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With Two Hundred and Eighty -Three Illustrations FOURTH EDITION, THOROUGHLY REVISED AND ENLARGED NEW YOEK D. VAN NOSTEAND COMPANY 25, PARK PLACE LONDON: WHITTAKER AND CO. 1914 y ■^^f. ,\\^ n - II lOh • » * • • • CHISWIClv PRESS : CHARLES WHITTINGHAM AND CO. TOOKS COURT, CHANCERY LANE, LONDON. 1 PREFACE TO FIRST EDITION This is an attempt to give a condensed account of the principles and practice of Iron Founding. It is written both for the student and for the practical man. I have stated and explained principles, and have also included the most recent practice, particu- larly as it relates to the two branches of machine moulding and the melting of iron. Joseph Horner. PREFACE TO FOURTH EDITION Since this voluine was written o-reat chan^'es have been accomplished in the Iron Foundry. This is the explanation of the fact that the amount of matter in the present edition is just double that of the previous one, and that certain portions, notably that of machine moulding, have been wholly re- written . Additional examples of moulds have been intro- duced, and some new chapters prepared. It is now more than an elementary treatise, and should pos- sess a correspondingly higher value than the pre- vious editions. Bath, 1914 VI CONTENTS CHAPTER PAGE I. Principles ....... 1 II. Sands and their Preparation ... 4 III. Iron — Melting and Testing ... 28 IV. Cupolas, Blast, and Ladles ... 47 V. The Shops, and their Equipment . . 71 VI. Moulding Boxes and Tools . . .93 VII. Shrinkage — Curving — Fractures — Faults . 113 VIII. Principles of Green Sand Moulding . . 137 IX. Examples of Green Sand Moulding . . 163 X. Dry Sand Moulding ..... 185 XL Cores 215 XII. Loam Work 234 XIII. The Elements of Machine Moulding . . 263 XIV. Examples of Moulding Machines . . 279 XV. Machine Moulded Gears .... 329 XVI. Miscellaneous Economies — Weights of Castings 347 Appendix : Tables L Sand Mixtures 385 II, in. Particulars, " Rapid " Cupolas . . 389 IV. Particulars, Boot's Blowers . . 392 V. Sturtevant Fans 393 VI. Crane Chains 394 VII. Bopes, various 394 VIIL Composition of Pig Iron . . . 395 IX. Mensuration 396 vii Vlll CONTENTS Appendix — continued Tables X. Weights of Various Metals . XI. Weights of Cast Iron Cylinders XII. Comparative Weights XIII. Weights, Cast Iron Balls XIV. Decimal Equivalents . XV. Decimal Approximations Index PAGE 399 400 402 403 404 404 405 PRACTICAL IRON FOUNDING ^ CHAPTEK I PRINCIPLES In this text-book the endeavour will be to explain and illustrate in a clear and concise manner the principles and practice of iron moulding and founding. Though a dirty trade, more of technical skill and forethought are required, more difficulties have to be encountered than in many trades of more apparent importance. And as it is one the practice of which is very varied and extensive, and as a thoroughly exhaustive treatment would occupy a much larger treatise than this, judicious condensation will be necessary. But if we endeavour to go down at once to first principles, and gain clear ideas as to the fundamentals involved in iron-moulding, we shall be able to obtain such a broad grasp of the subject as will assist subsequently in the comprehension of details. The matrices into which iron is poured in order to obtain castings of definite outlines are invariably either of sand or iron. The process in which the latter is used is a small and comparatively restricted section, known as chilling', the former embraces all the ordinary iron castings — those the surfaces of which are not required of a hard and steely character. Recently, however, the prac- tice has been developing of casting pipes, wheels, sash weights, etc., in permanent moulds of iron. Sand is eminently adapted for casting metals into. No material can take its place, because there is none 2 PBAGTIGAL IRON FOUNDING which is at the same time plastic, porous and firm, adhesive and refractory. Plasticity is necessary in order that the matrix may be moulded into any form, intricate or otherwise. Porosity is essential to permit of the escape from the moulds of the air and of the gases generated by the act of casting, and firmness and adhesiveness are re- quired to withstand the liquid pressure of the molten metal. A matrix must also be refractory, that is, able to resist the disintegrating influence of great heat, and the chemical action of the hot iron itself. It must, moreover, be cheap, readily available, and not difficult to manipu- late. All these qualities are possessed by certain sands, and mixtures of sands, and by no other materials. The leading branches of moulding derive their names from the different kinds of sand mixtures used, termed respectively green sand, dry sand, loam, to be explained directly. It will suffice just now to remark that the fact that sands differ widely in their physical qualities is apparent to any observant person, so that while one kind will be loose, open, friable, and free, another will appear as though clayey, greasy, close, and dense. Advantage is taken of these differences in quality to obtain mixtures suitable for every class of moulded work, from the thin- nest, lightest rain-water pipes to the most massive and heaviest engine cylinders and bedplates. Almost in- variably, therefore, foundry sand consists of mixtures of various separate kinds. By judicious mixture, grades of any required character can be obtained. To enable the sand to take the requisite definite im- pressions and outlines, it is necessary to emiAoy 2)atterns, the shapes of which are in the main the counterparts of those of the castings wanted. These patterns are in some cases absolutely like their castings, but in others they PRINCIPLES 3 resemble them only to a certain extent. Thus, if work is to be hollow, the hollow portions, instead of being pro- vided in the patterns, may be often much better formed in cores: — prints on the patterns indicating their posi- tions, and the print impressions affording them support. But in much large work, again, the patterns are mere skeletons, profile forms, and the mould is prepared mainly by a process of " sweeping " or " strickling " up. In order to effect delivery of patterns, a process of loosening by rapping has to be resorted to, and this, together with the lifting or withdrawal, tends to damage the mould. To prevent or to minimize this injury, taper is given to patterns, that is, their dimensions are slightly diminished in their lower portions, or in those which are last withdrawn from the mould. As iron shrinks during the process of cooling, an allow- ance has to be given for this "contraction," by making the pattern and mould larger by a corresponding amount than the casting is required to be. Moreover, the forms of some castings are such that they i'lirce in cooling, and for this also provision has properly to be made in their patterns. Iron when molten behaves similarly to a liquid in all respects; hence the conditions of liquid pressure exist in all moulds. The iron, therefore, has to be confined at the time of pouring by the resistance of large bodies of sand enclosed in boxes or flasks, which are weighted, or otherwise secured. Sufficient area of entry for the metal has to be provided by means of suitable gates and run- ners. The shrinkage of metal in mass must receive adequate compensation by feeder heads. Owing to the irregular outlines of cast work, flasks must be jointed, and joints of various kinds have to be made in the mould itself. CHAPTEE II SANDS, AND THEIR PREPARATION Although as stated, sand is not the only material used for moulds, yet ninety-nine one-hundredths of the moulds made are prepared in sand in some way or another, and cast into either moist or dried. Consisting, as this material does, of a vast number of distinct particles, it can readily be compelled by ramming or pressure to take any re- quired outlines and the finest impressions of the pattern. Though friable and destitute of cohesion in its natural dry condition, it is plastic and coherent when moistened with water; so that w^hen in this state it is capable not only of receiving but of retaining the impressions made by the pattern after its withdrawal. Further, the porosity of the sand much assists the free escape of the gases generated by casting, and which, in the absence of a free vent, would honeycomb the castings with innumerable blow- holes. But it is obvious that sands are not all alike, and a very superficial knowledge of moulding is sufQcient to show that different classes of moulds must require differ- ent kinds of mixtures of sands. In their judicious choice and proper mixture lies very much of the moulder's art; so that a foreman moulder will spend several months, or even years, in studying and experimenting in various mixtures before he gets the very best possible results in his shop. 4 SANDS, AND THEIB PREPARATION 5 Choice of sands. — Primarily the choice depends very much upon locaHties. When building a new foundry one would not go to the opposite end of England to get sand to lay down his floor, which will properly be from 2 ft. to 3 ft. or 4 ft. in depth. He would purchase cheap sand in his immediate neighbourhood, and there are few localities in which the new red sandstone, the green sand, and chalk formations, or the coal measures, do not furnish suitable material for the moulder. But there are several localities which are famous for some special qualities possessed by their sands which render them more suitable for some classes of work than for others, and small quantities of these sands are often purchased at considerable expense, due chiefly to the cost of transit, for special work. Thus, though the yellow and greenish-yellow sands usually form the basis of the foundry floor, the fine red sands are chiefly employed for facing and for fine moulding. The names and qualities of some of the best-known sands used in this country are summarized below: Erith sand, or London sand, is largely used for green, and loam moulds. It is suitable for light work, for ordinary and moderately heavy castings, and, mixed with old loam and cow hair, for loam work. Devizes and Seend sands, used in the West of England, are of a yellow or greenish-yellow colour, and are used for general and heavy work. They are not suitable for the finest work, being coarse and close. Worcester is a fine red sand, used for fine moulds and for facing moulds, in which a coarser sand is used for filling. Falkirk sand is coarse and open, and is suitable, therefore, for casting hollow ware into, its porosity allowing free vent for the gases. Belfast sand is fine ; it is used for general work, is mixed with rock sand, and aftbrds excellent facing. Doncaster sand is 6 PRACTICAL IRON FOUNDING suitable for jobbing work. It is of a red colour, and moderately open. Winmoor sand is very open, and used for strong moulds. Kippax, a yellow sand, is employed for cores, and for dry-sand moulds. Mansfield sand is close, and suitable for fine work. Derbyshire, Snaitb, Shropshire, Cheshire, the Birmingham district, and many others, produce good sands of various qualities. Sea sand is sometimes used for cores, and rock sand — i.e., rotten rock — is employed for imparting strength to weaker sands. Moulding sands are obtained in the coal measures, the new red sandstone, and the green sand and chalk. As local foundries largely use local supplies, a knowledge of the precise mixing of sands for any one locality has to be acquired there, and the experience thus gained is modified to be of service when the sands of another locality are employed. Nevertheless, there are certain general principles to be observed in the mixing and use of sands, which apply to all alike. The terms f/reen, dry, loam, floor, black, strong, iccak, core, facing, burnt, parting, road sands, have exclusive reference to mixtures, and physical conditions; none whatever to geological character, or to locality. Sand is green when the mixture is used in its natural condition, that is, damp, or mixed with just sufficient water to render it coherent. Immediately after the pattern has been withdrawn therefrom, the mould is ready, ex- cept for the necessary cleaning and mending up, and blackening, to receive the metal. It is also termed n-eak sand to distinguish it from the other mixtures, which by comparison therewith are strong, i.e., possessed of superior binding qualities — having more body — more coherence. Floor sand, — Every time that a casting is poured, the SANDS, AND THEIU PREPARATION 7 sand in the mould becomes baked dry by the heat of the metal, and before being allowed to mingle with the floor sand it is passed through a riddle to free it from small particles of metal, lifters, nails, etc., and is then moistened with water from a bucket or can, or hose pipe, and dug over two or three times, and it is then ready for use once more. The floor sand or black sand, therefore, forms an accumulation, always damp, always ready for filling boxes, or for moulding patterns by a process of bedding- in. It possesses no strength, and is only used for box- filling. When a mould requiring a fine sand is large, or only of moderate size, then the common sand would be used for its main body — or for box-filling — and only those portions which come next the pattern, and for an inch or so away from it, would be made with the more ex- pensive sand. There are certain primary methods of preparing sands which are, however, followed in all shops, no matter what kinds or what proportions are used. Except for mere box- filling, no sand is ever used just in the condition in which it is dug out of the quarry or pit. It is mixed wdth other sands, or other ingredients, and with water. Omitting loam mixtures we may therefore divide all prepared moulding sands into two classes, those which are used for box-filling^ and those employed for facing. In reference to the first, little preparation is required. The floor of a foundry is composed entirely of sand, which is being used and cast into over and over again, year after year, and only such portions as become burnt by direct contact with the castings are ever removed and thrown away. This sand is receiving continual addi- tions of new facing sand, used once in contact with the 8 PB. ACTIO AL IB ON FOUNDING castings, and then, excepting the burnt portions, allowed to mingle with the floor sand. Facing sand. — The actual sand which is rammed around, and in immediate contact with, the pattern, is termed facing sand, because it forms the actual faces of the mould, against which the metal is poured. This is the true moulding material, on the composition and character of which the quality of the casting itself depends in a very large measure, and which is varied by the skill and •experience of the founder to suit different classes of work. Facing sands are made to vary in strength, porosity, and binding qualities, for different kinds of work, the reasons of which will be apparent as we dis- cuss the different kinds of moulds. Some of these are more porous and sharp than others, and being 02)en, are suitable for light, thin castings, being more or less self- venting. Some of the more open sands are used alone, but most kinds require tempering by admixture with those of opposite qualities, in order to fit them for their specific uses. Thus strong sands, or those having a good body, or closeness of texture, are mixed in variable pro- portions with the open sharp sands, and by varying their proportions, sand, like iron, can be obtained in any re- quired grade. Hence the facing sands are prepared by a careful pro- cess of due proportioning of ingredients adapted to the several classes of work for which they are specially re- quired. For light, and for heavy work, and for all intermediate classes, the kinds and proportions of sands used, and the quantity of coal dust intermixed, will vary, and even in different parts of the same mould. In parts subject to much pressure, the sand should be close, rammed hard. SANDS, AND THEIB PBEPABATION 9 and well vented; and in sections where the opposite conditions exist, the sand may be light and open. It is therefore impossible to give any precise rules. But the broad principles upon which such mixtures are propor- tioned can be indicated. For lieavy moulds — that is, moulds for massive cast- ings — the sand will be mixed dense and strong to resist the great pressure and heat; in lif/ht moulds it will be more porous and weak. In the first case more, in the latter less, venting will be required. In heavy moulds more, in light moulds less, coal dust will be used; because the burning action is more intense in the former than in the latter, the action of the hot metal being continued longer in the case of the first than in that of the second. In a heavy mould, the proportions of coal dust may be one to six or eight of sand; in light moulds it may be one to fifteen of sand. The reason of its use is as follows: Molten metal slightly fuses the surface of sand with which it comes into contact, and the casting becomes roughened in consequence. A perfectly refractory sand cannot be employed, there must be a certain percentage of alumina and metallic oxides, which are binding ele- ments, present, to render it coherent and workable, and these happen to be readily fusible. The more silica pre- sent in a sand the more refractory it is; but too large a percentage of this in a moulding sand would diminish its necessary cohesive property. The facing sand there- fore is introduced into a mould to supply that which is lacking in the main body itself, and by forming a back- ing of an inch or two in thickness to the mould, pre- vents, by the oxidation of the coal dust, this burning and roughening from taking place. The carbon of the coal yields with the oxygen of the air, at the high tempera- 10 PRACTICAL IRON FOUNDING ture of the mould, either carbonic oxide, or carbon di-oxide, and the thin stratum of these gases largely prevents that amount of direct contact of metal with sand which would produce burning and roughening. Castings become scnid-hurnt when there is not sufficient coal dust used to prevent surface fusion from taking place. Dry sand. — Though ordinary green sand mixtures can- not be dried and yet retain coherence, mixtures of close heavy sands are made, which when dried in the stove, are comparatively hard and firm. Only the heavier sands of close clayey texture will bear drying: green sand mix- tures would become friable and pulverize under the action of heat. There is a superficial or skin drijing prac- tised with these. But that only affects the surface, and is quite distinct from the drying to which the present remarks have reference. Horse manure, cow hair, or, straw are mixed with dry sand to render its otherwise close texture sufficiently open for venting: the un- digested hay in the manure becoming partially car- bonized during the drying of the mould, while the moisture also evaporates at the same time. Coal dust is added to dry sand mixtures as to green sand. It is said to be strong to distinguish it from weak or green sand. It is a mixture which is used for a better class of moulds than green sand. It is also specially adapted for heavy work. Less gas is generated by the use of dry than of green sand, and the mould is, therefore, safer. It is mixed damp, and rammed like ordinary facing or moulding sand, but is dried in the core stove previous to casting. Being dried, it is hard, and will stand a greater degree of liquid pressure, approximating in these respects, and in being mixed with horse manure, SANDS, AND THEIB PREPARATION 11 to loam. But it differs from loam in containing coal dust, and in being rammed damp, like green sand, around a complete pattern. Core sand. — This is variously mixed. For light and thin castings it is open and porous, being chiefly or entirely moulding sand, and having just sufficient co- hesiveness imparted to it by the addition of clay water, peasemeal, beer grounds, or other substances, to make it bind together. But for heavy work, and that which has to stand much pressure, strong dry sand mixtures, having horse manure, are used. It is always rammed damp, like moulding sand, and dried similarly to dry sand moulds. Cores are also made with loam by sweeping up or striking up. Loam. — This is a mixture of clayey and of open sands ground up together in proportions varying with the essential nature of those sands. It is a strong mixture, which is wrought wet, and struck up while in a plastic condition, and being afterwards dried, forms a hard, compact mould. The close texture of the loam is not vented, as is usual with green and dry sand moulds, with the vent wire; but certain combustible substances are mixed and ground up with the sand, and these, in the drying stove, become carbonized, leaving the hard mass of loam quite porous. The material usually employed is horse manure, containing, as it does, a large proportion of half digested hay. Straw, cow hair, and tow are also employed ; but the horse manure appears to be almost universally made use of. Loam is used in different grades, being coarser for the rough sweeping up of a mould, and for bedding-in the bricks, than for facing and finishing the surface. Old loam, that is, the best un- burnt portions stripped from moulds which have been 12 PRACTICAL IRON FOUNDING cast in, is also ground up again with new sands, and used both in loam and dry sand mixtures. Loam, unlike the other mixtures, has no coal dust mixed with it. Parting sand. — This is burnt sand, used for making the joints between sections of moulds, which, without the intervention of the parting sand, w^ould stick together. The sand is red sand, baked, or brick-dust, or burnt sand scraped from the surface of castings. A thin layer only, of no sensible thickness, is used. Its value consists in its non-absorption of moisture, so that it forms a dry, non- adhesive stratum between damp and otherwise coherent faces. Parting sand is simply strewn lightly and evenly over with the hand. I have not given definite proportions of sands for different mixtures, because the proportions of such mix- tures must depend entirely upon locality as well as upon the class of work for which they are intended. The red sand or the yellow sand of one locality will not be pre- cisely like that of another, and therefore the practice will differ in different parts of the country. Moreover, the mixture of sands, like that of metals, is largely a matter of individual opinion and experience; each foundry foreman follows the practice which in his ex- perience has produced the best results. And again, green sand, dry sand, and loam mixtures are each prepared in various grades to suit different classes of work, differ- ences of strength or body being required, not only in distinct moulds, but even in individual portions of the same mould. As generally indicative only of the methods and proportions of mixing adopted, a few recipes are given in the Appendix. Facings. — The use of facing sand is not sufficient alone to ensure a clean face or skin on castings. Hence a thin SANDS, AND THEIR PREPARATION 13 film, a facing, or a paint of a carbonaceous substance, is always brushed over moulds, excepting those intended for castings of the roughest possible character. This film will be laid on wet or dry, according to the class of work. It is comprised of different ingredients also. Formerly the facings or paints were mostly made of ground wood-charcoal and coal-dust. At that time the moulder mixed his own facings to suit different kinds of work, and the muslin blacking-hag was in frequent re- quisition. Now, various preparations are ground and mixed, and sold under different names, for specific pur- poses. In the best foundries now, also, nearly pure plumbago or black-lead is used almost exclusively. Though costly, it produces a finer skin than the prepara- tions of charcoal and coal-dust, and is less troublesome to apply. It is dusted over the mould, and swept with a broad camel-hair brush, and then sleeked with the trowel. On green-sand moulds nothing more is required, because the porous face of the sand retains the plum- bago. But on all dried- sand and loam moulds, and on the faces of skin-dried green-sand moulds, the plumbago is made into a wash with water and clay, or other cementing substances. But on moulds of this kind, the paint, as it is called, is generally made of the cheaper coal-dust mixed into a black wash or wet blacking, with the clay water, the clay in the water binding the dust and preventing it from fiaking off' when in the stove. Since the best plumbago costs something like dBl per cwt., or about twenty times as much as coal-dust, there is reason for such economy. It, however, always peels better than the coal- dust or charcoal-dust — that is, the sand can be stripped from the casting more freely, leaving a smoother face, hence for good work it has superseded the common blackings. 14 PRACTICAL IRON FOUNDING There is much difference in the cost of foundry black- ings, the price increasing with the amount of pure black- lead present. All grades are obtainable, for green sand and loam, for light and fancy work, and for general and heavy work. There is no need to use a large quantity of blacking or plumbago on a mould. It tends to roll up before the metal, and form streaky lines or rough patches, which are unsightly. Neither should it be sleeked much, for much sleeking is always injurious to the face of a mould. Passing the trowel over it once or twice only lightly is sufficient to make it lay to the mould. It is put on dry- sand and loam moulds after they have been dried in the stove, and while yet warm. If the moulds are allowed to get cold first, then the blacking must be dried off. The effect of the blacking is to prevent the metal from being roughened by direct contact with the sand. The plumbago facing acts so efficiently that often when a casting is turned out, if the fingers are rubbed on it, the plumbago adherent to its surface will come off on the fingers, showing that it has remained unaffected by the heat. This protection has nothing to do with the pro- duction of sound castings, but it improves the appear- ance immensely. Chemistry of sands. — The time has not arrived when chemical analysis can displace the practical knowledge gained by experience in working in particular grades of sands. Analysis safely asserts that the purest sands should consist of little besides silica and alumina, the first the refractory element, the second the bond. Lime and iron oxide, with the alkalies — soda, potash, and sometimes traces of other ingredients — all detract from the value of a sand, lowering the fusing point and ren- SANDS, AND THEIR PREPARATION 15 dering it liable to flux. If the materials in a sand become fused by the molten metal the result will be the closing of the pores, so preventing the escape of the gases. Sizes of grains. — If the grains are large and regular in size and shape the sand will be more porous than with opposite conditions. The popular objection to large grains is that they will not produce castings with smooth skins. Also grains of equal size and of angular shapes favour porosity, while grains of unequal sizes, and which have smooth surfaces, do not, though they give a strong sand. Alumina or clay, being hydrated silicate of alumina, contains 46.4 per cent, of silica, 39.7 per cent, of alumina, and 13.9 per cent, of combined water, so that the total silica is a larger quantity than the free silica. Mechanical analysis deals with the sizes of sand grains, and is very useful because it reveals the texture of the sand, which is passed through a succession of sieves of different meshes, and the proportions which pass through the different meshes afford data for estimating the suit- ability of the sand for fine and coarse work. Weak sands are fine grained and usually have least alumina. They are used for light green sand work. For heavy green sand work a larger proportion of alumina is desirable, and coarser grained sands. For dry sand, loam, and cores, the largest proportion of alumina is suitable, and fine sand. That castings with smooth skins cannot be obtained from coarse sands is negatived by experience. The coarse grains favour the escape of the gases, and the applications of facings till up the spaces against which the metal is poured. The following are analyses of standard sands used for different kinds of work. 16 PRACTICAL IRON FOUNDING Sand for fine castings Silica 81.50 per cent. Alumina 9.88 ,, Iron Oxide 3.14 ,, Lime 1.04 Magnesia 0.65 ,, (Fine grain) Sand for avawjc castings Silica 84.86 per cent. Alumina 7.03 ,, Iron Oxide 2.18 Lime 0.62 Magnesia 0.98 ,, (Medium grain) Sand for hcavij castings Silica 82.92 per cent. Alumina 8.21 Iron Oxide 2.90 Lime . 0.62 Magnesia O.OU (Coarse grain) But Heinricli Eies has stated that there is no relation between the bonding power and plasticity, and the per- centage of alumina, as determined by chemical analysis. He says that the mechanical analysis affords an approxim- ate index of the cohesiveness of sand. In this analysis the grains, being passed through sieves of different mesh, yield percentages of the grains retained in each, while the clay group forms another percentage separated from the sand grains. The texture of a sand has a much greater influence SANDS, AND THEIB PBEPABATION 17 on its suitability for a given class of work than the chemical analysis. Heinrich Kies illustrates this fact by giving four sets of chemical and mechanical analyses of sands, as below. In these Nos. 1 and 2 agree closely in their chemical composition, but differ in their texture. Nos. 3 and 4 agree closely in chemical analysis, but differ widely in mechanical analysis. No. 1 was Albany sand used for stove plate work. No. 2, stove plate sand from Newport, Ky. No. 3, sand for general work from Peters- burg, Va. No. 4, sand for general work from Fredericks- burg, Ya. Chemical analyses No. 1 No. 2 No. 3 No. 4 Silica .... 79.36 79.38 84.40 85.04 per cent Alumina . . 9.36 9.38 7.50 5.90 „ Ferric Oxide 3.18 3.98 2.52 3.18 Lime .... 0.44 1.40 0.06 0.06 Magnesia . . 0.27 0.54 0.21 0.14 Potash . . 2.19 1.80 1.29 1.65 Soda .... 1.54 1.04 0.65 0.83 Titanic Oxide . . 0.34 0.44 0.44 0.78 Water . . . . 2.02 2.50 1.49 1.57 Moisture . . 0.74 0.80 1.76 1.11 Size Mesh 20 . 40 . 60 . 80 . 100 . 250 . Claj . Mechanical analyses Per Cent. Retained 1. 0.26 0.51 2.53 0.99 4.19 79.85 11.24 2. 0.06 0.12 0.32 0.16 0.83 23.38 24.73 3. 0.09 0.41 2.21 2.67 17.37 58.20 19.02 4. 0.19 0.19 0.39 0.19 0.98 81.92 15.97 18 PRACTICAL IRON FOUNDING Other materials. — Small quantities of certain very es- sential articles are used in foundries, as clay, resin, flour, oil, tar, straw, hay, tow, etc. The use of the first three is chiefly that of cementing agents for cores. Small cores are cemented with these, the resin and flour binding the sand together, beer grounds and mo- lasses being used for the same purpose. Specially pre- pared *' core gums," the elements of which are only known to the manufacturers, are sold. Clay, mixed with water to various degrees of consistence, is a valu- able cement for sticking the joints of cores together; for swabbing flasks, the better to retain the sand; for cementing broken edges of moulds and cores; for mix- ing with wet blacking; and for other purposes. Oil is used for pouring over the faces of chaplets, over the damp mended- up parts of moulds, and around metallic stops in order to lessen the risk of blowing occurring in those localities, the metal lying more quietly on the oil than on the bare metal or on the moist sand. Tar is used for painting over the ends of wrought-iron arms or shafts around which metal has to be cast, and for paint- ing loam patterns to harden their surfaces. Straw and hay are used for cores, being first spun into bands, which are then wound round the core -bar. These are usually spun in the foundry, but can also be purchased ready for use. Tow is wound round those portions of bars where the spun bands w^ould be too thick. Hay is also used in layers in cinder beds to prevent the sand from filling up the interstices of the cinders. Sand preparation. — To prepare and mix sands various methods are made use of. For the floor sand, simply moistening with water and turning over two or three times with the shovel suffices in most shops. But all SANDS, AND THEIR PREPARATION 19 facing sands have to be thoroughly pulverized and passed through sieves of varying sized mesh, according to the class of work for which they are required. Sand as it comes from the quarry is gritty and lumpy, and is riddled to separate the lumps, which are either thrown aside, or ground and crushed and re-riddled. The suit- able mixtures of sand and coal-dust having been made, they are thoroughly intermixed with water, and are then ready for use. In reference to the watering, it is as well to remark that this must not render the sand tvet, which would spoil any mould in which it might be used, but only moist, or damp, rendering it sufficiently coherent for moulding into. So that if a portion of such sand is taken up in the hand and squeezed, it will retain the impression imparted without falling apart of itself, which perfectly dry sand would do. Machines. — The growth of machinery for dealing with sands has been very rapid in recent years. Old methods have been extended, new ones have been introduced. The scores of designs made may be roughly classified under four heads : Machinery for sand drying, for grinding, for disintegrating, and for riddling and sifting. Machines for sand drying are of cylindrical form, of rotary designs, in which the wet sand fed in at one end through a hopper is conveyed to the other, the cylinder being disposed at an angle with the horizontal. During its passage it is subjected to a current of hot air. Several tons of sand can be treated thus daily. Machines for grinding sand are usually of the type employed for grinding loam. This is essentially a mortar- mill, having two heavy grinding rollers, plain or grooved, between which and the bottom of the pan the materials 20 TEAGTICAL IRON FOUNDING are crushed and ground. The rollers rotate on their hori- zontal axes, and either the rollers, or the pan, revolve on their vertical axis, either being driven by bevel gears. Sands are ground dry, and loam wet in these machines. The pan is emptied by opening a door in the side near the bottom. In the disintegrating machines the sand is knocked about between rapidly revolving prongs in the same or Fm. 1. — Sellers Sand Mixer. in opposite directions, being thrown outwards by centri- fugal force. Early machines were the Schiitze and the Sellers. Later ones more often have two sets of prongs, in which both sets may revolve, each in an opposite direction to the other, or one may revolve and the other be fixed. The speed of revolution is very high, and lumps are broken up effectively. T](C Sellers mud-mixinff maeliine (Fig. 1) operates centrifugally. The machine is circular, and the sand, SANDS, AND THEIR PREPARATION 21 on being thrown in through a hopper, A, falls among a number of vertical prongs standing up from a revolving plate, B. The prongs prevent the passage of stones, and disintegrate the sand in its passage outwards. By the covering plate, C, it is thrown to the ground beneath. The driving of the vertical shaft is done by belt pulley, set either above or below the machine, as most convenient, or by electric motor as in the Fig. The rate of revolution of the shaft is about 1,200 revolu- tions per minute. The hopper is hinged, and can be thrown back when necessary for the re- moval of obstructions. There is but little differ- ence between Schiitze's sand-mixer (Fig. 2) and that of Messrs. Sellers. In this mixer, vertical j^^. 2.— The Schutze Mixee. prongs on a rapidly re- volving plate, B, break up the sand falling through the hopper by centrifugal force. A is the hopper, C the 22 PRACTICAL IRON FOUNDING shaft driven by a pulley, IJ. An indiarubber guard round the machine throws the sand downwards. The hopper and cover (attached to each other) can be thrown back on a hinge to expose the plate, B. Fig. 3 illustrates a horizontal class of disintegrating mixer with double cages rotating in opposite directions, driven by separate pulleys. The hollow shaft which carries one cage runs in dust-proof ball-bearings, and the inner shaft is fitted in ring-oiling white-metal bearings. Fig. 3. — Double Cage Disintegrator. The sand is fed in through the shute at the side, and the hood is hinged to enable it to be thrown back for clean- ing purposes. The machine is constructed by Messrs. Alfred Gutmann, A.G. In mixing sand we seldom find moulders using weights or legal measures. It is always measured in "barrows," " sieves," " riddles," "buckets " — those being the utensils in common use in foundries. The mixing is done by hand riddles and sieves, or by mechanisms. The first are employed in small shops. SANDS, AND THEIR PREPARATION 23 The only difference between a riddle and a sieve is one of size of mesh. Both alike are circular, but while riddles em- brace meshes down to yV ii^-? sieves cover sizes below these. A screen is used only to separate the coarse lumps from the sand at the time of delivery from the quarry. The sand is intermixed, riddled, or sieved by hand upon a rude horse formed of wrought-iron bars. The riddle or sieve is thrust backwards and forwards, along the top bars, the sand falling on the ground below, whence it is removed to the heaps, or to the sand bins, which are large recesses conveniently prepared somewhere in the sides of the shop for the storage of sand in readiness for the moulder. All the sifting and wheeling away is done by the moulders' labourers. There are several good mechanical sifters in use in foundries, operated by power mechanism, which imparts a rocking motion to the sifters. The swinging sand sifter (Fig. 4, shown in plan and in elevation), made for driving by power, is suspended from the beams of a roof or floor above by loosely hung sling rods. The parts are as follow : A is the tray itself, formed of a piece of ^V i^- plate bent round to form three sides of a rectangle, the fourth side being open. There are three rows or tiers of \ in. round bars riveted across, so pitched out that the rods alternate with one another in the vertical direction the better to assist in breaking up the larger lumps oi sand. Over the lower row is laid the sieve bottom (not shown in this figure), the size of the mesh of which may vary from |^ to 1 in. Screwed stay rods pass across from side to side, and by means of those which come near the ends, the straps, B, are fastened, to which the sling rods, C, are hooked. The oscillatory motion is imparted by means of the three teeth, 24 PRACTICAL IRON FOUNDING D, thrusting against the pins in the slotted piece, E. F, F^ are the fast and loose pulleys for driving, having their Fig. 4. — Swinging Sand Sifter. shaft bearings in the bracket, G, bolted to a wall, or as convenient. The tray is suspended at a slight angle, the open end, or that farthest from the driving gear, SANDS, AND THEIR PBEPABATION 25 being lowermost. The fine sand then falls vertically down- wards through the sieve into a bin, while the larger lumps pass onwards and fall out at the open end. Many sieves are of double design, with the primary ■ y '-- rt>// / ' / ^y ■ 'y / // /y ^ - ' ' '' y V,V / , Fig. 5. — Combined Grinder and Sieve, object of dealing with old or floor sand. Two rectangular sieves, an upper and a lower one of coarser and finer mesh respectively, separate lumps, nails, and particles of iron from the sand and discharge it, while the fine sand is dropped through the lower sieve and discharged at 26 PBAGTICAL IRON FOUNDING one end. The sieves are set at an angle in opposite directions. Another design of sieve is rotary in action, and poly- gonal in outline, with a rapping device to assist the dis- charge. Each of these designs occurs in several modifica- tions. For grinding coal for facing sands, and blackening, a mill of another type is used; this is sometimes a revolv- ing cylinder, rotating with its longitudinal axis in the horizontal position, having loose heavy rollers inside. ^^^ Fig. 6. — Plan View of Combined G-rinder and Sieve. which, as the cylinder revolves, remain in the bottom by reason of their weight, and crush the coal or coke, intro- duced before the mill is started through a door at the top of the cylinder. An improved form is one in which heavy balls are set revolving within a pan in an annular groove, a vertical spindle passing through the cover. The spindle is driven through bevel wheels by a belt-pulley. There is a cover of wood for the introduction of the coal, and to prevent the flying out of the dust. The ground coal is taken away through a door in the bottom of the pan. SANDS, AND THEIR PREPARATION 27 A combined type of machine is seen in Figs. 5 and 6, comprising an edge-runner grinding pan, and an octa- gonal sieve, the rollers of the first named being driven by the bevel gears on the top shaft. The sieve is revolved by a belt pulley from the same shaft. When the rough lumpy sand has been ground in the pan, it passes down a sliute into the sieve. If it has been ground sufficiently small it falls through the meshes and is removed; but if there are lumps of too large a size, they are carried up around the top of the sieve, and fall down the top shute into the pan again to undergo further crushing. Fig. 7, PI. I, represents an electro-magnetic separator in conjunction with a reciprocating sieve, built by the London Emery Works Company. The rough sand is fed into the hopper at the top, and falls on to the magnetic drum which abstracts and retains all the nails and other scraps of iron or steel present, after which the sand drops into the sieve, and is thoroughly shaken and broken by the rapid reciprocations until it is fine enough to escape through the meshes. CHAPTEE III IRON MELTING AND TESTING Cast iron owes its value as a material of construction to the fact that it is not pure metal. If it were pure, it would be useless for the purposes to which it is now applied. Pure iron cannot be melted to fluidity, neither when cold is it rigid nor hard, but ductile and soft by comparison with commercial iron. Cast iron does not contain more than 93 or 94 parts of pure metal in the 100, the remaining 6 or 7 consisting of carbon, silicon, phosphorus, sulphur, and manganese, with occasional percentages of arsenic, titanium, and chromium. The element which more than any other influences the physical character of cast iron is carbon, and this occurs in allotropic forms, either as graphite or plumbago, in a state of mechanical admixture, forming gray iron; or as combined or dissolved carbon, producing white iron. In most, if not all commercial irons, the carbon occurs in both forms. The proportion of combined carbon is never more than a mere trace in the gray, while the white iron is almost destitute of graphitic carbon. The mottled varieties occupy a position midway between the gray and white, and are to be regarded as mixtures of the two kinds, the mottle being more pronounced as the propor- tion of white increases. Here, too, the proportions of combined and graphitic carbon become nearly equalized. Gray iron is the most fluid, but is the weakest. White 28 IRON— MELTING AND TESTING 29 iron runs pasty, and is strong, but brittle. Mottled iron melts very well, and is both strong and tough. Iron is adapted for general engineers' work in propor- tion to its amount of mottle, highly mottled iron being correspondingly prized by foundrymen. There are several varieties of pig supplied by the iron- masters, ranging from the No. 1 Clyde, which is the grayest iron, to the forge pigs, which are white irons (see the Appendix). Hence it is possible to obtain pigs suited to almost any class of work, being either used alone, or by intermixture. In foundries where the same class of castings is being constantly turned out, this is what is done; but in general foundries, where all kinds of castings are required in gray, white, and mottled iron, in all their grades, usually three or four kinds of pig only are kept in stock, and the numerous grades of metal required from day to day, or during the same day, are prepared by admixture of pig with scrap. It is in these mixtures that the skill of the practical foreman or furnaceman is seen, skill which comes only after long experience. There are many moulders who would not know how to mix metals to produce definite grades, and no rules can be laid down for this work except those of a somewhat general character. Thus it is easy, having ascertained the metal which results from the mixture of certain pigs in certain definite proportions, to repeat the operation as often as required, since a grade of pig of a given brand is fairly though not absolutely constant in character. But when scrap is used, the quality of each separate piece of scrap has to be estimated by its behaviour under the sledge, and by the eye. The use of scrap, if purchased judiciously, and mixed by a competent man, is more economical than that of pig, and there is therefore 30 PRACTICAL IRON FOUNDING advantage in its employment. Every furnaceman and foreman should therefore learn to judge of the quality of scrap and pig, and the effect of their intermixture. After- wards he may test the results experimentally at the testing machine; but he must know how to mix, or the testing machine will record only failures. Gray iron on being struck with a sledge fractures easily, and presents a highly crystalline structure, with a some- what dull bluish-gray metallic lustre. If very dull, the metal is inferior, and poor in quality. Iron follows the same law of crystallization as other substances. The slower the rate of cooling the larger the crystals produced. If a newly fractured surface of gray iron is shaded by the hand, and so viewed with reflected light only, the crystals of graphite become visible, appear- ing as black lustrous patches amongst the iron. If a portion of the iron is crushed and levigated, the graphite will float on the surface of the water. When the metal is molten it lies quietly in the ladle, breaking into large striations, without sparks or disturbance. After standing awhile it becomes covered with scum, composed of scales of graphite which have separated and floated to the sur- face. When cast, it runs fluid, and takes the sharpest impressions of the mould, being thus adapted for the finest castings. It is only moderately contractile. At the testing machine it breaks with a very moderate load, undergoing however a considerable amount of deflection first. It can be tooled easily. If we take wldte iron, whether in the form of pig or of scrap, and fracture it, we find that it requires more force than the gray to effect fracture, but that it breaks very short and clean. An inspection of the fractured surface reveals a highly crystalline structure, but the crystals are IRON— MELTING AND TESTING 31 long, fine, and needle-like in character, and of a bright, almost silvery-like lustre: no scales of graphite can be detected. The melted metal when in the ladle, though thick and somewhat viscous by comparison with gray iron, is in a state of violent ebullition; boiling, bubbling, and throwing off a quantity of sparks or jumpers. It does not run well except in considerable mass, and is highly contractile. Unlike the gray iron, it cannot be shaped with the chisel and file. At the testing machine it sus- tains a greater load before fracture than gray iron, but breaks with less deflection. The mottled iron being a mixture of gray and white, partakes more or less of the characteristics of each, and is therefore better adapted for most castings than either of those alone. Considerable force is required to fracture a good sample of mottled iron, and when the broken surface is examined it presents that peculiar mottled appearance from which it derives its name. The crys- tals are of the same form as those in gray iron, but smaller, and the dull bluish lustre of that is replaced by a more silvery hue. The colour alternates, being patchy, the white contrasting with the graphitic scales still pre- sent. It melts and runs well, is tolerably quiet in the ladle, is moderately contractile, takes a high strain and a good deflection at the machine, and tools with average ease. There are several grades of gray, mottled, and white irons, and the skill of the furnaceman consists in judg- ing of the minute differences in these and utilizing them accordingly. There is a grade of iron often found along with scrap, known as burnt iron. It is metal which, having been long subjected to an intense heat below the melting point, has lost much of its metallic character, being 32 PRACTICAL IRON FOUNDING largely in the condition of oxide. It is of an earthy red colour, and is found in scrap containing old fire bars, sugar and soap pans, retorts, and furnace grates. In the furnace it does not melt freely, but becomes viscous or pasty, and chokes the tuyeres and the fuel. In a furnace using much of this, the slagging hole has to be kept open during nearly all the time of melting, and much of the iron mixes with and runs away to waste with the slag. It damages the furnace lining, and when poured runs very thick, and produces almost white, but rotten cast- ings. Burnt iron can only be properly utilized by ad- mixture in slight proportions with good open gray pig. The largest proportion of pig used for foundry pur- poses is smelted either in Scotland from the Black Band ironstone; or in the Cleveland district in the North Bid- ing of Yorkshire, from the Cleveland ironstone. Smaller quantities come from Shropshire, Staffordshire, South Wales, and a few other localities. Pig is obtainable in five or six grades. No. 1 is the most gray and open, and as the numbers run up the iron becomes closer and mottled, or white. Scrap, — When a furnaceman or foreman has to pro- vide for a general run of work, as is the case in nearly every foundry, there are usually two courses open. One is to stock various brands of pig and melt from those brands, singly or variously mixed, to suit the various kinds of work on the floor. Thus, for cylinders and for liners a different quality will be required from that for fire- bars or ploughshare points, or, again, for machine fram- ings or gear wheels. Though each grade may be melted on the same day, in the same cupola, the difi'erent mix- tures required will be kept apart in the cupola. The ironmasters will send pig of any given quality, suitable PLATE I See p. z I Fig. 7. — Combined Separator and Sievj Seep. 63 [Facing p. S2 Fig. 18. — Roots' Blower, Motor driven inON— MELTING AND TESTING 38 for any class of work. Or, without a very large stock of different brands, a furnaceman who knows his business can, by judicious mixing, with or without remelting as occasion requires, make up metal to suit any job. At the two extremes there are the soft open gray, and the hard, close white pig. Between these there comes every variety of gray, mottled, and white. But in all foundries a cer- tain proportion of scrap is used along with the pig for most classes of work. A furnaceman or foreman who thoroughly understands the mixing of scrap and pig is a valuable acquisition to a firm, for he can not only improve the quality by such mixture, but can save much money also, because scrap is often to be bought at a cheaper rate than pig. There is this further advantage, too, that scrap has been remelted once at least, and therefore the cost of such remelting — supposing pure pig would other- wise have to be used and remelted — is saved. Further, metal is improved by the mixing of several kinds of pig and scrap, very much as hammered scrap is improved by the piling and welding of all kinds of bars. Only when a furnaceman cannot judge scrap well, is it desirable to make use chiefly of special brands of pig. There must be some scrap always used, because the runners and risers, the overflow metal, and the wasters have to be used again in any foundry. And there are few foundries that do not use one-third or one-half scrap in the mixing of metal. Good stocks of pig and scrap should be laid in when iron is cheap. Much money can be saved by watching the markets, and purchasing heavily when prices are low. A look-out should specially be kept for good cheap scrap. A competent man should be sent to see it previous to purchase. Water and gas pipes are D 34 PRACTICAL IRON FOUNDING about the worst scrap, old engine work and machinery the best, and the older it is, almost invariably the better it is. The scrap should be roughly sorted out according to quality, and kept in separate heaps. The quality of pig, though subject to slight variations in the same consignment, is sufficiently well known, and there is little need to look at every bar as it is broken. Not so with scrap. Every piece of this must be judged on its own merits. This is a rather tedious process, and there is only one way in which it can be done, and that is by the character of the fracture. The opinion is formed partly by the amount of work it takes to break a given piece, which is a measure of its strength and toughness; and partly by the appearance of the fractured surface, by which the nature of the iron is apparent. The broad ap- pearances of gray, mottled, and white irons are familiar to most; the furnaceman's skill lies in judging of minute variations in these broad differences. As a rule, the rougher and more uneven and exfoliated the aspect of the fracture, and the more metallic the lustre, the stronger is the iron. If a mass of iron has draws in it, that will in- dicate that the iron was of a strong nature, but was not properly fed. If an iron breaks off short, and is dull in appearance, and the crystals open, it is weak and poor. Gray weak iron can be made stronger by the addition of white or mottled; and mottled can be brought back to gray by the addition of open No. 1 Scotch pig, or stove scrap. Weak iron can be strengthened by once or twice re-melting. Test bars afford a valuable aid in estimating the quality of a mixture that is required for very specific purposes, and by their aid the foreman is enabled to keep a constant check on his experimental mixtures. Eepeated re-melting of gray iron tends to increased IRON— MELTING AND TESTING 35 strength, at the sacrifice of toughness and elasticity; the re-melted metal approaching to the white condition. Hence, after two or three re-meltings, more open pig should be added to preserve the toughness of the metal. It is by admixture therefore that nearly all the grades of cast iron for foundry service can be obtained. The difference in the qualities of these mixtures is, as we have stated, due largely to the amount and manner of occurrence of carbon. In reference to the remaining con- stituents of commercial pig, and the question of their relative influences upon the metal, it will be sufficient to note very briefly the leading facts which the founder should know in relation to these, and then pass on to the tests applied to cast w^ork. Silicon is one of the most valuable elements found associated with cast iron. Formerly it was regarded as an enemy, producing brittle and poor metal. Now, by mixing certain proportions of silicon with white iron, it is converted into gray, the silicon throwing out carbon from the combined to the graphitic condition. Pliosj^Jwrus is always present in pig, and does no harm so long as it does not exceed 0*5 or 0*75 per cent.; a higher proportion tends to brittleness. Phosphorus how- ever renders iron fluid, and this is an advantage for small castings, but at the same time it renders them hard. Sulpliur in small quantity produces mottled iron, separating carbon as graphite, but in excess it causes the iron to become white. Manganese is undesirable, producing a w^eak and white iron. Aluminium. — It has long been known that a very small percentage of aluminium, so little indeed as *01 per 36 PRACTICAL IRON FOUNDING cent., suffices to render molten wrought iron very fluid, and to prevent blow holes in steel castings. It is equally beneficial in cast iron. It causes iron at the instant of solidifying to throw out a portion of its combined carbon into the graphitic con- dition, producing gray iron. The formation of the gra- phite is also so uniform that the thin portions of the castings are as gray as the thicker portions. In this respect it resembles silicon. Since the aluminium sets free the carbon at the instant of solidification there is less tendency to chill, which result is caused by the run- ning of metal against a cold surface, and the consequent imprisonment of combined carbon before it has time to separate as graphite. When aluminium causes the separation of the carbon at the instant of solidification, the scales of graphite at the surface of the casting act similarly to blackening, protecting the surface from becoming sand-burnt, and therefore producing a softer skin for cutting tools. The presence of aluminium, by making the grain closer and finer, gives greater elasticity, and reduces the permanent set. The shrinkage of iron is lessened by the use of alumin- ium. This might naturally be expected, knowing, as we do, that gray iron is less contractile than white. It is a distinct advantage, as lessening shrinkage strains on disproportionate castings. Testing. — It is at the testing machine that the precise value of any mixture of metal made is ascertained, and no foundry of any pretensions can afibrd to be without such an instrument. Testing, in the hands of such men as Professors Unwin or Thurston, has become a scientific work, in comparison with which that of the foundry is inON— MELTING AND TESTING 37 rough and approximate only. But this is nevertheless sufficiently accurate and adequate for its purpose. The common method of testing is to cast bars having a cross section of 2 in. x 1 in., and a length of 3 ft. 2 in. These are placed upon supports 3 ft. apart, the 2 in. being in the vertical direction, and loaded until they fracture. Fracture in a good bar should not take place with a less load than 30 cwt., in exceptional instances it goes as high as 33 or 35 cwt.; 25 to 28 cwt. would indicate a poor bar. The amount of deflection is also noted, as being a measure of the elasticity of the metal. It should not be less than | in., and will in good bars be as high as 2 in. The behaviour of bars cast from the same ladleful of metal in the same set of moulds will often be found to vary, fracture variously occurring within a range of 2 or 3 cwts.; hence it is the practice to cast several bars for testing, and take the average of the whole. Test bars should be cast from the same metal, under the same conditions of melting, as the work for which they afford the test, and should be stamped or labelled with the date, and all particulars deemed of service. They should be ca.st in the same manner as the work for the strength of which they are to be the index, in dry sand if the work is in dry sand, in green sand if that is in green. The relative strength of the bars is affected by difference in dimensions, a bar of small area being relatively stronger than one of larger area, the reason being that the chilling effect of the sand hardens the outer skin, and so raises slightly its tensile strength. That which is often now regarded as the standard bar is 1 in. square and 1 ft. long. This sustains about one ton before fracture. Pounds weight on this bar divided by 84 give hundredweights on the 36 in. + 2 in. + 1 in. bar; and 38 PRACTICAL IRON FOUNDING hundredweights on the latter multiplied by 84 give pounds on the former. Testing machine. — A machine designed for making tensile, and also transverse tests on cast-iron specimens, is illustrated by Figs. 8 and 9, being manufactured by Messrs. W. and T. Avery, Limited, of Birmingham. The construction comprises a cast-iron bed-plate, with dogs having blunt knife-edges, these dogs being adjusted along to graduations on the base, either at 12 in., 24 in., or 36 in. between centres. The base carries a cast-iron standard, fitted with hardened steel bearing blocks, upon which the fulcra knife-edges of the steel- yard rest. The wrought-iron steelyard is provided with knife-edges of hardened steel, and is graduated up to the full capacity by 28 lb. divisions. It is fitted with a sliding poise by means of which it is kept in equilibrium, and the strain indicated. The poise is moved along by turning a small wheel'on its front. The strain is put on by turning the hand-wheel at the top, rotating the screw, and actuating the stirrup that carries the blunt knife- edge wdiich exerts the strain on the specimen. A spring buffer is fitted in the steelyard carrier in order to min- imize the shock when the specimen breaks. A graduated deflection scale is provided, by means of which the vary- ing deflections of a specimen under different strains can be ascertained during the test. Two series of gradua- tions are placed on, one decimally by ^q in. divisions up to 1 in., and the other by yV ii^- divisions up to 1 in. Tensile specimens h in. in diameter can be held in the hardened steel grip wedges, for which size the capacity of 60 cwt. allows for iron that will stand 15 tons per square inch, while bars of 2 in. by 1 in. section or less can be dealt with on the transverse testing dogs. « GO d P^ o M H M <1 00 6 M 40 PRACTICAL IRON FOUNDING Testing in the hands of an experienced foundryman reveals a great deal. For he not only notes breaking strength and deflection, but also the aspect of the frac- tured surfaces. He observes the extent of mottle or of graphite, the dull or lustrous appearance, homogeneity of texture or the opposite condition, the tendency to undue hardness or softness, whereby he learns how to make changes in his mixtures in order to insure the predominance of certain qualities which he desires to obtain. The iron for 'nine-tenths of the castings made is put together in this way. Still, the test bar tells little of real value to one who is not acquainted with foundry work, and it might tell a good deal more to the latter if used under a better method. There are other incongruities in the commonly ac- cepted tests of bars which strike one as rather curious. There are a few impact tests made in England. The value of impact tests is not so great as in the case of rails, because cast iron is distrusted for live loads, unless the mass of metal is so enormously in excess of that re- quired for strength as to absorb all injurious vibration. Yet since most ironwork is liable to more or less of shock, the impact test should be of even greater value than a purely tensile test, or a cross breaking test. There is another serious drawback inherent in foundry tests, and it is this: Little attempt is made to measure the shrinkage of iron by means of test bars. Yet many a casting is broken in consequence of excessive and un- equal shrinkages. Much of this could be avoided by the use of iron selected with suitable reference to the nature of the casting. To a large extent this is done in practice by the observation of the open or close nature of the fractured surfaces of test bars, or of pig and scrap IRON— MELTING AND TESTING 41 selected for making up the cast. But this is not an exact method, such as would be afforded by the meas- urement of a test bar. Some testing machines embody provision for the precise measurement of the shrinkage of test bars. The general adoption of this method would go far to lessen the internal stresses which frequently exist in castings, and which are a source of weakness, resulting often in serious danger. Further, since such great emphasis is laid by metal- lurgists upon the influence, injurious or otherwise, of the presence of small percentages of foreign elements upon cast iron, a very distinct advance has been made in this direction by Mr. Keep, of Detroit, a brief account of whose methods follow. Not by analysis, but through physical results, can the founder learn best how to grade his irons for their specific and varied purposes. The methods of testing adopted by Mr. Keep may be briefly summarized as follows: Though based on chemistry, they can be applied by anyone who has no knowledge of chemical reactions or of analysis. The basis of the system is the power which silicon possesses of causing carbon in iron to pass during cooling from the combined into the graphitic condition. So that, given an iron with a sufficient percentage of total carbon, it is possible to so vary the quantities of silicon added as to produce irons in which the relative proportions of combined and graphitic carbon shall be graded to suit any classes of foundry work. Mainly, Mr. Keep makes the shrinkage of the iron the crucial test. If equal shrinkages can be produced in different mixtures of iron, then each mixture will have similar qualities as regards strength, hardness, or softness. Moderate variations in the proportions of manganese, 42 PRACTICAL IRON FOUNDING sulphur, and phosphorus are of little or no practical consequence, provided the combined and graphitic car- bons are suitably proportioned, and this is evidenced by the shrinkage. When silicon is added it changes com- bined carbon into graphite, and the casting occupies a larger volume than it would previously have had. All the founder has to do is to be sure that there is sufficient combined carbon for the silicon to act upon, and through. Silicon alone would increase shrinkage and harden iron, but when acting through carbon it produces an exactly contrary effect. Making the crucial test one of shrinkage is one which is consonant with experience. Since hard white iron shrinks more than soft gray iron, and since the former contains its carbon mainly in the combined form, and the latter mainly in the graphitic form, a hard iron can be changed into a soft one by causing the carbon to separate out as graphite. Silicon effects this change, and therefore indirectly silicon added to hard white iron makes it soft and gray and diminishes its shrinkage. If, further, uniformity of shrinkage and hardness is secured in several different irons by the addition of variable pro- portions of silicon, the irons will be all equally graded for foundry purposes. The larger the mass in a casting, other conditions remaining the same, the less silicon will be required, because the cooling is slower, and the carbon has more time to separate out as graphite. The more carbon present, the less silicon will be required, because the presence of plenty of carbon is favourable to the separation of graphite. It is not, however, that a certain percentage of silicon is necessary to produce a bar or casting of definite strength. It is its infiuence relatively to the mass, and IRON— MELTING AND TESTING 43 not the exact proportion of silicon relatively to chemical composition, which is the essential crux of these methods. Irons of exactly the same chemical composition pom*ed from the same ladle will not produce bars of precisely the same strength. But the shrinkage of a casting, which can be controlled by silicon, can be measured, and the shrinkage determines the degree of crystallization, close- ness and uniformity of grain and texture, and therein lies its value. The necessary amount to be added de- pends not only on the percentage quantity of carbon present, but also, and much more, upon the mass of the casting. The addition of silicon retards cooling gener- ally, producing the separation of graphite, and diminishes shrinkage. The throwing out of graphite from combined carbon removes brittleness. If shrinkage is too great, increase the silicon, and rice versa. In small bars and castings the silicon must be high (up to 3 per cent.), and in large bars and castings it must be low. The reason lies in the difference in shrinkage. A small casting shrinks quickly, and therefore needs more silicon to throw out the combined carbon as graphite. A large casting shrinks slowly, and therefore requires less silicon to effect the separation of graphite. Without the silicon it is possible, and would in fact occur in extreme cases, that from the same metal a small casting may be white, one of average dimensions mottled, and a very large one in the main gray. The details of the tests are these: Bars are cast be- tween chills or yokes in order first to ensure absolute uniformity in length, and to get a chill on the ends. The bars are of two sizes, l^xhxh in., and 12 x 1 x yV in. The thin bar is used for fluidity test, because none but very fluid and hot iron will run the whole length of 44 PRACTICAL IRON FOUNDING the bar. The experience of the moulder soon enables him to judge of the behaviour of metal of a given quality in castings of different dimensions, made from metal which gives certain results in a test bar. And in order to furnish a ready means of comparison between bars of different dimensions Mr. Keep has constructed an ideal chart for ready reference. Great care is taken to ensure uniform results in the testing, metal patterns being used on a bottom board, and no rapping or touching up of the mould is done. The length between the end faces is 12 J in. There are four points noted — the amount of shrinkage of the bar, the strength under dead load and under impact, the depth of chill, and the aspect of the fractured surfaces. The dead load and imj)act tests are conducted in auto- graphic recording machines. The depth of chill is ascer- tained by fracturing a bit out of the bar next the end. The chill will run from -^V ^o ii ii^- inwards, according to quality, and is an important element in judging the suitability of an iron for a given purpose. At the same time, the aspect of the unchilled fractured surface is indicative of the open or close nature of the iron. CJdlUnfi. — When iron is poured into metallic moulds instead of into those of sand, the result is that the sur- face of the casting so poured becomes of a steely char- acter, so extremely hard that no cutting tool will attack it, and more durable, more capable of resisting the action of friction, than steel itself. It is believed that this chilling, as it is called, takes place in consequence of the combined carbon in the iron not having time to separate out as graphite. Poor irons will not chill deeply. To produce chilling of ^V in. or '; in. in depth, the metal must be tough, strong, and mottled. A strong iron IRON— MELTING AND TESTING 45 is also necessary, because there is tremendous stress in a chilled casting, owing to the inequality in the shrinkage strains in the contiguous portions, which are rapidly, or slowly cooled. The iron for chilling should not be poured very hot, but dull, it will then lay more quietly in the mould. The chill should also be heated in the stove to so high a temperature that it cannot be touched with the hands. To pour metal into a cold chill is always dangerous. The surface of the chill is protected with a coat of black wash or other refractory material. In no case should the metal be allowed to beat long against a localized spot, as burning of the chill and partial fusion of the same to the molten metal is certain to ensue. The mass of metal in a chill should be large. The chill should always be much heavier than the casting which has to be poured into it; without sufficient mass, fracture is almost certain to occur. Permanent moulds. — The experience now being gained with permanent moulds of metal promises economies in some classes of castings. If the ramming of a fresh sand mould for every casting could be abandoned in certain kinds of repetitive work, a great vista of cost-saving would be in sight. It has long been done in chilled castings; but, the chilling effect of a metal mould must be avoided in the general run of castings, such as it is desirable to produce in permanent moulds, and this tendency to chill is the principal difficulty met with in casting in these moulds. The remedy is to get the casting out before chill has formed. The time to be allowed lies within extremely narrow limits for any one shape or mass of casting, but it varies with different shapes and sizes. The chemical composition of the iron 46 PRACTICAL IRON FOUNDING has also some influence. The difference between the chemical composition of deep-chilling, and practically non-chilling irons is vital, whether the grading is done by fracture or l)y analysis. But the non-chilling irons will be hardened on the surface if allowed to cool in a metal mould, and this hardening must be prevented. Castings left to cool and chill in a metal mould have all their carbon in the form of hard, needle-like crystals, provided always that the silicon is low. If the same castings are taken out as soon as the exterior has set, the carbon will distribute itself in the graphitic form throughout the mass. This is the reason why castings are removed from permanent moulds immediately they have set, and while still at a bright yellow or orange tint. An interesting fact is that a large content of phosphorus and sulphur, sufficient to weaken a casting made in green sand, has no such result in castings poured in permanent moulds. Attempts have been made, but with little success, to coat the interior of the metal moulds when cold with various substances to prevent chill — pulverized talc, or chalk mixed with gasolene or kerosene, and dried. When moulds are hot, heavy oils or paraffin have been used. But in the latest practice no coatings are em- ployed. CHAPTEK IV CUPOLAS, BLAST, AND LADLES Although for special purposes iron is sometimes melted on the hearth of the reverberatory furnace, yet for all the usual run of work the cupola furnace is that which is everywhere employed. The best cupola furnaces which are in use to-day differ from those of half a century ago. Better cupolas have been designed in some respects, more economical in fuel, but many, the older ones, are retained, chiefly, it must be supposed, by virtue of their simplicity, and also because, in the hands of a careful furnaceman, fairly good commercial results can be ob- tained therefrom. Before noting some of the improve- ments which have been made in cupolas, I will briefly describe one of ordinary form (Figs. 10 and 11), and of moderate capacity, such as may be seen in daily work in many foundries. The base A is of brick, covered with a cast-iron plate, B. The shell C is of boiler plate, single riveted, lined with fire-brick, arranged as headers, set in fire-clay. In small cupolas there is only one course of bricks, in large ones they are two courses deep. The vitrified slag soon forms a glassy skin over the bricks, and thus becomes a protective coating to them. A bed of sand, D, is beaten hard down on the bottom, and upon this is placed the bed charge, E, of coke; metal, coke, and flux alternating thence all the way up to the charging door, 47 Fig. 10. — Cupola. Elevation. CUPOLAS, BLAST, AND LADLES 49 F, which is about a couple of feet above the charging platform, I. The blast necessary for combustion is brought in at the two tuyere pipes, G, G, from the blast main, H, which is properly placed below the ground, as SECTION N— N Fia. 11. — -Cupola. Sections. shown. The metal is tapped out at the hole, J, (Fig. 11), the spout of which, K, is usually brought through the foundry wall, outside of which the cupola is properly placed. L is the door closing the breast hole, through which the fire is lit, which is closed just previous to the turning on of the blast, and through which the E 50 PRACTICAL IRON FOUNDING embers are raked after the casting is done. Above the breast hole is the slag hole, M, placed just below the level of the tuyere openings. Through this the slag is tapped out at intervals during the process of melting. Charging. — The method of charging is as follows. First of all, the interior up to the height of the tuyere holes is lined for a thickness of f in. or 1 in. with fire-clay, or with loamy sand. The tap hole, J, is lined by ramming sand and fire-clay around a pointed bar inserted in the opening in the bricks. A fire is lit in the bottom, and a bed charge, E, of coke is laid upon this. Then follows a charge of iron and flux, and again a layer of coke, and so on alternately, as seen in Fig. 10. This is done two or three hours before the blast is put on, and in the meantime the various openings into the cupola remain- ing open, the fuel burns up quietly, and everything be- comes warmed equably throughout. When the time arrives for the melting down of the metal, the breast- plate, L, is lined with sand, and wedged in place, the tuyere pipes, G, the bends of which are made to swivel, are put into position and luted with clay, and the tap hole, J, being open, a gentle blast is put on for five or ten min- utes. This has the effect of hardening the clay in the tap hole. The blast is then stopped, the tap hole closed wdth clay by means of the bot-stick, and the full blast pressure is put on. In from ten to fifteen minutes the metal begins to run down, and presently, when the fur- naceman observes through the mica sight holes, H', H\ of the tuyeres that the metal is getting nearly to the level of the tuyere openings, he taps out a quantity into a ladle. This is done by driving the pointed end of the bot-stick through the hard-baked clay, giving the stick CUPOLAS, BLAST, AND LADLES 51 a rotary motion with his hands, to enlarge the hole. The metal then runs down the shoot, K, in a steady stream, and when the ladle is nearly filled, the tap hole is closed with a dauh of clay held on the flat end of a hot-stick, the stick being held diagonally downwards towards the hole at first, and then lowered sharply until the axis of the stick is in line with the hole J, so closing it up with- out risk of spluttering of the iron. As the metal runs down, additional quantities of iron, fuel, and flux are charged in at the door, F. Slag forms in quantity, and this has to be tapped out at intervals through the slagging hole, M. The slagging will have to be repeated more or less often according to the inferior, or superior class of the metal. As long as slag continues to run, the hole should be left open. If very inferior or burnt iron is being melted the slag may be running nearly all the while. The economy of cupola practice is largely dependent on keeping the surface of the metal free from slag. Charges of metal of different kinds are melted in the cupola at the same time, by interposing between each charge a stratum of coke rather thicker than those used in the ordinary work of melting. The charge which is lowermost is then tapped out, as the charge above begins to melt, and the furnaceman is able to see the beginning of the melting of an upper charge at the sight holes, //', 7/'. Large quantities of metal are tapped out in detail, a ton or a couple of tons at a time, until sufficient has accumulated in the ladle. Metal in the ladle will retain its heat for a very long time if radiation is prevented by sprinkling the surface with the blowings from a smith's forge, and by allowing the oxide and scum to remain thereon. 52 PRACTICAL IRON FOUNDING When the melting down is done, the whole of the fur- nace contents are raked out through the breast hole, or, if the cupola is of the drop bottom type, like Fig. 12, p. 55, by dropping the bottom. Under no circumstances can the metal and fuel remain safely in a cupola long after the blast is shut off, since, if it sets, the mass will hung up or goh up the furnace, forming a salamander, and the furnace lining may probably be destroyed in the re- moval of the obstruction. Economical melting, — The proper melting of metal is a task requiring a good deal of experience and caution. Economical melting is an excellent thing, but there are other points which have to be regarded besides the state- ment on paper that a ton of metal has been melted with a certain percentage of fuel. Iron may be melted so dull that poor, if not waster castings result, when a little more fuel \v^ould have dead-melted it thoroughly, producing good, sound, homogeneous castings. Then the size of the cupola, and the amount of w^ork being done, has to be taken into account. A small cupola is more wasteful in fuel than a large one. A cupola running two or three hours daily is more wasteful than one running all the day. Inferior iron is more wasteful of fuel than iron of superior quality. Hence general porportions only can be given for percentages of fuel. The total percentage of fuel to iron melted may range economically from 1-^- cwt. to 3 cwt. per ton, according to circumstances. Total percentage includes the fuel used in the bed charge. This always bears a large proportion to the total amount used, hence the reason why short meltings are so much more costly than lengthy casts. For a cupola like Fig. 10, 4 ft. diameter, a bed charge, E, of 10{r cwt. is used; for a similar cupola, 2 It. 4 in. in diameter, a bed charge of CUPOLAS, BLAST, AND LADLES 53 G cwt. is used. But the bed charge will equal about one half the quantity of coke required for a " blow " of moderate length, say of from two or three hours. The succession of charges in the cupolas of the two sizes above-named is as follows: 4 ft. cupola: bed charge 10^ cwt.; each charge of iron 21 cwt., separated by 2 1" cwt. of coke; \ cwt. of limestone (flux) in bed charge, and seven or eight pounds on each subsequent charge. 2 ft. 4 in. cupola: 6 cwt. bed charge, each charge of iron 14 cwt., 11 cwt. of coke in each subsequent charge. The first cupola will melt four tons per hour, the second from two and half to three tons per hour. But in the first cupola, with heavy casts, twelve tons can be melted with twenty-five cwt. of coke, including bed charges. In cupolas such as these, doing jobbing work, using different mixtures of iron, making many light casts, and running from two to four hours per day, the conditions for economy of fuel do not exist, and as much as two cwt. of fuel per ton of metal melted will not be an unreason- able proportion. Where contrary conditions exist, the proportions may be less by nearly one half. The chemical conditions which govern economical working are those which relate to the purity of the fuel, and to the complete utilization of the products of com- bustion. The coke should be the best and purest pro- curable, free from sulphur, hard, columnar, heavy, having metallic lustre, and clean. The height of a cupola, the position and number of tuyeres, the density of the blast, all vitally influence the ultimate results. Height is ne- cessary, because without it large quantities of combustible gas would escape unburnt and become lost. Comhustion. — The process of combustion is as follows: Air, under pressure, entering the cupola through the 54 PRACTICAL IRON FOUNDING tuyeres, meets with the heated fuel. The oxygen in the air combines with the incandescent carbon in the fuel, form- ing carbonic anhydride, COo, a gas which will not burn. This gas takes up more carbon, becoming carbonic oxide, CO, equivalent to Co O2, which is combustible. If, however, this gas does not meet with sufficient free oxygen at a high temperature, it cannot burn, but will pass away, representing a certain number of heat units wasted. But if it meets with a sufficiency of heated oxygen higher up in the furnace, it burns, giving out heat available for combustion. Hence the reason why the taller cupolas are more economical than the lower ones. Flame at, and above, the charging door represents heat lost, as far as useful work is concerned. Hence also the reason why two or three rows of tuyeres, to supply the zones of oxygen necessary for combustion, have been adopted in nearly all cupolas which have been designed to supersede the older forms, a mode of construction which is therefore seen to be quite correct in principle. The perfect combustion of carbon to COo evolves 14,647 British thermal units per pound of fuel. If onl}^ partially burned to CO, only 4,415 British thermal units are developed from each pound of carbon. A pound of carbon requires 1.33 lb. of oxygen in burning to CO, and 2.66 \h. in burning to CO^. If the air supply is in- sufficient, the first oxide only is formed, and hardly a third of the heat possible is obtained. In other words, more than two thirds of the possible heat units are lost at the top of the cupola. Even in the highest melting ratios which are obtained in practice the waste is excessive by comparison with the theoretical values. Even though the gases are burnt almost thoroughly there is much loss of heat in warming CUPOLAS, BLAST, AND LADLES 55 up of the inert nitrogen, in warming the blast, in radiation heat, and unavoidable heat losses in the iron and in the chimney. Actually a ratio of 10 to 1 is very good; 8 to 1 is good; 6 or 7 to 1 represents satisfactory practice. The rapid cupola. — The embodiment of this principle is illustrated by the Eapid cupola, by Thwaites Bros., Ltd., shown by Figs. 12 and 13. In this there are three zones of tuyeres enclosed by an air belt, and each zone of tuyeres can be opened and closed independently of the others by means of shut-off valves. The air belt, the zones of tuyeres, and ] '11 £ the boshes or sloping sides, are, however, r ^^> of older date than this particular ex- 11 ample. Ireland's cupolas, much used a few years since, were very tall, and were provided with boshes or sloping sides similarly to blast furnaces, by which the Fio. 12.— The "Rapid" Cupola. Pra. 13. — Plan of Cupola THROUGH Tuyeres. weight of the charge was sustained. They, or at least the earlier ones, had two rows of tuyeres, but the upper row was abandoned in later structures. Voison's cupolas 66 PRACTICAL IRON FOUNDING were made also with air belts and with two rows of tuyeres. Numbers of common cupolas, both in this country and in America, have the same arrangement. Cupolas have been made with shifting tuyeres, so that in the absence of an air belt the tuyere pipes can be moved to the zone above or below as required. The other features of the cupola are, a brick-lined receiver for the melted metal, by which means the heat is retained and oxidation prevented, while the blast pres- sure maintains its surface in agitation, conducing to proper mixture and homogeneity. The waste heat there- from is also utilized by passing up a ganister-lined pipe into the cupola, entering just above the air belt. The escape of the waste gases is regulated by a flap door at the side of the hooded top. The efficiency of this cupola ranks high, and it has given much satisfaction where it has been erected. In blows of ordinar}^ length it is capable of melting one ton of iron with from one, to one and a quarter hundred- weight of coke. Particulars of dimensions are given in the Appendix. The remarkable success of the air-belt design of cupola is due to the thoroughness with which theory has been translated into practice. It is based on the fact that there is no free oxj^gen above the tuyeres. Hence when the blast enters, its oxygen combines with the carbon in the fuel to form COo- This, in its ascent through the coke, unites with another atom of carbon, forming CO. This again demands oxygen for its con- version into COo, with development of intense heat of combustion. In other words, the conversion of as much as possible of the carbon in the fuel into COo within the melting CUPOLAS, BLAST, AND LADLES 57 zone is the object sought in order to develop all the heat units possible. The arrangement of supplementary tuyeres, of which there are usually half a dozen, sup- plies air in small volumes to the CO formed in the melt- ing zone. Tuyeres. — In arranging rows of tuyeres, diffusion and not concentration of blast must be accomplished, and to secure this the openings should not be arranged per- pendicularly, nor be very far apart vertically. If they Fia. 14. — Tuyeres of ISTewten Cupola. supply a uniform and sufficient quantity of air to the melting zone, which can be judged by the working of the cupola in economy of time and in hot metal, though not necessarily in fuel consumption, their real efficiency is demonstrated. The Newten cupola. Fig. 14, made by the Northern Engineering Works, of Detroit, Mich., has its lower tuyeres fitted with a differential device, the object of which is to send a portion of the blast right to the centre, while the larger volume is diffused more softly about the other 58 PRACTICAL IRON FOUNDING parts of the cupola. The tuyeres are of the enlarged form, giving nearly a continuous circle of blast; but near the centre of each, two plates are set to converge, en- closing the shape of a truncated cone through which the blast, being contracted, is forced to the centre of the cupola. The remainder of the blast is diffused more softly to right and left. Fig. 15 is a plan of the tuyere arrangements of the Whiting cupola, with a section through the wind-box. Fia. 15. — TuYETiics op WniTiNa Cupola. This shows in half plan the upper and the lower tuyeres, alternated or staggered in relation to each other. They are flared, being nearly double the width of opening at the inside than where they meet the belt. The position of the upper row is fixed, but the lower row may be adjusted to different heights. And when desired, the upper row may be closed with dampers if the amount of blast has to be lessened. Mdthuf ratio. — Various miscellaneous arrangements of relatively minor importance contribute to the economy or durability, or facilitate the working of the cupola. CUPOLAS, BLAST, AND LADLES 59 The ultimate object is to melt as much metal as possible with the smallest expenditure of fuel, consistently, of course, with thorough melting. A certain quantity of metal, say a ton, is melted by so many hundredweights of coke, say two, three, or four. The first divided by the last gives the " melting ratio," a quantity around which foundry managers are in rivalry, and concerning which no statement can be made which shall be of more than very general application. The melting ratio must obviously be variable within wide limits, because it is under the control of so many conditions. Hence comparisons and statements can be of real value only if they are made under identical cir- cumstances. Sometimes the ratio is stated without in- cluding the amount of coke in the bed charge, which, if included in the case of a melting of short duration, might reduce the ratio by nearly or quite one half. In a prolonged melting, running down a large quantity of metal, the bed charge will form but an insignificant pro- portion to the whole. Again, in casting light work, the metal must neces- sarily be hotter, that is, more thoroughly melted, than for very massive work, and this requires a larger propor- tion of fuel; besides, a pure clean pig and scrap will re- quire less fuel to melt thoroughly than a lot of dirty inferior scrap, with much slag, will want. But even observing these differences, and including the bed charge, in all comparisons there is much difference in cupola performances, greatly to the disadvantage of the older types. Drop bottom. — The hinged drop bottom, though not in any way related to the efficiency of a cupola, is much to be preferred to the older solid bottom. The hinged 60 PRACTICAL IRON FOUNDING door, on being released by a latch, allows all the con- tents to fall out at once. With a solid bottom they have to be raked out at the side, an operation which occupies ten or fifteen minutes, and is very hot work. It is neces- sary also to melt all the superfluous metal in order to run it out from a solid bottom, while it can be dis- charged from a drop bottom unmelted or partly melted, along with the partly burnt coke and slag. If water is thrown over it, the constituents can be separated and used again next day. Blast. — The proper pressure of blast is a matter of great importance. A soft blast will not melt the metal quickly nor thoroughly, and will cause wasteful ex- penditure of fuel. A sharp blast will blow away the fuel before perfect combustion ensues. Cupolas of large capacity have been made elliptical in plan instead of circular, to enable the blast to penetrate better to the interior. It is difficult to put in figures any rules for the blast pressure of cupolas, since it by no means follows that the pressure in a cupola is the same as that in the blast pipes ; it is really less — very much less — if the pipes are not selected of suitable size, and laid properly; and it is further very variable, depending on the condition in which the furnaceman keeps the cupola, the presence of slag, dirt, and partially choked tuyeres, and too close charging, so diminishing blast pressure. The pressure in a cupola varies within several ounces from the time of putting on the blast to the period of full melting. The differences are due to the increase of resistance of the molten iron and slag, preventing that ready escape of the air which occurs through interstices of the fuel and unmelted iron. A gauge supplies the means for reading CUPOLAS, BLAST, AND LADLES 61 these variations of pressure. It is graduated to ounces, and reads to 2 lb. No cupola should be without one of these specially-constructed blast pressure gauges, in which the pressure or density is measured in inches of water. An inch of water gives a pressure of 0.5773 oz. per square inch. Blast pressure may range from 5 oz. or (3 oz. to 18 oz. Say we have, as an example, a pressure of 12 oz., that would be equivalent to 6.9276 in. of water, or 0.88 in. of mercury, and this may be taken as a rough average approximation to ordinary cupola blast pressure ; or, putting it in round numbers, 7 in. or 8 in. of water, and 1 in. of mercury. The larger the furnace, the higher, of course, the pressure required. Fans and blowers. — For the production of blast, fans and blowers are employed, by which the air enters the cupola under pressure. There is no virtue in mere press- ure as such, but a certain rapidity of combustion is necessary in order to the efficient melting of metal. The pressure is not great, seldom more than 12 oz. per square inch, but at such a pressure an enormous volume of air passes through the tuyeres in the course of a min- ute. 30,000 to 40,000 cubic feet of air is necessary to melt a ton of iron, and from 20,000 to 30,000 cubic feet is necessary to consume 1 cwt. of coke. The volume of air is necessarily large, since, of the oxygen, much is lost through imperfect combustion, and the nitrogen is inert. The difference between a fan and a blower is, that the fan acts by inducing a current of air, the blower produces a positive pressure. The fan therefore has to revolve at a very high rate of speed, causing an attendant train of evils inseparable from high speeds; the blower need only revolve at a very moderate rate. The pressure and volume are under greater control with a blower than with a fan. 62 PRACTICAL IRON FOUNDING The common fan consists of an outer casing, cast in halves, and l)olted together. Within it revolve the hlades, or vanes, upon a spindle which runs in long hearings, and which is driven hy belt pulleys. The Figs. 16 and 17.— Types of Bloweks. revolution of the vanes produces a partial vacuum within the casing, into which air rushes from openings at the sides of the casing, gathering momentum, like a falling body, with increase of speed, and is forced out through the nozzle of the casing into the blast main. In the blower (Figs. 16 and 17), the air which enters CUPOLAS, BLAST, AND LADLES 63 the casing (from below in the figures) is forced forward under constant pressure by the revolving pistons or impellers into the outlet above, which communicates with the blast main. These impellers are of cast iron, shaped to templet, and fit so accurately into each other, and to the bored casing, that the thickness of a sheet of paper alone preserves them from actual contact. The narrow, almost pointed ends serve to sweep out any deposit of dirt or grit which may enter within the casing. Being lubricated with a very thin coating of red oxide paint, they run, though practically air-tight, with the very minimum of friction. Two examples of Koots' blowers are shown by Fig. 18, Plate I, and Fig. 19, Plate II, the first being geared direct to an electric motor, the second driven by the special type of engine which is used for these, with two connecting rods. Ordinary high- speed enclosed type engines are also employed for this function, with a heavy flywheel on the shaft, and con- nection to the second shaft by the usual gears. These are by Thwaites Bros., Ltd., of Bradford, Yorkshire. A table of the performances and other particulars of Boots' blowers is given in the Appendix. In Baker's blower there are three revolvers or drums, each of circular section. Two of these are slotted through- out their entire length in order to allow the pair of radial wings in the upper drum which propels the air to clear inside them. The lower drums are so arranged that contact is never broken between one or other of them and the upper drum. The upper drum is furnished with two radial arms which alternately sweep through the hollow portions of the two drums placed beneath it In this case also the casing is bored out truly to prevent escape of air and to ensure smooth working. 64 PRACTICAL lEON FOUNDING Controversy respecting the relative merits of fans and blowers is perennial. Each has its advocates, but an un- biassed mind will admit that between the best of each there is little if anything to choose. The points in favour of each are these. With the blower, practically the same volume of air which is drawn in must be forced out, for a well made machine should have no perceptible leakage. Hence the volume of air can be controlled exactly by varying the number of revolutions of the blower, an increase in which increases the melting capacity of a cupola. The volume of air supplied being uniform under similar conditions the pressure increases with resistance offered, so that a blower will force air through slag obstructions, or through charges of increasing density. So that pressure may rise from 8 oz. to 10 oz. in the course of a blow. This is all in favour of the blower. Moreover, very minute fluctua- tions occur in pressure during each revolution, occurring each time the arm of an impeller discharges air. This is also claimed as of value in regular melting. The fan acts by imparting momentum to the air and not by displacing a precise volume equal to the cubic capacity of the blower. The term centrifugal denotes that the air is delivered by centrifugal force at the circum- ference. The rotation produces a partial vacuum about the centre, to occupy which air enters at the openings in the sides. Pressure is increased with increase in the rapidity of the revolutions, and in the ratio of the square of the speed. The speed of a fan cannot be increased beyond the proper speed for which it is rated without absorbing additional power in the ratio of the cube of the number of revolutions. So that a fan will, under these circumstances, be a wasteful machine. Actually fans PLATE II See 2}. 63 [Facing p. 64 Fig. 19. — Roots' Blower, driven by Self-contained Steam Engine CUPOLAS, BLAST, AND LADLES 65 should be selected of capacities large enough for their work, and for this the tables of manufacturers may be accepted as a working basis. And further, the pipe arrangements must be free, large, short in length, and without any quick bends, if the fan pressure is to be maintained at the cupola. The fan is not so well able to force air through dense charges of slag as the blower is. On the other hand it produces a softer blast. It is desirable with fans to have a blast gate in the main pipe for regulating the supply as the demands made upon it vary. The elasticity or tlexibility of the fan, its self- adjusting capacity, is in its favour in the opinion of many foundrymen. But unless a fan is selected fully large enough for its work and run at suitable speeds, it will prove very inefficient. In its favour is that of costing less than the blower, requiring less solid foundations, and being less expensive for repairs. The attempt has been made to employ a jet of steam to induce the blast current. This was the peculiarity of Woodward's cupola. In the Herbertz cupola also the blast is induced by an exhausting jet of steam. The jet operates in a flue near the charging door, and the blast enters through an annu- lar opening immediately above the hearth. The width of this opening is capable of adjustment by means of screws for the production of a cutting or of a soft blast. Ladles. — For the pouring of metal into moulds, ladles of various kinds are employed. The ordinary forms are shown in the accompanying illustrations. In the group of Fig. 20, Plate III, the smallest, the second from the top, is a hand ladle holding a half hundredweight only, used for very light casts and supplying feeder heads with hot metal. Above it is seen the double handled shank ladle, F 66 PRACTICAL IRON FOUNDING made in capacities ranging from one to about four hun- dredweights: two, three, or four men carry these ladles, according to the weight. Thus there may be one, or two men at the cross handle; and one, or two at the straight shank. When made for two, the end of the shank is Fig. 21. — Double-geared Ladle. turned down, and is supported on a cross bar, each end of which is held by a labourer. The third do^vn in the group is a heavier, or crane ladle; it may range from ten hun- dredweights to a ton in capacity. It is slung in the crane hook; the catch seen on the right prevents the ladle from becoming accidentally up-tipped, and, when thrown back, a man standing at the cross handle turns the metal into CUPOLAS, BLAST, AND LADLES 67 the mould. The heaviest ladles are of the type shown below. These are r/eared ladles, which may range from one to twelve tons in capacity. The geared ladle was the Fig. 22. — Double-geared Ladle. invention of Mr. Nasmyth, and a graphic illus- tration of the contrast between it and the old ungeared form is given in his admirable autobiography. The ladle in the Fig. is double geared, having mitre wheels in 68 PB ACTIO AL IRON FOUNDING addition to the worm gear. Many ladles have the latter only. A weight of several tons is tipped easily and steadily into the mould by means of the geared ladles. Fig. 26. — Gtogdwin and How's Patent Ladle. Figs. 21 and 22 show the construction of a double- geared ladle by Charles McNeil, of Glasgow, of 25 cwt. capacity. The worm gear for tij^ping is turned by the application of the handle either directly on the square CUPOLAS, BLAST, AND LADLES 69 on the worm shaft, or if more convenient at right angles on the square of the mitre gear shaft. Fig. 23, Plate IV, represents a worm-geared ladle of 12 tons capacity, by Fig. 27. — Goodwin and How's Patent Ladle. Messrs. Thwaites Bros., Ltd., with riveted body, and Fig. 24 is a 10 cwt. ungeared ladle mounted on a four- wheel bogie. A heavier class of ladle — 5 tons capacity — Fig. 25, Plate lY, is provided with a lifting bar so that it may be lifted on and off by the crane. The eight- 70 PRACTICAL IRON FOUNDING wheel bogie carriage has ball-bearing swivels, and the wheels are flanged to run on a track. These ladles are, except the smallest, which are of cast iron, made of steel plate riveted together. The McNeil ladles are of pressed steel. Ladles are daubed every morning before casting with fire-clay, or loamy sand, and blackwashed. This lining is dried, in the case of the smaller ladles, over a coke fire, in the larger ones by lighting a fire of w-ood within them. After casting, the skulls are chipped out with a hand hammer. Skimmimg. — When metal is poured from a ladle, a boy holds a rectangular bar of iron across the mouth, to bay back the scoriae which floats on the surface, so prevent- ing it from entering the mould, to the detriment of the casting. The method is necessarily an unsatisfactory one, but few attempts have been made to remedy it. Two forms of ladles have been patented, having a bridge or bar dividing the spout from the body; the Craven and Chapman is one; the other, Goodwin and How's, is illustrated in Figs. 26 and 27. From these it is seen that the body of the ladle is pear-shaped, the shell being extended on one side to form an external spout, which is separated from the body by a skimmer or dividing plate, projecting above the top of the shell, and descending to the required distance from the bottom. It is held in position by eyes, pins, and cotters at the top, and by finger plates at the bottom. The skimmer plate is readily removable for repairs. The principle of taking the metal from the bottom is an excellent one, and has long been adopted in the steel-casting ladles, fitted with a goose neck and plug. CHAPTEE V THE SHOPS, AND THEIR EQUIPMENT Situation. — When designing an iron foundry, everything must depend upon situation and upon the space avail- able; but there are certain main considerations which may be briefly stated. In the first place, the soil ought to be dry. One of the greatest difficulties in some low- lying districts is to get a sufficiently dry site. This, which is a matter of slight consequence in the building of a machine shop or boiler shop, is of serious import when a foundry is concerned. In spongy ground, and ground liable to floods, moulds sunk in the floor are always liable to damage. In such cases new ground should be made up of a height sufficient to be above the reach of water, and especial care be taken in so lining the casting pits as to render them impervious to moisture. The building also ought to be lofty and well ventilated, to carry off the sulphurous fumes and smoke present in all foundries. There should be plenty of light. Ven- tilation and light are as essential in a foundry as in a machine shop. Both should be mainly provided in the roof. A foundry cannot be too well lighted. So much of the work is, in itself, involved in shadow, as in deep lifts, setting of cores, etc., that even in the best-lighted shop the use of lamps in the daytime is frequently necessary. If the roof is well lighted, little side light is required. Still, the more the better, and, whenever practicable, side 71 72 FB ACTIO AL IRON FOUNDING windows should be included. Further, the building should be of the same section throughout, in order that a tra- velling crane may run from end to end without hind- rance. Again, if a large area is required, it is better to obtain that by giving increase in width rather than ex- cessive increase in length, and this not by unduly widen- ing a single sj^an, but by doubling or trebling the spans, either making two of equal breadth, or flanking a main span with one or with two narrower side ones, according to circumstances. This arrangement is economical in respect of the carrying of metal and materials, flasks, and tackle ; and it permits also of better overlooking and supervision. In any span there should always be clear floor room throughout, and this is of prime importance. To have cranes stuck about in the middle of a shop is a bad arrangement, because they occupy valuable room, and make the transit of metal awkward. But these general conditions often have to be modified by circumstances, because the planning of any workshop may be hampered by the ground plan of the premises. The proximity of certain departments is desirable, and parallel bays are not always practicable. Enlargement. — The possibility of future enlargement must be considered in laying out a new foundry. And extension can only be effected on the ground. No shops can be built over, because the heat and sulphurous fumes forbid it. Future extension must be provided for, longitudinally, or laterally, by increasing the length of a bay, or by adding a new bay or bays at the sides of the primitive building. A beginning can be made with a square building, equipped with a central crane, and one or two wall cranes. That is not a very good plan, but many small shops are constructed thus. In a future THE SHOPS, AND THEIR EQUIPMENT 73 extension the shop would be made oblong, and the crane would remain to serve the heavy loam work, while the added length might be served with a traveller and light wall cranes. When starting a block of buildings, the proximity of stores, etc., must be borne in mind to save unnecessary handling of materials. Cupolas. — Two cupolas are necessary in any foundry. The smaller will be of about 2 ft. 6 in. diameter, the larger will range up to 4, 5, 6, or 7 ft., according to the weight of work done. In a large foundry two cupolas or more of the largest capacity may be required for the day's casts. Besides these, it is often convenient to have a small one of from 16 to 18, or 24 in. diameter, having a capacity of from 10 to 30 cwt., for the purpose of mak- ing tests of mixtures, casting test bars, making a special light cast, etc. Generally it is convenient to locate the cupolas to- gether for convenience of charging and blowing. Inside the foundry it would often be more convenient for the tapping of metal to locate cupolas apart from one another. In the case of special departments of work, such arrange- ments must sometimes be made. The general rule, how- ever, is to set cupolas together, as nearly centrally as possible, in order to lessen the distance of carriage of the metal, and the loss of blast pressure. In many foundries the practice is to locate the cupolas without the building, passing the tapping shoot through the wall into the in- terior. In others the lower portions are within the build- ing, and the upper parts pass out through the roof. The latter has the advantage over the former, that the furnace- men are protected from weather, and that the foreman can observe the melting without going outside. But if the cupolas are placed without, a door at the side permits 74 PRACTICAL IRON FOUNDING ready egress. Hydraulic hoists, or geared pulley-driven hoists, will be located at the cupola stagings for lifting iron and coke from below. Large ladles of metal are carried away with the tra- veller, or with a ^valking crane, or swung round in a jib crane to moulds within its radius. Light casting is some- times done from a tipping ladle on a bogle running on rails down the shop. The moulds are either poured directly from the ladle, or it is used to supply the smaller hand ladles which fill the moulds in its passage down the shop. Shank ladles, containing from 56 lb. to 4 cwt. are generally carried by hand. Core Ovens. — The dimensions of core ovens and drying stoves depend upon the nature of the work done in a given foundr}^ The largest stoves run to 20 ft. or 24 ft. long, by from 10 ft. to 12 ft. wdde. Height also will de- pend on the class of ^York, ranging from 6 ft. to 10 ft. Carriages will occupy from 1 ft. to 2 ft. of this height. In cases where work exceeds 6 ft. or 8 ft. in height, it is usual to effect a division in the mould, parting it into tw^o, which are placed separately on the carriage. The largest stoves should be adjacent to the area where loam work is done. The smallest stoves are better located else- where, adjacent to the small core-making departments, to be used for the drying of cores, or of small moulds. The stoves, except those for ver}^ small cores, are always built outside the foundry, the doors being flush with the interior of the foundry walls. Stoves are fired with coke from the outside — that is, from the end farthest from the doors. In some cases, however, the grate is built inside in the centre of the floor. The neatest way of firing is by producer gas, or the waste gas from furnaces. The car- riages containing the cores are made in cast iron, framed THE SHOPS, AND THEIR EQUIPMENT 75 together, and covered with loose plates. They are run in on rails which lead from the shop into the stove. Pro- vision is made in some foundries for drying large moulds in the foundry pits. The latter are of large area, and are heated by gas, being covered over with iron plates during the drying process. Tracks. — Narrow bogie tracks might advantageously be used to a greater extent than they are in English foundries. The objection to their use is that they occupy some floor space that might be required, and that the ladles are apt to spill some of their contents if the track becomes temporarily obstructed. In reference to the first, a fairly clear way down the centre of the shop must of necessity be kept for the transit of materials, and of metal if carried in hand ladles. In reference to the second, mishaps need not occur if a labourer is made re- sponsible for keeping the ways clear. Also, similar mis- haps occur with hand-carried ladles. Further, too, other materials beside metal are carried on the tracks, and tackle also. The advantages are: Facility in transit, avoiding the changing of heavy ladles from one crane to another and saving in labour, one man being able to push along a load which would require three or four men to carry in shank ladles and by hand. In the light foundry more especially, the tracks are of value, since a ladle carrying 5 cwt., 8 cwt., or 10 cwt. of metal can be run over from the cupola and made to feed a dozen or twenty small moulds ranged along its track. For small moulds not in the line of track, the light 561b. hand ladles can he dipped into the larger ladle close by, instead of run- ning across to the cupola with them. Probably most of our readers know that one of the largest foundries in England — that at Crewe — has tiny locomotives running 7Q PRACTICAL IRON FOUNDING on its tracks. Not only for pouring, but also for running along flasks, sand boxes, and other material, is the track serviceable, saving hand- carrying for light loads and fre- quent waiting for the traveller to be at liberty for heavy ones. With rare exceptions the tracks are always narrow, seldom exceeding about 18 inches gauge. The rails are either cast on plates, or they are fitted on cross-sleepers. Casting-on is a convenient device for several reasons. The rails may stand above the plates, or preferably be flush, flanked by recesses for the wheel flanges. Such tracks are arranged to connect with the yard tracks and thence with the other shops of the works. The narrow-gauge tracks may run uniformly through- out the works, or not go beyond the shop doors, as when wide-gauge standard tracks serve the yard. These then come up to the foundry doors so that articles can be loaded and unloaded from standard to narrow and vice versa. Suitable trolleys are built for foundry service, being plain, or with sides to suit different classes of castings. Casting pits. — These are either oblong, circular, or polygonal in form, and their purpose is twofold. The oblong pits are comparatively shallow, but of large area, and are used for moulding work which has to be dried, but which is so massive that it could not be dried in the ordinary core stove, or, if dried, could not be moved from the floor to the pit. Hence it is rammed, dried, and cast in situ. The circular and polygonal pits are usually very much deeper than the oblong pits, and the work may or may not be moulded and dried in them, but is as a rule moulded on the floor, dried in the drying stove, and only lowered into the pit finally for casting. The oblong pits being shallow, are generally lined only with brickwork, THE SHOPS, AND THEIB EQUIPMENT 77 except in damp and low-lying situations where water could gain access, when they are of iron. They are covered over with movable plates of cast iron to confine the heat while drying, and are dried with gas. The deep pits, on the contrary, have no covering, being simply receptacles for finished moulds; but, being deep, they are often liable to the entrance of water, and are therefore lined throughout with iron plates, consisting either of boiler plates riveted together in the form of a Fig. 28. — Foundry Pit. cylinder, or of cast-iron plates bolted together with flanges like tank plates (Fig. 28). The bottom is similarly formed of iron plates. When bricking-up work in the pit it is often necessary to erect staging at intervals for the men to stand upon while working; ladders, also, are sometimes placed in the pit, and planks laid across the rungs, but it is better to make provision when building the pit for such staging. When boiler plate is used, rings of angle iron can be riveted around at various heights for this special pur- 78 PRACTICAL IRON FOUNDING pose; ribs maybe cast on cast-iron plates when such are employed, or the pit itself may be constructed with rings or plates, the diameter of w^hich increases as the series ascends, so as to form ledges at intervals all the w^ay up. When it is required to diminish the size of a large pit for a temporary purpose in order to put a small job in, loose rings are lowered down and the work rammed up inside them as at A (Fig. 28). Large casting pits will range from 30 ft. to 70 ft. in length, by from 18 ft. to 22 ft. in width; small ones from 8 ft. to 12 ft. or 14 ft. in diameter. Offices, etc. — The foreman's office should overlook the entire shop, and be roomy enough to permit of the mak- ing of tests, and for the clerical work of the foundry. The pattern bench never need be large. Patterns ought not to lie about long in the foundry. The foundry bench is not a store, but simply a receptacle for jobs wanted, and as soon as they are done with they should be cleared away from the shelving and a fresh supply of patterns sent in. Narrow shelving — one or two rows — is arranged round the walls for the reception of small patterns after mould- ing, and a few moulders' small requisites — lamps, nails, etc. As soon as the castings are turned out and passed, the patterns must be removed, otherwise loose pieces will be lost and parts damaged. Stores for the foundry, and the various machinery for the same, should be located close to the building, in such a manner that time will not be wasted in obtaining any- thing required Coke, sand, iron will be kept in sheds, and the machines for grinding, mixing, and breaking will be adjacent, and rails, trucks, and hoists will convey the materials whenever required. The sand and other THE SHOPS, AND THEIR EQUIPMENT 79 sheds may open into the foundry, or may be located out- side. There is so much dust, dirt and Utter attending these, that it seems better to have them to open outside the foundry than into it, adjacent to the work of moulding. The fettling shop must always be parted from the foundry itself. The reason is that the chips, the fins, etc., that are chipped off the castings must not be permitted to mix with the foundry sand. In the fettling shop there will be a bench with vices, small emery wheels for grind- ing off fins, scabs, etc., and a tumbler or rattle barrel for cleaning off sand and smoothing surfaces. The location of the pig and scrap iron will depend on local conditions. It is not necessary that the iron shall be close to the cupolas. It may be elsewhere, provided a track is brought from the iron stores to the cupola. Departments. — If there are specialities in firms, as there are in most cases nowadays, each should be con- fined to a separate department. This is simply an exten- sion of the principle of keeping in a general shop certain men on certain classes of jobs. Thus, wheel moulding, cylinder moulding, light green-sand, heavy green-sand, etc., will be done by men who will be kept as far as prac- ticable each on his class of work. To keep separate classes of work in separate departments follows naturally as the volume of trade increases. Sometimes these de- partments will be located in separate buildings, or in different portions of a single building. It is always de- sirable to make a distinction between light and heavy work, because that permits of a suitable arrangement of hoisting tackle, flasks, proportion of unskilled labour required, and so on. Loam work must always be kei^t distinct from everything else, because of the special 80 PB ACTIO AL IRON FOUNDING tackle required, the ground area occupied, the proximity of drying stoves and casting pits, and heavy hoisting tackle, and because of the dust created in filing and finishing moulds. Plate moulding, with or without the aid of machines, requires its own special area and tackle. So does railway-chair work, ploughshare work, malle- able cast iron work, etc. Engine cylinders, liners, and slide valves, also, when made in large numbers, should have a separate shop, and a cupola for the melting of special metal. Brass work is always relegated to a dis- tinct shop. Everything which can be kept under cover should be so kept. A considerable weight of metal is lost in rust every year when tackle is left in the open. Standard grids, core bars, and the smaller flasks can all be kept in sheds without encroaching on the foundry area. Foundry doors must be made amply large enough to pass the largest patterns or castings ever likely to be constructed. The main doors should not, as a rule, be less than 12 to 14 ft. wide, and from 10 to 12 ft. high. They are made of sheet iron to slide sideways, or ver- tically; in the latter case being counterweighted. Hinged doors should never be used. Smaller doors will be placed at various parts to suit various requirements. The average foundry is almost invariably the most badly-equipped of any engineer's department in regard to labour-saving appliances. There are foundries now, considered good, in which there is no machinery and no labour-saving appliances worth mentioning — in which work is carried on by precisely the same methods which were in operation a quarter of a century ago, and where everything is still done by dint of pure physical effort; moulds made, metal carried, castings cleaned, etc., with- PLATE III Seep.^^ [Facing I). SU Fig. 20.— Ladles, by Thwaites Bros., Ltd. THE SHOPS, AND THEIB EQUIPMENT 81 out the most obvious economies which have long been practised in the leading firms. If a fractional part of the money which is lavished in the other departments to save unskilled labour were spent in the foundry to lessen the cost of skilled labour there, the results would in time prove eminently satisfactory. The reason why this condition of things exists is that the class of work done in pattern shop and foundry is of a different char- acter from that carried on in the boiler and machine shop, in this respect — that the work is not usually so re- petitive there as in these. There is some machinery which is indispensable in any foundry. There is much, also, of a more or less special character, the cost of which is either too heavy for small foundries, or else it is machinery which is adapted only for certain classes of work. Indispensable machines are the coal mill and loam mill. Those which are seldom used in small foundries, but which are found in most large ones, are sand- sifters, emery wheels, rattle barrels, testing machines, and ma- chines for breaking pig iron and coke. Machines of a special character used in special departments of large foundries doing general work, and in any shops doing special work, are the plate-moulding and the wheel- moulding machines. Articles which come under the head of appliances, and which are essential everywhere, are wheel-barrows, ladles, shovels, riddles, sieves, scratch brushes, core trestles, iron core boxes, flasks, etc. Cranes. — These are of three kinds — post cranes, which slew completely round; wall cranes, which slew within a more limited range, generally 180 degrees; and over- head travelling cranes, the range of travel of which covers the whole of the floor area of the shop. The post cranes G 82 PRACTICAL IBON FOUNDING are very useful when the shop is of moderate size and of quadrangular form. The framework, triangular in out- line, may be constructed either of steel or of wood. The post is pivoted in a toe step in the ground, and in a socket attached to cross timbers in the roof trusses. Pro- vision is made for lifting by single and double gear, and for racking inwards and outwards; the latter being essential for the precise adjustment of the ladles in relation to the moulds, which are arranged on the floor. The power of such cranes may range from three to fifteen tons. The wall cranes are necessarily of light construction, ranging between powers of one and two tons only. The framework consists of horizontal jib, and ties only, made in steel. The hoisting gears are attached to a bracket which is bolted to the w^all, independently of the main framework. A racking carriage travels on the horizontal jib, and is worked by means of an endless rope depending from a spider wdieel above. These are used for turning over and lifting the light moulds, and smaller ladles, and if ranged in series, each within range of the radius of its fellow, ladles can be passed down the shop rapidly, being transferred from crane to crane with changing hooks. But the overhead traveller has the best arrangement for all except the very small shops. The traveller moves along the gantry beams which are supported on the stone abutments of the walls, and the crab has a trans- verse motion across the traveller beams. The whole area of the floor can thus be covered at will. Travellers when of small size are worked by hand from below with endless ropes, many of those of larger size by a man stationed on the crab above. Travellers of all sizes are now actuated electrically. THE SHOPS, AND THEIR EQUIPMENT 83 These will be differently arranged according to cir- cumstances. There should be at least one overhead traveller in each bay, operated by hand or by electricity. It is well to have two travellers — one light and one heavy — in long shops where a lot of handling of flasks has to be done. In addition there must be several hand, electric, or hydraulic cranes. Columns can be utilized for the attachment of cranes which swing in a complete circle to serve adjacent bays. It is necessary to have jib cranes, as well as a traveller, in a foundry bay, be- cause a single traveller cannot serve all the requirements of a foundry. They should not be in the middle of the shop, because they would be in the way. If a crane is placed in the centre of a bay it must be located at one end, in order not to interfere with the work of the traveller, or with the clear floor area necessary. At one end it may serve for the heavy loam work, or heavy green-sand work. Any jib crane which is adjacent to another crane should cover its radius, for the conveni- ence of changing flasks or ladles from one to another. All jib cranes must have racking movement to cover any work lying between the post and the maximum radius, and therefore they must have horizontal jibs. Walking cranes are sometimes used in foundries, as in machine shops and turneries. They cover the whole area without remaining a permanent block. But they are not so well adapted for heavy work as the travellers. Converted and single-motor travellers are undesirable. Each motion, — hoisting, longitudinal, and cross traverse should have its own motor, and a heavy traveller should have in addition an auxiliary hoist for light loads. Poiver, — In making selection of power for a foundry at the present time, broader views have to be taken than 84 PRACTICAL IRON FOUNDING formerly. Not only have new applications of power agencies come into the field, hut the foundry itself has heen radically reorganized and remodelled. Many recent foundries are machine-moulding shops ; others have gone far in that direction. Human muscle — a hig asset in the older shops — is of less account now than it was at one time. Mechanical aids to lift and carry are uhiquitous. As foundries have heen re-designed, so also have power agencies hecome readapted. One fact should seem so ohvious as hardly to need stating, namely, that no single answer can he given to the question that would be of universal application. There is, for example, very little in common between a foundry doing all light work and another handling only heavy work. A foundry which deals with both classes stands in a different category from one manufacturing specialities, and so on. Each shop must be considered as an entity apart from any other. The following re- marks are intended to embrace the principal conditions which exist in foundries. The natural course to adopt in approaching the power question is to take first a brief survey of the services for which power is demanded or is desirable. These are hoisting and carrying power for the cupola, machinery for the preparation of materials, machinery for making moulds, and that for cleaning castings. Hoisting and carrying machinery. — These are included under one heading because they are intimately related, though carrying on tracks is independent of hoisting. But all cranes carry as well as lift, and one of the prin- cipal differences in them lies in their range of action, which is least in a swinging crane, and greatest in over- head travelling cranes, and hoists on overhead tracks. THE SHOPS, AND THEIR EQUIPMENT 85 The power agencies include hand, steam, electricity, compressed air, and pressure water. Hand power. — Hand power cannot be left out of ac- count, because small foundries in country places depend mainly upon it. Such foundries are not able to afford an expensive power plant of any kind. The demands for crane service are too limited, too intermittent, to justify the capital outlay involved. For these the hand-operated overhead travelling crane offers a cheap source of power. It is made to be operated by a labourer on the crab, or from the floor by a dependent chain. A swinging jib crane, or two, judiciously located against walls, to cover certain areas where such help is most needed, may well supplement the overhead traveller. Such cranes must have horizontal jibs along which the jenny can be racked. Neither cranes with fixed jibs, nor derrick cranes with luffing jibs, are suitable for foundry service. In shops equipped with hand cranes the power which can be most economically installed is a steam-engine for driving the blower, the sand and coke mills, and tum- blers. This is the simplest and cheapest, the driving then being done by means of belts. This machinery, small in amount, but indispensable, can be located adjacent to the blower and cupola, preferably in a shed outside the foundry wall. Steam power. — Steam power may be ruled out entirely now in all ordinary foundries of medium and large di- mensions for new installations of hoisting machines. Electricity has almost wholly superseded it, and where this is installed it serves also for the driving of the blower and the grinding mills. Overhead steam tra- vellers and rope -driven ones were always somewhat of a nuisance, which accounts for the rapidity with 86 PRACTICAL IRON FOUNDING which they disappeared as methods of electric driving improved. Electric power. — Electricitj^ is the agent which in foundries, as in other shops, is the most flexible and mobile form of power. The work of the foundry is more intermittent than that of the machine shop, and elec- tricity is eminently adaptable to such conditions. At casting time, and when castings are being removed from their moulds, the cranes are fully occupied. During the middle of the day their service is intermittent. When electric cranes are not running they are using no power, and when in operation they absorb only the amount which corresponds with the demands made upon them. Also, nearly all cranes now built have separate motors for each motion, and for heavy and light loads, rated suitably for the different speeds and loads, thus not only economizing power, but getting the most suitable speeds for every separate motion. The distribution of electric power from the power house entails the employment of a considerable number of motors distributed where required. But against their cost is to be set the fact that they are eminently adapted to foundry service where the cranes and machinery are scattered and used very intermittently, and they compare in this respect most favourably with any other method of power distribution. In a large foundry the average load on the motor is low, because the intermittent periods when no power is being used are frequent and long in the case of almost all machines. In a large foundry the facilities for transmission which the electric cables afford contrast most favourably with those of steam pipes, square shafts, or cotton ropes. One power house will supply all the current required THE SHOPS, AND THEIR EQUIPMENT 87 for cranes, blowers, and machinery used in the foundry. Cables supply the cranes with current, which is switched on to motors on the cranes only when required for service. Blowers and various machines are belted preferably from short lengths of motor-driven shafting suitably dis- posed. Blowers are designed to suit every kind of drive. A motor is directly coupled to the blower shaft, or it is driven through one set of reduction gear, or a belt drive is taken from a countershaft above, or from a counter- shaft on the same bedplate as the blower, with provision for belt tightening. Or a steam-engine often drives the blower direct, being mounted on the same bedplate. These variations are adaptable to different local con- ditions, and the reason why the blower is thus favoured lies in the desirability of locating it in a room by itself, away from other machines, in order to prevent access of dust to the interior. The sand and coal-grinding mills are better belted from a motor-driven countershaft. The machines in the fettling shop are similarly operated. Compressed air. — This is a source of power which is almost indispensable in any foundry of ordinary dimen- sions, apart from its utilities in operating light hoisting machinery running on overhead tracks, and in some types of moulding machines. The utilities of pneumatic rammers, and of pipes for blowing loose sand away from pattern faces and out of moulds, are of much value, as also is the sand blast for fettling castings. These alone are sufficient to justify the pneumatic installation. Whether to extend the system to the operation of hoists and of moulding machines must be answered differently in different foundries. The light pneumatic hoists on overhead tracks, covering 88 PRACTICAL IRON FOUNDING the entire floor area, are a great help in many foundries. But since electric power has been installed so generally, electric hoists have often been preferred. The electric cable is to be preferred to air-supply pipes with their risks of leakages. The elasticity of the air lift, though not very marked in the best modern hoists, is still ob- jectionable when withdrawing patterns, and when turn- ing over boxes of moulds. On the other hand, the cost of pneumatic hoists is less than that of electric ones, which have to include one or two motors, besides gears. Electric hoists are, however, better suited to the heavier loads than pneu- matic types. Compressed air is used in many power- rammed machines, and its use is increasing. But many firms prefer, or are committed to, hand machines. Then the air hose should be an adjunct for blowing surplus sand out of the moulds. Hydraulic power. — Pressure water is used very largely in German foundries. The reason of this, aj^parently, is that in the German shops heavy machine moulding has developed more extensively than in any other coun- try, and for this, hydraulic pressure has no rival. But apart from this service, pressure water is now rarely installed in foundries; that is, it would seldom be used for cranes, unless already in use or contemplated for heavy moulding machines. Formerly, in a fair number of foundries, hydraulic jib cranes were employed, and they have the advantage of being easily and minutely controlled. But there are several disadvantages incidental to the pipe connections and valves, and the liquid used, and the system is not adaptable to the other services of the foundry — the over- head travellers and the blowers and machines. The THE SHOPS, AND THEIR EQVIFMENT 89 combination of steam with water, the steam-hydrauHc system, has been employed rather extensively; but the disadvantages of the transmission apply to this as to the hydraulic, comparing unfavourably with the electric conductor. Miscellaneous machines. — Cupola hoists are operated by whatever source of power happens to be installed. Direct hydraulic operation is the best if pressure water is available. But failing that, either steam or electricity are quite suitable. The latter is now predominant. Some cupolas have bucket elevation, and transportation bucket gantries. Trolleys on tracks for transportation of materials, boxes, and castings are simply pulled or pushed by hand. In rare instances light locomotives are employed in extensive foundries. Machinery for the preparation of materials includes pig breakers, sand grinders, sand sifters and mixers, coal mills, and loam mills. The best arrangement for these is that of short lengths of countershaft, motor-driven, with fast and loose pulleys to throw any machine into or out of action. Machinery for making moulds includes chiefly the various moulding machines, and then all subsidiary con- veying systems, which, however, are used only in shops where the output is large, and where power is available. The employment of a large installation of moulding ma- chines need not, and often does not, involve a power plant, for the majority in use are still hand-operated. Patterns on machines of large dimensions can be dealt with thus, so nicely are heavy parts counterbalanced, and combinations of levers devised. Hand ramming and pressing is also more common than power ramming. 90 PRACTICAL IRON FOUNDING When power is used it is chiefly compressed air in this country, and hydraulic power in Germany. Machinery for cleaning castings includes tumbling barrels, sprue cutters, pneumatic chisels, cold saws, emery grinders, and sand-blasting apparatus. All ex- cept the last, and the pneumatic chisels, which are operated by compressed air, are usually belt-driven. The countershaft used can be driven by a steam-engine or electric motor. The direct motor-driven unit is, how- ever, gradually coming into favour. In the foregoing remarks the foundry has been re- garded as an isolated unit. But very often it is one de- partment among several of equal importance in a great engineering works, and then the question of power is one which embraces the works as a whole. In such a case one large power house may supply electric current to all the shops, where it is taken up by motors located as seems most desirable. The large works also is favourable to the best possible adaptabilities of power, because not only electricity, but also hydraulic and pneumatic plants are, of necessity, installed. The boiler shop must possess the last two. A stamping shop must have either hydraulic or steam or pneumatic power, often two of them if heavy and light work are both being carried on. In such works the foundry will be highly favoured in being able to utilize the best possible agents for its various services. Heating and ventilation. — The heating and ventilation of foundries have too often been neglected. Modern buildings are usually lofty, the areas are large, and large end doors, which are frequently opened, are essential; and these conditions, with louvre ventilation in the roof, or alternatively swinging sashes, are frequently sufficient THE SHOPS, AND THEIR EQUIPMENT 91 in foundries of large dimensions, such as those com- prising two or three adjacent bays. Hence, compara- tively few foundries have provision either for ventilation or for heating, where the temperature in the coldest weather seldom drops lower than about 18 degrees or 20 degrees Fahr., nor remains long at that. In the northern United States and Canada, where temperature is fre- quently a good way below zero for long periods, warming is imperative, and ventilation is made a part of the system. The plenum system, using a blower circulating cold air on the outsides of banks of steam pipes which con- stitute a heater, and discharging it through ducts within the building just above head room, is the ideal system. The temperature within the building depends on numer- ous conditions which have to be weighed carefully, such as cubic capacity, amount of glass, frequency of change, difference between the outside and inside temperatures required, the latter being usually in the winter 50 degrees to 55 degrees Fahr. for foundries. Thence the tempera- ture to be imparted to the air at the heater, the size and number of revolutions of the blower, the sizes of pipes and ducts and their numbers are calculated, being the work of engineers who make this a specialty. Small steel converters. — Steel castings are now used instead of those of iron for so many purposes where lightness has to be sought, as well as strength, that a steel foundry has become a frequent annexe to the iron foundry. The steel firms can supply castings, but delays and expense are lessened when the iron foundries make such steel castings as are required for their own use. This practice has been fostered and developed by the growth of the baby or small steel converters, the Tro- 92 PE ACTIO AL IRON FOUNDING penas being generally used. The choice lies between these small converters and the small open-hearth furnace, since the ordinary large converters handle quantities of metal too great for the small steel foundry. Moreover, the grade of metal is not so easily controlled as is that in the small converter or the open-hearth furnace. A good deal might be said in favour of each system. The baby converter requires a rather large plant, as the metal has to be melted in a separate cupola first, and a turning or tilting gear, power-operated, is essential. The open-hearth furnace requires no such aids, but it must have regenerators. On the whole, it appears that the small converter plant is being installed very extensively on the ground of its great utility in small castings made in small quan- tities, articles which have previously been forged, or made in malleable cast iron, or in one of the bronzes, or in cast steel in the regular foundries. Quantities much smaller than the contents of even a small open-hearth furnace can be melted in these converters. There are, moreover, considerable numbers of small, self-contained melting furnaces suitable either for steel or the bronzes, furnaces of tilting type and having blast pipes, as the Schwartz and others. These are extremely simple, more so than the baby Bessemer designs and therefore adapted to conditions which might not admit of the laying down of such a plant. CHAPTER VI MOULDING BOXES AND TOOLS Flasks or moulding boxes are employed for enclosing either in part or entirely all moulds excepting those which are made in open sand. The lower portion of a mould may be in the sand of the floor, and its upper portion in a flask. Or the entire mould may be contained in flasks above the level of the floor sand. The upper portion of a covered-in mould is termed the top or cope, and the flask corresponding therewith is also termed the cope, or often the top part. The flask in the bottom, or that which lies on the floor, is called the drag, or bottom part. If there is a central flask, that is named the middle or middle part. These are shown in Figs. 29 to 31. In this group. Fig. 29 is a cope. Fig. 30 a drag or bottom, and Fig. 31 a middle part. It follows from a consideration of the obvious functions of flasks that they must fulfil these main conditions — they must be rigid and strong enough to retain their enclosed sand without risk of a drop-out occurring, and their joints and fittings must be coincident, so that after the withdrawal of the pattern they shall be returned to the precise position for casting which they occupied during ramming up. Rigidity and strength are obtained by making the flasks of cast iron of sufficient thickness. Occasionally they are made in wood, this being a common practice in 93 94 PRACTICAL IBON FOUNDING the United States and Canada, but the general practice here, and by far the better, is to use cast iron. The evils of a weak and flimsy flask are, springing during the pro- cess of turning over and of lifting, causing fracture of the sand to take place, and portions to fall out; and springing or straining of the cope at the time of casting, producing a thickening of the metal over the strained P -^ ^ .T-l Fm. 29.— A Cope. area. A flask should not be excessively heavy, but at least it requires to be strong and rigid. Various devices are adopted in order to ensure the re- tention of the contents of flasks. Chief among these are the bars or staijs by which they are bridged, A' A^ in Figs. 29 and 30. These are ribs of metal usually cast with the frames, though sometimes bolted therein, to be MOULDING BOXES AND TOOLS 95 detachable therefrom. They are arranged for the most part at equi-distant intervals. Their forms differ. Thus the typical bars for bottom or drag flasks are flat, Fig. 30, A\ their function being the retention of the sand which lies thereon, and which but for the bars would mingle with the sand on the floor. Only in the case of special flasks, as for example those used for pipes, n liT" D k ^ V///.! "y^-.f -T^yAT ^i Y/A iVi'.i Z£. ..cJ Fig. 30.— a Drag. columns, and for repetitive work (Figs. 32 to 34) in which the bars follow the contour of the pattern, is this practice departed from. The bars in the cope (Fig. 29, A ^) are made on an essentially different plan. Here they are never flat, but always vertical, being rather of the nature of ribs than of bars. For^general work they are parallel, as in Fig. 29, but for special work their lower edges are cut to the contour of the pattern which they 9(J PRACTICAL Ih'ON FOUNDING cover (Figs. 32 to 84), but kept to a distance of } in. or f in. away from the patterns. They are always cham- fered also, Fig. 29, because if left flat, the sand lying immediately underneath the bars ^Y0uld bo insufficiently rammed. Being chamfered almost to a knife-edge, the full pressure of the rammer is exerted immediately un- derneath the bars, as elscAvhere. M /A_.^ UbJ Lk- ]Li w i^^ IF J: D sl^ Fig. 81. — A Middle. riy There are no stays in middle parts excepting for some special work. Middles for general work are always left clear of bars, as in Fig. 31, because they have usually to contain a zone of sand only, the central portions being open. To retain this zone of sand, rods and lifters are employed, the function and mode of use of which are described at p. 147. Lifters are also employed in the cope. A rib is cast around the inner bottom edge of a Fig. 23 Heavy Ladle PLATE IV Fig. 24 Carriage Ladle Fig. 25 Bogie Carriage Ladle Sea 2). 69 [Facing p. 96 -La. <- ^ cii a M O w M I I 00 6 M m 98 PRACTICAL IRON FOUNDING middle, Fig. 31, B, to assist in the retention of the sand, and also as a convenient support for the rods which help to carry the lifters and the sand. Flasks are always cast with a very rough skin, the better to retain their contents. They are frequently made in open moulds, no blackening is used, and their inner faces are often purposely hatched up to increase their adhesive powder. The coincidence of the joints of moulds is effected dif- ferently in the case of work which is bedded in, than in that which is turned over. Thus, the mould being bedded mainly in the floor, the cope is set by means of stakes of wood or iron; but being turned oveVj the flasks are fitted with 2)ins. In the first method, one example of which is shown on pp. 165 to 169, the pattern having been bedded in, and rammed up as far as the joint face, parting sand is strewn thereon, and the cope lowered into its position for ramming. Before being rammed, however, its per- manent place is definitely fixed by the stakes, which are driven deeply down into the sand of the floor alongside of the lugs, Fig. 29, E, E, or other projections standing from its sides. See also p. 174, Fig. 97, D. Being then rammed, and afterwards lifted off for withdrawal of the pattern, and cleaning and finishing of the mould, it is returned and guided to its original position by the stakes in the floor. In the second method the lugs cast upon the sides of the flask parts have holes drilled to correspond with each other, and long turned pins are bolted into the lugs which are lowermost, and pass into the corre- sponding holes in the lugs above. The more care which is taken with the fitting up of these lugs, the more accur- MOULDING BOXES AND TOOLS 99 ately will the boxes and consequently the mould joints correspond. The length of the pins should be settled with reference to the nature of the work. In any case the pins should enter their holes before any portions of the opposite mould faces come into contact. Unless the pins guide the closing mould there is always danger of a crush of the sand occurring. In shallow flat work, therefore, the pins may measure no more than 3 in. or 4 in. in length. But in work having deep vertical or c 3 Fia. 34. — Section of Column Box (Fig. 33). Fig. 35.- Pin and Cottar. diagonal joints the pins may require to be 8 in. or even 10 in. long. The practice is usually to make the pins point upwards. Thus, in Figs. 29, 30, and 31, the parts of the flasks are represented in their correct relations for super-position at the time of final closing of the mould. The drag (Fig. 30) has its pins G, G, pointing upwards ready to enter into the lugs C\ C\ of the middle (Fig. 31). The pins F, F, of Fig. 31 also point upwards to enter into the lugs E, E, of the cope (Fig. 29). The best method of securing the pins is with cottars (Fig. 35); sometimes, however, in deep moulds cast 100 PBACTICAL TBON FOUNDING vertically, the pins are short, and the ends are screwed and the tightening is effected with nuts. AVhen liasks are retained in position with stakes, cot- taring or screwing cannot of course be effected, yet great counter pressure is necessary to prevent a cope from being strained and lifted at the time of pouring. Wcicflits are therefore employed for this purpose, the amount re- quired being estimated roughly according to the area of the mould, and its depth from the pouring basin. If the contact area of a cope measures four feet square, and the height of the pouring basin is one foot above it, the amount of weight required by calculation to keep it down, including its own weight, will be 48" X 48" X I'l" X "^2()i^ lb., the latter being the weight of a cubic inch of iron. This would give 7,121 lb. re- quired for loading, or over 3] tons. Actuall}^ a moulder seldom attempts to calculate the weight necessary to load a flask properly, because so many other conditions have to be considered besides the simple laws of hydro- statics. There is a good deal of pressure due to momen- tum to be taken into account. ]\[etal poured directly into the mould will exercise more straining action than that led in at the side. Eapid pouring again will cause move momentum than slow pouring. Hot metal will in- duce more strain than dead metal. Risers relieve strain. The moulder, therefore, loads according to the best of his experience and judgment, and not by calculation merely, which alone would often lead him astray. There are numerous minor attachments to flasks, used both for general and for special purposes. All flasks re- quire to be turned over, either for ramming, or for clean- ing up of the mould. For this purpose handles are provideil in the small tlasks, and middles. Fig. 31, F, and MOULDING BOXES AND TOOLS 101 swivels in larger ones, Fig. 30, H, and Figs. 32 and 33. The swivels rest in slings depending from a cross beam, the beam being suspended from the crane the while. Since handles and swivels require to be very firmly secured in place, they are not only made of wrought iron and cast in position, but the metal is increased around that portion which is cast in, as shown in Figs. 29, 30, 31, 32, and 33. There are other attachments, as handles, Fig. 33, B, B, for turning over flasks which are too long to be slung in the crane in the manner just noted, and for lowering them into the foundry pit for vertical casts. There are also flanges, C, C, in the same figure, for the attachment of back plates, that is, plates of cast iron bolted to the backs of deep flasks which have to be poured vertically, and which are subject, as all deep moulds are, to enorm- ous liquid pressure. The back plates prevent all risk of the pressure forcing out the molten metal, and so pro- ducing a waster casting. The forms of flasks vary widely, being rectangular, both square and oblong, and having ordinary, or special bars. Or, cope and drag may be precisely alike, and bars be alike in each, as in Figs. 32 and 33, which repre- sent pipe and column boxes. Fig. 32 being for pipes, and Fig. 33 for columns. The sides are bevelled in Fig. 32, to economize the sand, and time spent in ramming, a con- sideration when large numbers of casts are required. In Fig. 32, and Figs. 33 and 34 the holes D in the ends are for the purpose of allowing the ends of the core bars to project through. Flasks are also circular for cir- cular work, or of irregular and unsymmetrical outlines to suit work of special character. In jobbing shops, flasks will be sometimes fitted with interchangeable bars bolted 102 PRACTICAL IRON FOUNDING in place. Pockets also are often fitted at the ends, which are then bolted on, to be removable, the object being to increase the length of the flask. Sometimes pockets are bolted on the sides to take branches, and holes are cut Fia. 36. — Wooden Snap Flask. through the flask sides next the pockets. In all these cases the question to be decided is one of relative cost, as between the expense of the alterations, and that of a new flask. Flasks cost little for making, and the metal is always worth nearly its first value for re-melting. The MOULDING BOXES AND TOOLS 103 dimensions of flasks will range from 6 in. to 12' 0" square, or from 1' Q" to 20' 0" long, if of oblong form. Sncq) flasks. — Figs. 86 and 37 show a wooden snap flask, made up^to about 14 in. square, with pins of tri- angular section, having provision for taking-up wear. Fig. 37. — Wooden Snap Flask. These are made of birch or other suitable hard wood, 1 in. to 1^ in. thick, by 3 in. deep, in standard sizes. As no bars or stays can be used, each side has two concave recesses cut longitudinally, so that the boxes can be lifted without risk of the sand falling out. The fast corners are bonded with ^ in. sheet iron running the whole depth. The hinge is made with ^ in. straps. The 104 PRACTICAL IRON FOUNDING snap at the opposite corner is of the latch type (compare with Fig. 38), and the latch cannot be locked in place unless the corners are in absolutely close contact. This fitting is of brass, to avoid rusting up. The pins, which are also of brass for the same reason, are seen in Figs. 36 and 38. The pin is cast on an angle bracket that is screwed to the side of the top box, and fits through a a hole in another angle bracket on the bottom box. This bracket is made in two pieces, one of which is screwed to the box side, and the other attached to the horizontal ■^v # V r@ CP^ W Fig. 38. — Details of Snap Flask. portion with two set bolts, over which slot holes in the adjustable piece slide^ permitting the taking np of wear. The pattern plate. Figs. 39 and 40, has triangular holes to receive the pins, and lugs on oj^posite corners for the purpose of rapping and lifting it by. The plate is of cast iron, 4- inch thick, planed on both sides. That shown in the figure has pattern parts on both sides, and ingates and runners on the top, Fig. 40. Presser boards for top and bottom, Fig. 41, stiflened with battens, fit freely inside the flask parts. A man and a boy operate a machine and set of moulds MOULDING BOXES AND TOOLS 105 thus : The sand bemg mixed and damped and thrown in a heap at the side of the machine, the man commences work by placing the complete flask on the machine upside down — that is, with the pins pointing downwards — and lifts off the upper part, Fig. 36 (the bottom part in the com- pletelj^-rammed mould). The pattern plate is next laid on the joint face of the box part — with the deepest por- tion of the patterns facing upwards — and the upper part is replaced over the plate, the pins passing therefore through the plate and the lower one. The lad now throws sand into the box from the heap, while the man tucks the sand round the patterns with his hands. When the box part is filled, the sand is strickled off level, and the bottom board, or carrying-down board, Fig, 41, is laid upon the strickled surface. During this time the table or platen has been standing out clear of the presser head, but now a catch on the right-hand side of the machine, which has hitherto re- tained the table in place, is released, and the table is moved to bring the mould under the presser head. The lever is pulled sharply once or twice, raising the table and bringing the press board in contact with the head, compressing the sand, and sending the presser board between the box sides to a depth of from f in. to 1 in. Keleasing now the lever and the catch, the table moves forward and remains locked in a slot, bringing the box clear of the head. The man now turns it over, and the same operation of shovelling in, tucking, and strickling off the sand is gone through. The second presser board, now put on, carries the pattern cup for the ingate, which comes plumb over the ingate boss on the pattern plate. The same operation of running the table back and press- ing is repeated. 106 PRACTICAL IRON FOUNDING The table is next drawn out, the pressing board lifted off, leaving the impression of the pouring cup, which is now connected to the boss beneath by removing the sand with a tubular cutter. The lad next raps the projecting lugs at the corners of the pattern plate, and the man lifts the top part of the flask and places it on edge on a stand at the left-hand side of the machine. The lad raps the plate on the top face, and the man draws it, together A L V Fig. 89. — Pattern Plate for Snap Flask. with the lower sections of the patterns, from the bottom part. The lugs, with their well-fitting pins, enable the man to give a steady perpendicular lift until the patterns are quite clear of the mould. At the next stage the halves of the moulds are closed, standing on the bottom press board. The catches or snaps at the corners are released, and the flasks are opened on their hinges away from the mould, which is left standing on the board. This is then carried away MOULDING BOXES AND TOOLS 107 bodily and laid on the floor, and other similar moulds made, so that instead of a separate flask for each mould, one flask suffices, and as many bottom boards as there are moulds in a day's work. As there is no cottar ing of pins done, the moulds are kept closed by flat weights — one to each mould. Each covers the area of the mould and has a centre hole through which pouring is done. They are lifted by ^ 'ZJ Fig. 40. — Pattern Plate for Snap Flask. wrought-iron eyes cast in at opposite ends. About six weights suffice, because they are being moved from the first moulds poured as the pouring is being done on the fifth or sixth. The lad does this as the man pours. With regard to the effect of the pressure of metal on moulds unsupported by flasks, no difficulty occurs unless the moulds contain rather heavy castings. In cases where their weight does not exceed about 12 lb. there is no trouble. In heavier ones, up to about 28 lb. weight, the 108 PRACTICAL IRON FOUNDING moulds are enclosed with sheet-iron binders, which are slipped over the moulds. As light castings form the staple in many foundries, the saving in cost and storage room for flasks mounts up. Actually a man and a boy can put down from 150 to 200 boxes in a day, besides ?^ m Fig. 41.^ — Presses, Board, getting the sand ready, coring when required, casting, and knocking out the castings. The illustration. Fig. 42, is drawn to give the relation of the box parts to the pattern plate, shown between them, and the top and bottom presser boards. m m. Fig. 42. — Shows Relation of Box Parts to Pattern Plate and Boards. Tools. — The small tools used by moulders, and mostly provided by themselves, though not numerous, are very characteristic of the work done. Foremost among them is the rammer, varieties of which are shown in Fig. 43, A being the usual form of pegging rammer, B another form, C and D flat rammers. A and B are employed for MOVLDING BOXES AND TOOLS 109 consolidating the sand in narrow spaces, and generally for all the earlier stages of ramming, C and D being used only for final flat ramming, or finishing over of surfaces. E shows the manner in which the flat rammer is handled, a wedge at the lower end being driven home by the forcing down of the handle into the socket of the rammer head. B Fig. 43. — Rammers. Vent wires are shown at Fig. 44, B being a small pricker or piercer, as it is sometimes called, the other, A, being larger and requiring considerable force to use. The smaller wire, which may be from ^ in. to -i% in. in diameter is employed for piercing the sand in the imme- diate vicinity of the pattern with innumerable holes, all leading into larger vents, or into the gutters in the joint faces. The larger wires will range from J in. to fin. and 110 PRACTICAL IRON FOUNDING are used for ventino- down to cinder beds underneath flasks, and around the edges of deep patterns, bringing off the vents from the smaller channels. The trowels (Fig. 15) are in perpetual request for FiOr. 44. — Vent Wires. Fig. 45. — Trowels. smoothing or sleeking the surfaces of moulds, for spread- ing and smoothing the blackening, and for mending up broken sections of moulds. They are also employed for Jiint'mii joints of dry sand moulds, for marking lines on m V\r,. k). — Cleaner. sand faces, and are improvised foi* many purposes beyond those for which they are legitimately designed. ^1 is the common }i('((rt shape, 7> the ^(luare trowel, and C the combination, or Jicurf (iiid f