The Iron Age 1942-02-05: Vol 149 Iss 5

orities opies are ake these times when everyone’s highest privilege serve the nation every way can, American manufacturers are fortunate have much contribute the common cause. Our vastly expanded output machines has long since been placed the government’s disposal. Our plant will continue work top speed night and day that those who need New Britain Automatics for wartime production may have the machines they 4 . od {e= : | * C3 | I, = q j ANGULAR KOT STUB BORING d : & 4 atv. sia. AND ANGLE { 4 4 — ow ing for chucking jobs nent handling ork. This “perma shop our recomme hundred jobs show that Studies turning the ado can reduc cut ools remain iety jobs ption Universal materially setup time and costs. The heavy flanged infinite ducing sha and boring bars, grinding and chuck jaws- Adjustable features Geared Heads and Quick Chuck Heads (Large Lot Pro- ter Stub Bats and Overhead Pilot Reversible Adjust Stub and Should you need any Attachment Angle Cutter Short Too Pilote Boring Bars Holders Holder the small tools shown, adopt and Spin Reversibl Straight Long Flanged Bushing and Cutter Holder this “permanent setup” your Adjustable single Holders Warner Swasey Turret Lathes, ick Action Set = select sizes from your sey Tool Swa Ba: a { VERHEAD CUTTER FEBRUARY 1942 VOL. 149, NO. VAN DEVENTER President and Editor BAUR Vice-President and General Manager Managing Editor, LIPPERT News Markets Editor, ROWAN Technical Editor, OLIVER Associate Editors JAMES Art Editor, WINTERS Editorial Assistants Washington MOFFETT Resident District Editors CAMPBELL HERMAN KLEIN Pittsburgh Chicago Cleveland Detroit CHARLES POST San Francisco Editorial Correspondents Buffalo Cincinnati FRAZAR RAYMOND KAY Boston Los Angeles HUGH SHARP JOHN McCUNE Milwaukee Birmingham SANDERSON ROY EDMONDS Toronto, Ontario St. Louis Newark, Seattle ° DIX, Manager Reader Service ° ° Advertising Staff Emerson Findley Herman, Chilton Bldg., Philadelphia Hottenstein, Otis Bldg., Chicago Leonard, 100 East 42nd New York Peirce Lewis, 7310 Woodward Ave., Detroit Ober, 100 East 42nd St., New York Fitzgerald 428 Park Bidg., Pittsburgh Johnson, Market Research Mgr. Hayes, Production Manager. Baur, Typography and Layout. ° Member, Audit Bureau Circulation Member, Associated Business Papers Indexed the Industrial Arts Index. lished every Thursday. Subscription United States and Possessions, Mexico, and South America, $6.00; Canada, Foreiqn, $12.00 year. Single cents. ° Owned and Published CHILTON COMPANY (Incorporated) Executive Editorial and Offices Advertising Offices Chestnut and Sts. 100 East 42nd St. Philadelphia, Pa. New York, U.S.A. OFFICERS AND DIRECTORS MUSSELMAN, President JOS. HILDRETH, Vice-President GRIFFITHS, Vice-President EVERIT TERHUNE, Vice-President BAUR, Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JULIAN CHASE, THOMAS KANE, HARRY DUFFY CHARLES HEALE This Week in... Editorial Salvage Technical Articles Industrial Powder Metallurgy Coining and Other Cold Press Work Six-Sided Press Speeds Aircraft Output More Production from Old Machine Tools Rectifiers Hard Chrome Plating Template Manufacture Load-Center Power Distribution Favored What's New Plant Service Equipment Features Assembly Line Washington West Coast Fatigue Cracks Dear Editor News and Markets This Industrial Week News Industry Personals and Obituaries Machine Tool Activity Non-Ferrous Metals Scrap Markets Iron and Steel Scrap Prices Comparison Prices Finished Steel Prices Warehouse Prices Products Advertised Index Advertisers Copyright, 1942, Chilten Company THE | Acting Ho! | — 4, 4 38—THE IRON AGE, February 1942 IMPORTANT ADVANTAGES for DEFENSE PLANT CONSTRUCTION FULL OPENING CLEARANCE Top... Bottom Fire... DETROIT CHICAGO Representatives Principal Cities Rolling Steel Doors, Shutters ond Grilles, Kalamein and Tin Doors, Steel Roof Deck and Cast Roof 4 7 A | 4 4 | 4 7 7 ° FEBRUARY 1942 ° ° ESTABLISHED 1855 Salvage Bureau Industrial Conservation, was recently announced, available pound paper, metal, rags and rubber, now unused shops homes, moved the plants and mills that must unceasing stream these materials achieve maximum production.” fine. But why lock the barn door after the horse stolen? The time begin the conservation materials, call salvage what you will, before waste and scrap are produced. Salvage, other words, begins the drawing board and ends the scrap pile. When reclaim scrap from the junk pile, are saving material. When prevent spoilage, cut down the amount scrap being made production, are saving material and what more important, time and labor. There lot precious time and labor, well material, going into our scrap piles today because unnecessary rigidity munitions specifications. And because local inspectors, who must follow these specifications the letter, are not permitted exercise the judgment that would and permitted them private industry. small part this unnecessary waste, which costing precious time well material, due, think, the fact that many munitions specifications are based upon shop practice years ago and not recognize the great engineering strides made since then the reclama- tion rejects. Under our present system munition part inspection, bore too large spindle diameter too small, the one the ten thousand pieces affected are thrown summarily the scrap heap, together with the labor that has gone into them and the precious time took make them. private industry, these parts would built the required diameters simple process such metallizing and the hours labor and pounds materials involved would salvaged before getting the scrap pile. Under our present system military and naval inspection, have known gear case covers having been discarded because minor sur- face defects, although their whole function was merely keep lubricating oil from splashing out of-gear reduction sets. private industry, these de- fects would have been with weld metal and made perfectly serviceable. would good thing had salvage engineering departments and Navy bureaus whom contractors could refer such cases. mistakes, when they can rectified, not dis- creditable; throwing away hours labor and pounds material is. not think Germany and its engineers are giving that sort comfort the enemy. — — 7 4 | | a 7 j q RO j 7 . | 7 | 7 q 7 Better Steels Are Coming— from the Tests War Out today’s grueling war tests are coming better steels for tomorrow. Britain, Russia, North Africa, and the Far East equipment built American steel setting new performance and endurance records. But, have not yet come the end, for world-wide battle tests are pointing the way new requirements that are being met the laboratories and the steel Inland actively taking its place this new phase the steel age. Before World War Inland gave industry such valuable steel mill products as: high- strength Hi-Steel; fast machining Ledloy; finer cold reduced tin plate; etc. Today, with greatly enlarged research facilities and the valuable experience exacting wartime produc- tion, Inland looking forward meeting the steel needs America peace. % ° ° KALISCHER Research Laboratories, Westinghouse Mfg. Co., East Pittsburgh appeared numerous publica- the past few years, there have tions articlest powder met- Other articles the metallurgy powders that have appeared IRON Ace are: “Powder Metallurgists Debate Techniques,” Oct. 30, 1941, 29. “Car- bides: From Powder Tool Bits,” Oct. 23, 1941, pp. 36-37. “Hot Pressing Iron Powder,” Sept. 1941, 37. “Powder Metallurgy: Some Important Technical Aspects,” April 17, 1941, 23. “Limita- tions Powder Metallurgy,” Dec. 19, 1940, 31. “Processing Trends Powder Metallurgy,” Sept. 19, 1940, 39. “Metal Powders—Effects Time, Temperature Feb. 22, 1940, 36. allurgy. general, these articles fall into two classes: Those treating the subject broadly, and those some specific topic wherein the author has given considerable data, but has limited his discussion that wide interest served. treating relatively new sub- ject, helpful compare with one that older and more familiar. apt comparison the case powder metallurgy can found the ceramic the case The German industry gives powder metallurgy the name, “Metalceramics.” common brick well known that the processes involved are the mixing clays and other ingredients, pressing the mix- ture die suitable shape and and then firing the pressed mixture obtain the final brick. powder metallurgy the Same general steps are followed. Metal powders the desired com- Industrial Powder Metallurgy Techniques and procedures, well the metallur- gical aspects, the manufacture parts from metal powders are examined this series two articles. Ad- vantages and restrictions using metal powders are discussed. ° position are mixed and then pressed die the desired shape and size. The pressed mixture then fired secure finished product the desired properties. Powder metallurgy counterpart the old and well-known ceramic indus- try dressed somewhat differ- ent terminology, divided metals working me- dium instead clays. should noted, however, that the analogy sense. Powder metallurgy has out- grown its infancy and rapidly be- coming important branch science and technology its own right. the case every science, there has grown vocabulary peculiar powder metallurgy, and familiarity with this terminology the literature. The following glos- sary, while incomplete, covers the more general terms use: METAL POWDER: Discrete metal par- ticles small size, generally less than 0.0! in., along their greatest dimension. FORMING PRESSURE: The pressure pressed per sq. in., some similar figure) that used compact the metal powder the die. POWDER COMPACT: The piece formed pressing the metal powders wherein the adhesive forces holding the metal particles together are probably mechanical. gen- eral, this term applies only before the pressed piece fired heat treated. SINTERING: The bonding together the separate metal particles powder com- pact the application heat. gen- eral, this term applies only the ture which the bonding takes place below the melting point the constituents. SINTERING TEMPERATURE: The tempera- ture which sintering takes place any particular operation. SINTERING TIME: The time required give the desired degree bonding the powder compact. IMPREGNATION: The bonding together the metal particles powder compact means absorbed molten material, either metallic non-metallic. GROWTH SHRINKAGE: The dimen- sional changes that occur during sintering. POROSITY: The volume voids the powder compact, generally expressed the percentage the total volume the piece. Thus, per cent porosity means that per cent the volume the piece com- posed voids between the metal particles. SOLID DIFFUSION: The mingling the metal particles form approach sound homogeneous mass similar materials the same composition. This intermingling occurs temperatures below the melting point the constituent metals. COINING: The repressing sintered part bring exact size. APPARENT DENSITY: powder al- lowed fall freely into container any specific shape and volume, the weight THE IRON AGE, February { q oe 4 : q ¥ 3 hy w i powder required fill the container will dependent upon the distance through which the particles fall. The apparent density powder then the weight powder re- quired fill cube when the distance through which the powder falls freely held constant. COMPRESSION RATIO: The ratio the initial volume powder die, loosely filled, the ratio the volume after com- pression under pressure tons per in. regards the fundamentals powder metallurgy, consider the start few irregularly shaped metal particles placed closely together and confined within die cavity, shown Fig. la. now, the die plunger forced down onto the metal particles they will dis- torted fill the die cavity and, the same time, will become interlocked that when the pres- sure the die plunger removed the particles will retain the shape they assumed under pressure shown Fig. 1b. While the pressure was being ap- plied the particles, they not only deformed but the same time slid slightly each other and broke the surface film oxide which always present the particles metals. When this oxide film was broken, the clean metal surfaces came into contact sufficient ex- tent that some spots welding took place thus helping hold the particles the form they assumed while under pressure. While the welding that takes place during pressing probably very slight, none the less real and great importance the subsequent be- havior the metal compact. Now assume that the compressed metal particles are removed from the die and placed furnace some predetermined high tempera- ture and suitable atmosphere that there will oxidation the metals but reduction the oxide films may occur. Over period time there will migra- tion atoms from each particle into others. sufficient time allowed, and solid solubility rela- tions are suitable, the particles will ultimately grow into single uni- form, coherent mass. This migra- tion the atoms shown schemat- ically Fig. the initial condi- tion the particles being shown Fig. and subsequent condi- tions the migration proceeds Fig. 2b. This migration the atoms occurs temperatures below the melting point the constituent metals and the phenomenon solid diffusion. Since there exists liquid phase 42—THE IRON AGE, February act solvent for any solid phase which might present, the importance solid diffusion can readily understood since the bonding can occur metal particles give the desired physical properties the powder part. This solid diffusion can take place only when there are clean metal surfaces contact with each other. For this reason the slight welding action that occurs during the pressing operation utmost importance since furnishes starting point for diffusion. Figs. and the particles are shown though they had com- pletely deformed that voids exist. Actually, however, there are always voids between the particles, shown Fig. their size being dependent upon the characteristics the powder and upon the form- ing pressures used. practice the voids, expressed porosity, may cent, and the sintered piece may porosity, depending upon the sinter- ing time and temperature, and the mechanism which the voids the powder compact are closed sintering not known. but probably due surface energy causing plastic flow the metals the sintering temperature. Regard- less the actual mechanism in- volved decreasing the percentage RIGHT akes place, two powder par- ticles may abutted, but there atoms from one particle the other. (b) well diffused powder compact, the particles have lost all individual identity and are two crystals homo- LEFT IG. Loosely packed powder the die cavity. The black areas voids open spaces. (b) After com- pression, the metal powders not show these voids, but some are still present although greatly reduced size. porosity during sintering, such tion does take place accompanied shrinkage the compact. The amount shrinkage and decrease porosity are, course, depen- dent upon such factors forming pressure, sintering temperatures and sintering time, which factors will discussed. any operation involving solid diffusion, the rate diffusion dependent upon the The relationship between rate diffusion and temperatures for variety metals the wrought massive state has been worked out, and from these rates known that under the best con- ditions solid diffusion slow. slow down the diffusion further the case powder compacts, there relatively small area contact between the metal stead the fairly large area avail- able the experimental deter- mination diffusion coefficients. However, from the experimental evidence known that ob- tain completely homogeneous ma- terial from metal powders within any commercially economic length time, certain fundamental con- ditions must met. These are: (1) The metals should chem- ically dissimilar possible, (2) the crystal structure the metals should similar, (3) the melt- ing points the metals should far apart possible, and, (4) geneous mass. b ee (a) (a) ° ° (b) (b) solid solubility the differ- ent metals each other should high. There are, course, other fac- tors that enter into the picture, but these four considerations are most important. now desir- able determine what these con- ditions mean practice. First, consider the case mixture iron and nickel powders. Here the rate solid diffusion will ex- cessively slow since the two metals are very similar chemically and have melting points that are close together. The crystal structures are, however, the same type that will aid diffusion. the other hand the case iron and chromium, these two metals are quite different chemical proper- ties, widely separated ing points, and, high tempera- tures, similar crystal structures that conditions for rapid diffu- sion are established. These con- clusions have been borne out experimental work. can thus decided advance which alloys can made most readily pow- der metallurgical processes and which cannot. illustrate ity alloying powder metal- lurgical processes, example can 3—There are always voids between the parti- cles, their size dependent upon the powder and form- ing pressures. The dark areas here are the voids. cited the case iron- chromium alloy containing per cent chromium. This alloy can made from powders, and sin- tering about 2102 deg. F., for duce piece having porosity less than per cent and corrosion and oxidation resistance properties equal superior wrought ma- terial the same composition. the other hand, the case alloy containing per cent chro- mium, per cent nickel and the re- mainder iron, sintering the same temperature for hr. pro- This alloy per cent iron and per cent nickel was made from metal powders, sintered for 100 hr., 2192 deg. This per cent iron and per cent nickel alloy wrought material, annealed for hr., 2192 deg. Both specimens were enlarged 100 diameters. duces alloy low density, with fair oxidation and corrosion resis- tance. However, the alloy mag- netic and even after several hun- dred hours sintering still more magnetic than the wrought mate- rial the same composition. This means, course, that the case this latter alloy there not ob- tained the austenitic structure characteristic this type mate- rial. Such alloy will, however, have oxidation and corrosion resis- per cent chromium alloy, but the added nickel probably wasted. Another fundamental considera- tion all metals grain size. With few exceptions the most desirable materials are those fine rela- tively fine grain, and means powder metallurgical processes possible produce materials having extremely fine grain size. can stated almost axiomatically that the grain size metal parts made from powder the grain size the powders used making the piece that almost any grain size size distribution desired can secured. the author’s edge, there only one outstanding exception this, and that the case high-nickel compacts after prolonged sintering very high temperatures. This one exception holds only partially that grain sizes cannot obtained from powder compacts large those from wrought materials, shown Fig. unless cold worked after sintering, followed annealing. Other examples this fine grain size resulting from powder metal- lurgical practices will brought out later. There are five basic variables which must considered any powder metallurgical process, name- ly: (1) Particle shape; (2) particle size distribution; (3) forming pressure; (4) sintering tempera- ture; (5) sintering time. These dividually. Particle Shape The shape the individual pow- der particles will vary according the method manufacture. For example, powders made the car- bonyl process are quite uniform spheres; electrolytic powders are generally dendritic; ball milled and stamp milled powders are generally very thin plates irregular out- line; sprayed powders are usually spheroids; and powders reduced from oxides are almost any ir- THE IRON AGE, February 1942—43 | | | | regular shape. For most applica- tions the shape the powder particle rather immaterial since the forming pressures used are al- ways sufficiently great give plastic flow the metal, except, course, the case such mate- rials the carbides. There is, however, considerable evidence support the contention that where porosity important, the case bearings and filters, spherical particle gives more uni- form porosity; that is, the indi- vidual pores are more nearly all the same size. the other hand, undeniably true that irreg- ularly shaped particle tends interlock better than sphere, that variation pore size not important, somewhat better pow- der compacts might attained from the more irregularly shaped particles. The thin flat plates re- sulting from stamping ball mill- ing are probably the most difficult use since they have far higher porosity, when loosely packed, than any other shape. This question particle shape, therefore, brings the importance the apparent density, compres- sion ratio and hardness the metal powders. density powder, defined here, purely empirical figure but is, nevertheless, considerable im- portance. Consider iron powder, for example, made one case uniformly spherical and the other case made flat plates. the screen analysis the two powders the same, wide difference their apparent densi- ties will found. This can shown the porosity loosely packed particles; the case the spherical particles porosity from per cent will ob- tained while the case the flat plates porosities will high per cent. The importance these figures that, die design, the die cavity may much shal- lower than when flat particles are used and this difference cavity size reflected the cost not only the die but also the press and die life. From this discussion apparent density, the real meaning com- pression ratio once obvious. Thus, for similar powders having the same screen analysis. the one with the apparent will have the lower compression ratio. However, other factors enter into the concept compression 44—THE IRON AGE, February 1942 such the hardness the metal particles and the degree which they work harden during compression. Here, again, the use which the powder compact put determines the most desir- able compression ratio. very dense parts are desired, powder that does not work harden appreciably most desirable. This means powder with high com- pression ratio where the comparison compression ratios made powders the same shape and screen analysis. the other hand, very excellent means control- ling porosity where some voids are desired use harder powder with lower compression ratio. There are fixed rules which the proper powder can selected (a) 5—{a) This type packing metal powder particles obtained when particles are uniform size and shape, showing the maximum voids. When there wide size distribu- tion particles uniform shape, this packing the metal powder particles obtained. This condition one minimum voids. and generally some experimental work necessary determine the most desirable material. the application these few rules, how- ever, often possible narrow down the number available pow- ders very considerably. Examples this will shown. Particle Size Distribution determining the porosity and size the individual pores sintered piece, the particle size dis- tribution the powders para- mount. batch metal powder which all the particles are exactly the same size and shape conceived, and assumed that die cavity filled with such powder, the loosely packed powder will fill the cavity such way that all the pores are the same size and shape shown Fig. 5a. This neglects any possible bridging the powder give few isolated pores larger size. Such ar- rangement the powders will give the maximum porosity possible for the particular particle size and this will carry through the pressing and sintering operations. Let now assumed that with the first powder mixed another one also uniform size and shape, but with the individual particles materially smaller than those the first powder. now this mixture poured into the die, instead the uniform pores pre- viously obtained, the smaller par- ticles will tend some extent fill the interstices, that the total percentage porosity reduced. This illustrated Fig. 5b. following this procedure the par- ticle size distribution that gives the minimum porosity the loosely packed condition finally arrived at, giving powder maximum apparent density for any given shape. the case particle shape. fixed rule for optimum particle size distribution given. Generally speaking, the per- centage fines and their size determined some extent the dies used. die good con- dition with very small clearances between the parts, finer powder can used than older die where there has been considerable wear. The use which the powder ing factor, and, before, some ex- perimental work always neces- sary arrive screen analysis for any specific use. Forming Pressure The forming pressure used making powder compact deter- mined several factors. the first place, limited the die steels available for use and the capacity the presses. simple shapes small area, pressures high 120 tons per sq. in. may used high speed production not required. However, the shape the piece becomes more complex. the pressures that can used must lowered because the limita- tions allowable stress the 7 7 | die. Parts large cross-sectional area generally require low forming pressures since the total pressure required the press becomes excep- tionally high. For example, disk in. diameter pressed tons per sq. in., requires nearly 1200 tons total pressure. Since high speed mechanical presses are lim- ited about 100 tons total pres- sure, such piece could not made high speed and hydraulic press would have used. this lower speed production not limiting factor, however, pieces large area can readily made. second factor determining the forming pressure the porosity desired the final piece. Where high perosities are desired rela- tively low forming pressure used, 0.2528 the density ofan iron compact. 01806 ° ° 0.1445 and the desired porosity de- creased the forming pressure increased. The effect forming pressure the ultimate density pure iron compacts shown Fig. third consideration that helps determine required forming pressure the thickness the oxide films the metal particles. the case metals with little oxide film, relatively low pres- sures will give adequate surface contact, the solid diffusion can take place most readily. the case metals with fairly thick tenacious oxide film, the higher pressures are aid the rupture the films and the cold welding the clean metal surfaces. out- standing example this effect the pressing aluminum com- pacts. Aluminum powder, particu- larly that relatively free oil films, covered rather thick and very tenacious oxide film. Using low forming pressures possible make powder compacts that can handled and even sintered under the right conditions, but get good physical properties from such piece nearly impossible. How- ever, the forming pressure in- creased sufficiently rupture the oxide film and allow the clean metal surfaces weld, compact can made having exceptionally high mechanical and physical properties the pressed conditions and one which will sinter easily sound, homogeneous metal. This welding the metal particles marked the case aluminum that the compact often adheres the die wall strongly enough require destruction the compact before can removed. Most the soft, low melting point metals exhibit this characteristic. Another factor governing the forming pressure the hardness the particles and amount work hardening they undergo. Obvious- ly, soft powder that does not appreciably work harden will re- quire lower forming pressure arrive any given density than harder powder one which work hardens appreciably. Thus, well annealed electrolytic iron powder pressed at, for example, tons per sq. in., will give more dense com- pact than unannealed powder compacted under the same pressure. The actual difference found two such powders that the annealed electrolytic has density 0.242 Ib. per cu. in., 6.7 gm. per while unannealed electrolytic powder has density 0.220 lb. per cu. in., 6.1 gm. per ce. the instance cited the powders had the same screen analysis, were pressed using tons per sq. in., forming pressure and were sintered together hydrogen for hr. 1832 deg. Thus, forming pres- sure another means controlling the porosity compact. Sintering Temperature One the most important vari- ables powder metallurgical prac- tice the temperature which sintering takes place. has been previously noted, the rate solid diffusion markedly influenced temperature, that for any given powder compact the highest pos- sible temperature should always used. many cases the sintering temperature above the melting point one the constituents that combination sintering and impregnating takes place. The limi- tations the sintering tempera- ture are first all economic since furnace costs, both first cost and operation, greatly increase the operating temperature raised. Another limitation furnace de- sign. For small pieces, relatively few number, quite easy design suitable furnace, but the size quantity the pieces increases, becomes necessary build larger, more complex furnaces for operation high temperatures and with atmospheres sufficient purity for powder metallurgical work, which are extremely difficult design. The effect variation tem- perature the final density sin- tered nickel shown Fig. From this curve quite apparent that the nearer the sintering tem- perature approaches the melting point, the higher will the den- sity. this case, not only does the higher temperature increase the rate solid diffusion, but the higher temperatures the metals are more plastic and will more readily deform fill voids. Sintering Time difficult differentiate be- tween the effects produced short time sintering high temperatures and long sintering somewhat lower temperatures. The effect time the sintering temperature the density iron compact noted that very similar the curve Fig. Probably the most important consideration involved selecting sintering time and temperature are the economics the operation. Generally speaking, possible arrive any re- THE AGE, February 1942—45 are that way ame ated ar- for this med xed lual han die, the the yed ler lie iS | sultant compact condition either high temperatures and relatively short times lower tempera- tures and longer times and the eco- nomics each particular operation will determine optimum conditions. From the foregoing discussion some the fundamental factors influencing the production pow- see how well the rules laid down can used select, advance, the type powder used, thus cutting down the amount experi- mental work necessary arrive final decision. For the following illustrations iron powders will considered, al- though factors pertinent iron will also applicable other metals. Now suppose that de- sired make simple shape high density, large cross-section area, and the greatest possible rate production. For high den- sity known that the powder must annealed first require- ment. Next, must not work harden, which means that must low carbon and low such impurities and man- ganese. Since large cross-section area high density desired, high unit pressures must em- ployed and hydraulic press must used. Since these presses are relatively slow compared with mechanical presses, desirable have short piston travel Mold Oven Handles 207 Tons per Load LTHOUGH originally designed tons and deadweight loads 100 tons flasks and cars, this mold oven currently being used bake loads made tons molds and 150 tons flasks and cars. Built the Gehnrich Corp., Long Island City, Y., the oven ft. long, ft. wide and ft. high. Wall, roof and door panels are packed with reinforced mineral wool insulation and are assembled such manner that there through metal. Heat supplied integral gas fired unit. Uniform tempera- tures throughout the unusually large area the oven are provided forced circulation through net- work ducts. The recirculating principle used heat the at- mosphere. 46—THE IRON AGE, February possible, which requires powder low compression ratio. obtain this high purity annealed pow- der, irregular spherical par- tical shape with wide range particle sizes ranging from about minus 200 mesh down required, with most the powder minus 325 mesh. Now considering the require- 02709 a 0.2528 Density, Density,gm — Sintering temperature, deg. 7—The effect the sintering temperature the density nickel compact, with forming pres- sure tons per sq. in. ments set forth, either annealed electrolytic iron powder an- nealed hydrogen reduced powder, probably the latter due its lower cost, can selected. another example, assume final part that small, complex shape, with per cent porosity and required large numbers, reasoning analogous the fore- going, selection would made 4 i relatively hard powder con- trolled shape, possible, with narrow particle size distribution and particles somewhat larger size than before. The pressing would done with rather low unit pressures mechanical press. the first case the sintering tem- perature would preferably 2012 deg. F., higher, for from hr., and the second case the sin- tering temperature would about 1832 deg. F., for min. While probably true that not all cases powder metallurgical production can analyzed these two cases, almost always pos- sible the application few rules decrease greatly the amount trial and error type work. Certain other methods producing specified result will discussed here making possible production method before starting the work. With this brief resumé some the fundamentals powder metallurgy, practical applications and considerations such things die design, sintering atmos- pheres, and powder production can examined. Editor Note: Next week, concluding this article, the author discusses the prac- tical applications powder metallurgy, powder pressing dies and die design, sintering atmospheres and the effects the addition metal hydrides. a q ~ ° fe) ° HERBERT CHASE Engineering Consultant, New York ° ° ° UMEROUS not unique are being pro- duced Bowen Products Corp., Ecorse, Mich. Much the work involves what well termed the “Coldflow” process the plant spe- cializes cold coining work, al- though large volume work forming, drawing and other more conventional press work also done. Fig. gives idea the character items produced, most which involve cold coining. great many parts are produced from bar rather than from sheet stock, but the not confused with cold heading*, such *For cold heading data, see THE IRON issue Dec. 1941. done elsewhere very differ- ent and highly specialized machines. Bowen employs chiefly conventional toggle presses, the latter preferred for most coining since the longer dwell the end the stroke favorable producing the desired metal flow. Cold coining in- volves relatively high unit pres- sures and the use correspond- ingly sturdy presses. The plug shown steps production Fig. parts Fig. typical one type part produced. made from hot rolled, SAE 1010 steel sheet, 0.120 0.128 in. thick. More unusual the two-armed hub, the successive operations which are indicated the numbered pieces, 10, Fig. This piece first blanked and drawn from SAE 1010 hot rolled sheets, 0.156 in. thick. After Coining and Other Cold Press Work Several unusual coining jobs being done the Bowen Products Corp., Ecorse, Mich., are discussed herein, along with details manufacturing processes and the high speeds production. annealing and pickling, five succes- sive “cones” are drawn while the piece advanced dial fixture. “Squaring” done 200-ton press and this followed ing the central hole, trimming, and few the many different parts pro- duce largely. -by cold coin- ing the Mich. These parts are described the text. half-piercing embossing the nibs the two legs. Subsequently the piece tumbled and inspected. Square headed plugs like that the early steps production Fig. Bowen Products Corp., Ecorse, 38. S- ° f a i ABOVE 4—The barrel the plug shown Fig. necked and then deliv- ered this press where the flange formed it. BELOW 5—The last three coining op- erations forming the hub felt re- tainers, Fig. performed this 800-ton Minster press. 4 dia. plating Finish all over Remove burrs LEFT 3—For forming the square head cups, shown Fig. this dial setup used. The cups are later formed into plugs. g H Z yu face square with diameter 0.003 in. indicator reading ABOVE IG. 2—This plug produced the steps and illustrated Fig. buttons shown Fig. are made from bar stock this press. The stock ad- vanced into the press hand-operated ratchet between the blows the press. After drawing, cup-shaped pieces are delivered the large press shown Fig. and loaded dial fixture designed index auto- matically successive positions, the press running continuously. The operator loads the cups over the punches carried the dial. Three dies carried the ram form the square head successive opera- tions, after which the piece auto- matically kicked off into waiting chute. These operations handle 700 pieces per hr. The parts are then delivered smaller press that necks the barrel and finally similar press, shown Fig. where the flange formed squeezing operation the rate 900 hr. The piece before and after each the operations shown Figs. and the fore- ground the illustrations. Flanged hub felt retainers, such conical bearing seat the center and are coined with considerable flow metal. Three coining opera- tions are required, the final one be- ing done 800-ton Minster press, shown Fig. Annealing necessary between the coining operations, the final which done the rate 650 per hr., producing piece that remark- ably smooth and accurately sized. drawing this piece, which made SAE 1010 steel, shown Fig. The section shown the drawing illustrates how the metal must flowed yield the marked variations thickness that are required. Buttons generally oblong shape with rounded ends, crowned one side and having short stem the other, shown Fig. marked are also among the parts coined large quantities, starting with round bar stock. One the presses and the die for pro- ducing these buttons are shown Fig. The stock advanced hand-operated ratchet mechanism between blows the press and is- sues lengths with flash between each piece. The flash, course, sheared off subsequent opera- tion. These parts are produced with high polish, primarily be- cause good metal flow requires honed die surface, and they need machining after flash removal. Parts marked and Fig. are produced similar manner. Another part, shown Fig. produced this instance from cold rolled bar stock, split washer with serrated face and measures IG. 6—This the part the hub felt liner which the final coining operation, performed. Outside diameter must concentric with center hole within 0.0/0 in. indicator reading . with hole within = These faces Limits all fractional dimension washer with ser- rated face in. Circular thick, and made wire from cold rolled bar must close stock. The case measured the wearing surface the finished part Section (Enlarged) Standard file hardness -Limits all fractional dimension ° ° 9—The machine used punch out the split washer, Fig. The circular die the left receives the rings, which are struck punch, causing the ring flattened and flows the metal into the serrations the die. | e, ° | | | | 2.005 -42R max. , «Ream | = ° 'S ~ NIN NN NIN ~ Tool marks outside Walls must uniform run out more than in. 10—This connecting rod bearing made and spot welded with two spots, indicated the drawing. Later babbitted and cut into halves, giving two half-bearings. IS. The flat stock used make the con- necting rod bear- ing, Fig. 10, curled over the mandrel shown this machine. The mandrel recip- rocated the lever the oper- ator's hand eject the piece after curling. 50—THE IRON AGE, February 1942 thickness. Formerly, this part was punched from sheet stock and embossed form the serra- tions, but the waste stock was too great for its very low selling price. Consequently, the dies shown Fig. were developed make the washer from bar stock with practically metal waste. The punch portion the first die, shown Fig. has cam for advancing the stock horizontally gripped two pairs ser- rated arms. This advance the stock forces the latter curl around pin helix. The punch also carries tool that shears off one turn the helix each stroke. Subsequently, the turns rings are fed, one time, into the circular die, shown the left Fig. The rings are struck blow punch that causes the ring stock flattened and flows the metal into the serration the die, producing the required serrated surface. Production large quan- tities very rapid economical. curling operation involved producing the backing for the connecting rod bearing shown Fig. 10. This part made com- plete the dimensions shown the drawing. Formerly the bearing was produced from sheet stock, the blank then requiring forming and multiple coining, well trim- ming size, total six opera- tions. Now the blank made three operations from rolled sec- tion, which cut off, coined and trimmed. The blank then curled around mandrel, shown Fig. 11. This mandrel recipro- cated hand lever eject the piece after curling. The operation produces 600 pieces hr. The curling, naturally, leaves the piece with small gap that must closed and fastened welding. special machine, illustrated Fig. 12, designed for this purpose does the welding. The electrodes for re- sistance welding two spots only, and not completely across the joint, are pressed downward against the piece automatically jaws close around the piece and force the joint close, shaping the bore around mandrel. toggle mech- anism operated air cylinder locks the piece before welding and the machine operates that 500 pieces hr. are handled through it. the drawing, Fig. 10, indicates, the joint not com- pletely closed through its full radial depth, but this significance + both i> i | om ° ° ° IG. 12—This resistance welding machine grips and closes the con- necting rod bearing ring around mandrel, the same time pressing two electrodes against the work effect the two spot welds. ° ° since the shell sawed apart diameter through the joint give two half-bearings. Before sawing, however, the bore accurately sized striking the mandrel. The customer coats the interior the bearing with babbitt metal before sawing into halves. These are just few jobs repre- sentative what being done this plant, but they give some idea the character the work that Bowen Products Corp. turning out economically and with great precision. Aluminum Scrap Conservation Metal Industries, London, Eyles presented number observations aluminum scrap conservation. there now large tonnage aluminum and aluminum alloy sheets used the construction aircraft, there produced corresponding amount scrap the form sheet clip- pings, punchings, and turnings. melting aluminum scrap doubtful whether any largest and most experienced re- finers average more than per cent recovery from the ordinary dirt-laden turnings and chips the general engineering workshop. assumed that the average re- covery from turnings, chips, and foundry waste per cent the metallic basis, and if, shown the case, turnings and chips kept perfectly clean and prop- erly melted will give per cent recovery, then per cent aluminum Thus, may safely said that much valuable metal lost through the low recovery melting down aluminum scrap. the December issue Sheet Aluminum peculiar, its erties being different from those brass bronze. When melted ‘ oxidizes readily, and the oxide, be- ing practically the same specific gravity the aluminum itself, does not does not float the top the metal, but intermingles with the metal and remains when poured. Feeding aluminum scrap into the molten electrolytic bath, used for producing pure aluminum, not practicable the case cor- roded and painted aluminum sheet dirty clippings and turnings account the fouling the rather expensive electrolyte. Bri- quetting methods tend decrease the melting loss, the melting time, and fuel cost, and increase the ease handling the scrap. However, briquetting involves expensive ma- chinery and only profitable refiners handling large quantities scrap. methods melting aluminum sheet mainly due the getting the tiny globules molten metal resulting from the fusion the very fine clippings and chips coalesce when covered with skin layer oxide and dirt. order pro- mote coalescence, two methods melting can successfully (1) The scrap kept just above the fusion point and the globules made coalesce hand puddling, which breaks through the oxide skin and makes the globules unite; (2) the employment flux which melts dissolves the skin oxide, producing clean globules which can unite. The latter method based the same principle that welding sheet aluminum, where fluxes composed chlorides and fluorides the alkalies al- kaline earths are used dissolve the film aluminum oxide. well known that the pro- duction aluminum electro- lytic means the electrolyte consists molten cryolite holding solu- tion about per cent alumina, this mixture having the lowest melting-point the series about 1679 deg. This temperature far too high for use the melting operations connected scrap aluminum, and flux useful scrap melting operations must therefore consist mixture hav- ing considerably lower melting- point than the cryolite-alumina so- lution. Such mixtures are obtained the addition chlorides fluorides the cryolite mixture; [CONTINUED PAGE 128] THE IRON AGE, February y n- y, Six-Sided Press Speeds Aircraft Production new six-sided hydraulic presses are now production Douglas Aircraft Co.’s blackout plant Long Beach, Cal. They cut and form sheet metal air- plane parts vastly increased speeds, and still use and retain the operating advantages the Guerin process, employing rubber pad which under great pressure becomes hard steel, and serves the upper platen hydraulic press universal female die. The presses were built for Douglas the Brooklyn plant Bliss Co. 2500 tons pres- sure capacity, these hydropresses weigh approximately 375,000 stand ft. high, and occupy area about ft. diameter. cooperation with Stein- bauer, Douglas’ superintendent machinery, Earl Cannon and other hydraulic engineers the Bliss company evolved the unique press, incorporating six loading tables for high speed operation. They signed six-post press with radiat- ing die slides, automatically con- operator and avoid all danger misoperation due human error. six-die slide press provides the same selectivity die slide the four slide press, any one die slide being available for movement into the press independent its relation the preceding slide. has the further advantage per- mitting more men load work, many four each die slide necessary. All die slides enter the press endways and there ample provision for stock racks between the several die slides that while two die slides have been added and while the loading capacity has been doubled, the actual floor space the press little more than that the four-die slide press. Since the slides all enter end- ways, they occupy different posi- LEFT Douglas Aircraft plant shown erecting one six-sided presses. Elaborate cribbing re- quired get the unit crown and inder place top the six strain rods. | | | 4 | | | 7 - res- ein- her ess, for the ent its er- two huge and unique six-sided hydraulic presses now Co.'s blackout plant Long Beach, Cal. Each 2500-ton capacity, these presses have six electrically operated loading tables, and are said the fastest and most efficient units their the Guerin process for forming aricraft parts means metal male rubber, process developed Douglas and now used throughout kind ever built. They dies and universal fema the aircraft industry under license. t production Douglas Aircraft THE IRON AGE, February | tions within the press bed; hence the rubber pad must rotated ac- cordingly. This rotation the pad coordinated with the die slide action, and the control arranged that the die slide en- ters the press, the rubber pad auto- matically and tates proper position. the diagonally opposite slide enters the press after given slide has been withdrawn, the rubber pad remains its original position, since one position suffices for either the diametrically opposed die slides. specific order die slide op- eration required. The rubber pad swings left right, much deg. necessary, meet the in- coming die slide. the operation sequence, the rubber pad con- tinues moving one station either direction, the pad holder being capable making full revolution necessary. Featuring the new press its ability exert different pressures the various die slides, each slide being provided with its own pres- sure adjustment that light pressure desired one pad, and heavy pressure another, the desired pressure selected auto- matically. Each die crew can ad- just the pressure for its particular slide without consulting other op- erators interfering with the other five die slides. automatic cycle provided that when the starting button pressed the die slide enters the press, and soon and the rubber pad are properly positioned, the press ram descends high speed. Change from this speed the actual forming speed can ac- complished either before the press reaches the work after contact made. soon the desired pressure obtained the press auto- matically reverses and returns the upper position, which time the die slide travels out its load- ing position. Slides may pre-selected. one die slide the press and the starting button pressed for another slide, that slide remains stationary until the previous one has cleared the press. Then auto- matically enters without further attention. master operator provided, the die slides being interlocked that only one can enter the press time. Each crew has its own starting button, controlled the chief operator that partic- ular crew. Once button pushed, the other slides are inactive al- though second button may pressed provide for the opera- tion next sequenc