UNIVERSITY OF ILLINOIS LIBRARY Class Book Volume GcLl 7 Je 07-1OM Return this book on or before the Latest Date stamped below. A charge is made on all overdue books. University of Illinois Library R 20 1948 M32 J \ SHOP INSTRUCTIONS FOR THE USE OF THERMIT IN REPAIR WORK GOLDSCHMIDT THERMIT COMPANY 9 0 West Street NEW YORK 432-436 Folsom Street, San Francisco, Cal. February, 1908 Copyright 1908 GOLDSCHMIDT THERMIT COMPANY All Applications of the Thermit Process are Covered by Patents Index Additions to Thermit . 11 Appliances, Prices of.31, 32 Appliances for Welding Electric Motor Cases. 25 Appliances for Welding Locomotive Frames. 21 Automatic Crucibles . 12 Castings, Repairing Flaws in.26, 27 Collar, Shape of. 7 Connecting Rods, Welding. 20 Crucibles, Automatic . 12 Crucibles, Plugging . 12 Crucibles, Relining .• •. 29 Crucibles, Special . 27 Crucibles, Prices of.31, 32 Electric Motor Cases, Welding. 22 Fire Brick Molds. 13 Flaws in Castings, Repairing.26, 27 Forgings, Repairing Flaws in.26, 27 General Description of Process. 4 Igniting Thermit . 9 Large Steel Sections, Repairing. 28 Lining Crucibles . 29 Locomotive Frame Welding...... 5 Materials for Welding Electric Motor Cases. 25 Materials for Welding Locomotive Frames. 21 Materials, Prices of.31, 32 Mold, Wax Pattern. 6 Mold, Fire Brick . 13 Motor Cases, Electric, Welding.i. 22 Plugging Crucibles . 12 Preheating . 9 Prices, Thermit and Appliances.31, 32 Quantity of Thermit Required. 10 Relining Crucibles . 29 Shrinkage Holes in Castings, Repairing.26, 27 Surface Flaws in Castings, Repairing. 27 Thermit Additions . 11 Thermit, Composition . 3 Thermit, Price of . 31 Thermit Steel, Analysis of . 3 Tripods, Prices of. 32 Wax Pattern Mold, How to Prepare. 6 THERMIT Composition 00 Thermit is a mixture of finely divided aluminum and a- iron oxide. When ignited in one spot, the combustion so n started continues throughout the entire mass without supply of heat or power from outside and produces super¬ heated liquid steel and superheated liquid slag (aluminum oxide). Temperature Produced by Reaction The Thermit reaction produces an exceedingly high temperature, the liquid mass attaining 5400 ° Fahrenheit in less than 30 seconds. Quantity Required to Produce Liquid Steel The liquid steel produced by the Thermit reaction repre¬ sents one-half of the original Thermit by weight and one- fourth by volume. Average Analysis of Thermit Steel Carbon.. . 0.05 to 0.10 Manganese . . 0.08 t( 0.10 Silicon . . 0.09 a 0.20 Sulphur . . 0.03 u 0.04 Phosphorus . . 0.04 “ 0.05 Aluminum . . 0.07 (t 0.18 3 105001 General Description W ELDING by the Thermit Process is accomplished by pouring superheated Thermit Steel around the parts to be united. Thermit Steel, being approxi¬ mately twice as hot as ordinary molten steel, dissolves the metal with which it comes in contact and amalgamates with it to form a single homogeneous mass when cooled. It is necessary, however, in all cases, to preheat the sections before pouring Thermit Steel as, otherwise, they would exert a chilling effect on the incoming metal and prevent successful fusion. The essential steps of the operation, therefore, are to clean the sections and remove enough metal to allow for a free flow of Thermit Steel, surround them with a mold, preheat by means of a gas¬ olene torch and then pour the Thermit Steel. 4 Welding Locomotive Frames The work can be done in the Division Shops and Round Houses, as all tools are part of the equipment of such shops. List of Tools Required 1 Pneumatic or Ratchet Drill. 1 Heavy Heating Torch, capable of heating metal at break to red heat with mold in place. 1 Small Screw Jack. 2 Cold Chisels. 1 Hammer. 1 Sack of Fire Sand. 1 Sack of Fire Clay. 1 Sack of Ground Fire Brick. 5 WELDING LOCOMOTIVE FRAMES Open up Fracture. Clean and Align Frame. Jack Frame Apart. Construction of Sand Mold. General Directions After having removed such parts of the engine as to make the fracture accessible and allow room for a mold box about 1 foot wide, a series of holes should be drilled along the line of the break. If the frame is a small one, ^-inch holes should be drilled; if a large one, 1-inch holes. Next clean the frame thoroughly at the fracture, as it is important that the Thermit Steel should come in contact with clean surfaces only. The frame should now be placed in perfect alignment and punch marks made on each side of the fracture within convenient reach of trammel points, yet far enough apart to be outside of the mold box so that there may be no difficulty in regaining true alignment at the end of the welding operation. Jack the frame open about T /s inch, to allow for con¬ traction when the metal cast around the frame cools. The amount of this opening, however, must often be left to the judgment of the operator, as it depends on the width of the Thermit Steel collar. Wax Pattern Mold For Vertical Members of Frames (For repairing horizontal members see page 13.) Where the fracture occurs in a vertical member, or “leg” of the frame, it is necessary to construct a sand mold of such design as to cause the Thermit Steel to run through a gate to the lowest point of the mold and rise through, and around, the parts to be welded and into a large riser. The gate should not allow the Thermit Steel to impinge directly upon the metal of the frame and the mold must allow for a band, or collar, of Thermit Steel to be cast around the defective parts or the ends of the pieces to be welded. The Thermit Steel flowing through this space in the mold will dissolve the metal with which it comes in contact and amalgamate with it, forming a reinforcement 6 WELDING LOCOMOTIVE FRAMES which adds to the strength of the original piece and must not be machined off entirely, although in case of neces¬ sity, it may be removed from one or two sides. The shape of this band, or collar, must resemble, in Shape of Re¬ cross section, approximately the segment of a circle, the inforcement. thickest part being directly over the fracture and sloping off gradually towards the edges. It should overlap the edges of the fracture at least one inch. The thicker the metal to be repaired, the thicker must be the band of Thermit Steel and the dimensions in gen¬ eral must make allowance for the nature of the repair. Fig. 1. Fracture on locomotive frame, opened up by drilling and held in place by jacks, in preparation for Thermit welding The matrix or pattern of the part to be repaired with the reinforcing band around it, is first made, and from this a mold is constructed. The best material for making molds is one part of Material for fire sand, one part good fire-clay and one part ground Mold Making, fire brick, thoroughly mixed in the dry state and moistened just enough to pack well. 7 WELDING LOCOMOTIVE FRAMES Making Wax Pattern. Patterns for Runner and Riser. As practically no two repairs are alike, the time and cost of making wooden patterns is considerable. A convenient way to make the molds for this class of work, therefore, is to use YELLOW WAX as a matrix. The parts to be welded are prepared for welding as previously described, and a wax pattern of the exact form desired in the final weld shaped about them, care being taken to fill up the opening between frame ends with wax. After this is done, molding sand is tamped around the matrix in the usual manner, except that a small hole is left at the very lowest part of the mold as shown in Figure 2. It is advisable to bend a small piece of copper tubing through the wax leading from the small hole at the bottom into the riser. This will make a passage way for the hot gases from the torch and greatly facilitate melting out the wax. Fig. 2. Sectional view of mold The patterns for runner and riser are best made of wood. Their volume should equal the volume of the reinforce¬ ment or collar which is cast around the fracture, as the first steel running out of the crucible into the mold be¬ comes chilled when coming in contact with the metal of the frame which—even when preheated—has a consider¬ ably lower temperature than the Thermit Steel. The chilling effect can only be overcome by a sufficient quan¬ tity of Thermit Steel, so that the chilled portion is driven up into the riser and is replaced in the reinforcement by metal which has practically the full temperature it re¬ ceived during the reaction. 8 WELDING LOCOMOTIVE FRAMES When the mold box is completely filled, the wooden Mold Heated runner and riser are withdrawn and the mold is then Without Re¬ ready for the preheating and drying operation, which moving from is performed without removing the mold from the frame, Frame, the wax running out during the preheating. Placing Crucible, Preheating and Pouring Place crucible in position with bottom directly over pouring gate and not more than 4 inches away. Charge crucible in accordance with directions given on page 12 but do not put in ignition powder. Now direct the flame of a powerful gasolene-compressed Heat Frame air torch into the hole at the bottom of the mold (see Red Hot. Figure 3) and continue heating until the frame is RED HOT. It is important that the frame be red hot at the moment of pouring the Thermit Steel in order that blow holes and shrinkage cavities in the weld be avoided. When it is assured, therefore, Remove that the frame is at a good red Torch and heat, quickly remove the torch Ignite and plug up the preheating hole Thermit, with a dry sand core, backing it up with a few shovelfuls of sand packed thoroughly. Place 14 teaspoonful of ignition pow¬ der on top of the Thermit in the crucible. (Thermit will not ig¬ nite from the heat of the torch and the reaction cannot be started without ignition pow¬ der.) Ignite this with a storm match, applying same immedi¬ ately after striking. When the reaction has ceased, the Ther¬ mit Steel may be tapped into the mold by giving the tapping pin a sharp knock upwards with the tapping spade. In about five minutes from time of pour, release the Counteract screw jack and allow the frame to return into its original Shrinkage alignment as shown by the punch marks. It is advisable, Strains, however, to draw up on the weld by means of clamps, Fig. 3 9 WELDING LOCOMOTIVE FRAMES Weight of Thermit per Cubic Inch to Be Filled. jacks or other means, in order to relieve this section from the strains incident to the cooling of the metal in the weld and adjacent parts of the frame. Do not disturb molds for at least two hours after pour. After removal of mold, drill through riser and knock off gate and riser. Preventing Unequal Strains It is important to remember that if the weld is to be made on one member of a double barred frame, it is nec¬ essary to heat the other member with a torch in order to get equal expansion and contraction in both members and prevent unequal strains. Fig. 4. Finished Thermit weld on locomotive frame. Reinforcing collar on each side of frame Quantity of Thermit Required One cubic inch of steel weighs 4 y 2 ounces. To pro¬ duce 4^2 ounces of liquid steel requires 9 ounces of Thermit. Therefore, to calculate the amount of Thermit to use for any repair, first find as closely as po_ssible the number of cubic inches in the reinforcement to be cast about the defective part. Double this to allow for metal in runner and riser. This number multiplied by nine gives the number of ounces of Thermit to use. 10 WELDING LOCOMOTIVE FRAMES A simple method of determining the amount of Thermit necessary, when wax is used for a pattern or matrix, is to weigh (in pounds) the quantity of wax on hand, before and after building up the matrix. The difference multi¬ plied by 32 gives the weight of Thermit required in pounds. Thermit Additions It is necessary, when more than 10 lbs. of Thermit are to be used, to mix steel punchings or particles of steel, free from grease, into the Thermit Powder. The in¬ tensity of the heat of the reaction will be moderated thereby without interfering with the efficiency of the weld. In all cases the punchings should be preheated before mixing with the Thermit. For 10 lbs. or more of Thermit, a proportion of 10 per cent, of punchings should Fig. 5. Automatic crucible be added. For quantities of over 50 lbs. of Thermit, as much as 15 per cent, of small, mild steel rivets may be mixed in. An addition of 2 per cent, of pure metallic manganese (based on weight of Thermit) should in all cases be added, as this materially increases the strength of the Thermit Steel. Where metallic manganese cannot be had, how¬ ever, ferro-manganese may be used, in which case 3 per cent, of the 20-80 alloy is recommended. The pure man¬ ganese is, nevertheless, preferred to the ferro-manganese, owing to the fact that where large quantities of Thermit are used, an addition of the latter tends to increase the violence of the chemical reaction. Weight of Thermit De¬ termined from Wax. Mild Steel Punchings Added to Thermit. Addition of Manganese Desirable. 11 WELDING LOCOMOTIVE FRAMES Construction of Crucible. Replacing Thimbles. “Plugging Material.” Care Should be Taken in Plugging Crucible. Automatic Crucibles The Thermit reaction takes place in a magnesia-lined crucible (Figure 5), which has at the bottom a hard burnt magnesia stone (“e”). This latter, again, has a tubular opening, into which a small magnesia stone or so- called “thimble” (“f”) of conical form is made to fit. This thimble provides the channel through which the liquid Thermit Steel is poured. The outlet must not be wider than y 2 inch. After a few runs have been made, the thimble should be replaced with a new one. It may be removed by carefully knocking upwards and a new thimble, folded around with a layer of uncreased paper, in¬ serted in place. The crucible is closed before charging with “plugging material” consisting of a tapping pin, asbestos washer, metal disk and refractory sand, made up in small paper packages and supplied ready for use by the Goldschmidt Thermit Company. Plugging the Crucible First the tapping pin is suspended by its scarfed end, inside the “thimble.” It must be cut down so that the end will project not more than 2 inches below the bot¬ tom of the crucible in order that it may be driven up when the crucible is to be tapped. With the pin cut to size and in place, close the top of the thimble—first with asbestos washers and then with the metal disk. Ram firmly into place with the handle of a hammer, then cover with re¬ fractory sand. This is done to prevent the Thermit Steel from running out prematurely. The crucible is tapped by knocking the tapping pin up¬ wards as previously described. Fig. 6. Sectional view of crucible with plugging material in place 12 WELDING LOCOMOTIVE FRAMES Fire Brick Molds For Horizontal Members of Frames (For repairing vertical members of frames see page 6.) Prepare frame for welding in accordance with the di- Adjusting rections given on page 6; then surround it with a fire Mold, brick mold of suitable size (determined by consulting tables given on pages 16 and 17 ), which should be adjusted in the following manner: Spread a thin layer of fire-clay on the contact surfaces of the right-hand and left-hand bricks and then bolt them together. Remove whatever clay may have squeezed into gate and riser, and place bricks in position on frame. Fig. 7. Fire brick mold for welding locomotive frames Next, coat contact surface of lower brick and press up Lute against bricks already in position. Now lute carefully Carefully, all around frame, squeezing fire-clay between mold and frame. Surround mold with a square sheet iron or wooden box Mold Dur¬ and pack the intervening space with sand, tamping thor- e y 13 WELDING LOCOMOTIVE FRAMES oughly as an additional precaution against escape of molten steel. In general, the dimensions of this box should allow for four inches of sand on all sides of frame. Mold partially assembled Now start torch in riser and proceed as directed on page 9. Weight of A series of tables will be found on pages 16 and 17 Thermit Re- showing the weight of Thermit, punchings and manganese quired. required for welds on various sized frame sections when fire brick molds are used. 14 WELDING LOCOMOTIVE FRAMES Fig. 8. Ready for pouring Crucible and sand box surrounding fire brick mold in position Fire Brick Molds Are Furnished in Four Sizes No. 3 —For frames 3 in. wide and 4 in. deep. No. 4 —For frames 4 in. wide and 6 in. deep. No. 4—For frames 4^4 in. wide and 6 in. deep. No. 5 —For frames 5 in. wide and 6 in. deep. Size number of mold indicates width of frame in inches. For intermediate widths use next smaller number of mold and cut to fit, taking care to maintain original collar dimensions in all three bricks. For intermediate depths cut off at bottom of right and left-hand bricks to fit. Tables of Dimensions and Quantities of Thermit. The following tables give the sizes of fire brick molds to be used for various sized frames, also the amount of Thermit and boiler punchings (or rivets) required for the weld. These quantities, however, are calculated solely for our fire brick molds and do not apply to molds of other di- Changing Mold to Fit Frames. Quantities do not apply to other Molds. 15 WELDING LOCOMOTIVE FRAMES mensions. When sand molds are used, the quantity of Thermit should be calculated in accordance with direc¬ tions given on page 10. No. 3 Fire Brick Molds Size of frame designed for = 3 inches wide and 4 inches deep. Welding portion = 50 lbs. Thermit and 7 lbs. rivets or boiler punchings. By cutting down they will fit the following frames: Width of Frame. Depth of Frame. Weight of Thermit required for Weld. Weight of Rivets (or Boiler Punchings)to be mixed with Thermit. Metallic Manganese. Inches. Inches. Pounds. Pounds. Pounds. 3 2 40 7 0.8 3 2'A 45 7 0.9 3 3 50 7 1.0 3 3 % 50 7 1.0 No. 4 Fire Brick Molds Size of frame designed for = 4 inches wide and 6 inches deep. Welding portion = 70 lbs. Thermit and 10 lbs. rivets or boiler punchings. By cutting down they will fit the following frames: Width of Frame. Depth of Frame. Weight of Thermit required for Weld. Weight of Rivets (or Boiler Punchings) to be mixed with Thermit. Metallic Manganese. Inches. Inches. Pounds. Pounds. Pounds. 4 4 65 9 1.3 4 4 ^ 65 9 1.3 4 5 65 9 1.3 4 5 ^ 70 10 1.4 16 WELDING LOCOMOTIVE FRAMES No. Fire Brick Molds Size of frame designed for = 4 Yz inches wide and 6 inches deep. Welding portion = 75 lbs. Thermit and 11 lbs. rivets or boiler punchings. By cutting down they will fit the following frames: Width of Frame. Depth of Frame. Weight of Thermit required for Weld. Weight of Rivets (or Boiler Punchings) to be mixed with Thermit. Metallic Manganese. Inches. Inches. Pounds. Pounds. Pounds. 4 ^ 4J4 65 9 1.3 4^ 5 70 10 1.4 4^ 5^ 70 10 1.4 No. 5 Fire Brick Molds Size of frame designed for = 5 inches wide and 6 inches deep. Welding portion = 80 lbs. Thermit and 12 lbs. rivets or boiler punchings. By cutting down they will fit the following frames: Width of Frame. Depth of Frame. Weight of Thermit required for Weld. Weight of Rivets (or Boiler Punchings)to be mixed with Thermit. Metallic Manganese. Inches. Inches. Pounds. Pounds. Pounds. 5 5 75 11 1.5 5 5 l A 80 12 1.6 17 WELDING LOCOMOTIVE DRIVERS Preparing for Weld. Heating Ad¬ jacent Spokes, Repairing Locomotive Drivers In making repairs on spokes of locomotive drivers, es¬ sentially the same method of procedure should be fol¬ lowed as given for repairing locomotive frames by the wax pattern method. It is first necessary, of course, to remove the tire, after which the fracture is cleaned and metal cut away in ac¬ cordance with previous directions. A pattern of yellow wax is then constructed as described on page 6. This pattern may usually be made about 4 inches long and % inch thick at the middle ordinate, the cross section showing, approximately, the segment of a circle. The method of heating and pouring would be the same Fig. 9. Broken spoke in locomotive wheel, welded by Thermit process. Section of broken spoke was removed before weld was made as given for locomotive frame welds, with the exception that in this case it is necessary to heat adjacent spokes in order to eliminate unequal strains due to expansion and contraction. 18 WELDING LOCOMOTIVE DRIVERS After pouring it is advisable to keep the mold on for Anneal several hours in order that the weld may cool slowly Thoroughly, and become thoroughly annealed. It is sometimes possible, where a section of spoke is procedure if broken out completely, to cast in a piece of Thermit steel piece Is En- to replace that broken out. This should not be done, tirely Broken however, where the section is over 6 inches in length, Out. owing to the increased strains which would be caused by the contraction of a piece of metal of that length. It would be better in such a case to insert a section of steel of the proper length and weld it at each end to the parts remaining of the original spoke, allowing one weld to cool before making the other one. 19 WELDING CONNECTING RODS Reheat Rod after Welding. Importance Preheating. Repairing Connecting Rods In repairing broken connecting rods the method of pro¬ cedure would be the same as given for repairing loco¬ motive frames by the wax pattern method. Owing to the fact, however, that it is usually necessary to machine off the Thermit Steel Collar, it is advisable, as soon as the Thermit Steel has set, to reheat the rod to a dull red and allow it to cool slowly in order to eliminate any shrinkage strains that may have been set up. This heat Fig. 10. Welded connecting rod treatment should be extended to a distance of at least two feet on either side of the weld and to the entire rod if possible. In making repairs of this nature it should be borne in mind that efficient preheating is one of the most essential points and that the parts to be welded should be at a bright red heat when the Thermit Steel is poured. 20 THERMIT AND APPLIANCES Prices of Appliances Complete Appliances for Making Locomotive Repairs (All prices net F. O. B. New York or Jersey City) Fire Brick Molds are furnished at the uniform price of $5.00 per set of three pieces. 1 Automatic Crucible, size 6 (capacity 75 lbs.)... .$16.50 (With careful handling will stand 25 reactions.) 1 Tripod (optional) . 5.50 Thermit (50 or 100 lbs. drums), per lb.25 Ignition Powder, per lb. .90 (1 lb. Powder to 100 lbs. Thermit.) Metallic Manganese, per lb.75 Ferro-Manganese, per lb.10 Tapping Spade .50 Plugging Material, package.10 Thimbles, each .10 Magnesia Tar for Relining Crucible (135 lbs.), per lb. .03 Magnesia Stones .15 Yellow Wax, per lb. 35 For a successful application of the Thermit Process it is necessary to use crucibles lined with magnesia tar which this company supplies at cost price. Instructions for relining will be found on page 29. Each crucible requires 135 lbs. of magnesia tar and one magnesia stone. For shipping weights see pages 31 and 32. 21 WELDING ELECTRIC MOTOR CASES Clamp Broken Part in Position. Repairing Electric Motor Cases Fig. 11 The first step in the operation is to clamp the parts to be welded in position. (If the metal is very thick at the fracture, a space of from *4 to 24 inch should be cut out before clamping.) In case the part to be welded is a lug, it is a very simple matter to clamp this in position, by simply bolting it to an angle bar which has previously been bent to the proper size, as shown in Figure 11. A collar of yellow wax is then formed about the fracture. This should be about 2 to 3 inches wide and about 24 inch thick directly over the break. A sheet iron mold box is next placed in position, allowing for a clearance of about 3 inches on either side of the collar. Wooden patterns 22 WELDING ELECTRIC MOTOR CASES are constructed to allow for a narrow gate and large riser, Make Wax as shown in Figure 13 and provision should be made for Pattern and leaving a small hole at the bottom of the mold, so that Pack with when the wax is heated it can run out. Molding sand Sand, should then be packed around the pattern and a good mixture for this has been found to be 40 per cent, of fire¬ clay and 60 per cent, of clean, sharp sand, which should be mixed dry and moistened just enough to tamp well. The mold should then be thoroughly vented and the pat¬ terns for gate and riser withdrawn. Fig. 12 The flame of a strong blow torch is next directed into Heat Section the hole at the bottom and the heating continued until all to Red Heat, the wax has run out and the parts to be welded have been brought to a bright red heat. The torch should then be withdrawn and the hole plugged up with a dry sand core and backed with several shovelfuls of sand to prevent leakage. While the heating is in progress, the crucible contain- Plug ing the necessary quantity of Thermit (calculated by Crucible, multiplying the number of pounds of wax used in build¬ ing up the collar by 32) placed in position over the pour¬ ing gate, so that the interval between withdrawing the torch and pouring the Thermit Steel may be as short as possible. It will be seen that when the wax is melted out, 23 WELDING ELECTRIC MOTOR CASES Weld Stronger Original Section. Fig. 13 Fig. 14 the space thus vacated will be filled with Thermit Steel than from the crucible, which, being superheated, is sufficient to thoroughly fuse with the parts to be welded and pro¬ duce a weld which can easily be made stronger than the 24 WELDING ELECTRIC MOTOR CASES original section, owing to the thickness of the collar or reinforcement which is left after the operation. Figure 12 shows the mold box, torch and crucible in position, preliminary to pouring the Thermit Steel; Figure 13 shows the metal left in mold, gate and riser after removing mold box, while Figure 14 shows the finished weld. Complete Appliances for Repairing Motor Cases (All prices are net F. O. B. New York or Jersey City.) 1 Automatic Crucible, size 5 (capacity 45 lbs.).... $11.00 (With careful handling will stand 25 reactions.) 1 Tripod (optional) . 5.50 Thermit (50 or 100 lbs. drums), per lb.25 Metallic Manganese, per lb. .75 Ferro-Manganese, per lb.10 Yellow Wax, per lb.35 Ignition Powder, per lb.90 (1 lb. Powder to 100 lbs. Thermit.) Tapping Spade .50 Plugging Material, each.10 Thimbles, each . 10 Magnesia Tar for Relining Crucible (85 lbs.), per lb. .03 Magnesia Stones .15 For shipping weights see pages 31 and 32. For a successful application of the Thermit Process it is necessary to use crucibles lined with magnesia tar, which this company supplies at cost price. Instructions for relining will be found on page 29. Each crucible requires 85 lbs. of magnesia tar and one magnesia stone. 25 WELDING STEEL CASTINGS Chip out Flaw and Preheat. Weight of Thermit Required. Method Used Only when Flaw Does Not Affect Strength of Casting. Repairing Flaws in Castings Pouring Cup Method (To be employed when flaw is small, and does not affect the strength of the piece.) In cases where the flaw is fairly circular in shape, does not exceed some 3 inches in area and has no effect on the strength of the casting, the pouring cup method may be employed in making the repair by the Thermit process. In such cases the flaw should be chipped out in order to make sure of its extent. The casting should then be heated to a red heat at the defect. A “pouring cup” made of dry sand or fire brick piping is then placed over the flaw, allowing an overlap of about half an inch all around. A thin asbestos washer should next be placed over the flaw and the correct quantity of Thermit placed in the pouring cup. This quantity is determined by al¬ lowing 18 ounces to the cubic inch of space to be filled. A pinch of ignition powder is then put on top of the Thermit and ignited with a storm match or a small bundle of parlor matches. This in turn will ignite the Thermit, causing the reaction to take place on top of the casting and obviating the need of crucibles or ladles. A certain amount of judg¬ ment should be used, how¬ ever, in calculating the quan¬ tity of Thermit, as the casting acts as a chill to the Thermit Steel. As a general rule a flaw in a heavy casting re¬ quires more Thermit than one in a light casting. The Pouring Cup Method is the only case where Ther¬ mit may be ignited while in direct contact with the metal and should never be employed when the flaw might have an effect on the strength of the piece, as there is a possibility of minute particles of slag being deposited be¬ tween the Thermit Steel and the surface of the metal, thus preventing a perfect union of the two. The process is very convenient for repairing small surface flaws, but care should be taken to use enough Thermit to leave a 26 WELDING STEEL CASTINGS button of Thermit Steel at least Yi inch thick over the Button surface of the casting. This may afterwards be ground Ground down with an emery wheel, but should not be chipped Down, off with a chipping hammer. Shrinkage Holes and Surface Flaws in Castings and Forgings (Cases where the flaw might affect the strength of the piece.) These repairs usually require from 2 to 10 pounds of Thermit and should be made in the following manner: Place an open mold around the part to be filled, allow- open Mold ing an overlap of *4 inch all around the defect. Clean Constructed the flaw thoroughly by means of a compressed air blast, an( j Flaw steam jet, or other means, and heat to a red heat by Preheated, means of a strong blow torch. Weigh out Thermit at the rate of 18 ounces to the cubic inch of space to be filled, but under no circumstances use less than two pounds for the operation. Fig. 15. Flat bottomed crucible (so-called “special crucible”) Place a small amount of Thermit in a special crucible (for price list and sizes of special crucibles see page 32), which should be in readiness with tongs already adjusted. Ignite with a pinch of ignition powder, which may be lighted in turn by applying a storm match, as previously Ignite Thermit in Special Crucible. 27 Pour Off Slag, Then Direct Steel Into Mold. Keep Combustion Going After Pour. This Work Will Be Done by Contract if Desired. WELDING STEEL CASTINGS described. As soon as the Thermit begins to burn, add remainder of Thermit from scoops, feeding it fast enough to keep combustion going. When reaction is com¬ pleted, quickly pick up the crucible, pour slag (which represents three- quarters of the total liquid) into dry sand. The steel should then be poured into the open mold. Sprinkle loose Thermit on top of steel to feed it, as every casting, even when preheated, acts as a chill on the Thermit Steel and it is therefore necessary to prolong the Thermit reaction in order to obtain good results. Repairs on Larger Sections The Thermit Process is extensively used in making re¬ pairs on large steel sections, such as stern posts and rud¬ der stocks of steamships, gear wheels and other large machinery castings. In general, the method of making these repairs is essentially the same as that given for re¬ pairing locomotive frames by the wax pattern method. It is usually advisable, however, to make such repairs under the supervision of an experienced .engineer and the Goldschmidt Thermit Company is in a position to either do the work by contract or furnish expert super¬ vision until such time as the customer may be able to carry on the work without assistance. Careful attention will be paid to all requests for in¬ formation and directions. Correspondence with firms having work of the above nature is solicited. 28 R E L I N I N G CRUCIBLES Crucible Lining The crucible and the thimble through which the metal runs after the reaction are two of the most important factors in the whole process. The high temperature, to¬ gether with the violent ebullition of the molten metal during the reaction, necessitates a lining that is not only mechanically strong, but of a very high refractory sub¬ stance. It has been found that magnesia lined crucibles are the only ones which satisfy these conditions. Preparation of Material for, and Lining of, Crucibles In order to protect and hold the mass together, a sheet- iron shell, conical in shape, is provided, having at its bot¬ tom an iron plate with a hole in it through which the liquid Thermit Steel will pass. A magnesia stone, described on page 12, is placed in the bottom of shell and centered over the hole. Over this is placed a cast iron matrix of the same taper as the shell, but smaller, so as to allow for an intervening space, into which the lining material is tamped. In order to maintain the proper space between the shell and the matrix during the process of tamping, several wooden wedges should be inserted at the top, at equal distances along the circumference. The lining material should then be heated until it is plastic and pushed into place slowly, taking time to tamp well, for upon the density or hardness of the lining de¬ pends the life of the crucible. The special iron tool for tamping should have a flat end, and good hard blows should be used. Do not put in the material too rapidly, and let it be re¬ membered that the better and more uniform the tamping, the longer the crucible will last. As the mass nears the top, the wooden wedges may be removed, for the lining already in place will hold the matrix in position. When completely filled and tamped, the matrix should be removed, which should be done with great care. Then wind a thick sheet of wrapping paper, or several thick- Special Lining Necessary. Crucible Shell. Preparing Shell for Lining. Packing Lining Material. Important to Pack Hard. Wrap Paper Around Matrix. 29 Bake in Oven. Shell May Be Used Over and Over Again. Special Thimble Necessary. Fit Into Magnesia Stones. Thimble Not Allowed to Fuse to Stone. RE LINING CRUCIBLES nesses of newspaper, around the matrix, and put it back into place, carefully luting up the top and bottom with wet clay where the lining may be exposed to the air. The crucible is now ready to bake, and it should be gradually raised to a dull red heat, and retained so for six hours, after which it may be allowed to cool gradu¬ ally before removing from the oven, when the clay luting may be removed, the matrix taken out and the crucible is ready for use. If properly made the crucible should withstand 20 to 25 reactions before giving out, and then the shell may be used for other linings. Thimbles The portion that has to withstand the most severe strain of all is the part at the bottom of the crucible, or walls of the hole through which the metal is tapped. It has to stand the strain and pressure of the weight of the moving liquid metal and slag under great heat. The magnesia stone which is centered in the bottom of the crucible and around which the material for lining is packed, has a tapering hole in the center. The thimbles are of the same taper as the hole in the magnesia stone and are set into the latter. When the thimble is spent (either through enlargement of hole or by splitting) it can be knocked out and a new one placed, so that the full life of the crucible may be utilized. Insertion of Thimble in Crucible The thimble should be inserted into the magnesia stone after wrapping one thickness of newspaper around it. This is done so that after the paper has carbonized, there is but little chance of the thimble fusing with the magnesia stone during the discharge, and this makes it easy to remove it when it becomes necessary to make renewal. 30 PRICES OF APPLIANCES Prices (All prices net, F. O. B. New York or Jersey City.) Shipping Weight Price Pounds Thermit (sold only in 50 and 100-lb. drums) — 50-lb. drums .$12.50 55^2 100-lb. drums . 25.00 109 Ignition Powder— 14-lb. cans .45 1-lb. cans .90 Metallic Manganese, per pound.75 Ferro-Manganese, per pound.10 Yellow Wax, per pound.35 Fire Brick Molds, per set. 5.00 150 Automatic Crucibles No. 1, for 4 lbs. Thermit, with cap and ring. .$3.50 40 “ 2, “ 7 “ “ “ “ .. 5.50 60 “ 3, “ 16 “ “ “ “ .. 6.50 110 “ 4, “ 24 “ “ “ “ .. 8.00 125 “ 5, “ 45 “ “ “ “ ..11.00 150 “ 6, “ 75 “ “ “ “ ..16.50 225 “ 7, “ 135 “ “ “ “ ..30.00 385 “ 8, “ 200 “ “ u “ ..35.00 480 “ 9, 260 “ “ “ " ..43.50 580 u 10, 400 “ u u ..55.00 720 Tapping Spade .50 Plugging Material, each. 10 Extra “Thimbles” “f,” each.10 (Tapping Pin, Asbestos and Metal Washers, Refractory Sand.) Note.—For a successful application of the Thermit Process it is necessary to use crucibles lined with magnesia tar, which this company supplies at cost price. Instructions for relining will be found on page 29. 31 PRICES OF APPLIANCES Tripods for Automatic Crucibles No. 1 2-3 4-5 6-7 Price $2.10 $2.50 $3.00 $5.50 Shipping Weight Pounds 11 19 24 65 Flat Bottom Crucibles (So-called “Special Crucibles”) Price Shipping Weight Pounds No. 2, capacity 4 lbs. Thermit_ .$1.75 35 “ 3, “ 8 “ “ . 3.00 45 “ 4, “ 16 “ (i . 4.75 65 “ 5, “ 40 “ “ . 7.00 85 Cost of Relining Crucible Shells No. 2 3 4 5 Price $0.75 $1.25 $2.50 $4.00 Tongs (For Flat Bottom Crucibles) No. 2 3 4 5 Price $2.00 $2.50 $3.25 $4.50 Shipping Weight 6'/ 2 17'/ 2 25 30 % Pounds Thermit Powder must be well mixed before using and must be kept dry. Crucibles must be kept in a dry place. 32 I