The Iron Age 1940-02-08: Vol 45 Iss 6

Vanagino Editor Vews J. H. VAN DEVENTER President and Editor c. S. BAUR Vice-President and General Manager WRIGHT J. A. ROWAN A. I. FINDLEY Editor Editor Emeritus R. E. Mitver F.J. WINTERS T. W. LIPPERT Machinery Editor F. J. OLIVER L, Art Editor Vetallurgical Bditor Associate Editors W. A. PHAIR G. RICCIARD Washington Fditors W. MOFFETT JAMES G. ELLIS Resident District Editors (, CAMPBELI Pittsburgh KR Cleveland AMES {OBERT G. BINGHAM Chicago W. F. SHERMAN Detroit Editorial Correspondent- 3. RICE-OXLEY London, England G. FRAZAR Bos ton I’. MEYER Milwaukee SANDERSON Toronto, Ontarit LEROY W. ALLISON \ Newark, Emerson Findley / Robert F. Blair W. J. Fitzgerald Warren, B. L H. K H. E Peirce Ww. B. b. Cc Don F. H ROBERT G. MCINTOSH Cincinnati P. FIDRMUC Hamburg, Germany CHARLES Post San Francisce CLYDE W. ENNIS Birmingham Roy M. EDMONDS N.¢ St. Louis F. T. TURNER, J! Buffal DIN, Manager Reade Service 1DVERTISING STAFF , 621 Union Bldg., Cleveland Herman, Chilton Bldg., Phila. Hottenstein. 1012 Otis Bldg Chicago Leonard, 239 W Lewis, 7310 Woodward Ave Detroit C. H. Ober, 239 W. 39th St., New York Robinson Harner, 1595 Beach, Cal Member Member, Indexed in the tion sessions, Mexico, ada, Single copy, her $1.00 Price: United 39th St New York } 428 Park Bidg., Pitts P. O. Box 81, Hartford, Conn Pacific Avenue, Long Audit Bureau of Circulations Associated Industrial Arts Index. Published every Thursday Subscrip- Business Papers States and Pos- Cuba, $6.00; Can- $8.50; Foreign, $12.00 a year. * 25 cents. Annual Num- Cable Address, ‘‘Tronage, mM aa Owned and Published by CHILTON COMPANY (Incorporated) ® Publications Office Chestnut and 56th Sts., Philadelphia, Pa., U.S.A. Editorial and Executive Offices 239 West 39th St., New York, N. Y., U.S.A OFFICERS AND DIRECTORS C. A. MUSSELMAN, President JOS. 8. HILDRETH, Vice-President GEORGE H. GRIFFITHS, Vice-President EVERIT B. TERHUNE, Vice-President J. H. VAN DEVENTER, Vice-President Cc. S. BAUR, Vice-President WILLIAM A. BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JULIAN CHASE RUZBY, P HARRY THOMAS L. KANI \ M. FAHRENDORF DUFFY THE IRON AGE Contents February 8 1940 Surrender? We've Just Begun to Fight! Zine Alloy Dies for Drop Hammer Work Pointers on Gear Cutting Flow of Metals Electroplating on Aluminum Inland Rebuilds First Stack Heat Treating Speed Nuts What's New in Materials Handling On the Assembly Line Washington News THE NEWS IN BRIEF Weekly Ingot Operating Rates Statistics on Metal Working Activity Plant Expansion and Equipment Buying New Industrial Literature Just Between Us Two Products Advertised Index to Advertisers Copyright, 1940, by Chilton Company (Ine.) 27 29 33 36 43 48 52 56 74 8! 8 101 120 126 129 158 wt, —_ A\ WwW Wy UY \ Si Wy The words 26—THE IRON AGE, February 8, 1940 As one Linde Customer said . ‘We can depend on LINDE for just what we need for any Oxy-Acetylene Application.’ You, too, can profit by this dependability of Linde products and service for welding, cutting, flame-hardening, flame-clean- ing, descaling, gouging, or any other oxy-acetylene process. y Gases — Linde Oxygen is sold throughout the nation in gray- and-green cylinders. Each cyl- inder contains 110 cubic feet or 220 cubic feet of oxygen at a pressure of 2,000 pounds per square inch. All Linde Oxygen—whether for industrial or therapeutic use—is the same high and uniform quality. Prest-O-Lite Dissolved Acetylene is pro- duced from Union Carbide. For welding and cutting, it is sold in portable black steel cyl- inders having rated capacities of 100 cubic feet and 300 cubic feet of acetylene. For use with Prest-O-Lite appliances — heating torches, soldering irons and portable lights—Prest-O- Lite Dissolved Acetylene is sold in small steel tanks of 10- and 40-cubic feet capacity. Calcium Carbide— Union Carbide is packed in 100- pound lots in blue-and-gray drums. Because of its uniform quality, high gas yield, accurate sizing, and careful packing, it has been recognized as a standard of excel- Ws lence for over forty years. Union Carbide, an electric furnace product, is crushed and screened to all standard generator sizes. Carbic Processed Carbide is high-grade *“Linde,”” “* *“Prest-O-Lite,’’ ‘“Prest-O-Weld,” *‘Purox,’’ ** Union,’ The Linde Air Products Company Unit of Union Carbide and Carbon Corporation New York and Principal Cities * In Canada: Oxweld”’ and calcium carbide, specially treated and com- pressed into cakes for use in Carbic acety- lene generators and Carbic acetylene flood lights. The most frequently used size of Carbic cakes is No. 20. The orange drum contains 40 cakes weighing 100 pounds. Carbide and Carbic Processed Carbide are readily available from ware- Union houses, jobbers, and distributors throughout the country, located for quick delivery. PY Oxweld, pparatus —, ; sail P7rest-O- w Weld, and Purox lines of weld- ; ing and cutting blowpipes, reg- / ulators, manifolds, and outfits; Op, Oxweld cutting machines; Ox- a weld and Carbic acetylene generators; and the full Oxweld line of accessories, weld- ing rod, and supplies—all are sold by Linde. Service — The Linde service wv, organization brings to users of \ the oxy-acetylene process prac- : tical field experience, based on comprehensive research and de- velopment facilities. This proc- oD ess service is available from field engineers —also through technical books, booklets, magazine articles, motion pictures, and in numerous other ways. Dominion Oxygen Company, Limited, Toronto *““Carbic’’ are trade-marks of Units of Union Carbide and Carbon Corporation. ESTABLISHED 1855 ... THE IRON AGE ... FEBRUARY 8, 1940 Vol. 145, No. 6 Surrender? We've Just Begun to Fight! MERICAN business and the American System of Enterprise have received so many rights to the chin and lefts to the solar plexus during the past seven years of nudeelism' that it would not be at all strange if they felt somewhat groggy. Two telling blows, for example, were delivered to private enterprise and employment this past week. One of these was the "'majority'’ decision of the Supreme Court of the United States enabling the money hungry politicians of any city to levy taxes, at their pleasure, upon citizens in connection with interstate as well as intrastate commerce. This decision, made over the vehement protest of Charles E. Hughes and his non-packed minority associates, opens the door to the greatest pork barrel yet discovered in Amer- ica and to the ruthless rooking of millions of taxpayers. The second blow was a decision of the Appellate Division of the Supreme Court of New York State, which gave to union labor the right to strike against the introduction of improved machinery, whenever in its estimation such machinery by reason of "labor sav- ing'' qualities might reduce employment. Nothing, of course, was said about the employ- ment that such devices might create through eventual stimulation of the industry or in other circles than that of the immediate application. Offsetting these two discouraging deterrents to the sadly needed flow of private in- vestment funds was the action of the executive committee of the AFL last week. This great labor body, as part of its conclusions said: We urge that all Government actions that tend unnecessarily to discourage busi- ness expansion cease and that a positive effort be made to encourage industrial activity." After seven years of fighting for its life in a ring where no Marquess of Queensberry rules applied and where administrative and legislative blackjacks were indiscriminately used by their antagonists, American business and industry are just beginning to fight. And with skilled labor now coming to their rescue, they will fight with a new assurance of vic- tory. It is true that a small portion of industry and business has adopted the defeatest attitude as portrayed by the poet Whittier: “For of all sad words of tongue or pen, The saddest are these: ‘It might have been!” But most of us, thank God, prefer the modern version: Of all brave words of press or typewriter, The bravest are: “I’m still a fighter!” Surrender? We've just begun to fight! i) Workinc closely with each customer, Inland metallurgists thoroughly weigh all factors of use and fabrication of cold rolled sheets. Their recommendation is a “balanced” temper—one that is neither too hard nor too soft—a temper specifically selected for the job. The Inland method for producing cold rolled sheets uses the most modern types of equip- ment fitted with special devices which aid in achieving exact qualities of steel with un- varying uniformity. Working side by side with skilled heaters and rollers are specially trained technicians who follow every step of the process. They check and recheck to make certain that the metallurgists’ specifi- cations for each customer are accurately followed. Thus, “balanced” temper is defi- nitely assured in Inland’s Cold Rolled Sheets. Give Inland metallurgists the opportunity to prove how “balanced” temper can help in your production —write today! SHEETS * STRIP + TIN PLATE « BARS + PLATES « FLOOR PLATES * STRUCTURALS °* PILING + RAILS + TRACK ACCESSORIES + REINFORCING BARS De STEEL CO. 38 S. Dearborn Street, Chicago e Sales Offices: Milwaukee, Detroit, St. Paul, St. Louis, Kansas City, fete h ZINC-ALLOY DIE Pyar wen Wonk N the articles concerning the pro duction of “Job-Lot Aircraft Stampings,”’ which appeared in THe Iron AGE in the issues of Oct. 19 and 26, 1939, the statement was made that what has really made the drop hammer feasible for short run work in the aircraft industry has been the development of combination, low- cost, lead-zine dies, made from a single wood or plaster pattern. The technique of drop hammer work was then briefly described, with particular emphasis on the trend toward the use of air pow- ered drop stamps in place of the less efficient rope drop hammers still in use in many aircraft factories. Little in- formation was given as to the metal- lurgical and foundry practice aspects of the die materials, however, except to point out that the lower melting point of lead made it possible to cast the lead punch directly into the female zinc die, eliminating the need of a second mold and thereby cutting an- other cost corner. Up until a year ago, about the only material used for such drop hammer dies was either special high grade zinc (99.99 per cent pure zinc) or Prime Western zinc. The chief drawback of straight zinc is that, because of its low ultimate strength and elastic limit, it cannot withstand, without deforma- tion, the blows of a drop hammer. The By W. W. BROUGHTON Morris P. Kirk & Son, Inc., Los Angeles twentieth stamping trom a zine die ts always appreciably larger than the first. The drop hammer technique as applied to aircraft stampings was pio- neered on the West Coast, and it was only natural that the industry there should turn to its principal supplier of lead and zinc to solve this problem of short die life. The company, Morris P. Kirk & Son, Inc., Los Angeles, is also a large producer of zinc-base al- loys for die castings and hence was familiar with the tremendous improve- ment in physical properties obtainable by alloying zinc with aluminum, cop per and magnesium. The very first tests made by this firm indicated that the standard die casting alloys, although developed for an entirely different purpose, were greatly superior to straight zine for stamping dies. Many such dies were produced in the alloy known as Kirk- site 2, made under license from the New Jersey Zinc Co. and correspond- ing to its alloy, Zamak 2, covered by SAE specifications No. 921, and ASTM alloy XXI. This zine alloy contains 3.5 to 4.5 per cent aluminum, 2.5 to 3.5 per cent copper and 0.02 to 0.10 per cent magnesium. The alloying elements have the effect of refining the grain and this tendency is greatly enhanced by the chilling effect in die casting under pressure. Although the physical properties of a sand casting, such as aircraft drop hammer dies, are obviously lower than those of die castings, nevertheless they are marked- ly superior to straight zinc, as can be seen in the accompanying table. Engineers of the Kirk company were of the opinion, however, that by slight modifications in the alloy com- position, additional strength and hard- ness could be secured. Because of the basic difference between die casting and sand casting technique, these mod- ifications were possible and the de- sired physical properties achieved. Limits were established and a new alloy produced which the manufac- turer claims gives both a higher ten- sile strength and increased hardness. This alloy is said to cast equally well in sand and produces clean, bright, smooth surfaces which need no finish- ing beyond a light buffing with a port- able power driven disk. This material is known as Kirksite A, and dies made from it are now producing from 10 to 50 times as many stampings as did their predecessors made from straight zinc. When wear becomes noticeable, the Kirksite or Zamak dies can be re- claimed by welding, an operation im- possible on a straight zine die. Be- cause of the absence of any plastic range in the zinc-base alloys, however, THE IRON AGE, February 8, 1940—29 the technique of building up worn edges is somewhat difficult to one not familiar with this work. It is usually necessary to rotate the die while build- ing up the edges, so that the portion being welded is nearly horizontal. A reducing flame should be used. Any flux that is satisfactory for welding cast aluminum will give good results, but should be used sparingly. Leveling of the bottom of the dies may be done in any one of three ways. The most expensive way, and the one least used, is to plane or mill the base. Another method is to play an oxy- acetylene or oxy-hydrogen torch on the top of the casting while it is still in the sand, since the female die is always poured upside down. A large tip is used and the flame is maintained slightly reducing. By working around the edge of the casting, the shrinkage depressions are kept supplied with molten alloy and the high portions are worked down to the average level. A faster method is to wait until the cast- ing has just frozen and then pour a cap of molten alloy into the shrinkage depression. Elimination of Warpage While in general, sand castings of the zinc-base alloys are freer from warpage than those of straight zinc, the alloys are so tough and strong that 30—THE IRON AGE, February 8, 1940 once a die is warped, the heaviest blow of the hammer will not straighten it. In order to reduce warpage to mini- mum, therefore, engineers of the Kirk company recommend pouring the die in three stages, the first covering the entire surface of the mold to a depth of 1 in. The second pour, to an addi- tional depth of 1 or 2 in., is then made when all except a molten spot in the center of the heaviest part of the first pouring has solidified. When solidifi- cation of the second pour is about to be completed, the balance of the cast- ing is poured. Another method of reducing warp- age is to cover the newly poured cast- ings while still in the sand with a sheet of asbestos board, or a sheet of iron over which a layer of sand is shoveled, the purpose being to retard radiation losses and the freezing of the top of the casting until a strong crust of solid metal is formed in contact with the sand. The drier the sand used, the more need there is for a cover. Molding Practice In making sand molds, straight Al- bany sand with no more moisture than necessary has been found very satis- factory for casting zinc alloy dies. Patterns may be either plaster or wood. Plaster patterns for large dies are made hollow for lightness, and [ROCESS of leveling the bot- tom of a large size zinc-base alloy drop hammer die while it is still in the sand mold. A reduc- ing flame is used with a large size tip. lax or other fibrous material is added to increase the strength. Wood pat- terns should be well shellacked to avoid warpage due to moisture in the sand. For many stamping dies, a plaster pattern corresponding in size and shape to the completed die, is made from a wood master pattern. Consid- erable advantage can be taken of the greater strength of the alloys to re- duce the thickness of metal under the deepest portion of the die (by at least one-third that required for straight zinc) and also to reduce the corre- sponding length and breadth of the die. Where a wide bearing area is re- quired around the cavity in order to produce smooth stampings, with the high strength alloys such a surface can be obtained without excessive weight and bulk by forming a ledge around the top of the die. In molding, the cavity for this ledge is formed by loose pieces that are withdrawn hori- zontally into the main mold cavity after the pattern proper is withdrawn. Since these low cost dies are seldom given more than a polishing operation for finish, although they are readily machinable, it is necessary to exercise care in molding, particularly in seeing that the walls of the mold are not compressed or otherwise distorted when the pattern is withdrawn from the sand. As much draft as possible should be used on the pattern to facil itate its removal. Screw type lifts sus- pended from cross bars and applied at four corners of the pattern are a great help in easing it out of the mold in an absolutely vertical direction. Gating A variety of forms of gates are used, but a horn type appears best. It should be somewhat heavier than is customary with zinc. About 1% in. diameter seems the most satisfactory size. One gate is better than two, ex- cept where there are two heavy, deep sections separated by a light, shallow section, in which case a gate to each heavy section should be made. Pour- ing should be done from one ladle at a time and very slowly until the whole bottom of the mold is covered. After this, faster pouring can be done through the gate, and when the mold is fairly well filled up, the balance of the metal can be poured directly into the cavity. No risers are needed since the dies are poured with base up, open to the air. Melting Practice In melting these zinc-base alloys, two dangers must be avoided—con tamination from low melting point metals like lead, tin and cadmium, also from iron; and overheating. For die castings, SAE and ASTM specifica- tions are very rigidly drawn as to limits of impurities in order to keep to a minimum the loss of strength and changes in dimension that occur as the casting ages. Fortunately, the re quirements of an alloy for drop ham mer dies are not so severe as those for die castings, because the dies have a much shorter useful life, and aging phenomena are not so important. Dhi- mensional tolerances are larger on stampings than on die castings, and the tendency to crack in the mold is not so great in a sand mold as in a steel die. For hammer dies, the chief contam- inating metals are lead and iron. Melt- ing of the lead male dies should be done in a separate room, if possible. Care should also be taken in remelting zinc-base dies to see that none of the lead used to anchor the die on the platen of the hammer adheres to the zinc die. Limited experience indicates that more than 0.500 per cent lead cannot be tolerated in the alloy for drop hammer dies (as against 0.007 per cent max. for die castings). With 0.500 per cent lead in the alloy, the aging effect at the end of two years will reduce the tensile strength by about 40 per cent and the impact value by more than 75 per cent. It should be noted, however, that these strengths are still comparable with straight zinc. Remelting and recasting will tempo- rarily restore the original physical properties. [ron is a harmful impurity which will adversely affect the surface smoothness of the die as well as in- crease shrinkage draws at corners and cause brittleness. The presence of more than 0.25 per cent iron will manifest itself by peculiar marks on both inside and outside vertical walls of the die that resemble the delta of a river and that are known in the par- lance of West Coast aircraft factories ABOVE IE produced from the mold shown below. This zinc-base alloy die weighed over 2 tons. No finishing was required other than polishing the cavity. AT LEFT AND mold of large gasoline tank stamping die, ready for pouring. THE IRON AGE, February 8, 1940—31! pont renenennoanrny es of two diameters showing the grain structure of Prime Western zinc (left) and of Kirksite A (right). The introduction of alloying elements reduces the grain size markedly and results in greater strength and toughness. as Dural Bug marks. Keeping the temperature below 900 deg. F. is the one cure for iron contamination. Overheating increases the amount of iron pick-up from the pot, al- though much of this iron combines with the aluminum and is removed as a dross from the surface of the molten metal. Higher pouring temperatures also cause excess shrinkage in the casting. Low temperatures cause a sludge, rich in copper and low in alu- minum, to form on the bottom of the pot. The temperature range of the pot should be carefully maintained be- tween 775 and 825 deg. F. The use of a throttling type indicating or record- ing controller is a worth while invest- ment in maintaining this range. Pot Corrosion Just as the alloy picks up iron from the pot, so also the pot may be affected by the soluble action of the molten alloy. Oddly, pots made of steel plate are very satisfactory with straight zinc but are rapidly corroded by zinc aluminum alloys. Cast iron pots are Comparative Physical Values of Sand Castings much more resistant to the solvent ac- tion of Kirksite A or Zamak 2. An iron of the following approximate composition has proved quite satisfac- tory, one such pot having given more than five months of continuous ser- vice: I:lement Per Cent SN oteGaewidiew sen 3.4 ME eS iatkwic ty xnkds 1.6 BIGMOERESE ..ca oes ons 0.6 PRONE +e das 645. Ae 2.2 re is Pot castings of this analysis should be normalized for 10 hr. at 750 deg. F. Foundry scale should not be removed. A coating of rust, in fact, is the best preventive against attack from the molten zinc alloy. Rust can be hastened by storing the pot outdoors and spraying with water occasionally. When the pot is first put into service, a wash of fireclay and water to which a small amount of sodium silicate has been added, applied after the pot is warmed to about 200 deg. F., will ap- preciably increase its life. Kirksite A metal and the Zamak Pure Zinc-Base Property Zinc Alloys Cast Iron! Tensile strength, lb. per sq. in. .................. 5300 35,000-38,000 40,000 to 50,000 Impact strength, ft. —Ib.2 .............. Under | 24 Compressive strength, lb. per sq. in. .......... 60,000-75,000 200,0008 MD. cdi wnkescnssvdeoeen 787 717 Solidification shrinkage, in. per ff. ............ 0.125 0.140 MA TDL: c'cis chiKecksieedacnenne 0.27 0.24 to 0.25 CE ic cvccecunedaicdece niin ehawws 200-240 30-60 80-107 1 Typical auto body and fender die iron containing 1.50 to 2.00 per cent nickel and 0.50 to 0.60 per cent chromium. (Cast Metals Handbook-1940.) 2 Charpy impact strength of 4 in. square test bars with 40 mm. span. 3 Rough estimate. 32—THE IRON AGE, February 8, 1940 allovs are obviously more expensive materials than Prime Western zinc, but dies made from these higher strength alloys are approximately the same in cost if advantage is taken of the possibility of greatly reduced sec- tions as a result of higher physicals. On the basis of die cost per stamping produced, the advantage goes to the alloys, because of the much greater die life obtainable. There are other advantages also that tend to lower production costs. Zine alloy dies as they come from the sand are cleaner and smoother than straight zine dies and therefore require less finishing, The castings are sounder and never have to be repoured because of the presence of blow holes. The lower melting point of the alloy results in measurable fuel saving and lower dross loss. Both labor and drop ham- mer time is saved by reason of the longer life of the alloy dies and their freedom from breakage. Greater speed is obtainable when the operator knows that the die will stand the punishment of a full blow of the hammer. It is also possible to use harder lead punches (obtained by increasing the antimony content up to about 10 per cent), thus resulting in fewer punch recasting jobs. The net result is better uniformity in the stampings produced. Some users are making both punch and die of the alloy although a punch pattern is necessary if the die is much over a foot long. The lack of plas- ticity in the alloy makes it impossible to pound out the punch into the die to compensate for shrinkage. The use of a zine-base alloy punch and die often makes a starting die unnecessary, the finished shape being obtained gradu- ally if necessary by the use of shims of plywood, removed one or more at a time between hammer blows. While the use of dies of this type is confined almost exclusively to the air- craft industry at present, there is no apparent reason why this drop ham- mer technique cannot be applied to other stamping work in small quan- tities. As many as 2300 14-gage stain- less steel exhaust manifold stampings have been produced from a Kirksite die. As indicated in the earlier arti- cles, the savings in die costs are tre- mendous over conventional methods, and the use of the alloys mentioned above by extending the die life widens the range of application to stamping runs of a fairly substantial nature. Besides being obtainable through Mor- ris P. Kirk & Son, Inc., Los Angeles, Kirksite A is also available through the various branch plants of the National Lead Co., New York, the parent com- pany. The Zamak alloys are sold through the New Jersey Zine Sales Co., Inec., New York. a th b — POINTERS ON GEAR NEW gear cutting § machine A should be thoroughly oiled and run for at least half a day to be sure that the oil is circulating through the bearings. ‘The machines should be lubricated every morning and the main drive parts at noon also. This takes only a few minutes and will increase the life of the machine considerably. Care should be exercised to keep the oil clean and the oil holes free from chips and dirt; this applies also where a central lubricating system is used. The ways of the machine should not be used as an anvil or a convenient shelf for wrenches as this tends to bruise the finished surface. Also, any- thing left on the ways sometimes will become jammed between the moving part and the rest of the machine, with disastrous results. When an order has been received and preparations are being made to cut the gears, it must be remembered that the accuracy of the gear cannot be any better than that of the blank. This is a problem when only the teeth are be ing cut. Sometimes it is necessary to true the sides of the blank or turn the blank if it is a worm or a solid pinion, as the blank must be held true and rigid to get a good gear. The author believes it is economical to spend a little more time in turning the blanks to insure that the hole, outside diameter, and sides run true with each other. This extra time, if any, is usually more than saved when setting the blank in the gear cutter. This has been proved in many instances, In one case where large quantities of small gears were being cut, the cus tomer was shown that the time being taken to set the blanks running true in the gear cutter was longer than the turning time. In this shop the lathe department was working on piece-work andthe straight gear-cutter operators on time. This point of good blanks can hardly be overemphasized. \ little education and care in the turn CUT TING By U. SETH EBERHARDT Vice-President, Newark Gear Cutting Machine Co., Newark, N. J. ing department will save considerable time in setting up the blank in the gear cutter. The gear cutting machine should be on a good solid floor or foundation. It is not necessary to bolt the machine down, but it should bear on as much of the floor as possible. Either thin REPARATION of machine | and cutters, economy of | accurately turned blanks, number of cuts, and proce- dure in cutting large, hard cast iron gears are covered in this article. The article is trom a paper on "Experiences in the Gear Industry", pre- sented at the 22nd semi-an- nual meeting of the American Gear Manufacturers Associa- tion, of which Mr. Eberhardt is vice-president. wooden wedges or shims can be in stalled around the base, or the machine can be grouted in with sulphur, lead or cement after it is leveled. less of the stiffness of the machine base, it should be leveled and then well supported. . The author’s company usually checks the level of the base at Regard each end to be sure there is no twist in the bed, then lengthwise in three places to be sure it has no high or low spot in the middle. adjusted with the minimum of backlash, but not Change gears should be tight, it being better to have a few thousandths play. The blank to be cut should be set true with the surface by which the gear will subsequently be held when installed in its final position. That is, on a gear which will be held on a shaft the hole should run true. [his may be checked by revolving the gear on the work arbor and testing the O.D. with an indicator. The high spots are marked in thousandths, the amount the O.D. runs out. Then, when the gear is tightened on the arbor the whole assembly is revolved and the O.D. must run out the same amount in the same spot as it did when loose. The side run-out of the gear should be tested in the same manner. Hob Grinding, Mounting The cutter, whether disk type or hob, should be properly sharpened and mounted true. The shape of the tooth space or the quality of the gear will be governed very much by the care used in setting the cutter. If a disk cutter runs out on the O.D. only a few teeth will be doing the cutting, and they will become dull very quickly. If the cutter runs out sidewise or wobbles it will not produce the proper shape, be- sides making a thin tooth. If a hob ruins out a proper tooth shape will not be obtained, as it requires the full revolution of the hob to generate the shape. It is good practice to check the top of the teeth of the cutters with an indicator on a true lathe mandrel, as carelessness in grinding the cutters will give the same effect as if the hole in the cutter is running out. In grinding hobs the original gash must be followed closely. If the cut- ting edge is radial or hooking, it is very important that this be followed closely whenever the cutter is sharp- ened. A complaint on some large her- ringbone gears which were cut on one machine was recently received. The gears certainly ran noisily. Investiga- tion showed the right-hand hob was ground about one-eighth hooking and the left-hand hob about one-eighth dragging. Of course the mating gears THE IRON AGE, February 8, 1940—33 ABOVE 1G. |—The lathe-type steady-rest on this ma- chine provides maximum support for the outer end of the pinion being cut. AT RIGHT IG. 2—Newark gear cutting machine with tangential attachment fly tooling a bronze worm wheel. The fly tool is economically em- ployed where quantities do not justify making of a hob. had the effect of being cut at different pressure angles. The number of cuts taken depends on the job. When it is necessary to take two cuts it is good practice to leave enough for the second cut, from 10 to 20 per cent of the depth being a good amount. If the amount left for the second cut is too little, there will not be enough metal to hold the blank being cut steady. Cutting Cast Iron Gears In cutting large cast iron gears a lot of heat is generated, On a disk cutting machine this will usually leave a thick tooth at the end. In hobbing, the gear will expand between the spokes, and 34—THE IRON AGE, February 8, 1940 NEWARA GEAR CUTTING MOH. en ee ned ao WET AIA Ginn vv: Scaaaain this expansion will increase as the hob is fed across the blank so that when the gear cools a scalloped bevel gear results. The rate of speed and feed will govern this generation of heat and expansion. In some cases it is neces- sary to rough the gear and then let it cool before finishing. A short time ago a customer brought in the problem as to what was causing his machine to hob cam-shaped gears. It was found that the steel castings had not been thoroughly annealed; the hardness specifications were quite high and the customer thought that money was being saved this way in- stead of annealing the blanks. As the | 1) teeth were cut the strains were re- lieved and the rim proceeded to bulge out between the spokes about 1/32 jn, Most of these gears were scrapped, The advice given was to either proper- ly heat treat the blanks or rough out about two-thirds of the depth and then in a day or two finish the cut. This latter method was found completely successful. Quite a number of large, hard, cast iron spur gears are cut which have to be extremely accurate as regards tooth spacing. This is done on a No, 7 Newark Gear Cutting machine. The practice is to rough cut enough teeth so that just a little warmth can be felt, this usually being about one-twelfth the circumference. Then, skip about the same amount and rough again. This prevents the heat from increasing enough to cause excessive expansion. Next, a semi-finishing cut is taken about nine-tenths of the depth all the way around. The finishing cut is started half way around from the start of the second cut, and is continued around the gear. Also, the machine is not stopped on the second or third cut until the complete cycle is finished. Some of the work a gear jobbing shop should be prepared to handle is shown in the accompanying illustra- “=a =~ <— 424 ¢*.4 4 «aa Fig. 1 shows a No. 3 Newark tions. gear hobber equipped with lathe-type steady-rest to assure maximum support of the outer end of the solid pinion be- ing cut. Fig. 2 shows the same ma- chine with the tangential attachment, fly tooling a bronze worm wheel. The fly tool is an inexpensive substitute for a hob, where the quantities to be made at one time do not justify the making of a hob. It is suprising how quickly a worm wheel can be fly tooled. On multiple-thread worms, if there FIs. 4—The spur gear cutting ma- chine in the fore- ground is in opera- tion on pinion at the end of a long shaft; the machine next to it is cutting a large ting gear mounted on a faceplate. are more than two, a star cutter is made. There are as many teeth in the cutter as there are threads in the worm. This saves indexing and gives more cutting edges. Fig. 3 shows the end mill attachment of the No. 5 gear hobber, with a roughing hob (A) mounted in the attachment. of the flutes Notice the coarse spiral This cutter is used on a The finish- ing cutter (B) is a plate with two cut number of different jobs ting edges; it is suitable for small quantities, but four teeth would be bet ter. Fig. 4 shows a No. 5 spur gear cut- ting machine cutting a pinion on the end of a long shaft. Pinions have often been cut similar to this where the out- side diameter was the same as that of the shaft. These are used for bending rolls. In this case reverse the cutter and cut backwards. The machine next to the one on the long shafts is in op- eration on a ring gear strapped to arms which are in turn strapped to the face- plate of the machine. IG. 3—End mill at- tachment with rough- ing hob mounted in it. The finishing cutter for the same work is on the table of the machine. 4 ea I i 1 rt past decade has witnessed great progress in both the equipment used for hot and cold working of metals and also in the knowledge of basic principles underlying the flow of metals in the forming operations. This paper presents an abstraction and correlation of the present knowledge on the plastic flow of metal. In the first section last week, the author covered fundamental stress-strain relationships, the resistance to flow, and power consumption. Herein, in conclusion, the path or course of the deformation in the different working processes is considered, and data are presented on the effect of friction and lubrication. HE path or course of the defor- mation in the different working processes has been extensively investigated by several methods.’ Com posite test samples have been made from layers of slightly different ma- terials, which are fastened together by means of inserted screws or bolts. The segregated regions in mild steel can also serve to follow the flow of this alloy. A very satisfactory procedure” which will reveal the flow qualitatively and also yield a quantitative measure is to cut the test sample of the metal in half, scratch or machine a square grating on the interior surface of one half and in the case of hot work fill the grooves with paint or a refractory material, such as graphite, to prevent welding. The two halves are then matched and rigidly assembled by means of bolts or wires, machined to size, if necessary, and subjected to the working process. The method has been used especially for extrusion experi- ments on a commercial scale, Figs. 10 and 11. Accurate measurements of the deformations of small test samples produced by working operations have ®°W. E. Remmers, Transactions, Ameri- can Institute of Mining and Metallurgical Engineers, Institute of Metals Division (1930), pp. 107-120. H. C. Jennison, Transactions, American Institute of Mining and Metallurgical Engineers, Institute of Metals Division (1930), pp. 121-139. H. Unckel, Journal Institute of Metals (London), Vol. 61 (1937), pp. 171-196. 0G. Sachs, Spanlose Formung, Berlin, 1930, pp. 74, 85; C. E. Pearson, Journal Institute of Metals (London), Vol. 64 (1939), pp. 299-310. u FE. Siebel, Steel, Vol. 94 (1934), Nos. 12 to 15. 2J. Winlock and R. W. E. Leiter, Transactions, American Society for Metals, Vol. 25 (1937), pp. 163-205. 13K. Fink, Z. Berg-, Huetten- and Sal.- Wesen (1874), p. 200. 36—THE IRON AGE, February 8, 1940 also been made by this method, to calculate the actual work expended.” The speed of deformation generally rt 1 of deformat g Ih _ |0O—The flow of metal in the extrusion of tin at room temperature. has little effect on the cold working processes.'* The flow resistance increases slightly with the increasing rate of strain, Fig. 12. How- ever, at high deformation speeds the heat generated by the working cannot be conducted away sufficiently fast, so that the actual tem perature of deformation is raised with a corresponding decrease in flow resistance. The flow stress generally decreases almost lineally a with increasing temperature down to a very low value at the melt- ing temperature. However, in some instances, a high rate of deformation may be detrimen- tal. Thus, in any cold process, where the forming is produced by a tension of the metal (the different drawing processes, or rolling with front and back tension), high impact stresses in addition to the actual working stresses are momentarily created at the start of the operation and may cause rup- ture. Also, the tendency of soft steel sheet to form stretcher strains in- creases with an increasing rate of deformation, Fig. 12, and therefore slow starting speeds are beneficial for the forming of soft steel. in hot deformation is the rate of the metal flow, while the amount of deformation has practically no effect on the flow stress. The flow stress can be determined from compression tests (in per cent per sec.) corre- sponding to the actual work- ing speeds. The quantita- tive effect of the rate of deformation on the flow stress varies with the metal and the temperature, see ‘igs. 13 and 14. If the value of the flow | |—The flow of metal in the hot extrusion of high brass. The determining factor i l_ aaa stress k under specific conditions 1s known, the power consumption for a certain type of deformation, disre- garding friction, can be obtained from the following considerations. In ten- sion, for example, the work expended during a small elongation dl is: By GEORGE SACHS Case School of Applied Science In the rolling process, where the only dA = k-f-dl external force is the pressure of the rolls: and with a constant volume: is p a= s 5 al the deformation of a volume V cu" hb (1 = length, h = height, b f width) yields the same relation :' | und : dA = k-l-b-dh ine _ dh i Thi uy > . P ™ » ASS he This gives the work consumed, assum toe ia ieee ing that k is constant: hy the product of the volume by the A = kVel, K-V-€max flow stress by effective deformation is 1000 1000 800}-—_++-_+ — 5-=—{800 :« = « AT LEFT £ 600 600 |; IG. |12—The effect - 6 of the rate of S 8 strain on the stress- 400 400~ straindiagram of soft steels. (Winlock and Leiter). 200 200 ° ° ° re) 0 0 5 10 I5 20 0 5 10 [5 20 Strain in 2in., per cent AT RIGHT IG. |13—Effect of temperature ana rate of strain on the flow stress of different steels in compres sion (Siebel). Rate 6 per cent per sec. (left), and 1000 per cent per sec. (right). Flow stress, 1000 Ib. per sq. in Temperature, deg. F. 0 0 1000 1200 1400 1600 1800 2000 22001000 |200 1400 1600 1800 2000 2200 the basic and minimum value for any calculation of the power consumption. The result is the power consumption for a frictionless and uniform defor mation. The flow stress can generally be taken for all practical purposes as an average of the values at the begin ning and at the end of the process. he actual power consumption is always higher than this basic value. lwo corrections should be added, (1) for the effect of the previously dis- cussed heterogeneous deformation (see Fig. 9), and (2) for the effect of friction. FRICTION AND LUBRICATION : A con- siderable part of the power consumed in a process is used to overcome the friction between the working tools and the metal. is particularly important, because it is This portion of the work expended to control the quality of the product and depends on more or less variable factors such as the die mate- rial, the surface condition of tools and stock, the design of the tools, the type of lubrication, the speed, etc. The power required to satisfy the friction demands in a drawing process, for example, can be approximately calculated in a very simple manner according to Fig. 15. If no friction exists, a body of cross-section f,, trans- formed into a final cross-section f, will require a drawing force: fp — fi 7a & = p-sina: =p (i, — fh Sin @ where the angle a the half die angle. Now assuming that the wall 100 | | Co Oo a Oo > So Flow stress, 1000 Ib. per sq.in. ~m © Temperature, deg. F. THE IRON AGE, February 8, 1940—37 Extrusion pressure, 1000 Ib. per sq. in 0 5 10 I5 20 25 Velocity of extrusion,in. per min. ABOVE IG. 14—Effect of temperature and rate of strain on the extrusion pressure required for high (60/40) brass. pressure p is not changed when the friction w.p is active on the die wall, the drawing force becomes, Fig. 16: f, — f, SsIn @ v¥r = > fe = f,) Sa Mp-COS a: = £,-(1 + u-cot a) The friction effect is therefore in- creased by both an increasing friction coefficient and decreasing die angles. With a friction coefficient p = 0.1 and a (half) die angle of 6 deg., the power consumption for drawing is twice the frictionless value. However, the ac- tual power consumed by friction is more complicated and requires consid- 4 E. Siebel, Kaiser-Wilhelm Institute, Eisenforsch, Vol. 12 (1930), pp. 225-244; Vol. 16 (1934), pp. 485-491. 6E. L. Francis and F. C. Thompson, Journal Institute of Metals (London), Vol. 46 (1931), pp. 313-351. 1¢@W. Trinks, Blast Furnace and Steel Plant, Vol. 25 (1937), pp. 713-715. 17G. Sachs, Spanlose Formung, Berlin, 1930, p. 38. A. Pomp and A. Koch, Mitt. Kaiser- Wilhelm Inst., Eisenforsch., Vol. 13 (1931), pp. 261-271. 18R. C. Williams, Wire and Wire Prod- ucts, Vol. 10 (1935), pp. 145-146, 160. 122°G. Sachs, Spanlose Formung, Berlin, 1930, p. 11. 2 J. J. Trillat, Compt. Rend., Vol. 202 (1936), pp. 2134-2136. 2E, L. Francis, Carnegie Scholarship Memoirs, Iron and Steel Institute, Vol. 23 (1934), pp. 47-63. 2K. B. Lewis, Wire and Wire Products, Vol. 8 (1933), pp. 197-200, 219, 234-239, 243, 251, 266-269, 331-333. 3D. E. Washburn, Wire and Wire Products, Vol. 12 (1937), pp. 57 % FE. Siebel, Steel, Vol. 94 ( 2, pp. 24-25, 43; No. 3, pp. 27 38—THE IRON AGE, February 8, 1940 which will be discussed in detail for the individual working processes. erable calculations, Thus, as shown in Fig. 17, the force required for drawing wire through conical dies de- pends in a rather complicated manner upon the drawing con- ditions, and attains a minimum value at a certain die angle, other factors being equal. This may be explained by the de- scribed combined action of the different factors which contrib- ute to the total drawing force, Fig. 18: (1) the minimum flow 30 - 6h (sing 1 Zo Q : — i ! p:sina Fic. 15—Drawing force without friction. Fic. |6—Drawing force with friction. 100 Fi falf angle of ale 4 2aeg. © 4deg. ° 8deg. “x /6 deg +32dleg § 3 S ~ © Drawing stress, 1000 Ib. per sq. in 0 0 20 30 40 = 50 | TUNGSTEN- CARBIDE | , DIE, resistance required for the external shape, (2) the non-uni- formity of the strain, and (3) the external friction. As_ previously shown, the non-uniformity of strain increases with change of increasing die-angle, while the total friction resistance de- creases with increasing die-angle, thus creating the minimum at a die-angle. certain In rolling, the action of friction de- termines, for example, the effect of different roll diameters.“ Figs. 19 and 20. The unit roll pressure generally increases with the roll diameter, and this especially applies to the hot rolling of steel with rough rolls. However, the friction effect is small in cold roll- ing with polished and lubricated rolls, Also, in most cases the friction is considered to be determined only by the conditions of stress, that is, the solid friction type. This relation ap- pears to be justified from the observa- tions that the power consumption for cold work is not appreciably affected by the rate of deformation, for exam- ple, in wire drawing.” In the case of a liquid friction, the drawing force would increase with the drawing speed. Friction coefficients for various con- ditions have been determined bv dif- ferent methods. They can be accu- rately obtained only by using the theoretical relations, to be discussed for the specific working processes. In the rolling of carbon steels, the fol- lowing friction coefficients have been found: Hot rolling with steel rolls 0.4 between 700 and 1650 deg. F. (400 to 900 deg. C.), 0.3 at 1800 deg. F. (1000 deg. C.), and 0.2 above 2000 deg. IF. (1100 deg. C.), and with cast iron rolls these values are increased about 50 per cent; and for cold rolling 0 0 20 30 4 50 Reduction in area, per cent (single draw) — |7—Effect of die material, die shape, and reduction on drawing force for high (67/33) brass. INARA ik mer ew im Reaunmea etrece uw oO > oO a Oo rm oO Nonuniform strain lubrication capacity, have been developed by special processes or by the introduction of some constituents, which are not en tirely neutral. Some of the cor rosion problems of high speed bearings are attributed to this chemical condition. The viscos ity of the oil can be varied within wide limits, and gener- ally the more viscous lubricants Drawing stress, 1000 Ib. per sq. in. 10 are used for high pressures, high temperatures or slow work ing speeds. [The most viscous 0 and effective lubricant is bees 0 Half angle dian ba a. 35 wax, with or without an addi- O29 tion of 10 to 20 per cent graph- IG. |18—The effect of die shape on the ite. It is used for lubricating stress required for wire drawing the value is 0.04 with high speed pol ished rolls and flood lubrication, rang ing up to 0.15 for rough rolls without lubrication. In wire drawing, friction coefficients have been computed from certain experiments that investigated the effect of different shaped dies :” Steel, with tungsten carbide dies and different lubricants, 0.03 to 0.06: brass, with tungsten carbide dies and rape oil, 0.06; brass, with soft steel 0.10. Another estimated values be- dies and rape oil, source” gives tween 0.07 to 0.29 for the drawing of copper and stainless steel with tung sten carbide dies, the lower values for wax and the higher for mineral oil lubricants. In deep drawing the fol- lowing coefficients have been deter- mined: Copper, with rape oil, 0.15; brasses, with rape oil, 0.08 to 0.12; bronze, with rape oil, 0.14; aluminum, with tallow, 0.10. The mechanism of a lubricating ac tion in a working i involved. The classical theory of lu- brication assumes that the contact between metal and die is interrupted by the lubricant. Actually, however, there is always some direct contact between the metal and the tool. It has also been found, by X-ray and elec tron diffraction investigations,” that a type of unstable compound is formed between the metal and the lubricant at the interface, in such a way that a very thin layer, perhaps only one mole process 1S very cule thick, functions as a sliding cush ion. This explains the well-known fact that organic lubricants have a higher lubricating capacity than neutral min eral oils. However, organic lubricants are often unstable, attack the metal, and form stains and residues which are difficult to remove. Recently, mineral oils, with a higher the punches in the extrusion of so Su ott CIN 35 30 nm nn Oo ul nit-roll pressure , 1000 Ib. per sq.in. ‘1 VU 0 0.0] 004 0.2! 0A 1.0 - Thickness material Ratio Diameter of rolls IS. 19—Effect of roll diameter on hot rolling of steel structures (Siebel). aluminum and bronze tubes. allow and castor oil are also potent lubricants, which are used deformations which tend to for very drastic and for metals scour and drag. Viscous mix- tures of lime, or sodium soap with mineral grease and oil are breakdown wire In the roll- ing of sheet, strip, foil and light used for the drawin