
uniform texture, so that the pieces will break clean when it is
necessary to fit them to the shape. An old 12-inch half-round file
makes a handy tool for cutting these. Sometimes brick is molded
98
FOUNDRY WORK
up from loam, and air-dried. It is much more fragile than red
brick, and may be used in pockets, or where the shell of the casting
is quite thin, and ordinary brick might resist the shrinkage strain
to such an extent as to endanger cracking the casting.
Mud. For laying up the brickwork, mud is used, loam facing
being applied only to those surfaces which come in actual contact
Construction of Mold
at A/ozz/e-D-
Fig. 122. Complete Typical Loam Mold
with the iron. Mud is made from burnt loam or old floor sand, mixed
with clay wash to the consistency of mortar.
Facing. The composition of loam facing and slip have already
been given under the description of making a barrel core.
Cinders. Cinders are an important material in this work. Their
size will depend upon their position in the mold. For working in
between brick, the cinders should be crushed if necessary, put through
a No. 4 sieve to remove smallest pieces, then passed through a No. 2
sieve to remove the larger pieces.
FOUNDRY WORK
99
Principles of Work. Parts of Mold. The names of the main
parts of a loam mold differ somewhat from those applied when molding
in flasks. As will be seen from the section, Fig. 122, there are three
main divisions in the mold: A, which corresponds to the drag in a
three-part mold, is called the core. B, which corresponds to the cheek,
is called the cope in loam work. And C, which serves the same purpose
as the cope of a green-sand mold, is spoken of as the cover in loam
molding. When the central core is actually made a separate piece,
as in Fig. 123, the lower part of the mold is called the bed or foundation.
Laying-Up. In laying-up a loam mold, Fig. 120, set the
plate central with the spindle and approximately level. Then set
the sweep and finish leveling the plate until repeated measure¬
ments at the four quarters of the circle show a uniform space
between the lower edge of the sweep and the surface of the plate,
lor the building plate this measurement should be 5 inches; for a
sticker plate the sweep should clear the sticker points by | to 1 inch
according to the thickness of the casting.
dhe hands are used in spreading mud or loam upon the plates
or brickwork when building the mold. The brick must ahvays be
set well apart, leaving a space at least the width of a finger between
them. Fill in these spaces with fine cinders. The reason for this is
100
FOUNDRY WORK
fourfold. It facilitates drying; it provides good vent; it gives or crushes
sufficiently when the casting shrinks not to cause undue strain;
and it reduces the labor in cleaning. In each course of brick the
joints should lead as directly as possible away from the casting, but
the joints should be broken between courses. These points are illus¬
trated in the sketch A, Fig. 120. As shown, the first two courses of
the core are usually set edgewise. For the rest of the core and for the
cope, the bricks are laid flat. These bricks run lengthwise around the
circumference, with a course of headers about every four to six
courses.
Venting. Cinders between brick form the ordinary means of
leading the vent from the loam facing. In confined places or pockets,
as, for example, between the flange D and the main casting, Fig. 122,
additional provision is made by laying long wisps of straw between
the courses of brick. The service of the straw is similar to that of
the hay rope of a barrel core.
Jointing. The joint in loam work is made by a plate lifting away
from a loam seat, or by two loam surfaces separating one from
another. In forming the first of these the loam seat is swept up and
allowed to partially set, then the surface is brushed with oil, and part¬
ing sand is thrown over it. The seat should then be soft enough to
allow the iron plate to sink into it sufficiently to find a good bearing,
while the oil and parting sand will prevent the loam facing from
adhering to the underside of the plate. For the loam-to-loam joint,
the same method is used, but the loam is allowed to set somewhat
harder before building the joint against it. The angle of the main
joint should be about 1 in 4 inches.
To insure the different parts being put together for casting in
exactly the same position in which they were built, a guide surface of
loam is smoothed across the joint at three or four convenient points
on the outside walls of the mold. These surfaces are each marked
differently with the edge of the trowel, similar to the cut at C,
Fig. 120.
Drawback. To properly separate and finish some molds, it is
necessary to lift away a portion of the mold before lifting the main
part. Such a portion is called a drawback. The drawback is always
built up in position against a pattern or sweep. With the cover
plate, which on a smaller scale often serves the same purpose, as at
FOUNDRY WORK
101
7), Fig. 122, a flat joint is made on the outer wall of the mold, but the
cover plate is swept up separately. At 3, Fig. 123, is shown a
drawback which carries but a few courses of brick. It may be lifted
away by lugs cast in the drawback plate with little danger of dis¬
placing its brickwork in handling.
If the shape of the drawback renders it impracticable to handle
it by the lower plate alone, the brickwork should be bound together
by means of hook bolts which clamp on a top plate set sufficiently
below the upper joint to be entirely protected from the metal. This
upper plate has staples cast in it by which the whole drawback may
be lifted. At B, Fig. 120, the typical construction of such a piece is
illustrated. The drawing shows one-half the length of the brickwork
removed to bring out more clearly the rigging used. The upper
end of the second lifting staple shows at a, with the loam cut neatly
away to allow hooking into the staple.
Where the main core lifts away or is to be covered with metal
over its top, it must be bound together in a similar manner. This is
illustrated in the mold for the marine-engine cylinder, Fig. 123, in
which both of these conditions occur.
Example of Internal Flange. If a casting has an internal flange
requiring thickness of metal underneath the main core, the rigging
will be altered to fit these conditions, as shown at D, Fig. 120. In
this sketch a is a sticker plate and so will carry the loam necessary
to face the bottom of the core. To this the small bearing plate b is
securely bolted by the hook bolt c. This plate must set directly upon
solid brickwork, as it carries the weight of the entire core. On this
bearing plate are cast three studs which firmly support the sticker
plate at the required height above the flange surface. The sticker
plate carrying this print is filled with loam or dry sand and given a
first baking, then swept to a finished surface before being inverted
into position. Then the remainder of the core is built up on top and
bound together, as in the previous example. Another wTay to form
the bottom of this core is to sweep up a dummy flange d, in mud.
Set the bearing plate b, and work the loam in around the studs to
form the short neck to the level of the top of the flange. Then
spread over this flange % inch of loam and bed down onto this the
sticker plate which has been previously filled with loam and dried,
as is described below. Be sure that the studs on b bring up to a
102
FOUNDRY WORK
firm bearing against the plate a, then clamp tight with hook bolts
and proceed to sweep-up the body of the core.
Bedding Cover Plate. In case a cover plate must be bedded down
against a flat surface, as in the example just mentioned, or must
take the impression of an irregular surface on the top of a mold or
pattern, as illustrated in Fig. 123, the method to pursue is as follows:
After casting, invert the plate and carefully lower it into position,
and make sure that all fingers clear the surface by at least % or f
inch. Now set the plate with the fingers up, fill in with loam enough
to just clear their tops, leaving the proper openings for runners, risers,
tie bolts, etc., and dry thoroughly in the oven. Upon removal
from the oven, invert and try this loam cover again on the surface
it must fit; scrape away any portions which project too much. Now
hoist away the cover and coat the face with clay wash. Having
previously prepared the surface of the pattern with oil and any
loam joint with oil and parting sand, spread an even thickness of
fresh loam all over and bed the plate down upon this. The cover
plate, being still hot, will, by the aid of the clay wash, cause the
thin layer of fresh loam to dry out and stick fast to the dry loam
forming the body of the plate.
Simple Mold. As an example of a simple loam mold let us
consider the details of a large casting, having the shape of the
frustrum of a cone, with a flange at the top and bottom and a
flanged nozzle projecting from one side, such as the section clearly
shown in Fig. 122.
Foundation. Set the sweep, level up the building plate, and,
building the brickwork as shown in A, Fig. 120, sweep the seat, joint,
and bottom surface of flange, as shown at A, Fig. 121. The lower
flange may be formed by a wooden pattern furnished by the pattern
maker, but it is more common to have the sweep made with the
small board x, which may be removed. By doing this the exact shape
of the flange may be swept up without changing the main sweep,
as shown at B, Fig. 121. This dummy flange, as it is called, is swept-
up from fairly stiff mud.
Cope. The next step is to seat the cope ring and set the cope
sweep, as shown at C, Fig. 121. This sweep shapes the mold for the
outside of the casting, for the top flange, and for the top joint of the
mold. Loam is thrown, a handful at a time, against the joint and
FOUNDRY WORK
103
dummy flange, and the engaging faces of bricks are rubbed with
loam and pressed into position.
When the top of the lower flange is reached in this way, the
courses are laid-up for about 2 feet before the loam is spread upon
their inner surface and struck off. This method is pursued until the
mold is built to its full height.
The projecting nozzle is formed by a wooden pattern; this should
be well oiled, and the brickwork and loam laid-up under it to support
it at the proper level, as given by the center line on the pattern and
corresponding line on the sweep. Such projections frequently must
be supported in their exact position with reference to the main
pattern by temporary wooden framework or skeleton work until
the mold is built up under them.
A finger y nailed to the top member of the cope sweep, shapes the
guide surfaces on the outside of the mold which are used to center the
cover plate in closing the mold. A similar finger exactly the same
distance from the spindle, is fastened to the sweep used to form the
cover plate.
After the finishing coat of slip has been swept on the surface of
the cope, a joint surface about 4 inches wide is struck off flush with
the outer face of the nozzle and that pattern is drawn out.
Then the whole cope is lifted off and set on iron supports where it
may be conveniently finished with black wash and slicks. It is then
baked over night in the oven.
Center Core. The dummy flange is now entirely removed from
the first part swept, the core sweep is set, Z), Fig. 121, and the
center core is struck up. This core is then blackened, slicked off, and
baked. The cover plate is struck off with the stickers up, and baked
so. This cover carries six 1-inch round holes through it, which will
be just over the shell of the metal when the mold is closed. Five of
them connect with the pouring basin and serve as runners, while
the sixth serves as a riser.
Closing. In assembling the mold for pouring, the core is first set
on a level bed of sand, the cope is accurately closed over it by the
aid of the guide marks, and lastly the cover plate is closed in position.
Now the whole mold is firmly clamped by blocking under the spider,
from which wrought-iron loops or strings connect under the lugs of
the building plate, as shown in Fig. 122.
104
FOUNDRY WORK
The small core for the nozzle is now set, resting on stud chaplets.
The cover plate D is slid over the end of this core and thus holds it
firmly in position.
The casing is now placed around the mold and molding sand
rammed in to support the bricks against the casting pressure. At the
level of the nozzle core cinders are placed, and a pipe leads off to
carry away the vent gases. The sand is rammed to about 12 inches
over the cover plate and in it are cut the channels connecting the
pouring basin and runners. A couple of bricks are set in the bottom
of the basin to receive the first fall of metal from the ladle.
Pouring. In pouring, the runners must be flooded at once and
kept so until the mold is full.
In heavy cylindrical castings it was formerly thought necessary
to carry the shell of the casting some 6 inches higher than the top
flange. This head served to collect all dirt and slag that perchance
entered the mold with the iron, and it was cut off in the machine shop
and returned to the foundry as scrap. With the increased knowl¬
edge of iron mixtures this head is now done away with in most
instances.
Where a large casting is to finish practically all over, and very
clean metal is therefore necessary, overflow channels, connecting with
pig beds, are often constructed in modern practice. Then, when
pouring, the metal is not stopped until a certain per cent of it has
been flowed entirely through the mold. This of course tends to wash
out any dirt which may have gotten into the mold when pouring
began.
When the casting is cold, the casing and packing sand as well as
the blocking under the spider are removed. Then the whole mold is
carried to the cleaning shed where the bricks are removed and the
casting cleaned.
Intricate Mold. As an example of a complex piece of loam work,
let us consider the molding of a modern marine-engine cylinder, as
shown in section, Fig. 123. The example given is that of a double-
ported low-pressure cylinder of a triple-expansion type. In this
case a full wooden pattern should be built, with core boxes for the
various dry-sand cores that enter into the construction of the mold.
Foundation. The limits of this article prevent a detailed discus¬
sion of this subject; we will, therefore, confine ourselves mainlyr with
FOUNDRY WORK
105
an explanation of the drawing, Fig. 123. The heavy building plate
has a spindle opening somewhat to one side of its middle to be under
the center of the cylinder. Upon this building plate the foundation
of the mold is swept, carrying the seat for the cope ring, the bottom
face of the flange, and the seat for the main cylinder core. The cope
ring 1 is made wide enough on one side to carry that part of the
mold forming the steam chest. The main cylinder core 2, the
construction of which has already been explained, is next swept-up
and lifted away, finished, and baked.
Cope. Now the cope ring is seated, and the mold built and struck
off for the bottom of the steam chest on a level with the bottom face
of flange. Then the pattern may be set. Its position is accurately
determined by the main cylinder print and the smaller prints of the
steam chest which are bedded into the loam in accordance with
measurements along a radial line marked off on the loam surface.
With the pattern well oiled, the cope is built to the height of the upper
flange of the cylinder; the entire back of the steam-chest core print
being left open. The top of the steam chest is lifted off with the
drawback 3, which joints at the middle of the upper steam nozzle,
and carries that part of the mold to the level of the main cope joint.
The two steam nozzles and the exhaust nozzle may be made with
separate cores as explained in 1), Fig. 122. By using the drawback,
the entire top of the chest core print is left open for convenience in
setting the chest and port cores.
The top of the cylinder is jacketed, and through it pass the
stuffing-box and manhole openings. The flanges of these two open¬
ings connect and in the pattern are left loose. The whole top surface
is so irregular that it requires three levels of sticker plates to mold
it, aside from two small cover plates over flanges.
Covers. To the main cover 4 4 4 4 with its various lengths
of fingers, is bolted a crab 5 5 5 to carry the loam below the flanges
of the stuffing box and manhole; and below this again are hung the
dry-sand cores, 8 8 8, forming the jacketed part of the cylinder
head. On top of the main cover is fastened a separate plate, 6,
to shape the top of the upper steam inlet. And at 7 a plate with
wrought-iron bars cast along its edge carries the loam back of the
steam-chest flange. The small cover plates, 9 and 1G, allow the
flanges to be drawn for the parts which they mold.
106
FOUNDRY WORK
The pattern is made in many parts so as to properly draw from
the mold. When this has been done, all mold surfaces are carefully
blackened and slicked before baking.
Coring. While the mold proper is being built, the dry-sand
cores should be made up by the core makers, with the necessary rods,
hangers, vent cinders, etc., as described under Core Making.
The manhole core, 11, is made with a stop-off piece in the
box to give the proper angle at the bottom of the core. It is hung to
the cover and clears the main core by f inch. The stuffing-box core
rests in a print in the main cylinder core, and is held by a taper print
in the cover plate 10.
The jacket cores are hung as shown. The openings made in the
loam above the crab, to allow the hook bolts to be drawn up tight,
are stopped off with green sand as previously described. The inlet
cores 12 12, the exhaust core, 13, and the lightening cores, 14 14 H>
are all bolted directly through the steam-chest core, 15, to horizon¬
tal bars which are long enough to bear against the sides of the mold
at the back. The upper inlet core, 12, is kept from lifting under the
pouring strain by being bolted to the body of the main cylinder core.
Stud chaplets are also set between the inlet and exhaust cores to
ensure correct thickness of metal at these points.
Venting. The vent is taken off from the main cylinder core
through the stuffing-box core at the top. Sometimes a small ladle¬
ful of metal is poured through this opening, when the piece is being
poured, to ensure lighting these gases. The vent for the series of port
cores is taken off by ramming a cinder bed up the entire back of the
steam-chest core, allowing the gases to escape at the top. For safety,
also, vents are taken from the bottom of the port and chest cores
by the usual pipe vent.
Pouring. The provision for pouring this mold requires especial
attention. Notice the construction of the main basin, 16. The long
runner 17, leading to the bottom gate, is left open on one side when
the mold is built, so that it may be easily finished and kept free
from dirt. Its open side is closed by cover cores when the mold is
rammed up.
Ten or twelve small gates like 18 are connected with the
pouring basin, by semicircular channels, but are so placed that no
metal shall fall on a core. With the basin arranged as shown, the
FOUNDRY WORK
107
bottom part of the mold is first flooded with iron. When this has
been done, the metal is poured in faster, so that hot iron is well
distributed around the shell of the casting through the small top
gates. Should the mold be poured at first from these top gates, the
fall of the iron through the full height of the cylinder to the lower
flange might result in cutting the loam on that surface.
Molds of this size are usually rammed in a pit so as to bring the
pouring basin conveniently near the floor. The portion above the
floor level is, of course, rammed inside a casing, as described in the
previous example.
To guard against uneven cooling strains in this intricate casting,
the clamping pressure on the mold is relieved when the metal has
solidified, but the sand is not removed from around the brickwork for
several days. This allows very gradual even cooling.
It will be noticed that the piston does not work directly upon the
inner walls of this type of cylinder. A separate hollow shell or lining
is cast of strong tough iron. This has outside annular ribs at top
and bottom and middle, which are turned to fit correspondingly pro¬
jecting ribs seen on the inside of the casting just under consideration.
An air space is thus left between the lining and main casting which
forms a jacket around the bore of the cylinder.
FOUNDRY WORK
PART II
CASTING OPERATIONS
MELTING
General Characteristics. The subject of melting the metal
which is to be poured into molds is one of the most important con¬
siderations in the foundry. It is also one which has received much
attention in the last few years, the endeavor being to get away from
the old rule-of-thumb methods and to arrive in the iron foundry
at something near the precision in resulting metal that is already
attained in the brass shops or the steel foundry.
The heat for all melting is obtained from practically the same
two chemical elements—carbon, and oxygen—carbon coming from
the fuel, be it coal, coke, oil, or gas; and oxygen coming from the
air of the blast.
The design of the furnace, the kind of fuel used, and the applica¬
tion of the blast vary in accordance with the peculiar properties of the
different metals and the degree of heat required to melt them.
The melting of steel, copper alloys, and malleable cast iron will
be dealt with under separate headings. We shall now consider only
the melting of gray foundry irons.
CUPOLA FURNACE
Furnace Parts. Foundry iron is melted in direct contact with
the fuel in a cupola furnace. The name was derived from the resem¬
blance of the furnace to the cupola formerly very common on the
top of dwelling houses.
Bottom. The cupola consists of a circular shell of boiler plate,
lined wdth a double thickness of fire brick and resting on a square
bedplate, with a central opening the size of the inside of the lining.
This bottom is supported some 3| feet above a solid foundation, on
four cast-iron legs. The bottom opening may be closed by cast-iron
doors, which swing up into position, and are held so by an upright
Fig. 124. Section Through Modern Cupola Furnace
FOUNDRY WORK
111
iron bar placed centrally under them. These doors, protected by a
sand bed, support the charge during the heat, and drop it out of the
furnace when all the iron has been melted. The legs curve outward
and the doors are hinged as far back as possible to protect them as
much as can be from the heat of this “drop”.
Breast. At one side, level with the bottom, is the breast opening,
at which place the fire is lighted, and in which the tap hole is formed
for drawing off the melted metal. The spout, protected by a fire-sand
mixture, projects in front of the breast and guides the metal into
the ladles.
Slag Hole. On cupolas over 36 inches inside of the lining, a
slag hole is provided, which is similar to the tap hole, and is placed
opposite the spout and about 2 inches lower than the main tuyeres.
Fig. 124 shows a section through a modern cupola furnace, and needs
but little further explanation.
Lining. In lining the stack, the layer next the shell is usually
made of boiler-arch brick about the size of regular fire brick. These
are set on end, and should be fitted as tightly together as possible,
and laid in a thin fire cement, made of very refractory fire clay
and fine sharp silica sand. The object is to fill every crevice with a
highly refractory material. Specially made curved fire brick can be
purchased for the inside lining, although some foundrymen use the
arch brick for this lining as well. The lining over the tuyeres is shaped
to overhang them slightly, to prevent melted slag dropping into them
during the heat. The lining burns out quickest about 22 inches
above the tuyeres, at what is practically the melting zone. The angle
shelves riveted to the shell, as seen in the illustration, allow this
section of the lining to be renewed without disturbing the rest of
the stack.
Tuyeres. The oblong air inlets, called tuyeres, are placed about
12 inches above the bed, and connect with an air-tight wind box
which surrounds the outside of the stack near the base. The tuyeres
direct the blast into the fuel, increasing the heat sufficiently to melt
the charge. In the wind box, opposite each tuyere, is an air-tight
sliding gate with a peephole, which allows the melter to look directly
into the furnace.
In the larger cupolas a second set of tuyeres is arranged about
10 inches above the main ones. They are used, when long heats are
112
FOUNDRY WORK
TABLE III
Sizes of Cupola Furnaces
Diameter
Inside of
Lining
(inches)
Cupola
Height
(feet)
Charging Door
Size
(inches)
Melting Capacity
LPer Hour
(tons)
Per Heat
(tons)
18
6 to 7
15 by 18
I to f
1 to 2
20
7 to 8
18 by 20
h to 1
2 to 3
24
8 to 9
20 by 24
1 to 2
3 to 5
30
9 to 12
24 by 24
2 to 5
4 to 10
40
12 to 15
30 by 36
4 to 8
8 to 20
50
15 to 18
30 by 40
6 to 14
15 to 40
60
16 to 20
30 by 45
8 to 16
25 to 60
run off, to make up for loss of wind caused by the main tuyeres
becoming partially choked by slag.
The height of the tuyeres above the bed varies with the class of
work to be poured. Where the metal is tapped and kept running
continuously and is taken away by hand ladles, as in stove-plate
work, the tuyeres are as low as 8 inches or 10 inches above the bed;
while in shops where several tons of metal may be required to fill
one mold, the tuyeres are as high as 18 inches above the bed. The
height of the spout above the molding floor also varies in the same
way; for hand-ladle work it may be but 18 inches above the floor,
while a height of 5 or 0 feet may be required to serve the largest
crane ladles.
Charging. Several feet above the bottom, there is a door in the
side of the stack, through which the stock is charged into the furnace.
A platform or scaffold is constructed at a convenient level below
the charging door, and all stock is charged into the cupola from
this platform. It should be at least large enough to store the stock
for the first two charges of fuel and iron.
Table III, prepared by Dr. Edwin Kirk, gives the approximate
height and size of charging door and the practical melting capacity
of cupolas of different diameters.
Blast. Fan Blower. Blast for the cupola is furnished by either
a fan blower or a pressure blower. Fig. 125 shows a modern fan
blower, of which the blast wheel is detailed at A. The high speed of
the blades forces the air, by centrifugal action, away from the
center of the shaft. The casing is so designed that the blades cut
FOUNDRY WORK
113
TABLE IV
Fan=Blower Performance
Fan Diameter
(inches)
Speed
(revolutions per minute)
Wind Pressure
(ounces per square inch)
18
4100
5
24
3750
6
36
2900
10
48
2600
14
off, as it were, at the top of the main outlet, the air being thus forced
through the blast pipe. The current of air is continually being drawn
into the fan through the central opening around the shaft.
Since air is very elastic, and the pressure in this case depends
entirely upon the centrifugal action of the blades, should the tuyeres
become clogged, the amount of air forced into the furnace will be
reduced proportionately. On the other hand, it requires less power to
operate the fan with reduced area of outlet than it does when the
discharge is open free.
An idea of the speeds at which blowers should run may be
obtained from Table IV.
Pressure Blower. In the pressure blower shown in Fig. 12G,
the action is positive, as will be seen from the sectional view A,
114
FOUNDRY WORK
Fig. 126. The wipers mesh into each other in such a way that they
entrap a quantity of air and force it out of the opening.
The full quantity of air is therefore forced through the tuyeres at
all times. In such case, the power necessary to operate the blower
increases as the tuyeres become choked, and the excessive force of
the blast, due to choked tuyeres, is hard on the lining of the
cupola.
Gage. The cupola should have a blast gage attached to the wind
box to measure the pressure of air which enters the tuyeres. The
pressure should be sufficient to force the air into the middle of the
cupola to insure complete combustion. The unit of air pressure is
1 ounce. From 8 to 16 ounces is approximately the range usual in
cupolas of from 48 inches to 70 inches diameter, inside lining.
This pressure is measured by the displacement of water or mer¬
cury in a U-shaped tube. With both legs of the tube the same size,
as in A, Fig. 127, the graduations represent the pressure of double
that height of liquid. Such graduations would be as follows:
FOUNDRY WORK
115
With a water gage, a difference in levels of 1.73 inches corre¬
sponds to 1 ounce wind pressure, so that the scale graduations per
ounce would be spaced
1.735
2
oo
1 .
= -865 =6i = Tin-64m'
With mercury, a difference in levels of 0.127 inch corresponds to a
pressure of 1 ounce so that the scale graduations would be spaced
0.127
2
= . 0635 in. = — in.
16
As this last spacing would be too small for practical use, mercury
gages, as at B, Fig. 127, are made with an increased area exposed to
the blast pressure, and are graduated
accordingly.
Principles of Melting. Combus¬
tion cannot take place without oxy¬
gen, of which the air is the most
abundant source of supply. For
example, in the incandescent electric
light, a strip of carbon is heated to
a white heat, but it does not consume,
or burn up, because all air has been
exhausted from within the globe.
In the cupola furnace, both coal
and coke are used as fuel. They con¬
sist largely of carbon, and, after being
lighted by the kindlings, are kept at
a glowing red heat by the natural
draft through the open tuyeres. The
blast supplies the oxygen necessary
for a melting heat. The quantity of
air forced in by the blast cannot be
entirely taken up by the layers of fuel immediately above the tuyeres;
thus, complete combustion does not take place until a distance of
18 to 23 inches above the tuyeres is reached. This is termed the
melting zone. It is the aim of the melter to keep the top of his bed
as nearly as possible at this level, so that the iron resting on it shall
be exposed to this intense heat and melt rapidly. As the fuel oi
— JO
— 9
— 8
— 7
— 6
— 5
y
— 4
— 3
y
—2
:
—7
-
0
B
/a
-/e
~/4
ri- J2
1:7 JO
a
—4
Fig. 127. Wind Gages
116
FOUNDRY WORK
the bed burns away, this level tends to be lowered. But the iron
on top of it melts and drops to the bottom of the cupola; and
the subsequent charge of coke restores the level of the bed for the
next charge of iron; and so on.
Cupola Operation
Running a Heat. The following routine must be pursued each
time a heat is run off in the cupola:
(1) Clear away the dump from the former heat.
(2) Chip out the inside of the furnace with a special hand pick,
removing the lumps of slag which collect about the lower part of
the cupola walls, especially above the tuyeres. Where the slag coating
is comparatively smooth, do not touch it, as that is the best coating
possible for the lining.
(3) Daub up with a mixture of fire sand, held together with
about 1:4 fire clay, and, wet with clay, wash to a consistency of thick
mortar. Smear the surface to be repaired with clay wash; then,
using the hands, plaster the daubing mixture into the broken spots in
the lining, being careful to rub it in well, especially about the tuyeres.
The top of the tuyeres should be kept slightly overhanging.
The greater part of the daubing will be required from the
bottom to the level of melting zone, about 22 inches above tuyeres.
(4) Siving up the bottom doors, and support them by a prop
of gas pipe.
(5) Build the bottom; first cover the doors with a 1-inch layer of
gangway sand or fine cinders; then ram in burnt sand tempered about
the same as for molds. This must be rammed evenly all over the
bottom, and especially firm around the edges. The bottom should
be made flat and level from side to side, with only a slight rise around
the lining which should not extend more than 1 or 2 inches from the
lining. The pitch varies with size of cupola; 1 inch to the foot will
answer for cupolas of 24 inches to 30 inches diameter inside lining,
while one-half that pitch will do for the larger furnaces.
The cupola bottom should be able to vent so that it will dry out
quickly, and not cause the metal to boil before the furnace is tapped.
It should be strong enough to hold its surface during the heat, but
to break and drop at once when the bottom is dropped. Too much
pitch causes excess of pressure on the bott, making trouble in botting
FOUNDRY WORK
117
up; with too little pitch the metal will not drain well, causing
a tendency to chill at the tap hole. A little daubing mixture
should be worked into the sand bottom just inside the tap hole,
to prevent breaking at this point when the tapping bar is forced
through.
(6) Lay the fire with shavings first, just inside the breast;
then with fine kindling; then with enough large kindling to make
sure of lighting a layer of coke sufficient to form the bed. When the
gases from the lower part of the bed burn up through, showing that
the fuel is well lighted, level up the bed with the addition of a little
more coke.
(7) The first charge of iron should
be put on now. Follow this with
alternate charges of fuel and iron, to
the level of charging door.
(8) Form the tap hole; lay a bar
of iron about | inch round in the
spout, projecting in through the breast
opening; fill in the breast around the
bar with a strong loamy molding sand
rammed hard. Recess this in well to
leave the actual tap hole as short as
possible.
(9) Put on the blast when ready
for the metal, and leave the tap hole
open. Bott up when the metal begins
to run freely—generally about 7 min¬
utes after blast is on.
Bott clay should be mixed with about § sawdust, to make it more
fragile when tapping, and is made up in small balls, and shaped onto
the end of the bott stick A, Fig. 128.
(10) Tap when sufficient metal has collected to supply the
first ladles.
The tapping bar B, Fig. 128, has simply a round taper point;
C is a gouge or spoon-shape, useful for trimming sides of hole if the
bott does not entirely free itself when tapped.
(11) Drop the bottom, when all the iron has been melted and run
off. This is done by pulling away the bar that supports the bottom
B
Fig. 128. Tapping Bara
118
FOUNDRY WORK
TABLE V
Foundry=Ladle Data
—
Hand Ladle
Bull Ladle
Crane Ladle
Geared Ladle
Illustration
Fig. 129 A
Fig. 129 B, C
Like C, with
bail
Fig. 130
Control
Hand shank
Single or
double hand
shank
Bail with
single or
double hand
shank
Worm gear
on heavy
bail
Capacity
30
80
300
1,000
(pounds)
50
350
2,000
35,000
Weight
15
35
115
1,900
(pounds)
16
100
350
7,000
Dimensions
(inches)
Inside
Shell
Lining
Thick-
Inside
Shell
Lining
Thick-
Inside
Shell
Lining
Thick-
Inside
Shell
Lining |
Thick-
ness
ness
ness
ness
Top
7 to 8
3
4
9 to 15
li
14 to 26
1 4
20 to 75
2 to 4
Side
7 to 8
1
2
9 to 15
1 to f
14 to 26
I to 1
20 to 60
1 to 4£
Bottom
6 to 7
§ to f
8 to 13
f to 1
12 to 23
1 to 3
18 to 66
1§ to
doors. Throw water on the dump by bucket or hose, to deaden the
heat, and leave it to cool off over night.
Foundry Ladles. As the melted metal flows from the spout of
the cupola, it is caught in ladles. The sizes of these are designated
by the weight of metal they will hold; they vary from 30 pounds
to 20 tons capacity.
Table V, containing references to Figs. 129 and 130, give compact
data regarding foundry ladles.
The names of ladles relate to the method of carrying them.
Hand ladles are made of cast iron or pressed steel. The larger
ladles are built up of boiler plate. Cast iron is poured from the top
of the ladle, which should therefore be provided with lips.
Lining. Ladles must be lined to protect them from burning
through. Up to 1-ton capacity, the cupola daubing mixture is used.
The bowl is smeared with thick clay wash, and the clay pressed in
hard with the hands, being rubbed smooth on the inside. The
lining should be kept as thin as possible, f to f inch on hand ladles,
1 inch to 12 inches on large ones; the bottom lining being from
FOUNDRY WORK
119
one-third to one-half thicker than sides, as it receives the first fall
of the incoming metal.
The larger ladles are first lined with fire brick of thickness pro¬
portionate to their size, and then daubed on the inside with clay
mixture similar to cupola lining. The lining must be well dried before
use, to drive out moisture. In stove-plate and hardware shops,
where most of the pouring is done with hand ladles, a special ladle
drying stove similar to a shallow core oven is provided. A wood fire
is built inside of the larger ladles to dry them out. To preserve a
lining as long as possible, slight breaks are repaired daily. As with
the cupola, the slag formed by the hot metal forms the best coating
possible for the inside lining.
Pouring. The first thing to be considered in connection with
pouring is skimming off the slag which collects on top of the metal.
This should be done on
the larger ladles before
leaving cupola, and again
while metal is being
poured. For this, a long
iron rod is used, with
blade shaped as in D,
Fig. 128. This is rested
across the top of the ladle near the lip, and effectively holds the
slag back; the long handle permits the skimmer to stand well back
from the heat of the metal. On small ladles, skimmers are of course
shorter, and the end is bent up more, for convenience, as the ladles
will be much nearer the floor when pouring with them.
Hand and bull ladles are shown in Fig. 129, while Fig. 130 shows
a crane ladle.
General Precautions. Much skill is required in pouring a mold.
A molder must knowr the character of the work, and judge whether
it must be poured fast or slowly. In general, light work cannot
be poured too fast. Heavier work is poured more slowly. Care
must be exercised to keep the stream steady from the first, and not
to spill into the mold, as this may cause cold-shuts or leave shot iron
in the castings. The runner basin must be kept full, for gates and
runners are made with this express purpose in view, as has been stated
previously.
Fig. 129. Hand and Bull Ladles
120
FOUNDRY WORK
Metal must not be allowed to chill or freeze in the ladle, as this
would destroy the lining when it came to removing the cold metal.
Metal left in the ladles when the mold is full, must be poured back
into a larger ladle or emptied into a convenient pig bed. These latter
are built in a sand bed usually near the cupola; or stout cast-iron pig
troughs or chills are provided. The chills should taper well on the
inside, holding about GO pounds each. Some are arranged to swing
on trunnions for convenience in dumping. They should be smeared
with a heavy oil and dusted with graphite, to prevent the metal stick¬
ing in them. It is safer to heat these pig molds as well, so that no
moisture will form and cause a kick or explosion when hot metal is
first poured into them.
Cupola Mixtures
Requirements. By the term cupola mixture is meant the propor¬
tioning of the various pig irons and the scrap that make up cupola
charges, with the object of obtaining definite physical and chemical
properties in the resulting castings.
The requirements of castings vary; and metal that would be good
if run into thin stove plate, would be entirely too soft for heavy
machine castings. Again, iron that might answer all requirements of
a bed plate would not be strong and tough enough for steam-cylinder
FOUNDRY WORK
121
work. The one in charge of this work, therefore, must so mix the
different irons that his castings shall be soft enough to machine well if
necessary, and at the same time be hard enough to stand the wear and
tear of use.
Precision Essential. Formerly the appearance of the fracture of
a pig or of scrap was the sole guide in determining mixtures. Unques¬
tionably the fracture of iron indicates to the experienced eye much
as to its physical properties, but this method of mixing has repeatedly
proved misleading.
Representative practice today recognizes chemical analysis of
the various irons as most essential to the proper mixing. Many firms
now buy their pig iron and many other allied supplies by specification;
and the chemical analysis of the iron must show that its various
metalloids come within certain limited per cents.
To understand, then, these modern methods, we must consider
the subject of the chemistry of iron.
Affecting Elements. By the chemical definition, an element
is a form of matter which cannot be decomposed, or, in other words,
cannot be broken up into other forms by any means known to science.
Iron is such an element; but absolutely pure iron is of no com¬
mercial value; it is only when it is combined with impurities—or, as
we must recognize them, other chemical elements—that mankind is
interested in it.
In the forms of iron with which we are dealing—pig iron, and
cast iron—five elements are considered as affecting their physical
properties. These elements are carbon, silicon, sulphur, phosphorus,
and manganese.
Carbon. Carbon is the most important and most abundant of
all the chemical elements. It forms the principal part of many
substances in daily use about us, such as coal, coke, lead pencils,
graphite facings, etc.
In its relation to iron, carbon is peculiar in that it occurs in iron
m two forms. One is in a chemical combination forming a hard
substance with a fine grain, of which tool steel is the purest type. The
other is simply a mechanical mixture forming minute facets of free
carbon interposed between the crystals of the combined form. It
softens cast iron, but weakens it by causing larger crystals to form.
In drawing the finger across a freshly cut surface or fracture of cast
122
FOUNDRY WORK
iron, some of this free carbon may be rubbed off, and shows as dirt
on the finger. We shall use the term graphite in referring to this form
of free carbon, and the term combined carbon in referring to the element
in its combined state.
Silicon. Silicon, of itself, is a hardening element in cast iron,
but on account of its marked influence upon carbon formations, it is
usually considered a softener. During the cooling process, silicon
retards the formation of combined carbon, thus increasing the forma¬
tion of graphite in proportion to the increase of silicon. At the same
time, through its own influence on iron, it preserves the fine
character of the grain, and so maintains the strength of the cast¬
ing. In other words, within certain limits, the addition of silicon
softens castings without impairing their strength. It makes iron
run more fluid, and reduces shrinkage. Silicon varies in castings
from 1.50 to 2.50 per cent.
Sulphur. Sulphur is the most injurious element in iron. It
makes castings hard, red-short, and tends to the formation of blow¬
holes. At the melting temperature, iron absorbs sulphur from the
fuel—a decided reason why foundry coke should be as free as possible
from this element. Sulphur in castings should not exceed 0.07
per cent.
Phosphorus. Phosphorus tends to make iron run very fluid
when melted. It is a hardener: For machine castings it should not
exceed 1 per cent.
Manganese. Manganese strengthens, and, of itself, hardens
iron. Chemists are beginning to consider its proportions more care¬
fully, in the belief that under certain conditions it acts as does silicon,
softening the castings while retaining their strength. It is usual to
keep it below 0.50 per cent.
Factors of Quality. The strength of a casting and the finish
which it is capable of taking are largely dependent upon its having a
fine even grain. We have seen that the porportions between the com¬
bined carbon, the graphite, and the silicon have decided influence
upon this condition. But the rate of cooling must also be taken into
account. A thin casting cools rapidly, tends to increase the combined
carbon, and, without the influence of silicon, would be hard and
brittle. In a heavy casting, the metal stays liquid longer, more
graphite is thrown off, and the casting is naturally softer. There-
FOUNDRY WORK
123
fore light work requires a larger proportion of silicon to counteract
the effect of the rapid cooling than does larger work.
Chemical Analysis. Modern practice makes daily analysis for
the two carbons, for the silicon, and the sulphur, occasionally testing
for the other elements to see that they are kept within their safe
limits. Silicon, however, is used as the guide for regulating mixtures.
Proportions of Silicon. The following shows good proportions
of silicon for different classes of work:
Casting
Silicon
(per cent)
Steam cylinders
Medium heavy work U-inch to 2-inch thickness)
Light work (less than -Fkmh thickness)
1.70
2.00
2.50
A more complete analysis of results to be aimed for is:
Casting
Elements
(per cent)
Silicon
Phosphorus
Sulphur
Manganese
Automobile cylinders
2.25
1.0
0.075
0.5
Corliss engine cylinders (lj- to
U-inch thickness)
1.20 to 1.70
below 0.1
below 0.095
0.5
To calculate for any result, we must first know the analysis of the
irons to be used in making the charge. We shall consider silicon as
the guide.
In keeping track of results, the proportion of silicon in the
local scrap of an establishment can be accurately estimated. With
miscellaneous machinery scrap, this is more difficult; the following,
however, are safe estimates:
Casting
Silicon
(per cent)
Small thin scrap
Large scrap ranges
2.0 to 2.4
1.50 to 2.0
Method. The analysis of pig iron is made from drillings taken
from a fresh fracture. Between the very fine grain about the chilled
sides of the pig and the very coarse grain in the center, average-sized
124
FOUNDRY WORK
crystals will be noticed in the fracture. It is here that the drillings
for analysis should be made, as indicated in Fig. 131. About a
f-inch flat drill is best to use, as it cuts a more uniform chip from the
varying grades of pig than does a twist drill.
To determine the analysis of a carload lot of pig iron, the
following method is employed: Select ten pigs which will represent
an average of the close, medium, and coarse-grained iron in the car.
These pigs should be broken, and drillings taken from the fresh
fracture. The drillings from these ten fractures are thoroughly
mixed together, and about 2 ounces by
weight, or a large tablespoonful by meas¬
ure, is sufficient for the chemical analysis.
The result is taken as the average analysis
of the carload.
The smaller foundries who do not
employ a chemist can get a good work¬
ing analysis of their iron from the fur
nace from which it is bought. Or, in
many cases, sample drillings are sent to a practicing chemist.
Usual Silicon and Sulphur. The proportions of silicon and
sulphur contained in the ordinary grades of pig iron are approximately
as follows:
Fig. 131. Section of Pig Drilled
for Analysis
Grade of Pig
Silicon
(per cent)
Sulphur
(per cent)
Ferrosilicon
7 to 12
0.03
Silvery
3 to 5
0.03
No. 1 foundry
2.50 to 2.90
0.03
No. 2 foundry
1.95 to 2.40
0.04
No. 3 foundry
1.40 to 1.90
0.05
Calculation of Mixture. When we have the analysis of our iron,
we can proceed to calculate the mixture, bearing in mind that some
of the silicon will be burned out of the iron during the heat. From
0.15 to 0.25 per cent is a fair estimate for this loss in cupolas ranging
in size from 36 inches to 72 inches inside lining. This loss must be
deducted from the final estimate.
Illustrative Examples. It is proposed to make a mixture for
miscellaneous machinery castings which require about 2 per cent
FOUNDRY WORK
125
of silicon, and we wish to use one-half scrap and three other irons,
whose silicon contents are as follows:
Grade of Iron
Silicon
(per cent)
Silvery
4
No. 1 foundry
2.65
No. 2 foundry
2.22
No. 3 foundry
1.75
Scrap
2.00
The student should bear in mind that per cent means tId
or .01. To multiply a whole number by per cent, set the decimal
point two places to the left in the percentage; thus 35 per cent of
5,000= .35X5,000 = 1,750. In multiplying per cent by per cent
set decimal points in the percentages one place to the left before
multiplying, and the result is expressed as per cent; thus 25% of
35% = 2.5X3.5 = 8.75 per cent.
Then we may have the following proportions of silicon, using the
above irons:
(A)
(B)
(C)
(D)
No. 1
25%
X2
.65% =
= 0.6625%
No. 2
20%
X2
•22% =
= 0.4440%
No. 3
5%
XI
•75% =
= 0.0875%
Scrap
50%
X2
•00% =
= 1.0000%
Total silicon content =2.194 %
Deduct for loss in heat = 0.20 %
Estimated silicon in result =1.994 %
Or, -with No. 2 and silvery irons, we may have:
(A) (B) (C) (D)
No. 2 45%X2.22% =0.999 %
Silvery 5%X4.00% = 0.200 %
Scrap 50% X2.00% = 1.000 %
Total silicon content =2.199 %
Deduct for loss in heat =0.17 %
Estimated silicon in result =2.029 %
In these examples, column (A) is the kind of iron; (B), per
cent of this iron used in charge; (C), per cent of silicon in single
grade of iron; (D), per cent of silicon to whole charge as supplied
by each grade. One or more per cents in column (B) are usually
126
FOUNDRY WORK
decided upon before beginning calculations, and then the others are
varied until the desired silicon content is obtained.
With this as a guide, it is a simple matter to find the actual weight
for each grade, to make up any size of charge. For example, we wish
to put 5,000 pounds on the bed and 3,000 pounds on other charges.
Then, using the first mixture and the ratio 5:3 between the bed and
the other charges, we have:
From column (B) Bed Other charges
No. 1 25% X5,000 = 1,250 lb. 750 1b.
No. 2 20% X5,000 = 1,000 lb. 600 1b.
No. 3 5% X5,000= 2501b. 150 1b.
Scrap 50%X5,000 = 2,500 lb. 1,5001b.
Total iron 5,000 lb. 3,000 lb.
Fuel. Both anthracite coal and foundry coke are used in the
cupola. Coal, owing to its density, carries a heavier load than coke,
but it requires greater blast pressure and does not melt as fast
as coke.
Foundry Coke. Coke, for foundry use, should be what is known
as “72-hour” coke, as free as possible from dust and cinders. Coke is
made up of a sponge-like coke structure which is almost pure fixed
carbon, and an open cellular structure, which makes it especially
valuable as a furnace fuel because it is so readily penetrated by
the blast.
A representative analysis of a strong 72-hour coke is as follows:
Item
Proportion
(per cent)
Moisture
0.49
Volatile matter
1.31
Fixed carbon
87.46
Sulphur
0.72
Ash
10.02
Cellular structure
50.04
Coke structure
49.96
Heat units per pound
12,937 B.t.u.
Specific gravity
1.89
Proportions of Charge. The proportions of the bed fuel, the
first charge of iron, and the subsequent charges of fuel and iron vary
FOUNDRY WORK
127
greatly with the size and design of the cupola, the grade of fuel used,
and the method of charging. To determine the right amount of fuel
for the bed, the most practical thing to do is to cut and try, especially
with a new equipment.
For 36- to 48-inch cupolas, averaging 22 inches above the tuyeres
for the melting zone, with a 10-ounce blast to start, the best way to
proceed is to chalk off this distance inside the cupola before daubing
up. Then, from a |-inch rod of iron, bend a shape like Fig. 132.
The distance a equals the distance from the mark inside the cupola
to about 4 inches above the bottom of the charging door. When the
coke is well lighted, before charging the iron, level off the bed accord¬
ing to this gage. The safe practice is to have the bed too high. If the
bed is too high, it is indicated by slow but hot metal; if the bed
is too low, the metal is dull. After n
the first heat, the height may be - a -
adjusted until proper melting is y- 1 ===J)
obtained; then try always to work
to the same height.
The weight and character of the T. „ , „
° Fig. 132. Bed Gage
coke charged on the bed should be
carefully noted. The first charge of metal should be in the pro¬
portions of 2 pounds of metal to 1 of fuel; all others in the ratio of
10 of metal to 1 of fuel. Intermediate charges of coke should be
just sufficient to preserve the upper level of the bed. The layer is
usually about 6 inches thick; its weight should be carefully taken.
The action of the furnace must be carefully watched, with the
object of making it melt the iron charged as rapidly as possible and
of bringing it down white hot. Also, the ratio of iron to fuel should
be reduced as low as may be, without sacrificing either of these other
objects.
Supplementary Operations
Sand Mixing. When a mold is poured, the intense heat of the
iron burns out those properties in the sand which give it its bond,
making it necessary that a certain proportion of new sand shall
be mixed with the heap sand and used as facing, as has been explained
in earlier paragraphs.
The facing sand should be mixed daily for the molders by one
or more of the laborers, at a place convenient to the storage sheds
128
FOUNDRY WORK
and molding floors. A hard smooth floor of clay or of iron plates
is a great advantage.
The proportions of the different sands are measured by the
shovelful, bucketful, or barrowful, and the sands are spread over each
other in flat layers, sufficient water being sprinkled on to temper the
pile. The sand then is cut through once with the shovel, is put through
a No. 2 sieve, all lumps being broken up, and the refuse thrown
out is put through a No. 4 sieve, and finally is thrown in a pile
ready for use.
When this work is done by hand, the ordinary screen sieve com¬
monly employed by masons is used for the riddling, and a round
foundry riddle for the final sifting. To reduce the labor of this, the
riddle is slid back and forth on a pair of parallel bars supported
conveniently above the storage pile.
Mixing Machines. The two classes of labor-saving machines
used in mixing facings, core sand, etc., are those which mix by
FOUNDRY WORK
129
riddling; and those which mix by a combined breaking and stirring
action. There are many varieties on the market, the illustrations
shown being typical.
The rotary sieve shown in Fig. 133 is made with wire screen on
the revolving sides, and is driven by belt or connected motor. Sand
shoveled into the central
opening is sifted in a pile
on the floor, or directly
into a barrow. The rub¬
ber hammer on top auto¬
matically raps each face
of the sieve as it re¬
volves, knocking the
meshes free of sand.
Fig. 134 shows one
of the latest labor savers
in this line. Here a
foundry riddle is supported in a metal ring attached to the piston
of the machine. It is made to vibrate rapidly by means of com¬
pressed air or steam. These shakers are made with portable tripod,
as shown; they are also made stationary or are fastened on a post
130
FOUNDRY WORK
by means of a swivel joint, to be swung over a wheelbarrow or over
a molding machine, and out of the way again when not in use.
Fig. 135 shows a centrifugal mixer. Inside of the umbrella
casing, a horizontal plate about 12 inches in diameter and carrying
a number of vertical steel pins about 6 inches long is fastened to the
top of a short upright shaft driven by a belt running inside of the
casing shown at the base of the machine. The machine runs about
1,500 revolutions per minute; and sand shoveled into the hopper is
very evenly broken up by the pins and thrown against the steel hood,
breaking and shattering any lumps of clay or loam and making a
very uniform mixture. The hopper may easily be removed to clean
the plate. The machine is used for the final mixing.
Fig. 136 shows a foundry grinder or facing mill. It is the type
of mill used for mixing loam. Either the pan or the rollers are
attached to the driving shaft and made to revolve, crushing and
mixing whatever is shoveled into the pan. Frequently, a stout blade,
something like a plowshare, is fixed between the rollers, and prevents
the mixture caking to the bottom of the pan. The faces of the rolls
are of very hard or of chilled cast iron to withstand wear. When the
loam mixture is sufficiently ground, it must be shoveled from the pan,
FOUNDRY WORK
131
and delivered to the molders or stored temporarily. It will set if
stored too long. This is the type of mill used in the steel foundries,
for grinding the facing materials. The various sands are dumped
into the pan at one side, and, when ground sufficiently, are shoveled
directly from the pan into a centrifugal mixer. This prepares them
for use.
Cleaning Castings. After a casting has solidified in the mold,
the flash should be removed, leaving the casting in the sand. For
light bench work and snap-flask work, the mold is lifted bodily and
the sand dumped on the pile; the bottom boards are piled in one
place, and the cases are piled in another ready for the next day’s
work. As the molds are dumped, the castings are removed from the
sand and piled at the edge
of the gangway. When all
castings have been removed
from the sand, the gates
are broken and thrown in a
pile by themselves. When
cold enough to handle, the
castings are removed to the
cleaning room, and the gates
and sprues are sent to the
scrap pile. With heavier
n i,ii Fig. 137. Dustless Tumbling Barrel
floor work, the clamps are
removed as soon as the casting has set; the flash is rapped with a sledge
hammer and is stripped off the mold, leaving the castings to cool
gradually in the sand. Sometimes a sharp blow is given on top of the
runner while it is still red; this breaks it off before the flask is shaken
out. At a red heat, cast iron is very weak and can easily be broken.
Tumbling. The most effective way to clean small castings is in
a rattling barrel. Fig. 137 shows a modern set of dustless barrels.
The shell of the barrel is f-inch boiler plate riveted to cast-iron
heads, with a door arranged to be entirely removed for packing and
dumping. The bearings are hollow, and from one end the dust is
drawn off through a galvanized-iron pipe. This pipe connects with
an air-tight wooden chamber, as shown in Fig. 138, varying in size
with the number of barrels connected with it. In this chamber hang
a number of cloth-covered screens. An exhaust fan is connected to
132
FOUNDRY WORK
this chamber at the opposite end from the inlet pipe. When the fan
is in operation, a strong current of air is drawn through the barrels
and through the chamber. The dust, entering the chamber, settles
on the screens, so that but little dust escapes to the outside air.
When necessary, the exhaust is stopped, and, by means of a crank
on the outside of the dust chamber, the screens are shaken and
the dust drops off, when it can be removed through a trap into an
ash can or wheelbarrow.
The driving shaft
carrying the pinion re¬
volves all the time, and
any barrel may be thrown
over into gear or drawn
out of gear by the opera¬
tion of a hand lever. The
barrels should run about
25 revolutions per minute.
Each barrel should be
packed as full as possible
with several shovelfuls of
gates, shot iron, or hard¬
ened stars thrown in with
the castings. The clean¬
ing is accomplished in
from 20 minutes to half
an hour by the scouring
action of castings, scrap,
Fig. 138. Dust Collector for Tumbling Barrel . i i • • , ,
etc., rubbing against each
other. Castings up to 50 or 100 pounds can be rattled, but only
those of a similar character as to design or weight should be packed
in together, otherwise the lighter castings will be broken by the
heavier. When removed from the barrel, the work should show a
smooth clean surface of an even gray color.
From the rattlers, castings go to the grinding room, where pro¬
jecting gates or other slight roughness is removed on the emery
wheel.
Heavy castings are cleaned by hand, by pickling, or by sand¬
blasting.
FOUNDRY WORK
133
Fig. 139. Steel Bristle Brush
Hand-Cleaning. When cleaning by hand, the worst of the sand
is rapped off by light hammering, the remainder scraped off with
old files and with steel-wire brushes such as that shown in Fig. 139.
Some shops rub off finally with broken
pieces of coarse emery wheel. Risers
and fins are removed with cold chisels.
The pneumatic chisel, shown in
Fig. 140, is used as a timesaver.
Where work is light enough to handle,
small fins are removed by emery
wheels; medium coarse wheels will
cut faster on cast iron than fine ones,
and will hold their shape better.
It is when castings must be
cleaned by hand, that the value of a good facing dust shows itself.
With the proper facing, the sand parts readily from the casting
leaving a fine-looking smooth surface. With poor facings, on the
other hand, the iron burns
into the sand, making it
hard to clean, and leaves
a rough surface on the
work.
Pickling. Pickling is
a method of cleaning re¬
sorted to where there is
much machining to be done
on a casting. The work is
placed in a pile on a suit¬
able platform, and dilute
sulphuric acid is thrown
over it during one day,
frequently enough to keep
it well wet. The platform
should be arranged to drain
the acid back into the vat. Acid is diluted from 1:8 to 1:10. After
about 12 hours’ bath with acid, the castings are washed clean with hot
water. The acid acts on the hard skin of oxide of iron which forms
when the iron strikes the damp sand, and it eats through this skin to
Fig. 140.
Pneumatic Chisel for Cutting
Risers and Fins
134
FOUNDRY WORK
the iron itself. The washing water should be hot enough to warm
the castings sufficiently for them to dry rapidly without rusting.
The acid must be thoroughly washed off, or it will continue to eat
into the iron and cause a white powder—sulphate of iron—to form
on the surface.
An excellent arrangement for a pickling department is to have
the trough arranged on skids which allow it to be rocked endwise.
FOUNDRY WORK
135
This drains into the pickling vat when acid is being thrown on, and
into the gutter when the castings are being washed. Sheet lead is the
best protective covering for small pickling troughs, but it is expensive
and not durable enough to stand for heavy work.
Sand-Blasting. For castings of such shape and size that they
cannot well be rattled, but are too small to be cleaned by hand, the
sand blast has been used to advantage in many shops.
Fig. 141 gives an idea of the arrangement of the cleaning stall.
Castings are placed on the wooden grating. By means of coin-
Fig. 142. Core Rod Straightener
pressed air a sharp silica sand is forced through a strong rubber hose
and is directed against the castings by a hardened-steel nozzle.
The operator wears a helmet supplied with fresh air by an air hose,
to protect his eyes and lungs from the clouds of fine dust. An exhaust
hood is arranged also to take off as much of the dust as possible.
The manual labor of this method is practically reduced to noth¬
ing, aside from handling the castings. The system, however, requires
the installation of a rather considerable equipment, which has debarred
its use in many foundries.
136
FOUNDRY WORK
Re-Use of Core Rods. In removing cores, the bars become very
much bent. In such shape they were formerly scrapped, or refitted
to suit new cores with a hammer and block of iron. Fig. 142 shows a
very practical power machine which delivers the bars perfectly
straight. The machine consists of a pair of rolls, with different
sizes of grooves turned in them, which pull a rod through a flaring
mouthpiece and deliver it through a corresponding eye on the
opposite side. The machines are made in different sizes, and take
rods'from 1-inch to f-inch diameter.
STEEL WORK
Present Development. This class of work has developed within
the last few years, and, beginning with the heavier parts of marine
and engine construction, it is now crowding the field of drop forgings.
Steel castings are malleable, and are very much stronger than iron
ones. The principles of molding involved are similar to those in
other classes of molding, but practice is varied to meet special
conditions.
Processes. The art of making steel castings may be divided
into three heads: (1) preparation and melting of the metal; (2)
making and pouring the molds; (3) heat-treatment of finished castings.
As the first and third heads come more properly under other depart¬
ments, we shall here simply outline these processes, dealing in detail
with the second heading only.
Characteristics of Metal. This branch of foundry work has
developed to a great extent since the early nineties. The metal is
similar in mixture, method of melting, and physical properties to the
steel which is poured into ingot molds for forging purposes. The
graphitic carbon is entirely burned out; the strength of the metal is
therefore very much greater than that of cast iron. Combined carbon,
manganese, and silicon are the elements depended upon for this
strength; sulphur and phosphorus are kept very low. A typical
analysis shows these elements in the following proportions:
Carbon Manganese Silicon Sulphur Phosphorus
0.27% 0.85% 0.35% 0.020% 0.025%
Owing to the purity of this form of iron, about 50 per cent more
heat is required to melt it than is necessary in the case of pig iron—
or about 3,300 degrees Fahrenheit. When melted, the metal runs
FOUNDRY WORK
137
much more sluggishly than cast iron, and, on account of the absence
of graphitic carbon, it does not expand at the moment of solidifying,
and therefore does not take as sharp an impression. To insure as
perfect an impression as possible, the molds are constructed with a
good head of metal in the risers, and they are poured under pressure.
The shrinkage is double that of iron; the risers are made very large,
and are placed directly on the casting to insure feeding well. Great
care must be exercised
that neither mold faces
nor cores bind during
cooling, as such binding
might cause a flaw.
Shrinkage. When
two surfaces meet at right
angles, the corner re¬
mains hot longest, and
the sides shrink away, tending to cause a fracture at a, Fig. 143.
To overcome this, thin webs are cut by the molder about every
4 inches or G inches—shown at b. These cool first, and hold the
adjacent sides in position, preventing them from pulling away from
each other. The internal strain due to this cooling is relieved by the
annealing. After the casting is annealed, the webs are cut away.
STEEL MOLDS
Facing Mixtures. To withstand the high heat, pure silica sand
is used as the basis of the facing mixtures for steel molds. Pure
quartz or silica rock is quarried, and reduced to sand form through
a series of rock crushers. At the foundry the necessary bond is given
by the addition of fire clay and molasses water. These are thor¬
oughly mixed with the sand in a facing mill and mixer, Figs. 135 and
136. A typical mixture is as follows:
1 barrow silica sand
3 pails powdered fire clay
Temper with molasses water
Where quartz sand is very expensive, the following mixtures,
I, II, III, or IV, will reduce the cost. The old crucibles and fire brick
should be crushed separately in the mill before mixing.
138
FOUNDRY WORK
Ingredients
Proportions
(Castings up to 2 In.
Thick)
(Castings over 2 In.
Thick)
(I)
(II)
(HI) •
(IV)
Old facing sand
8
12
1
Old crucibles
2
10
Fire brick
2
5
Fire clay
2
1
3
1
Coke
1
1
Silica sand
5
5
Graphite
2
Tempering medium, molasses water
Forfeiting wash, these mixtures are ground very fine, and thinned
with molasses water.
Core sand for steel work is practically the same mixture as the
mold facing. For thin metal a somewhat less refractory natural
sand may be added to reduce the cost of the mixture.
For small round or flat cores, -gV part rosin, with silica sand,
tempered with molasses water, makes a good core. It should,
however, be thoroughly
burnt.
For core-wash mix¬
ture, use 3 parts silica
flour; 1 part Ceylon
graphite; molasses
water.
Flasks. Flasks for
steel work are built of
cast iron, Fig. 4, Part I.
Full-length crossbars are
bolted in the cope, 6
inches to 8 inches on centers, depending on the size of the flask.
Short crossbars are fastened between these as needed, say 12 inches to
16 inches on centers, as seen in Fig. 144. Oblong bolt holes 4 inches
on centers are cast in the sides of the flask and in all crossbars.
Slots to correspond are cast in flanges of bars, so that they may be
readily removed or shifted when fitting the cope to the pattern.
FOUNDRY WORK
139
The holes for pins should be drilled to template in all flasks of the
same size, so that copes and drags may be interchanged. Flask pins
are slipped through the holes temporarily when the flask is being
closed or opened.
On large work the cope is bolted to the drag while being rammed.
The bottom plate is of cast iron, and is clamped to the flange of the
drag with short clamps and steel wedges. The same tools are used
for packing and finishing the mold as those described in connection
with iron molding.
Flasks of from 18 inches to 48 inches in length have two handles
bolted on the ends to lift them with. Larger flasks have trunnions,
rockers, or U-shaped handles cast on the sides.
Fig. 145. Small Flask for Steel Molds
Fig. 145 shows type of convenient small flask built up of channel
and angle iron, size 14 by 20 to 24 by 48 inches.
Packing. In packing the mold, place the pattern on the board
and cover with 1| to 3 inches of facing, depending on the size of the
job. Tuck well with the fingers. The facing is used as prepared by
the mixer, not sifted. Set the drag on the board, shovel in heap sand,
and ram the mold somewhat harder than for iron. Strike off, and
seat the bottom plate, fastening it firmly to the flange of drag with
clamps or bolts. When this is done, roll the mold over, and remove
the moldboard.
Press with the fingers all over the joint surface, especially
around the pattern, to make sure of firm packing. If soft places are
140
FOUNDRY WORK
found, they should be tucked in with facing sand. When needed
repairs are made, slick the joint all over. Use burnt core sand for
making the parting.
Try on the cope and adjust bars to fit the pattern. Clay-wash
the cope before packing. Put on necessary facing over the joint
and the pattern. Set the gate on the joint, but place risers directly
on the pattern. Set the necessary gaggers, shovel in heap sand, and
Fig. 146. Section Through Steel Mold
ram the cope. Vent well, lift the cope, moisten the edges, and
draw the pattern.
In finishing the mold, nails are used freely, about 1| to 2 inches
apart, driven in till the heads are flush with the surface of the sand.
This is to prevent the cutting of the surface by the rush of hot metal
when the mold is poured.
It is at this stage that the thin webs previously mentioned, are
cut into the corner fillets where needed. The whole surface of the
mold must be smoothly slicked over with the trowel and convenient
slicks. When this is done, paint on the facing wash with a very
flexible long-bristled brush.
FOUNDRY WORK
141
Fig. 146 shows the section of a mold for a shrouded pinion, and
illustrates the points above mentioned. The runner is lead in at the
bottom by use of a cover core, as described in Dry-Sand Molding.
Molds for steel should be more than dried; they should be
thoroughly baked to drive off every particle of moisture. This
prevents the steel boiling in the mold and causing imperfections in
the casting.
Where but little machine work is to be done on small work up to
1| inches thick, the molds may be made up in wooden flasks and
poured green. For this class of work, only pure quartz sand and
fire clay are used, tempered with molasses water. These may be
made up and poured on the same day.
Cores. Cores for steel molds are made up in boxes similar to
those used in the iron foundry. Although using special sands, the
cores are strengthened with iron rods, vented with cinders, and
provided with convenient hangers for lifting, as described in previous
paragraphs.
Where cores must be made in halves, one set of half-cores may
be made and baked. The other half is then made and rolled over
directly on the baked half. Fire-clay wash is used to cement the
joint. This method allows the joint between the halves of a core to
be nicely slicked down.
Steel cores must be more collapsible than those for iron, on
account of the excessive shrinkage of the metal. This is provided
for in the mixture of the sand used, and by thoroughly baking the
core to reduce the effect of the binding materials to a minimum.
STEEL CASTINGS
Running a Heat. Open-Hearth Melting. The melting of steel
is a science by itself, and cannot be dealt with adequately in an
article of this character. Only a very brief description of the
process is given.
The main feature is the difference in application of heat. Metal
is melted in what is termed the open-hearth furnace, a sectional plan,
of which is shown in Fig. 147. The charge of scrap steel and pig iron
is placed on the central hearth. Heat is obtained by producer gas
supplied with air blast. Both gas and air are heated in one set of
regenerators before entering the combustion chamber. The flame
142
FOUNDRY WORK
plays on top of the charge, and the waste gases pass off through
the other regenerator section of the furnace, heating up its brick¬
work. The direction of the gases is changed about every 20 minutes.
The regenerator is practically a tunnel about 15 feet long, filled with
brickwork built up as shown in Fig. 148. About 4 heats a day are
run from the furnaces.
Samples of the bath are analyzed at intervals during the heat.
Guided by these analyses the proper proportions of ores, fluxes,
Regenerators
Regen era tors
Fig. 147. Section through Open-Hearth Furnace with Regenerators
and pig are added to the bath to give it the right composition, a
typical analysis of which has been given.
Vowing. When the bath is in proper condition, the entire charge,
be it 5 tons or 40 tons, is drawn off into a ladle previously heated by
a special gas burner. This ladle is lifted by the crane and carried to
the pouring floor.
In order to secure the soundest metal free from pent gases or
slag, all steel for casting purposes is tapped from the bottom of the
ladle. The stopper is carried by a stiff round bar encased in fire-clay
tubing. This passes through the liquid metal, as in Fig. 149, and may
be raised or lowered by an arm attached to a rack-and-pinion mech¬
anism bolted to the outer shell of the ladle and operated by means of
a large hand wheel. The ladle is swung into position with the tap
FOUNDRY WORK
143
hole directly over the pouring head. Four men hold the ladle steady
with long iron rods. The metal thus enters the mold under the head
of pressure of all the steel above
XL
n
Fig. 148.
XL
u cr
TT
How Brick Is Set in Regenerators
it in the ladle.
When all the steel is drawn
from the ladle, the latter is swung
on its side near the furnaces, the
stopper is removed, and all the
slag possible is racked out. The
ladles must be repaired after each
heat, often to the extent of replac¬
ing one-half of the thin fire-brick
lining. The casing of the
stopper will last for but one
heat, as the rod is sure to
get bent out of shape. The
rods are repaired by a black¬
smith before recasing them.
Setting Up Molds. Set¬
ting up is usually done by
a different set of men from
those employed to make the
molds.
For convenience in pour¬
ing, runner boxes, such as
shown in Fig. 150, and which
serve simply as funnel-shaped
mouths to the runners, are rammed up
in small round shbet-metal boxes, using
a wooden pattern to form the hole.
These are baked in the oven.
When the molds are properly dried,
they should be removed from the even,
placed on the pouring floor, and have the
dust blown out with compressed air.
Now set the cores, close the molds, and clamp along joint flanges.
Set runner boxes over the runners, and tuck heap sand around to
prevent leakage. In pouring, a mold is filled only to the level of
Fig. 149. Section of Steel Ladle
Fig. 150. Runner Box for
Steel Mold
144
FOUNDRY WORK
the top of the risers. The metal drains from the runner box, thus
allowing it to be used more than once.
Cleaning Castings. Steel castings do not run as smoothly as
cast-iron ones, but they have this advantage, that, if they show only
slight surface defects, the metal may be peened over with a hammer
to improve appearance. The intense heat makes the metal burn into
the sand greatly, so that cleaning is much more difficult, and the
sand often must be almost cut from the castings by means of long
cold chisels, struck with sledges. Pneumatic hammers are used to
a large extent in cleaning and in removing fins and slight projections.
Where shrinkage webs show, they must be cut out. Steel does not
break off as does cast iron. The heavy gates and risers must be
Fig. 151. Cutting Off Riser
removed by metal saws, as shown in Fig. 151, or by drilling a number
of 1-inch holes side by side through the base of the riser and then
breaking it off. The castings are generally annealed before the
risers are cut off.
Annealing. In all steel castings of any size, cooling strains will
develop on account of the shrinkage, and these should be relieved by
annealing. In suitable trench-like ovens, the steel is heated to a dull
redness. This allows the grain to assume normal conditions. The
heating is usually done with a wood fire. Overheating renders the
grain coarse, and weakens the casting. As indicated by the following
figures, proper heat-treatment materially increases strength and
toughness, and the work which is properly annealed is not only
actually stronger, but being tougher, will stand more hard usage.
FOUNDRY WORK
145
Conditions
Tensile
Strength
,1b. persq. in.)
Elongation
(per cent)
Reduction
op Area
(per cent)
Raw
80,360
13.31
16.2
Annealed
81,767
27.6
40.4
Improperly annealed
79,421
14.3
17.8
MALLEABLE PRACTICE
Development. It is believed that early attempts to soften hard
castings by reheating them, and the collection and publication of
the results of these operations in 1722, by Reaumur, which led to the
taking out of patents on the process by Lucas in 1804, comprised
the early history of the malleable-iron industry
Seth Boy den of Newark, New Jersey, produced the first mal¬
leable iron in America. It is recorded that in 1828, The Franklin
Institute of Philadelphia, Pennsylvania, awarded him a premium
for the best specimens of annealed cast iron. These were mainly
harness trimmings.
Before 1890, the secrets of the process of malleableizing were
closely guarded, which accounts for its slow growth, but since then
great advances have been made both in quality and tonnage, due to
a better knowledge of the principles involved. As the industry
now stands it is farthest advanced in the United States. It is
estimated that for the year 1907 the output for all Europe was but
50,000 tons as compared with a production of 980,000 tons in America
for the same year.
It is rather surprising that, while there is more skill required to
produce malleables—and there are several extra operations—the price
is so little in advance of that for gray iron. This is accounted for in
part by the large number of castings ordered from a given pattern.
Comparative Characteristics of Metal. An idea of the value of
this material is best obtained by a comparison of its properties with
those of similar substances. Thus, gray-iron castings range from
those nearly black in fracture, to white, with all degrees of softness
up to glass hardness. They may be strong or weak and still serve
their purpose. The desirable characteristics of the gray-iron casting
is its extreme resistance to compression. Where great shock is to be
cared for, great massiveness is required.
146
FOUNDRY WORK
The steel casting has the highest strength of any cast metal:
it may be deformed considerably without danger, and is cheaper than
a corresponding forging.
The malleable casting is the connecting link between the two
above mentioned. It is stronger than the gray casting but not as
strong as cast steel. It can be bent or twisted considerably without
breaking, and approaches gray iron in compressive strength; but its
most valuable characteristic is resistance to shock. This property
is best illustrated by the car coupler, a large number of drop tests
having shown the value of the malleable coupler as compared with
one of cast steel.
TESTING
Methods. There are two general ways for testing malleable
cast iron: (1) by so-called shop tests; and (2) by laboratory tests of
bars cast from every heat and annealed with the castings.
Shop Tests. The usual shop tests consist of bending occasional
castings, as well as of twisting the longer pieces, and also of the
making and breaking of test wedges. These wedges are about 6
inches long and 1 inch square for 3 inches of their total length, then
tapering down in thickness to nothing for the last 3 inches, but
keeping the full inch width; this gives thick iron as well as thin on
the same piece. When the test wedges come from the annealing,
they should be broken on an anvil by striking them with short light
blows, the object being to see how much the thin end of the wedge
can be bent before the piece breaks, after which, by holding the two
parts together and observing the bend, a very fair idea of the quality
of the castings these wedges represent, may be had.
Laboratory Tests. The regulation test bars are rectangular in
form and are of two sizes: the 1-inch square bar to represent castings
| inch thick and over; while a 1- by |-inch section bar cares for the
lighter castings.
The following specifications adopted by the American Society
for Testing Materials form the only official standard in existence.
Specifications for Malleable Cast Iron
Process of Manufacture. Malleable-iron castings may be made by the
open-hearth, air-furnace, or cupola process. Cupola iron, however, is not
recommended for heavy or important castings.
FOUNDRY WORK
147
Chemical Properties. Castings for which physical requirements are
specified shall not contain over 0.06 per cent of sulphur or over 0.225 per cent of
phosphorus.
Physical Properties. (1) Standard Test Bar. This bar shall be 1 inch
square and 14 inches long, cast without chills and left perfectly free in the mold.
Three bars shall be cast in one mold, heavy risers insuring sound bars.
Where the full heat goes into the castings, which are subject to specifica¬
tion, one mold shall be poured 2 minutes after tapping into the first ladle, and
another mold shall be poured from the last iron of the heat.
Molds shall be suitably stamped to insure identification of the bars, the
bars being annealed with the castings. Where only a partial heat is required
for the work in hand, one mold shall be cast from the first ladle used and another
after the required iron has been tapped.
(2) Of the three test bars from the two molds required for each heat, one
shall be tested for tensile strength and elongation, the other for transverse
strength and deflection. The other remaining bar is reserved for either tensile
or transverse test, in case of failure of the other two bars to come up to require¬
ments. The halves of the bars broken transversely may also be used for the
tensile test.
(3) Failure to reach the required limit for the tensile test with elongation,
as also for the transverse test with deflection, on the part of at least one test,
rejects the castings from that heat.
(4) Tensile Test. The tensile strength of a standard test bar for casting
under specification shall not be less than 40,000 pounds per square inch. The
elongation measured in 2 inches shall not be less than 2\ per cent.
(5) Transverse Test. The transverse strength of a standard test bar on
supports 12 inches apart, pressure being applied at the center, shall not be less
than 3,000 pounds with deflection at least \ inch.
Test Lugs. Castings of special design or special importance may be
provided with suitable test lugs at the option of the inspector. At his request,
at least one of these lugs shall be left on the casting for his inspection.
Annealing. (1) Malleable castings shall neither be over- nor under¬
annealed. They must have received their full heat in the oven at least 60 hours
after reaching that temperature.
(2) The saggers shall not be dumped until the contents shall be at least
black hot.
Finish. Castings shall be true to pattern, free from blemishes, scale, or
shrinkage cracks. A variation of r? inch per foot shall be permissible. Found¬
ers shall not be held responsible for defects due to irregular cross-sections and
unevenly distributed metal.
Inspection. The inspector representing the purchaser shall have all
reasonable facilities given him by the founder to satisfy him that the finished
material is furnished in accordance with these specifications. All tests and
inspections shall be made prior to shipment.
In general it may be said it is not necessary to have a metal
very high in tensile strength but rather one which has high transverse
strength and good deflection. This means a soft ductile metal which
148
FOUNDRY WORK
adjusts itself to conditions more readily than a stiff strong product,
for it is very hard to produce a strong and at the same time soft
material, especially in the foundry making only the lighter grades of
castings.
PRODUCTION PROCESSES
Preparing Molds
Patterns. One of the most important departments of the
malleable works is the pattern shop. Malleable castings are com¬
paratively light when considered in connection with general gray-
iron practice and many times are ordered in enormous quantities
from the same pattern.
Every refinement in pattern-making for light castings is found
in this branch of the foundry industry. When developing a new
article, the pattern-maker must practically live in the foundry.
As trial castings are made he must measure them up with the pattern
and make changes as found necessary; he must try them out again
both before and after annealing, and with iron from different parts of
the heat, and thus bring out new points calculated to help the molder
and to lessen difficulties from shrinkage. It is the rule never to start
an order for a quantity until the pattern has been tried out, the hard
castings have been broken for evidence of shrinkage, and everyone
has been satisfied it is safe to proceed.
Construction Difficulties. The terms shrinkage and contraction,
as applied to malleable castings, should be clearly understood before
any further mention is made of this subject. While shrinkage in
gray-iron practice is often considered as the shortening of a casting
in cooling, in malleable practice shrinkage means the tearing apart
of the particles of iron in the interior of a larger section, close to a
small one, leaving a spongy mass which is weak and very dangerous
to the life of a casting. Contraction being simply reduction in size
while the casting is cooling, amounts roughly to \ inch per foot in
the hard, i.e., before annealing. During the annealing, about half
of this is recovered, so that the net result is about the same as in gray-
iron practice. It should be plain, however, that this big contraction
causes the tearing as above mentioned when there are heavy sections
which remain in a molten state a little longer than do adjoining
light sections, unless liquid iron can be fed in. Where this is impos-
FOUNDRY WORK
149
sibie, the use of chills must be resorted to and fillets made much
larger.
In gating patterns it is to be remembered that white iron chills
easily and must be poured rapidly. To a certain extent, this limits
the number of pieces that may be run successfully, unless the gates
be made so large there would be danger of dirty castings. The run¬
ners should be large and the sprues heavy, the idea being to get a
large amount of metal in front of the gate for the individual casting.
The use of the match
plate is largely resorted
to also, as being well
adapted to this class of
work. Fig. 152 shows a
group of three of the
gated patterns in daily
use in the Arcade Mal¬
leable Iron Foundry,
Worcester, Massachu¬
setts. In Fig. 153 there
are shown 84 small
thumb nuts on one gate;
also 18 hinge patterns
mounted on a match
plate.
Molding Methods.
But little difference from
ordinary gray-iron meth¬
ods, occurs in molding
practice other than in
gating and in pouring.
Since white iron melts at a somewhat lower temperature, there is
less danger of sand burning into the casting, so less attention is paid
to facing sand.
A large per cent of the work is made in the snap flask on tin*
bench, as illustrated in Fig. 154. From the fact that nearly all
work is in quantity, here is where molding machines may be used to
great advantage. As these are explained elsewhere, no more need be
said except that care should be exercised in the selection of types
Fig. 152. Gated Patterns
150
FOUNDRY WORK
Fig. 153. Typical Gated Pattern and Match Plate
Fig. 154. Molds in Position for Pouring
FOUNDRY WORK
151
Fig. 155. View of Molding Floor, Fig. 154, Taken from Opposite End of Plant
Fig. 156. Sand-Mixing Machine
Courtesy of Standard Sand and Machine Company, Cleveland, Ohio
152
FOUNDRY WORK
best suited to local conditions. Fig. 155 is a view from the opposite
end of the same foundry floor.
Flasks. While much of the work is handled in snap flasks, it
is not unusual to find metal flasks closely conforming to the shape
of the pattern, thereby greatly reducing the amount of sand to be
handled, with a corresponding reduction in cost of production.
Cores. Practically all castings are cored and the problem is
to produce a sufficient number of cores that there may be no delay
for the molder. As there is no important difference in the preparation
of cores—the same sand and binders being used—the large number
required warrants the introduction of modern sand-handling and
mixing machinery to a somewhat greater extent than in gray iron.
Fig. 157. Mixing Paddles of Standard Sand-Mixing Machine
The batch mixer alone proves of great value by the reduction of
binder required due to its more even distribution; oftentimes this
amounts to nearly 100 per cent. The type of batch mixer shown
in Fig. 156 is made by the Standard Sand and Machine Company,
Cleveland, Ohio. Fig. 157 is a view of the mixing paddles.
Melting Metal
Methods of Melting. Under this head the several methods in
use will be described, which are as follows: (1) crucible; (2) cupola;
(3) air-furnace; and (4) open-hearth.
Crucible Melting. The quality of metal produced by this method
is without doubt of the best. Being melted out of contact of the
fuel, there is no danger of absorbing impurities therefrom, but the
small amount of metal available at one time limits the production
to only the smaller work. Partly for this reason, the excessive cost of
FOUNDRY WORK
153
production does not admit of competition with other methods which,
while lacking somewhat in quality, yet meet actual requirements.
A more detailed description of melting in the crucible is given in
the subsequent section on Brass Melting.
Cupola Melting. As in gray iron, the cupola offers the most
economical method of melting iron, not only in cost of installation
154
FOUNDRY WORK
and saving of fuel, but in ease of manipulation as well. It has some
disadvantages which restrict its use, the greatest being the inferior
quality of metal produced, which is caused by the contact of metal
with the fuel, and also the danger of burned iron which in turn makes
sluggish iron, with the result that castings are likely to show pin¬
holes.
There is also greater difficulty in annealing—usually it requires
200 or 300 degrees Fahrenheit higher temperature. This method may
be safely used only when the property of bending, rather than
strength, is required. Pipe fittings form a large part of the pro¬
duction of the cupola method. However, it makes a convenient
melting medium for the production of anealing boxes.
Fig. 160. Section of Roof of Air Furnace
Air-Furnace Melting. The number of furnaces of this type far
exceeds all others. In the issue of the Foundry Magazine for Feb¬
ruary, 1910, the number of the different types of furnaces engaged in
the production of malleable in America was given as follows: air
furnaces, 3G9; cupolas, 42; open-hearth furnaces, 21.
Figs. 158 and 159 show two general types of air furnace. In
the furnace represented in Fig. 159 the bath is immediately behind
the bridge, while that shown in Fig. 158 has its bath at the end,
remote from the bridge.
Fuel is placed on the gate through the charging door D, which is
of cast iron lined with fire brick. The hearth II is where the metal
is placed when charged. E is the stack through which the gases
FOUNDRY WORK
155
finally escape. B is the bath where the molten metal collects and at
its lowest point the tapping hole is located. The metal is charged by
Fig. 161. Complete Installation of Air Furnace
removing a part of the roof as shown at 0, a section of which is shown
in Fig. 160. Peepholes are shown at PPP, which are for observation.
Fig. 162. View Showing Method of Firing Air Furnace
The iron is charged on the hearth so as to leave openings between
the pieces, and the molten metal should be skimmed from time to
15G
FOUNDRY WORK
time so that it may receive the direct action of the burning gases
passing over it.
Fig. 161 shows a type of air furnace complete. Fig. 162 is a view
of the opposite side with a melter in the act of firing. Fig. 163 shows
the slag hole, and the slag just skimmed off.
The air furnace requires greater skill to operate than does the
cupola, and the fuel ratio is higher, but, if of good quality and
Fig. 163. Slag Hole
properly fired, is not excessive and should average about 3 of metal
to 1 of fuel.
Open-Hearth Melting. It is said the open-hearth installation
represents the highest type of melting yet devised, but the high
first cost, combined with frequent and heavy repairs and skill required
to operate, confine its use to the largest plants, and as long as the
trade is satisfied with the quality of the product of the more easily
operated air furnace, it is quite doubtful if the open hearth will be
generally adopted. The description of the open-hearth furnace which
has been given in Steel-Casting Practice may be referred to.
Iron Mixture. Without the proper mixture of iron no furnace
will produce satisfactory iron, hence the importance of using the
greatest care in this part of malleable practice.
FOUNDRY WORK
157
That the reader may clearly understand the basic principles
involved, it is necessary first to discuss the various materials entering
into the mixture. These include pig iron, sprues, faulty castings,
annealed scrap, steel scrap, and ferro-alloys.
Good Composition. As all the materials have a bearing on the
finished casting and should only be used as they affect this, it is at
this time well to give an analysis for good malleable castings, which
is as follows:
.Element
Proportion
(per cent)
Silicon
0.75 to 1.25
Carbon
3.00
Sulphur
0.04 (extreme)
Manganese
0.60 (extreme)
Phosphorus
0.20 (extreme)
There is considerable latitude allowed due to the class of work to
be produced. Makers of heavy castings exclusively may specify
their silicon from 0.75 to 1.50 per cent, while for very light work
silicon from 1.25 to 2.00 per cent may be the rule. Total carbon
shou’d never run below 2.75 per cent in the hard, i.e., before the
annealing. Manganese should average about 0.40, not much lower,
and never above 0.60. Sulphur should always be as low as possible,
0.07 per cent being the high limit in the casting, hence the necessity
for choosing irons for the mixture which will insure this. Phos¬
phorus below 0.225 per cent is desired.
Pig Iron. Formerly it was thought that only charcoal pig was
suitable for malleable practice, but today, owing to improved blast*
lurnace practice, coke irons which are known to the trade as coke
r.ialleable give first-rate results and are used to a considerable extent,
yet it is seldom that the writer has heard of a mixture that did not
include one or more of the well-known brands of charcoal iron known
to the trade as Mabel, Briar Hill, Hinckley, and Ella. It is generally
conceded that a mixture containing several brands of iron, or at least
two or three grades of the same brand, produces better castings.
Scrap. The next problem which presents itself is the dispo¬
sition of gates, sprues, and discards, which are daily accumulated
in the works, and the per cent of which varies with the class of work
158
FOUNDRY WORK
produced, running as high as 60 per cent in the lightest work or not
exceeding 25 per cent for very heavy castings. From this it will be
seen that it is quite likely to be a varying element. The practice
of taking the silicon content for every heat before castings go into
the annealing operation gives opportunity for fairly exact calcu¬
lations. Corrections may be made in the mixtures as may be found
necessary, otherwise, should there be an accumulation of such
material, it would soon become an unknown quantity and so be a
source of annoyance as well as of loss to the management.
The annealed scrap offers more difficulties owing to the effect
which even small amounts have on the quality of the product. Quite
frequently there is no attempt to use this in the regular mixture but
rather to utilize it in the production of annealing pots of which more
will be said later.
The use of steel scrap in malleable mixtures is proving beneficial
although the amount is at present limited to something like 10 per
cent. This material should not be charged with the regular mixture,
but should be introduced into the bath of molten metal so that it may
be quickly covered by the protecting slag, for the steel must not be
allowed to burn as this would seriously injure the quality of the
castings.
It is also possible to use small amounts of gray-iron scrap,
though it is seldom necessary to do so, and usually 5 per cent is the
limit.
Ferrosilicon. This material is carried in stock, either as a 0.50
or 0.75 per cent alloy for use in the ladle, or as a 14 to 20 per cent
pig for use in the furnace.
In choosing metals for the heat it first is necessary to ascertain
the silicon content desired in the castings, and then to select such
amounts of the different brands of pig iron at hand as are required
to bring about the desired result, first making careful calculation of
the amount of scrap to be cared for and its effect on the mixture as
regards its silicon content. The previous section on Melting may
be referred to regarding gray-iron mixture.
In conclusion, it would be well for the reader to clearly under¬
stand that it requires greater skill to produce malleables, and for
this reason a well-equipped laboratory and a good metallurgist are
almost necessities where high quality is the order of the day.
FOUNDRY WORK
159
Malleable Casting
Variation from Gray=Iron Practice. The furnace having been
duly charged for the day’s melt with the desired mixture of metal, we
will now consider the casting operation which differs only from gray-
iron practice in that the metal contains a larger per cent of carbon
in the combined form, melts at a lower temperature, and also cools
more quickly in the ladle, and for this reason must be handled more
rapidly. The hand ladles are of somewhat smaller capacity, usually
about 25 pounds, as compared with 40 to 60 pounds in gray-iron
practice.
Carrying. This lighter burden allows the molder greater free¬
dom in his movements. It is common practice to see the molder
catching-in to the stream of molten metal and running to his floor
that the molds may receive the benefit of the hottest metal possible.
While this is possible in malleable-iron work, with the larger
ladles of gray-iron practice, this would not only be exhausting, but
highly dangerous as well.
It must be remembered that the majority of work is light and
that the floor space required for the setting-up of sufficient molds to
pour, say, a 30-ton heat, is considerable, and even with the furnace
ocated as it should be in the center of the works, there must be long
carries. These are in part overcome by the installation of some
overhead trolley system using 500-pound ladles; and where the
nature of the work permits—i.e., it is not too light—this method is
of course preferable.
Cooling. As there is great danger of the castings developing
cracks if exposed to the air while still red hot, it is far better practice
to let them remain in the sand until they are at least black hot when
they may be safely shaken out: the exception being some special
work, as brake wheels, for example, in which there are developed great
casting strains. In this case it is found best to shake out while still
red hot and quickly place them in a so-called reheating oven which is
already fired very hot. This furnace, after being fully charged with
the day’s output of this special work, is closed and the fire allowed
to die out over night, when the castings will be found to be partly
annealed, though not in a malleable sense. This treatment is found
of considerable value in certain classes of work which otherwise
might be hard to save.
160
FOUNDRY WORK
Cleaning Castings. The castings having become cool so that they
may be readily handled, a rough separation of castings and gates
should be undertaken and the cores removed as far as possible, after
which the castings should be inspected and all missruns or otherwise
defective castings removed. The discards along with the gates and
sprues should then be tumbled to remove the sand scale before being
returned for remelting, otherwise it would form an excessive slag and
require a larger amount of fuel to remelt.
Fig. 164. Modern Exhaust Tumbling Barrel
Hard-Rolling. After this rough sorting the castings are ready
for the hard-rolling room which contains a series of tumbling barrels,
all of which should be equipped with an exhaust system, or else the
dust created in this department will become the bane of the plant.
Fig. 164 shows an installation of modern exhaust tumbling barrels.
The castings should be rolled only long enough for the removal
of the sand scale, usually accomplished in from 20 to 30 minutes.
Some classes of work may be so delicate that it would be impossible
to clean them in this manner without too great a loss from breakage,
and in such cases the acid bath may be resorted to, or perhaps the
FOUNDRY WORK
161
sand blast which is fast superseding other methods of cleaning all
classes of castings. Fig. 165 shows a New Haven sand-blast tumbling
barrel which is well adapted to this work.
After this hard-rolling process the castings are removed to the
trimming room where the gates and fins remaining may be easily
removed with a hammer, thus saving much time in the grinding room
after the annealifig.
Annealing. We now arrive at one of the most important depart¬
ments of the plant. No matter how carefully all previous operations
may have been conducted, all will have been in vain should any
Fig. 165. Sand-Blast Tumbling Barrel
neglect creep into this part of the practice, for it is here that the very
nature of the casting is changed from its hard and brittle state showing
a white fracture, to the so-called black-heart malleable, the fracture
showing a steely rim with a black velvety core.
This change is brought about by gradually bringing the tem¬
perature in the annealing ovens up to about 1600 degrees Fahren¬
heit, and by maintaining that temperature from 3 to 4 days, after
which the fire is allowed to slowly die down; this whole process requires
from 8 to 10 days. There have been attempts made to shorten this
162
FOUNDRY WORK
annealing process, usually by increasing the temperature some 200
degrees, thereby reducing the total period of the process to about 6
Fig. 1G6. Packing Annealing Boxes
Fig. 167. Hand Charging Truck
days; but this has been done at the expense of quality, and the best
results are obtained by the former method.
Preparation of Castings. After inspection in the trimming room,
the castings are brought to the annealing room which has its floor
FOUNDRY WORK
163
space divided into two parts—the packing floor, and the ovens.
There are usually two rows of ovens, one on each side of the build¬
ing, and the clear space between is used for packing the pots and
also for dumping, them after the annealing. The floor of this is made
of 1-inch iron plates.
The annealing boxes, or laggers, may be either square or round,
or perhaps more generally oblong, and are first cast 1 inch thick.
These pots are piled three or four high—the first one is placed on
an iron stool—all joints being luted up with mud made by adding
water to the burnt sand from the rolling room with perhaps the
Fig. 168. Interior View of Annealing Oven
addition of a little fire clay. The scale used for packing is cinder
squeezed from muck balls where wrought iron is made. It was
formerly the practice to spread this scale upon the floor and sprinkle
it daily with a solution of sal ammoniac to rust it, but later-day
practice has proven this unnecessary.
As the castings come into the annealing room the operator
places a pot on the stool, shovels in some scale, carefully placing in a
ayer of castings in such manner that none comes in contact with
the sides of the pot or no two castings touch each other, then more
scale and more castings are added until the pot is filled, as shown
in Fig. 166. On this another pot is placed and duly packed, this to
164
FOUNDRY WORK
be continued until the pots are piled as high as desired, after which
all joints are sealed with mud making the whole pile more or less
Fig. 169. Oven Charged
Fig. 170. Ash Pit. and Firing Doors
air-tight. After this has been accomplished, the pots are placed in
the oven either by a hand or by a power charging machine, as
illustrated in Fig. 167.
FOUNDRY WORK
165
Oven. The annealing oven is quite simple. The principle
involved is the introduction of heat from some convenient point
and its distribution in a uniform manner, and the introduction of as
Fig. 171. Final Sorting of Castings
Fig. 172. Shipping Room
little air as possible. The combustion space should be no larger
than necessary, the draft regulation perfect, and the bottom of the
oven underlaid by a series of flues which allow the gases to circulate
166
FOUNDRY WORK
before escaping into the stack, so there may be as little loss of heat
as possible. Oil, gas, or coal may be used for fuel as best adapted
to the locality.
Fig. 168 shows the interior of an oven, while Fig. 169 shows
the boxes in place. Fig. 170 is a side view of an oven showing the
firing doors and the ash pits. Having placed the full number of
l ig. 173. according Pyrometer
Courtesy of The Bristol Company, Waterbury, Connecticut
boxes in the oven, the front is closed and the ovens are fired. As
before stated this operation requires from 6 to 10 days from the time
the fire is started until the oven has cooled sufficiently to allow the
removal of the boxes.
As the boxes are withdrawn from the oven and are taken to the
floor of the annealing room, they are suspended from an overhead
trolley, or by a crane, and the castings are removed by striking the
FOUNDRY WORK
167
boxes several sharp blows with a medium-weight sledge hammer,
the castings and scale falling upon the floor. The castings are now
picked from the scale and it will be noted that there is some tendency
for the scale to adhere to them. This may be removed by the
ordinary rolling barrels, after which any gates or fins remaining
should be ground off. The amount of labor required for this oper¬
ation depends upon how carefully the gates were moved while castings
were in the hard. After a final inspection, the castings should be
ready for shipment. Figs. 171 and 172 show the castings being
sorted out and ready for shipment in the shipping room.
Pyrometer. The use of the pyrometer in connection with the
annealing furnace is almost obligatory. Fig. 173 shows a standard
type of recording pyrometer. The pyrometer equipment is often
placed in the office of the head executive of a local plant; it is pos¬
sible for him to plug into any two of his battery of annealing
furnaces at any time during the day. Also, in the morning, there
is recorded a true record of temperatures for the night before. As
no operator knows whether his furnace is under observation or not,
this system has the tendency to keep the men at all times alert.
Finishing. The amount of finish given the castings varies
with local conditions and class of castings produced. There are some
classes of work where, by the use of leather scraps in the soft-rolling
room, the work is so carefully cleaned and polished that the castings
may be tinned or nickeled and sometimes gold- or silver-plated,
making very beautiful work in which great strength is combined with
cheapness of production.
BRASS WORK
ALLOYS
Distinctions. Cast iron, cast steel, and malleable iron, which we
have previously considered, are three forms of the same metal—iron.
The difference in their physical characteristics is due solely to a
variation in the proportions of certain elements or metaloids combined
with the iron.
The metals to be dealt with in this section are termed alloys—
that is, mixtures of two or more separate metals. The common
alloys in use in the foundry, for casting various machine parts, are
168
FOUNDRY WORK
made from combinations of copper, tin, and zinc, and are called
brass, or bronze.
Brass and Bronze. Although the term brass is held by some
authorities to cover any of these combinations, the general classifica¬
tion accepts brass as an alloy of copper and zinc, and bronze as an
alloy of copper and tin. In some sections the latter is spoken of as
composition.
Bronze has been used by man in all ages. Centuries before the
Christian Era the Egyptians employed it for making coin, armor,
and weapons, as well as household utensils, and statuettes of their
gods. Analyses of many of these ancient relics show the composition
to be almost identical with the bronzes of the present day. Brass
also was in use before the time of Christ, but unquestionably bronze
was of earlier origin.
Metals. A short discussion of the separate metals will help in
understanding the properties of their alloys.
Copper. Copper has a red color; it is hard, ductile, and very
tough. It melts at about 2000 degrees F.; but it is difficult to make
castings of the pure metal. Copper does not rust as does iron, and
is one of the best conductors of heat and electricity. For this reason
it is largely used in sheet form as a sheathing metal, and in the form
of wire or rods for electrical transmission. Casting copper is put
on the market in ingots of special form weighing from 18 to 25
pounds each.
Tin. Tin is a white lustrous metal, very malleable, but lacking
tenacity. It may be reduced extremely thin by rolling, as is shown
by tin foil. It melts at 450 degrees F. When a bar of tin is bent
it will give a crackling sound known as the cry, which at once dis¬
tinguishes it from other metals such as solder, lead, etc., which have
similar external appearance. It is put on the market in pigs weighing
about 30 pounds and also in bars of about 1 pound each. Its cost is
approximately 1| times that of copper and 5 times as much as zinc.
Tin may be cast unalloyed, and is sometimes used to run pattern
letters or small duplicate patterns cast in zinc chill molds. The
addition of J to ^ by weight of lead gives a cheaper metal, however,
and one that will run equally well.
Tin mixed with copper gives greater fluidity, lower melting
point, and greater strength, changing the color from red to bright
FOUNDRY WORK
169
yellow. Serviceable alloys may contain as high as 20 per cent of tin.
This gives a metal of golden yellow color, very hard, tough, and
difficult to work. With larger percentages of tin the color shades to
gray, the metal is hard, brittle, and has little strength, and has no
value for engineering purposes.
Zinc. Zinc has a bluish white color; it is hard, but weak and
brittle. The fracture shows very large crystals of characteristic
shape. It melts at about 700 degrees F., and shrinks but little
in cooling. For this reason it may be used to cast directly for small
metal patterns to form chills from which soft-metal castings may be
made for duplicating these patterns. If exposed to the air at high
temperatures, zinc will volatilize, that is, turn to a gas and burn.
It burns with a bluish flame, and throws off clouds of dense white
smoke. For this reason great care must be used to keep the air away
from it as much as possible when being melted or mixed in an alloy,
for, aside from the loss of metal, an oxide is formed in the mixture
which impairs the quality of the alloy.
Zinc is known in commerce under two names: when rolled into
sheets it is called zinc; when in ingot form for casting, it is called
spelter. These ingots are flat, approximately 8 by 1 by 17 inches,
and weigh about 30 pounds. In this form they may be easily broken
in small pieces for convenience in charging.
Zinc may be added to copper in a very wide range of proportions,
the alloy increasing in hardness and losing ductility with the increase
in the proportion of zinc. The color changes from the red of the cop¬
per to a full yellow when ^ zinc is used. Further additions of zinc
change the color to red, yellow, violet, and gray. The alloys are
serviceable up to 40 or 50 per cent of zinc.
When zinc is mixed with melted metal, considerable reaction or
boiling takes place, which tends to make a more thorough mixture
and to drive impurities to the surface. For this reason a small pro¬
portion of zinc—2 or 3 per cent—is often stirred into bronze mixtures
after the pot is drawn.
Lead. Lead has a bluish white color, and considerable luster
when freshly cut. It is malleable, soft, and tough, but very weak.
It melts at about 600 degrees F.
Lead is not used by itself as an alloy with copper. A very small
proportion may be added to the standard mixture for brass or bronze.
170
FOUNDRY WORK
TABLE VI
Proportions of Mixtures
Copper
Tin
Zinc
Lead
Use
( per \
\cent )
(ounce)
( Per \
\ cent/
(ounce)
f Per 'N
Vcent )
(ounce)
( per ^
\ cent)
(ounce)
Gun metal—for bearings;
very tough hard mix¬
ture
83
16
12
2^
2.5
1
2
2.5
1
Steam or valve metal—
cuts freely; very tough;
resists corrosion
85
16
7
U
5
3
3
I
Composition metal—for
general use on small
machine parts
90
16
5
1
5
1
2
Art bronze—rich color;
runs fluid at compara¬
tively low heat
90
16
6
1
3
1
2
1
1
4
Common yellow brass—
for general run of ma¬
chine castings
G6.5
16
33.5
8
Brass—to machine easier
than the above; for
same purposes
66
16
33
8
1
1
2
Antifriction metal—f o r
journal boxes
Mixture—for small pat¬
terns; runs well; shrinks
little
1.8
1
64.7
32
33.35
16
1
1
2
66
2
34
1
It will cause them to run more fluidly in pouring, and be softer for
machining. For this reason, lead is added to bearing mixtures to
advantage. But it tends to deaden the color and reduce the conduc¬
tivity of the metal for electrical purposes.
Mixtures. General Proportions. The percentages given in
Table VI are for convenience in comparison and for figuring large
heats. The beginner, however, will generally melt but 1 or 2 pigs of
copper at one time. These he will weigh first., and then figure the
other portions of his mixture from this weight. In this case a
formula given in pounds and ounces is much simpler.
Variation. From what has been said, it is understood that it
is possible to vary these mixtures to meet special conditions. To
harden or toughen an alloy, increase the tin; to soften it, reduce the
tin. The same is true with zinc, but it will require larger proportion¬
ate changes in this metal to effect similar results in the alloy.
Phosphorus. Phosphorus is not a metal, but is a very active
chemical element manufactured from bone ash. It has such ap
FOUNDRY WORK
171
TABLE VII
Phosphor=Bronze Mixtures
Proportions of Alloy
Element
Hard
Tough
(per cent)
(pounds)
(per cent)
(pounds)
Copper
87.5
81
90.
9
Tin
12.25
1
9.75
I
Phosphorus
Phosphor tin
0.25
1
.25
I
Total
100.
10
100.
10
affinity for the oxygen of the air, that in its pure state it must be kept
under water, because the slightest scratch would cause it to burn
fiercely. It forms the principal substance used in making the heads
of matches.
As a rule it is never used in the foundry in its pure state. For
the production of phosphor-bronze castings there are several combined
forms of phosphorus on the market. The most convenient of these
is known as phosphor tin, which is metallic tin carrying various
fixed percentages of phosphorus, of which 5 per cent is one very
common proportion. Knowing the amount of phosphorus carried
by the tin, the exact proportion for the entire alloy may be readily
calculated. This element should not be used in alloys containing
zinc or lead.
Phosphorus acts as a flux, combining with any oxidized or burned
impurities in the bath of metal and driving them to the top. It tends
to make the tin crystalline in form, in which condition it unites
more firmly with the copper. It apparently unites chemically with
copper, making that metal harder. The proportion of phosphorus
should not exceed 0.75 per cent, while 0.25 to 0.40 per cent are safer
proportions.
Two typical mixtures, one using 5 per cent phosphor tin, are
given in Table VII.
PRODUCTION
Molding Materials. Natural molding sands are used for brass
work. They are usually finer than sands used in iron work, because
172
FOUNDRY WORK
brass parts are generally small and often have fine detail which must
be brought out very sharply in the mold. For this reason, also, the
sands should have more alumina or bond than iron sands. This
increase of bond is possible because the metals entering the
mold are not as hot as iron would be, and therefore do not require
as much vent, but they have a greater tendency to cut the mold.
Fig. 174. A—Flask for Brass; B—Screw Clamp
For the general run of work the whole heap is kept in good con¬
dition by the frequent addition of new sand, but on large work a
facing mixture is used similar to that of the iron foundry.
Burnt sand, powdered charcoal, and partainol are all good
parting materials; the last two are best on small work, as they make
a cleaner joint. Since they make a good facing for the mold, they
are not blown off of the patterns.
Equipment. Tools. The brass molder uses practically the same
kind of tools, such as shovels, sieves, rammers, and molder’s tools
generally, as already have been described.
Flasks. Snap flasks may be used, but the pins, hinges, and
catches must be kept in careful adjustment so that the parts of the
mold shall register perfectly. The same is true of the larger box
flasks for floor work.
FOUNDRY WORK
173
The most typical brass flasks are of cast iron with accurately
fitting round steel pins, as seen in Fig. 174 at A. They have holes on
the joint at one end of the flask so that the mold may be set upright
when pouring. This gives a decided additional pouring pressure
with a minimum thickness of sand over the castings.
Boards without cleats support the sand in the flask, and the
whole is clamped, before setting on end, by means of some form of
double-screw clamp similar to the illustration B, in Fig. 174.
Fig. 176. Drying Stove
Spill Trough. Great care is taken in the brass shop to save all
the shot and spilled metal possible. To this end, when the molds
are to be poured on end, they are leaned against a cast-iron spill
trough such as shown in Fig. 175. There should be a 1-inch layer
of sand over the bottom of this tray. The crucible is held over it
when pouring the molds, thus making it possible to conveniently
catch, any metal that is spilled.
Drying Stove. For thin work the face of the molds are skin-
dried to drive off the moisture before the metal enters the mold.
Drying stoves, similar to that shown in Fig. 176, are used for this
purpose. When the mold is finished, the two halves are carefully
174
FOUNDRY WORK
sprayed with a weak molasses water, and the flask is set on end on
the wide platform with the face of the mold next to the stove. When
sufficiently dry, the mold is closed and poured at once.
Principles of Work. Size of Heat. Brass work deals, as a rule,
with smaller quantities in every way than does iron work. The
patterns are generally smaller, and the brass molder takes particular
pride in making all his joints so neat that hardly a fin shows on his
castings. The matter of catching the shot metal has been mentioned.
Up to the time of the introduction of the oil-melting furnace, it was
customary to heat a pot of metal for each molder. These heats were
comparatively small, so that the molder would make up possibly G
or 8 molds, then draw his pot and pour them, running in this way
several heats in a day. Using the furnace, several heats are run
each day, but a much larger quantity of metal is melted at each heat,
so that the work of several molders is poured with exactly the same
metal.
Molds. A mold for brass should be rammed about the same as
for iron. On name plates and thin work, after the initial facing of
sifted sand has been properly tucked with the fingers, the flask is
filled heaping full of sand. Then by the aid of a rope hanging down
from the ceiling, the molder springs up on top of the flask and packs
the mold with his feet, the weight of his body giving the right degree
of firmness to the sand. Stove-plate molders often pack their flasks
in the same way.
The main differences between making up molds for brass and
those for iron are due to the three following causes: brass melts
at a lower heat; it does not run as fluid as iron; it has about double
the shrinkage of iron. For these reasons the sand may be somewhat
less porous and still vent sufficiently, if risers are placed to allow for
the escape of the air. On bench work the vent wire is not used.
The runners for brass should be larger than for iron, and the gates,
instead of being broad and shallow, should be more semicircular in
section. Pouring molds on end gives the pressure necessary to force
a more sluggish metal to take a sharp impression, and the heavy
runners shown in the following examples serve to feed the casting
as it shrinks. Forms of skimming gates, as explained in an earlier
section, are used to good advantage when the work is of a very
particular nature.
FOUNDRY WORK
175
Cores for brass work are made lip as previously described. To
give a smoother surface on the small cores, about 3- molding sand is
often mixed in with the beach sand of the stock mixture.
Examples of Work. To illustrate more clearly some of the
typical methods of brass work, let our first example be a thin flat
plate with decoration in low relief on one side.
Place the pattern face down, a little below the center of flask.
Sift on facing through a No. 1G sieve, then tuck, fill, and pack, as
previously described. Roll over and make a joint. Now cut a half
section of the main runners and risers, but do not connect them with
the mold at this stage. Dust on parting material from a bag, and
ram the other half of the flask just hard enough to stand handling.
Fig. 177. A—Mold for Thin Plate; B—Mold for Heavy Plate
Separate the flask; spray the face of the mold with weak molasses
water, and dust on it from a bag some finely powdered pumice stone,
or any fine strong sand, and over this a little parting dust. Now
replace this half over the pattern, and re-ram to the required firm¬
ness, and again separate and this time draw the pattern.
The impression of the runners and risers cut in the first half of
the mold show as ridges on the second half packed, and serve as
guides for cutting the runners to a full round section. Connect the
gates in four places, as shown in A, Fig. 177. Skin-dry the mold and
it is ready to close and pour.
Dusting fine sand on the face of the mold, then reprinting, as it
is termed, ensures a very smooth, perfect mold face. Where the
mold is not skin-dried, flour is dusted over the face, allowed to stand
176
FOUNDRY WORK
TABLE VIII
Crucible Sizes
r
Number
Holding Capacity
(Liquid Measure)
Measurements Outside
Capacity
Weight
of
Water
Height
Diameter
Top
Bilge
Bottom
(gallon)
(quart)
(pint)
(inches)
(inches)
(inches)
(inches)
(pounds)
0
2
u
U
11
0000
3
to
21
If
6
1
61
51
51
3!
2.08
12
2
8
61
6f
5
4.16
30
1
1
1
11
GO
91
61
11.5
60
3
14
lot
Hf
8
25
90
4
15|
m
121
9
33.3
300
12
2
22
161
171
121
104.
for a short time, and then blown off. This makes a good facing.
Cutting the heavy runner over the top of the thin plate ensures a
sufficient supply of clean hot metal to the gates
under a large enough pressure to force the
metal into every detail of the mold before it
has time to chill.
In B, Fig. 177, is shown the difference
in construction of the gate when a heavier
piece is cast with the flask setting horizontally.
The gate proper is cut in the drag, but a good
feeding head is cut out of the cope side to keep
the metal in the riser liquid until the casting
has solidified.
Duplication. For duplicating work, the
sand match, oil match, or follow board are
used, the same as for iron work. Fig. 178
shows a typical set of castings run from the
Fig' Gated wo?kicated end aRd made from gated patterns set in an
oil match. Steady pins are placed on the
gates to facilitate a clean lift.
Melting. Characteristics. All alloy metals, and especially zinc
and tin, burn if exposed to the air while melting. To prevent this
FOUNDRY WORK
177
burning the brass melter endeavors to so control the draft in his
furnace that all oxygen entering the gates combines with the fuel,
and that the gases which may reach the metal shall contain no free
oxygen. For this reason, the ordinary brass furnace is a natural-
draft furnace, although a forced draft is often
connected below the grates to make combustion
independent of atmospheric conditions.
The metal does not come in direct contact
with the fuel, but is contained in fire-clay pots
called crucibles, which are bedded in the fire.
Hard coal or coke is used for fuel. These cruci¬
bles, Fig. 179, A, are manufactured from a very
refractory fire-clay mixture, and are strong and
tough, even at a high temperature. They are
lifted in and out of the furnace by the tongs shown
at B, Fig. 179. For the larger sizes a crane is
used for hoisting the pot. Crucibles are classed
by number, as seen in Table VIII. New crucibles
should always be annealed before using, that is,
brought very slowly to a low red heat.
Natural-Draft Furnace. Furnaces of this
type are usually called brass furnaces, and may
be bought on the market made up in single com¬
plete units. Fig. ISO illustrates one of a battery
of several furnaces connecting with a common
flue. The top is on a level with the molding
floor. The sketch shows clearly the principles
of construction. A cast-iron bottom plate A,
with a circular opening, carries a shell of boiler
plate lined with fire brick. The diameter inside
the lining should be 6 inches larger than the
crucible to be used. A top plate, with a similar
opening, binds the whole together. On one side,
below the top, the opening B, which may be formed by a cast-iron
box, connects with the flue or stack. Two heavy ribs cast on the
bottom plate rest on a pair of rails as shown, and these rails are
supported by suitable piers of brickwork about 2 feet high, so that
ashes may be conveniently removed when the furnace is dumped.
179. Crucible and
Tongs
178
FOUNDRY WORK
In the space made by the ribs, between the bottom plate and the
rails, the grate bars C are set. These bars are loose and may be
pulled out when it is desired to dump the fire for the day.
Operation. Before starting the fire in preparing to run off a
heat, a good plan is to use a half fire brick on which to rest the
crucible, or the bottom of a worn-out crucible cut off to the height
of 4 inches or 5 inches may be turned upside down and used for this
purpose.
Sufficient time and special care should be exercised in placing
the metal in a crucible. It is more or less dangerous to jam in the
charges, so particular care should be taken to see that they are placed
Fig. 180. Natural-Draft Furnace
in the crucible loosely. Graphite is the crucible’s principal ingre¬
dient; the only expansion possible to a crucible comes from its clay
body, hence, if the charges are wedged in a crucible and jammed to
fit tight, their expansion, which is much greater than the expansion
of the crucible, cracks the latter before the melting point is reached.
The crucible should be kept covered, especially for brass.
In melting brass, melt down the copper first, then the scrap
When this is melted, charge the zinc and stir wrnll before lifting the
pot. Allow the mixture to come to the proper heat again, then pull
the pot, skim off the dross, and stir in the lead if any is called for, just
before pouring. In bronze the same method is pursued, but both the
FOUNDRY WORK
179
tin and zinc are stirred in after the pot is drawn. In mixing in the
zinc in brass, care must be taken to plunge it well under the surface
Fig. 181. Section through Oil Furnace
of the copper with long handled pick-up tongs, and to hold the piece
down with the stirring bar until it has melted.
Where a large casting requires more metal than can be melted
in a single crucible, several furnaces must be used and the contents
of their various crucibles assembled into one large pouring ladle just
before pouring.
Gas or Oil Furnace. With the development of natural-gas and
crude-oil burners for commercial heating, several good furnaces have
been designed in which a large quantity of metal can be melted at
ISO
FOUNDRY WORK
one time. Fig. 1S1 shows a furnace of this character in section. This
type has tandem melting chambers with burners at the end, which
may be used separately or both together. The waste gases from the
Fig. 1S3. Sprue Trimmer
Courtesy of Toledo Machine and Tool Company, Toledo, Ohio
bath of liquid metal are used to heat up a fresh charge in the other
chamber. The metal is charged and poured from the openings at the
top of the furnace. Each chamber may be revolved separately, to
FOUNDRY WORK
181
Fig. 184. Dipping Basket
empty the furnace when the charge is melted. Fig. 182 shows the
general arrangement of the oil feed pump and blower for these melting
furnaces. The flame plays directly on to the metal. The oil pressure
should remain constant at about 5 pounds per square inch. But the
air pressure is regulated to vary the intensity
of the heat as desired.
The pouring ladle must be well heated
before using. This is done with a special gas
burner, or, when crucibles are used, they are
often heated by means of a small fire in an
ordinary furnace.
Different sizes of furnaces are built to
melt from 250 to 2000 pounds of metal at a
heat. Twelve or fourteen heats a day can be run. The saving is
approximately 50 per cent in time, and is also very considerable in
expense, over ordinary crucible furnaces of equal capacity.
Cleaning. When the castings are taken from the sand they
should be rapped smartly to free all loose sand, then, if machining
is to be done on them, they should be plunged, while hot, into water.
This softens the castings. This method is used also to blow out cores
from small work.
Since brass does not
burn into the sand as much
as iron, the small castings
in many shops are brushed
clean, before being cut from
the gates, by means of a
circular scratch brush
mounted on a spindle sim¬
ilar to a polishing wheel.
A sprue-trim'mer,
shown in Fig. 183, is part
of the equipment of a brass
foundry. These machines are made to operate by foot as shown,
or by power. With them the castings are cut neatly and quickly
from the runners.
Pickling. A good method of cleaning brass and bronze is by
pickling. Make a mixture of 2 parts common nitric acid and 1 part
Fig. 185. Magnetic Separator
182
FOUNDRY WORK
sulphuric acid, in a stone jar. Place the piece to be cleaned in a stone
dipping basket, Fig. 184, and dip once into the acid, then wash off
in clean water, and dry in sawdust.
Chip Separation. In many cases, brass chips and filings are
turned back to the foundry to be remelted. The smallest portions of
steel or iron in these would prevent their being used in this way, as
they make extremely hard spots in the castings.
Fig. 185 shows a magnetic separator which effectively removes
all steel and iron chips. The brass chips and sweepings from the
machine shop are placed in the hopper of this machine. They are
caused to be spread out on one side of a slowly revolving brass covered
drum. Inside of this brass shell are strong magnets which hold to
their surfaces the steel and iron chips, while the brass chips drop off
into a tote box. A stiff brush at the back of the cylinder removes the
iron chips, and they drop into a separate box.
SHOP MANAGEMENT
PLANT ARRANGEMENT
Governing Factors. The success of a foundry depends upon the
ability of its managers to promptly turn out castings which meet
the requirements demanded of them, at the lowest possible cost
commensurate with the quality of the work. In this article we wish
to direct the attention of students to some features in the way of
equipment and management which aid in accomplishing these results.
The most important processes in the foundry are the following:
melting metal, making molds, and pouring them. Much of the work
necessary in preparing for these processes consists in handling heavy
materials such as coke, iron, sand, etc. To reduce this handling
to its lowest limits, as to distances, number.of re-handlings, and
methods of conveyance, are problems to be considered in the plan
of the shop as a whole.
TYPICAL FOUNDRY
General Plan. To briefly illustrate some of the points to be
brought out, let us consider the plan of the shop shown in Fig. 186,
and its sectional elevation shown in Fig. 187.
FOUNDRY WORK
183
Building. The building is of steel construction, and the columns
supporting the roof trusses serve also to carry the tracks for the
overhead traveling cranes.
The outer walls should be filled in with some good weather-
resisting material, of which there is nothing better than brick. These
walls should be of good height and have a sufficient window area to
supply light well in toward the middle of the shop.
Ventilation. The method of heating and ventilating best
adapted for a foundry is the indirect fan system. One or more large
Upper Level Storage
Coke Bins Pig Iron Yard
M
1—“1
! i
1 1
1 J_--|
M
1 C
K 1 J
•*-
mr
u
F
© © © '
K | Moulding Machine
’i Z Z Z Z X
‘ /
E
7
s ^
£ hj Loam
r. 4 * i
Dry Sane/
I I X. t
Heavy Green Sand
f\\
z z x zii
D
H - -'/Medium,' y
: /
1 T
Jen b lJ
Light 1
Office
A
^ Carpenter ^
| Shop
Fig. 186. Typical Plan of Foundry
fans, situated generally toward the ends of the shop, draw fresh air
in through a compact system of steam coils, and, by means of over¬
head piping, deliver it to all portions of the shop. The impure gases
are carried off through ventilators in the clearstory at the top of
the roof.
Floor. The floor of the foundry should consist of molding sand,
the depth of the sand floor varying with the class of work to be done.
If the natural soil of the grounds is open and porous, a thickness of
3 or 4 inches of clay, well rolled down, should be put in underneath
184
FOUNDRY WORK
the sand floor. This will help greatly in keeping the molding floor ii
good condition, as it prevents the moisture draining out of the sand
Shop Office. The foundry office should be located at such £
point that the foreman can command a view of the whole shop. Ii
should be convenient to the different departments and at the same
time be protected as far as possible from dust. The office room,
shown in Fig. 186 at A, is built on the outside of the main building,
but has a large bay window which projects a few feet into the shop
from which all corners of the foundry can be seen.
Pattern Room. A space B, having suitable low tables and shelv¬
ing, is reserved near the office for the temporary storing of patterns
in daily use. This brings them directly under the attention of
the foreman and his assistants who can readily check the patterns
as they come in and quickly find those requiring prompt attention.
Cupolas. At C are shown the cupolas, directly opposite the
foreman’s office, and so situated that all of the molding floors may
be served as quickly as possible without interfering one with the
other.
In large foundries there are two or more cupolas, to admit of
different mixtures being melted simultaneously. Often a compara¬
tively small cupola is installed near the floor for light work for the
service of that floor alone.
The blowers should be placed near the cupolas, avoiding long
connecting wind pipes. The application of electric motors removes
the necessity of concentrating the power at one point in the shop.
Molding Divisions. Heavy Work. The main bay of the foundry
is devoted to the heaviest work and is served by at least two
overhead cranes.
FOUNDRY WORK
185
The heavy green-sand castings are made at one end so that the
flasks for this work may be stored in yards near by and be brought in
through the door D. These molds are made up farthest from the
cleaning shed, because only the castings themselves need be trans¬
ferred there.
The flasks and rigging for the dry-sand and loam molds should
be brought in through the opposite door E. The loam work, as a
rule, is the most bulky to handle and should be nearest the cleaning
sheds so that it need not be carried across the other floors. Both
dry-sand and loam floors are convenient to the large ovens F.
Core Shop. The core shop is situated in the side bay at G, to
make it convenient to swing the large cores on to the buggies to be
run into the large ovens. A jib crane near the corner of these ovens
makes the men working on such cores independent of the traveling
crane. The ovens for small cores are built along the side of the
large ovens and utilize the same stoke hole, ash pit, and stack.
Light Work. Distributed through the side bays also are the
medium-work floor II, the light-work floor I, and the molding-
machine floor J. This ensures a supply of good light necessary to
the smaller details of this class of work.
186
FOUNDRY WORK
Machines. The molding machines are placed on that side of
the shop near the sand storage sheds, to allow for handling the sand
by means of belt conveyors with hoppers above the machines, an
illustration of which is shown in Fig. 188.
The sand-mixing space is in the side bay near the cupolas at K,
and is furnished with power from independent motors or from a jack
shaft leading from the blower room. This position affords direct access
to the sand bins. The raw material after being mixed and tempered is
delivered by barrow or sand car direct to theVarious floors. The mix¬
ers might be installed in one of the storage vaults across the roadway.
Materials. Unloading. The quickest means of unloading either
wagon or carload lots of material is by dumping, where the material
can be so handled. One of two things is necessary to accomplish
this: either the storage bins must be placed in a basement under¬
neath the roadbed; or the roadway must be run up an incline over
the top of the bins. The former method is more frequently met with
in the crowded condition of the large cities, but the latter is preferable
because less time is consumed in running material up an incline in
large quantities than is required to hoist small quantities more
frequently from a basement.
Storage. At L and L', Figs. 186 and 187, are shown the storage
yards for pig iron and coke; these are on a level with the charging
platform of the cupola, C and C', and the materials can be loaded
on cars and pushed directly to the charging door. In some modern
shops these push cars are built so that their load may be dumped
as a whole into the cupola.
The storage for core-oven fuel, sands, and clay, is shown at
MM, in bins built underneath the tracks and on a level with the
foundry floor. These bins should be arranged to open on top, with a
chute under the track and a trap at the side, so that coal or sand may
either be dumped or shoveled directly into them.
Handling Systems. Tracks. In the largest shops a standard-
gage track should run directly through the main foundry, and there
should be also similar tracks through the roadway next the cupola
bay for convenience in removing the dump. The track over the
storage bins has been mentioned.
Two methods of transferring material between departments
within the shop, aside from the cranes, are the overhead-trolley
FOUNDRY WORK
187
system, Fig. ISO, and the narrow-gage industrial railway. The
former is of advantage in manufacturing plants where the loads to
be transferred are nearly uniform in weight and frequency of hand¬
ling. This system leaves gangways smooth and free from obstruc¬
tions. For general work, however, the industrial railways are more
frequently installed. These serve all floors to deliver flasks, sand,’or
iron, and to remove castings.
Cranes. Of the many styles of overhead traveling cranes that
are on the market, those using electricity as the motive power are
undoubtedly the most
serviceable. The cranes
in the main foundry in¬
dicated at O', Fig. 187,
should have two hoisting
drums on the carriage;
one for such light work as
handling flasks, rigging,
and patterns; the other
for the heavy work on the
large ladles and castings.
Small jib cranes fur¬
nished with a 2- to 4-ton
air or electric hoist placed
on the side of a man’s floor
make it possible for the
molder and helper to han¬
dle work of considerable size by themselves, and prevent loss of time
from waiting for the overhead crane.
The method of distributing the melted metal varies with the
class of work made. In shops doing general jobbing work, the ladles
for pouring the largest work are carried from the cupola directly
by the overhead cranes.
Bay Floor. For serving the floors in the bays one of the systems
mentioned above is generally used. The metal is conveyed to the
floor in a large ladle and from this smaller ones are filled and carried
by hand or by a small crane to the molds.
Cleaning Department. The cleaning department should be
situated at one end of the shop near E, Fig. 180, or in a shed extension
188
FOUNDRY WORK
to the foundry proper. It requires space to pile the castings as they
are brought from the floors with sufficient room for the men to begin
work on these piles. As a rule, the smaller castings are first collected
and put through the tumbling barrels, then the medium work is
cleaned by hand or by sand blast; this leaves room for work around
the largest pieces. As soon as castings are cleaned they are weighed
and shipped to the customer, store house, or to the department which
does the next operation upon them.
PERFORMANCE
LABOR
Division. The division of labor in a foundry is briefly as follows:
Superintendent. The superintendent is responsible for the
operation of the foundry as a whole. He hires the men and oversees
the purchase of materials and supplies, having under him clerks who
keep track of the details of this work. Some of the things to which
he gives personal attention are: In consultation with his foreman he
gives personal attention to the receipt of the most important patterns;
decides how they shall be molded; on what floor and with what
mixture they shall be poured. Fie devises ways and means of increas¬
ing the productiveness of his shop.
Foreman. The foreman or his assistants must be in the shop
a sufficient time before work begins for the day to see that each
molder has work laid out for him, and must keep the men supplied
with work through the day. He estimates the amount of the charge
for the day and directs the melter as to mixtures.
It is the duty of the foreman and his assistants to give directions
to the apprentice boys and to see that these directions are carried
out to the best of the boys’ ability.
Holders. The molders should give their entire time to making
up molds. On floor work they are usually given a helper who carries
flasks, cores, chaplets, etc., and does the heavier work when handling
the sand. When the molds are poured and his flasks stripped off
the molder is through for the day.
Laborers. Most modern shops employ a night gang of laborers
to put the shop in proper shape for the molders to start their special
work immediately when the whistle blows in the morning. These
men remove the castings from the sand and transfer them to the
FOUNDRY WORK
189
cleaning shed. They pick out all bars and gaggers used in the molds
and stow them in place. They temper and cut the sand and dig any
pits necessary for bedding in work.
SAFETY FIRST
Accident Prevention. While it may be an impossibility to wholly
prevent accidents in and about the foundry, much has been accom¬
plished in that line. Mechanical safeguards are now in pretty general
use in modern foundries. It is only the out-of-date shop which is
conspicuous for neglect in providing them.
Personal Factor. Only some of the more important items regard¬
ing safety are called to the reader’s attention, and perhaps the most
important one of all is to teach the workman to think safety first.
As an example, in a foundry employing 850 men there were, during a
period of 6 months, 57 accidents involving loss of time. Not one of
these was due to the lack of mechanical safeguards; all were results
of carelessness on the part of the injured, or of negligence by their
fellow workmen.
Clothing. A large percentage of accidents in the foundry are
in the nature of burns from hot metal, and again by far the greater
part of these are below the knee. This shows the practical necessity
for a legging of some material which would resist the hot metal. All
employes in the foundry who come in contact in any manner with
the work of pouring, or of shaking out flasks after pouring, when the
hot sand may be just as dangerous as the molten metal, should be
compelled to wear the foundry or congress shoe.
Shop Equipment. There should be frequent inspection of all
foundry rigging, such as crane hooks, chains, and ladle shanks, also
great care should be used under the cupola and tapping spout, as
any excess of moisture, were molten metal to be spilled upon it,
would cause explosions and probably seriously injure someone.
In the cleaning room, protection for the eyes from flying chips
of metal is important; so, also, are guards over grinding wheels which
should be equipped with an efficient exhaust to care for dust.
While there are many more things which might be mentioned
regarding safety, as applied to foundry practice, those already men¬
tioned should be sufficient to cause the student to think safety, to
put his thoughts in practice and to teach others to do likewise.
190
FOUNDRY WORK
PHYSICAL RESULTS
Checking. The methods of mixing iron by analysis have been
previously dealt with, but these mixtures must be checked by physi¬
cal tests on the resulting castings. Two systems of checking are
now in more or less general use throughout the United States.
Keep’s Mechanical Analysis. A very complete system of regu¬
lating mixtures, termed by the inventor Mechanical Analysis has
been devised by W. J. Keep, of Detroit, Michigan, who has had long
experience in this subject. In Fig. 190, A shows a follow board
arranged with patterns and yokes. The test bars are § inch square
and 12 inches long. They are cast in green sand with their ends
chilled against the faces of the cast-iron yokes, shown in the cut.
Three molds should be cast each heat, and the test bars allowed to
cool in the molds.
Silicon and Shrinkage. The analysis is based on the fact that
silicon is the most important variable chemical element in cast iron,
Fig. 190. A—Keep’s Test-Bar Pattern; B—Measuring Shrinkage
and that shrinkage in castings is inversely proportionate to the
silicon in the mixture.
The first test, as shown at B, Fig. 190, is to replace each bar in
the same yoke in which it was cast and by means of a specially
graduated taper scale to ascertain accurately the amount of shrinkage.
The shrinkage of the bars when the castings prove satisfactory,
should be considered the standard for that class of work for that
shop. If at any time the shrinkage is greater than the standard,
increase the silicon by using more soft pig; if it is less, decrease
silicon by using more scrap or cheaper iron.
Chilled Depth. The depth of chill on the castings is measured
after chipping off a piece from the end of the bar.
Transverse Strength. The third test is to obtain the transverse
strength of each bar. This is done on a special testing machine
FOUNDRY WORK
191
which gives a graphical record of the deflection and the ultimate
breaking load. These dead loads will vary with different mixtures
approximately from 340 to 500 pounds.
Deductions. Quoting from Mr. Keep’s circular:
With high shrinkage and high strength of a l-inch square test bar, heavy
castings will be strong but small castings may be brittle.
With low shrinkage and high strength, large castings will be weak and
small castings will be strong.
With uniform shrinkage, an increase in the strength of a §-inch square
test bar will increase the strength of all castings proportionately.
Arbitration=Bar Tests. The other form of tests was devised
by a committee of the American Foundrymen’s Association, and is
recommended in the Proposed Standard Specifications
for Gray-Iron Castings by the American Society for
Testing Materials.
Test Bar. The test bar specified is 1J inches in
diameter and 15 inches long, and is known as the
arbitration bar.
The tensile test is not recommended, but, if called
for, a special threaded test piece is turned down from
the arbitration bar, and has a test section 0.8 inch in
diameter and 1 inch between shoulders.
The transverse test is made with supports 12
inches apart.
Fig. 191 shows a sketch of the patterns for these
bars. Two bars are rammed in a flask and poured
on end. The small prints on the two bar patterns
project into the cope and are connected by one pouring
basin. A special green-sand mixture is specified for
making these molds; the molds are to be baked before
pouring, and the bars allowed to remain in the sand
until cold.
Specifications. Table IX shows the specified requirements;
in this connection castings are distinguished as follows:
Unless furnace iron is specified, all gray castings are understood to be
made by the cupola process.
Light castings are those having any section less than 5 inch.
Heavy castings have no section less than 2 inches.
Medium castings are those not included in the above.
rh
hf-i
*nlThi.
-â– 
Fig. 191. Pat¬
tern for Arbi¬
tration Bar
192
FOUNDRY WORK
TABLE IX
Arbitration=Bar Standards
Grade of Castings
Chemical Prop¬
erties
Physical Properties
Sulphur Content
High Limit
(per cent)
Transverse Test*
Minimum Load
(lb.)
Tensile Strength
Low Limit
(lb. per sq. in.)
Light
o.os
2500
18,000
Medium
0.10
2900
21,000
Heavy
0.12
3300
24,000
PRACTICAL DATA
Using Percentage
(1) To find the percentage of any number when the rate per
cent is given: Multiply the number by the rate per cent and set the
decimal point two places to the left.
Example: Find 7.5 per cent of 35. 35x7.5 = 262.5; decimal
point moved two places to the left gives Ans. 2.625
(2) To find what rate per cent one number is of another:
Add two ciphers to the percentage and divide by the number on
which the percentage is reckoned.
Example: What per cent of 75 tons is 9 tons? 900-4-75 = 12.
Ans. 12 per cent
(3) To find a number when the rate per cent and the percentage
are known: Add two ciphers to the percentage and divide by the
rate per cent.
Example: If 68 pounds is 15 per cent of the entire charge, how
many pounds in the total charge? Ans. 6800-4- 15 = 453.33 pounds
(4) To find what number is a certain per cent more or less
than a given number: (a) When the given number is more than the
required number, add two ciphers to the number and divide by 100
plus the rate per cent.
Example: 465 is 35 per cent more than what number?
Ans. 46500-4- (100+35)135 = 344.4
(,b) When the given number is less than the required number
add two ciphers to the number and divide by 100 minus the rate
per cent.
*In no case, shall the deflection be under 0.10 of an inch.
FOUNDRY WORK
193
Storage Data
Square Box Measure
Size
(inches)
Capacity
24 X16 X28
1 barrel
16 X16fX 8
1 bushel
8j X 8j X 4
1 gallon
4 X 4iX 4
1 quart
Molding Material Weights
Material
Amount
(cu. ft.)
Weight
(ton)
River sand
21
1
Pit sand
22
1
Stiff clay
28
1
Example. 526 is 23 per cent less than what number?
Ans. 52600 -f- (100 — 23) = 52600 -4- 77 = 683 116
Mensuration
Circumference of a circle
Area of a square or rectangle
Area of a triangle
Area of a circle
Convex surface of a cylinder
Convex surface of a sphere
Contents of a rectangular solid=
Contents of a cylinder
Contents of a sphere
One side of square having same
area as given circle
= diameter X3.1416
= base side X height
= base X \ X perpendicular height
= diameter squared X .7854
= circumference X height
= circumference X diameter
= area of base X height
= area of base circle X height
= cube of diameterX.5236
f diameter X .8862
= j or
[circumference X .2821
Inches
Square inches
Cubic inches
Cubic inches
Cubic feet
Cubic yards
Conversion Factors
X 0.08333 =
X 0.00695 =
X 0.00058 =
X 0.004329=
X1728
X 27
U. S. gallons of waterX 8.33
U. S. gallons of water X 231.00
Pounds of water X 27.72
Ounces of water X 1.735
= feet
=sq.feet
=cu.feet
= U. S. gallons
= cu. inches
=cu.feet
= pounds
= cu.inches
= cu.inches
=cu.inches
194
FOUNDRY WORK
Circular Areas and Circumferences
J Diameter
Area
Circumference
Diameter
1
Area
Circumference
Diameter
Area
Circumference
Diameter
Area
Circumference
0.0123
.3926
10
78.54
31.41
30
706.86
94.24
65
3318.3
204.2
0.0491
.7854
i
86.59
32.98
31
754.76
97.38
66
3421.2
207.3
t
0.1104
1.178
11
95.03
34.55
32
804.24
100.5
67
3525.6
210.4
0.1963
1.570
\
103.86
36.12
33
855.30
103.6
68
3631.6
213.6
0.3067
1.963
12
113.09
37.69
34
907.92
106.8
69
3739.2
216.7
a
0.4417
2.356
i
122.71
39.27
35
962.11
109.9
70
3848.4
219.9
|
0.6013
2.748
13
132.73
40.85
36
1017.8
113.0
71
3959.2
223.0
i
0.7854
3.141
143.13
42.41
37
1075.2
116.2
72
4071.5
226.1
j
0.9940
3.534
14
153.93
43.98
38
1134.1
119.3
73
4185.3
229.3
]
1.227
3.927
165.13
45.55
39
1194.5
122.5
74
4300.8
232.4
I
1.484
4.319
15
176.71
47.12
40
1256.6
125.6
75
4417.8
235.6
rj
1.767
4.713
J
188.69
48.69
41
1320.2
128.8
76
4536.4
238.7
§
2.078
5.105
16
201.06
50.26
42
1385.4
131.9
77
4656.0
241.9
a
2.405
5.497
213.82
51.83
43
1452.2
135.0
78
4778.3
245.0
2.761
5.890
17
226.98
53.40
44
1520.5
138.2
79
4901.6
248.1
2
3.141
6.283
240.52
54.97
45
1590.4
141.3
80
5026.5
251.3
\
3.976
7.068
18
254.46
56.54
46
1661.9
144.5
81
5153.0
254.4
\
4.908
7.854
J
268.80
58.11
47
1734.9
147.6
82
5281.0
257.6
a
5.939
8.639
19
283.52
59.69
48
1809.5
150.7
83
5410.6
260.7
3
7.068
9.424
298.64
61.26
49
1885.7
153.9
84
5541.7
263.8
J
8.295
10.21
20
314.16
62.83
50
1963.5
157.0
85
5674.5
267.0
\
9.621
10.99
330.06
64.40
51
2042.8
160.2
86
5808.8
270.1
3
11.044
11.78
21
346.36
65.97
52
2123.7
163.3
87
5944.6
273.3
4
12.566
12.56
363.05
67.54
53
2206.1
166.5
88
6082.1
276.4
15.904
14.13
22
380.13
69.11
54
2290.2
169.6
89
6221.1
270.6
5
19.635
15.70
397.60
70.68
55
2375.8
172.7
90
6361.7
282.7
i
23.758
17.27
23
415.47
72.25
56
2463.0
175.9
91
6503.8
285.8
6
28.274
18.84
i
433.73
73.82
57
2551.7
179.0
92
6647.6
289.0
5
33.183
20.42
24
452.39
75.39
58
2642.0
182.2
93
6792.9
292.1
7
38.484
21.99
471.43
76.96
59
2733.9
185.3
94
6939.7
295.3
44.178
23.56
25
490.87
78.54
60
2827.4
188.4
95
7088.2
298.4
8
50.265
25.13
26
530.93
81.68
61
2922.4
191.6
96
7238.2
301.5
56.745
26.70
27
572.55
84.82
62
3019.0
194.7
97
7389.8
304.7
y
63.617
28.27
28
615.75
87.96
63
3117.2
197.9
98
7542.9
307.8
*
70.882
29.84
29
660.52
91.10
64
3216.9
201.0
99
7697.7
311.0
Weight Calculation
Weight of round iron per foot = Diameter (quarter inches) squared X 0.1666
Weight of flat iron per foot = WidthXthicknessX3.333
= 5 pounds for each £ inch in thickness
= Diameter squared X 10.7 (approximate)
= Bar diameter (quarter inches) squared X
2000
To compute weight of metal from weight of pattern, with no allowance for
cores or runners, multiply as follows:
Weight of plates per sq. ft.
Weight of chain
Safe load (pounds) for chain
Multiplication Factors
White Pine
Mahogany
Result
16.7
10.7
Cast iron
18
12.2
Brass
23
15.
Lead
15
9.
Tin
16
10.4
Zinc
Weight of brass patternX .9= weight of iron casting, approximately,
FOUNDRY WORK
195
Specific Gravities and Weights of Metals
Material
Specific
Gravitv
Weight per
Cubic Inch
(pounds)
Water, at 39.1° F.
1.
.036
Aluminum
2.6
.094
Antimony, cast 6.64 to 6.74
6.7
.237
Bismuth
9.74
.352
Brass, cast 7.8 to 8.4
8.1
.30
Bronze 8.4 to 8.6
8.5
.305
Copper, cast 8.6 to 8.8
8.7
.32
Gold, pure, 24 carat
19.25
.70
Iron, cast 6.9 to 7.4
7.21
.263
Iron, wrought 7.6 to 7.9
7.77
.281
Lead
11.4
.41
Mercury, at 60° F.
13.58
.49
Platinum 21. to 22.
21.5
.775
Silver
10.5
.386
Steel, average
7.8
.283
Spelter or zinc 6.8 to 7.2
7.
.26
Tin, cast 7.2 to 7.5
7.35
.262
Pressure In Molds
Depth
(ft.) (in.)
Pounds
(per sq. in.)
Depth
(ft.) (in.)
Pounds
(per sq. in.)
Depth
(ft.) (in.)
Pounds
(per sq. in.)
1
.26
19
4.94
3
6
10.92
2
.52
20
5.20
4
12.48
3
.78
21
5.46
4
6
14.04
4
1.04
22
5.72
5
15.60
5
1.30
23
5.98
5
6
17.16
6
1.56
2
00
6.24
6
IS. 72
7
1.82
25
6.50
6
6
20.28
8
2.08
26
6.76
7
21.84
9
2.34
27
7.02
7
6
23.40
10
2.60
28
7.28
8
24.96
11
2.86
29
7.54
8
6
26.52
1 00
3.12
2
6
7.80
9
28.08
13
3.38
31
8.06
9
6
29.64
14
3.64
32
8.32
10
31.20
15
3.90
33
8.58
10
6
32.76
16
4.16
34
8.84
11
34.32
17
4.42
35
9.10
11
6
35.88
1 6
4.68
3
00
9.36
12
37.44
To find the total lifting pressure on the cope, multiply the pressure per
square inch at a given depth below the pouring basin by the area (square inches)
of the surface acted against. The result is in pounds.
196
FOUNDRY WORK
Temperatures*
Connection
Heat
(Degrees
Fahrenheit)
Core ovens
f yellow
Bright iron becomes <
[gray
Tin melts
Mercury boils
Lead melts
Zinc melts
Silver melts
Copper melts
Gold melts
fa dark room, just visible
Iron bar red in j ordinary office
1 daylight, open air
Cast iron melts
Igray
Steel melts
Annealing malleable iron
250 to 450
435
500
550
750
445
660
612
775
1775
1885
1900
950
1075
1450
2075
2230
2750
1600 to 1750
*From late scientific investigations.
INDEX
INDEX
PAGE
A
Air furnace for melting malleable iron 154
Alloys, brass and bronze 167
Analysis of cast iron 190
arbitration bar 191
Keep’s mechanical 190
Analysis of cupola mixtures, chemical 123
Annealing malleable-iron castings 161
oven for 165
Annealing steel castings 144
Arbitration-bar tests of cast iron 191
specifications for 191
test bar in 191
Arbors for core work 56, 63
B
Balanced cores 60
Barrel cores, making 92
Batch sand mixer 152
Binders, core 9, 47, 51
Blast 112
fan-blower 112
gage for 114
pressure-blower 113
Blowholes 22, 31
Bottom doors, cupola-furnace 109
Brass 167
chip separation 182
cleaning castings of 181
heats, size of 174
melting 176
molding equipment 172
molding materials 171
molding process 174
pattern weight 194
specific gravity and weight 195
work, examples of 175
Brass work 167
alloys in 167
production processes in 171
Breast, cupola-furnace 111
Bronze 168
specific gravity and weight of 195
2 INDEX
PAGE
C
Carbon 121, 136
Cast-iron analysis 190
Casting operations 109
brass work 167
malleable practice 145
melting gray iron 109
steel work 136
Centrifugal sand mixer 129
Chaplets 21
setting 60
^Charcoal foundry facing 7
Charging door, cupola-furnace 112
Cheek 9
Clamps 17
Clay wash 8
Cleaning castings, methods of 131
malleable-iron work, in 160
steel work, in 144
Coke, foundry 126
Cold-shuts 1 31
Cope 9
flat joint, for 33
floor bedding, in 44
loam molding, in 99, 102, 105
pressure head on 28
Coping out 35
Copper 168
specific gravity and weight __ _ 195
temperature, melting 196
Core-making machines : C 57jj
Core ovens 48
Core plates 48
racks for 50
Core sand 6, 46
mixtures 51
Core work _2, 46
barrel 92
for brass molding 175
dry-sand 46
general equipment for 48
green-sand-. 39, 62
for malleable-iron molding 152
setting cores in 58
for steel molding 141
Core-rod straightening machine 134
Cover core 90
Cover plates in loam molding 95, 105
Crucible malleable-iron melting 152
INDEX
3
Cupola furnace 109
mixtures for 120
operation of 116
parts of 109
Cupola malleable-iron melting 153
Cutting and tempering sand 19
D
Drag
flat-joint
floor-bedding pit
Draw sticks
Drawback
Drying stove for brass molds
Dry-sand cores
equipment for making
methods of making
materials for
setting of
use of
Dry-sand molding
Duplicating of castings, multiple
brass
gated-pattern method
jolt ramming machine
machine molding
malleable-iron
permanent match
roller ramming machine
roll-over machine
squeezer machine
stripping-plate machine
Facings
dry-sand core
for steel molding
Ferrosilicon in malleable iron
Fire clay
Fire sand
Flasks for
brass molding
malleable-iron moldings _
steel molding
Flat joint
Floor bedding
Foremen, duties of
Foundry, typical
cleaning department
F
9
32
43
17
100
173
46
48
53
46
58
51
2, 89
66
176
67
79
67
14S
67
86
73, 77
.71, 75, 86
68
6
47, 51
.. 137
.. 158
.. 7
9
172
__ 152
.. 138
.. 32
23, 42
.. 1S8
.. 182
__ 187
4
INDEX
PAGE
Foundry, typical (continued)
core shop
cranes
cupolas
floor plan
heavy-molding division.
light-molding division
molding machines
pattern room
shop office
storage of materials
tracks
type of building
unloading of materials
ventilation
Foundry work
casting operations
molding practice
practical data
shop management
Free sands
.. 185
.. 187
.. 184
.. 183
.. 185
185
186
.. 184
184
. 186
.. 186
. 183
. 186
. 183
1-196
. 109
. 1
_ 192
_ 182
. 6
G
Gaggers 21
Gas furnace for brass melting 179
Gated patterns for duplicate castings 67
Gating 24
Graphite foundry facing 7
Gray iron 109
Green-sand cores 39, 62
Green-sand molding 1
principles of 18
typical problems in 31
H
Hard-rolling of castings 160
Heat, running a 116
for brass work 174
for malleable casting 159
for steel casting 141
I
Iron 109
specific gravity and weight of 195
temperature indications 196
J
Jointing 32
loam molds 100 ,
INDEX
5
PAGE
Iv
Keep's mechanical analysis of cast iron 190
chilled depth 190
deductions by 191
silicon and shrinkage 190
transverse strength 190
L
Labor, shop management of foundry 188
foremen 188
laborers 188
molders 188
superintendent 188
Laborers, duties of foundry 188
Ladles for 118
brass work 177
malleable-iron work 159
steel work 142
Laying up loam mold 99
Lead 169
melting temperature 196
specific gravity and weight of 195
Lifters 15
Lifting ring, core 40
Lining 111
. cupola-furnace 111
foundry-ladle 118
Loam mixtures 92
Loam molding 2, 94
example of complex cylinder 104
example of simple 102
materials for 97
principles of 99
rigging for 94
M
Malleable cast iron 145
annealing 161, 196
cleaning 160
finishing - 167
melting, methods of 152
metal characteristics 145
method of casting 159
methods of testing 146
mixture for 156
molding 148
patterns for 148
specifications for 146
6 INDEX
PAGE
Malleable practice 145
development of 145
production processes 148
Manganese 122, 136
Match, sand 36
permanent oil 67
Materials, molding 3
brick for loam molding 97
cinders 98
facings 6, 98
miscellaneous 7
mud for loam molding 98
sands 3, 171
Melting 109
brass 176
malleable-iron 152
principles of iron 115
steel 141
supplementary operations in iron 127
Mixing machines, sand 128
Mixing of sand 127
Mixtures, cupola-furnace 120
calculation of 124
chemical analysis of 123
elements in 121
fuel in 126
proportions of charge in 126
Mold board 9
Molders, duties of 188
Molding machines 67
Molding practice 1
brass 167
divisions of iron molding 1
general molding equipment 3
malleable-iron 145
processes 18
steel — 137, 143
N
Natural-draft furnace for brass work 177
Nowel or drag 9
0
Open sand molding— 45
Open-hearth malleable-iron melting 156
Open-hearth steel, casting 141
T>
Packing steel molds 139
Parting dusts 8
INDEX
7
Patterns for malleable castings
Phosphor bronze
phosphor tin in
Phosphorus 122, 136,
Pickling castings
of brass and bronze
Pig iron in malleable work
Pouring
brass -
loam molds 104,
malleable iron
short
steel
venting action during
Practical data
circular areas and circumferences
conversion factors
mensuration
percentage, examples of using
pressure in molds â– _
specific gravities and weights
square box measure
temperatures
weight of metal and patterns
weights, molding material
Pressure in molds 27,
pressure distribution examples
pressure-head examples
Pyrometer for annealing furnace
R
Ramming
Ramming machine
jar or jolt
roller
Rammers
core work, for
Rapping plate
Rattler or tumbling barrel
Reinforcement, core 47
Risers
Roll-over machine
power type
Rotary sieve
Runners
S
Safety-first factors
clothing
personal
PAGE
148
171
171
170
133
181
157
119
174
106
159
31
142
23
192
194
193
193
192
195
195
193
196
194
193
195
28
28
167
20
79
79
86
13
48
17
131
’, 55
22
73
77
129
24
189
189
189
8 INDEX
PAGE
Safety-first factors (continued)
shop equipment 189
Sand shaker 129
Sand-blasting 135
Sands, molding 3
core sand 6, 46
elements in 4
fire sand 5
for brass work 171
for malleable iron work 149
for steel work 137
free sands 6
grades of 5
green-sand mixture 18
volume per ton 193
Scabs 31
Scrap iron in malleable work 157
Sea-coal foundry facing 7
Setting cores 58
Shop management 182
governing factors in 182
labor 188
of typical foundry 182
physical results 190
safety first in 189
Shovel 12
Shrinkage cracks 31
Shrinkage heads or feeders 26
Shrinkage in malleable casting 148
Shrinkage in steel work 137
Sieve, riddle or foundry 13, 129
Sifting 19
Silicon 122, 136
Skimming gate 24
Slag hole, cupola-furnace 111
Slicks ___ 15
corner 16
Slip or skinning loam 94
Snap flask 9
Spill trough for brass pouring 173
Spindle for loam mold sweeping 94
Split-pattern molds 38
core lifting ring 40
green-sand core 39
loose-piece 39
three-part 41
Spraying can for core work 48
Sprues 24
Squeezer machine 71
INDEX
9
PAGE
Squeezer machine (continued)
automatic 86
power type 75
Steel 137
annealing castings of 144
casting, running a heat for 141
cleaning castings of 144
cores in molding 141
facings for, mold 137
flasks for molding 138
molds for, setting up 143
packing process in molding 13S
specific gravity and weight of 195
temperature, melting 196
Steel work 136
casting 141
molding 137
Stripping-plate machine 68
Sulphur 122, 136
Superintendent, duties of 188
Swabs 16
Sweeping . 95
cores 56
Swells - 31
T
Tables
alloys, proportions of mixtures in 170
arbitration-bar standards for cast iron 192
crucible sizes 176
cupola^fumace sizes 112
fan-blower performance 113
flasks, sizes of wooden 11
ladle data, foundry- 118
phosphor-bronze mixtures 171
sands, proportions of elements in 4
Tapping 117
Tempering 19
cores, dry-sand 47
Testing cast iron 191
malleable 146
Three-part mold 41
Tin 168
specific gravity and weight of 195
temperature, melting 196
Tools, hand-molding 9
for finishing 14
for brass work 172
Trowels 15. 48
10 INDEX
P/ QE
Tumbling castings 131
Tuyeres 111
V
Vent rods 16
Ventilation systems in typical foundry 183
Venting 22
dry-sand cores 47
loam molds 100, 106
W
Warping 31
White iron in malleable practice 149
Z
Zinc 169
melting temperature.. 196
ENGRG LIBRARY *-ht-1^
University of Washington Library
Date Due
nap 2 7 ^977
nov :
NOV 1
4 1986
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ENGRG
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DEC i (
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Engr Stacks-Floors 3&4