The Iron Age 1945-11-22: Vol 156 Iss 21

VAN DEVENTER Vice-President General Manager LEONARD Assistant General Manager year HAYES Bre. Advertising Manager Reader Service and Market Research CLEARY, Technical Research and Promotion Manager Son, enen- Executive Offices Chestnut and Sts. 39, Pa., U.S.A. Editorial and Advertising Offices 100 East 42nd St., New York 17, Regional Business Managers New York New York 100 East 42nd St. East 42nd St. ROBERT BLAIR GIBBS Cleveland Pittsburgh Chicago Chilton Bidg. 1134 Otis Bidg. PEIRCE LEWIS WARREN Detroit Hartford Conn. 7310 Woodward Ave. Box RAYMOND KAY Los Angeles 2420 Cheremoya Ave. ° ° ° Owned and Published CHILTON COMPANY (Incorporated) OFFICERS AND DIRECTORS MUSSELMAN, Chairman JOS. HILDRETH, President GEORGE GRIFFITHS Vice-President EVERIT TERHUNE Vice-President VAN DEVENTER Vice-President BAUR Vice-President Vice-President JULIAN CHASE Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR Secretary BUZBY HARRY DUFFY THOMAS KANE CHARLES HEALE WILLIAM VALLAR, Asst. Treas. Chilton Editorial PAUL WOOTON Washington Representative ° ° ° Member, Audit Bureau Circulation Member, Business Indexed the Industrial Arts Index. Pub- lished every Thursday. Subscription Price North America, South America and Possessions, $8; Foreign, per year. Single Copy, cents. Annual Review Number $2.00. Vol. 156, No. Editorial AGE The Quarrelsome Brothers ° Technical Articles Cutter Design Evaluated Production Runs Selection Die Steels for Cold Work New Uses for Hardsteel Ray Standards for Purchasing Castings Soft-Grit Blasting Cylinders Precision Founding (Part Welding Fluxes for Magnesium Form Dies Resin Impregnated Plaster Fast Stenciling Tubing Anodic Coatings Aluminum New Equipment Features News Front Assembly Line Washington West European Letter Personals and Obituaries Dear This Industrial News Industry News and Markets Machine Tool Developments Nonferrous Market News and Prices Iron and Steel Scrap News and Prices Comparison Prices Week and Year Finished and Semifinished Steel Prices Alloy Steel Prices Fabricated Steel Products Prices Warehouse Steel and Pig Iron Prices Ferroalloy Prices Cites Uses Fine Steels Holds Allied Bombings Not Decisive Hold ASTE Exposition Cleveland Reports Chemical Aid Given Germany Ray Penetration Possibilities German Tool Steels Claimed Inferior Reports ASM Meeting New Construction Awards and Inquiries Index Advertisers November 22, 1945 124 128-9 130 132 133 134 135 136 142 146 148 151 152 153 155 158 160 229-30 For rgh, High production, yes but Pre New Mac | During the war was mat- ter production speed and carbide cutting tools were the answer. Today it’s matter also Car keeping operating costs down. costs that meet beat competition. Again Firthite sintered carbide tools will help you keep red ink out your records, while turning out better, more salable product. PA. NEW YORK HARTFORD PHILADELPHIA PITTSBURGH CLEVELAND DAYTON DETROIT CHICAGO LOS ANGELES 50—THE IRON AGE, November 22, 1945 Keep that pencil sharp with FIRTHITE you have tool die problem STEEL COMPANY AGE ESPABLISHED 1855 ° November. 22, VAN DEVENTER President and Director BAUR Vice-President and General Manager Editorial News Markets Editor CAMPBELL Machine Tool Editor...H. LINSLEY Associate Editors WINTERS ALBIN JOHN ANTHONY BARMASEL Editorial Assistants SCHIEN at- SCHIMKO TOWNE SPEAR Foreign Editors (Contrib.)......F. Sanderson Regional News and Editors LLOYD Pittsburgh 428 Park POST Chicago 1134 Otis Bidg. EUGENE HARDY elp ANSBORO Washington National Press Bidg. LLOYD Cleveland 1016 Bidg. BRAMS Detroit Woodward Ave. OSGOOD MURDOCK WORTH HALE Sen 1355 Market St. Editorial Correspondents ROBERT McINTOSH Cincinnati DEAN Buffalo FRAZAR Boston HUGH SHARP Milwaukee RAYMOND KAY Los Angeles JOHN McCUNE Birmingham ROY EDMONDS St. JAMES DOUGLAS Seattie The Quarrelsome Brothers NCE upon time twe brothers died and reported the recording angel for judgment. They had been business together for all their adult lives, but had quarreled with each other most that time. seems that while one brother could not get along with the other, both them were indispensable the business that they were and neither one could really without the other. When they reported the nearest divisional judgment office, the recording angel charge brought out the books, found their records and added the scores. the case each the brothers was the bare minimum passing mark 75. seems that while this was the passing mark, averages less than were regarded with suspicion the Heavenly authorities. such cases, the keeper the Pearly Gates was notified watch out for the newcomers and give them additional once over before pushing the gate button admit them. Jack and Jim, although quite unaware it, were under close audio and visual scrutiny the HBI they climbed the hill the gates their cloud shoes. And usual, they were quarreling. The argument was who should first and speak for the two them. will the spokesman,” insisted Jack. made you what you were earth and had not been for me, you would have been headed the opposite direction long ago.” “Why you overgrown ape,” replied Jim, “you would never have gotten even second base earth hadn’t batted you in. I’m going first and the spokesman, else!” When they finally surmounted the heights and reached the gates, they were still indulging recriminations. But the chairman the reception committee for new arrivals put stop their arguments. “Gentlemen,” said he, “it known that you could not get along together earth, even though neither one you could have gotten along without the other. equally evident that you will not able get along together even Heaven, which land peace and quiet. separate you, let one you and not the other, would unfair since you are both blame for your bickering. Since cannot admit you Heaven, our decision that you can both But before the sentence could completed, the two brothers taneously fainted. Let hope that will not come that extremity our present management-labor controversy. MUNZER O'CONNOR a | | ¥ for MEN AND MOTION Inland 4-Way Floor Plate super-tough floor- ing just made for heavy loads and hard service. Reg. Pat. Office you want sure-grip traction for men and machines, the Inland design and pattern spacing provide it. Yet the projections never catch hold dust, grease mois- ture. Nor could this rolled steel plate possibly splinter, crack, absorb odors. Furthermore, you get flooring that fireproof, and very easy sweep and clean. most economical maintain, because its ability support heavy loads and wear for years and From every standpoint ideal for busy factory floors, aisles, areas around machines, shipping platforms and stairs. Also cover strengthen old, rough uneven heavy machines and equipment too, often used structurally the form supporting platforms, steps and walkways. And, course, has many other practical applications, indoors and out, where men and machines must have secure footing traction. booklet describing and illustrating its helpful and money-saving uses available. Ask for your copy today. Inland Steel Company, Dearborn Chicago Sales Cincinnati, Detroit, Indianapolis, Kansas City. Milwaukee, New York, St. Louis, St. Paul. Principal Products: Bars Structurals Plates Sheets Strip Tin Plate Floor Plate Piling Reinforcing Bars Rails Track Accessories. Inland 4-Way Floor Plate stocked leading warehouses. soli cutt crit fect allo are thre chic Oct thi 52—THE IRON AGE, November 22, 1945 NEWSFRONT Nov. 20, 1945 The nature postwar competition between metals forecast news the sale more than 100 carloads aluminum sheet for roofing the three West Coast states. Ford has projected $10 million expansion its foundry. Motor block ing lines will require the pouring 750 tons molten iron every hr. Among nany improvements powdered materials used the foundry will handled largely pipeline. After selling its Farrell plant last week the Sharon Steel Corp., the Steel Corp. now completing negotiations sell its Mingo plant Wheeling Steel Corp. This latter plant has two blast furnaces, two bessemers and large power unit. Both these Steel Corp. plants got extended lease life due the war, they were scheduled for some form disposal after completion the very modern plant mid-1938. industry may soon compelled disclose most its secrets gov-| ernment officials the British Census Committee has its way. Data required will include wages, salaries, depreciation, rent, rates and taxes, and other principal items cost, such advertising. Combining the increased strength afforded negative radial rake angles with lower power requirements redial reke angles face milling cutters results definitely superior other designs current use, laboratory and long preduction results reveal. Chief characteristic the new milling cutter design the location solid carbide blade wedged into the cutter body positive secondary radial rake angle with negative primary radial rake angle imposed the peripheral cutting edge. Casting specifications can simplified designating the critical and non- critical areas the casting and then picking the sizes intensities fects that can accepted the critical areas and selecting much more generous allowances made for defects that can accepted the noncritical areas. coconut shell meal, ground apricot pits and other soft grits are being used sandblast equipment American Airlines remove carbon deposits from airplane engine pistons and cylinders. Soft grit blast cleaning can controlled that damage critical surfaces| through abrasive action avoided while production increased about pct. Low melting point fluxes have been developed achieve satisfactory welding the magnesium base alloys containing These fluxes, containing lithium chloride, potassium fluoride, potassium chioride and sodium chloride, melt and, therefore, shield the metal suffi- ciently low temperature before any appreciable quantity zirconium oxide formed. These fluxes also provide sufficient fluidity the welding temperature insure maximum covering the metal prevent oxidation. plaster paris dies and forms with synthetic resins eliminates shrinkage either the time curing during service while increasing sistance chipping, breaking and mechanical handling encountered press work. Coal production, key factor European recovery, reached 4,200,000 tons October from the British controlled mines the Ruhr. The figure about third the best prewar figure. Stocks mines amounting about 6,500,000 tons are being converted into coke and benzine. These supplies were mostly left rail yards the moment occupation, and are just now being moved. British Indian troops are reported have been used Malayan tin producing states quell native disturbances. Placards demanding "work and food" were carried demonstrators. Ate, 4 7 7 4 i | q TABLE Cemented Carbide Face Milling Tests Wing Hinges (All Face Mills in. Diam. Teeth—Cutting Speed 524 FPM, 200 RPME) Face Face Mills and Removed Impacts Type Passes Machine Stalled 136 266 22.2 12,879 0.0054 162 13.5 160 Machine Stalled Rgh. Mill Sides 0.0067 TYPE WEAR Face Radial Axial Corner Method Mill Rake Rake Angle Holding Carbide 2—Corner Wear 3—Face Wear 15° Pos. and 10° Neg. 0.025 In. 30° Solid carbide blade wedged back rater Neg. Solid carbide biade wedged front —Slight Chipping 15° Carbide tips brazed dir 54—THE IRON AGE, November 22, 1945 | Cutter Desi Eva uate Res Feed Kee | j | | 0.0067 220 264 22.0 8,893 2,4 0.0067 120 8.0 4.851 2,4 | ° SCHMIDT Research Engineer, Kearney Treck- Corp., kee. Laboratory investigations can lead valuable conclusions which, however, often find little acceptance from production men, since controlled laboratory conditions vary widely from those exist- ing the shop. Having established preliminary tests that new design face milling cutter showed characteristics superior those general use, the author placed operation long pro- duction runs under normal shop conditions and competition with two other types recent design. reported ASME meeting Cincinnati, the findings obtained from these runs defin- itely establish the superiority the new design. NVESTIGATIONS carried the Kearney Trecker Corp. over considerable peridd time have indicated that there was defi- nite benefit derived from combining the increased strength afforded radial rake angles with lower power requirements positive radial rake angles. The chief characteristic milling cutter designed accordance with this prin- ciple the location solid carbide blade wedged into the cutter body positive secondary radial rake angle with negative primary radial rake angle imposed the peripheral cut- ting edge. Cutters this design were accordingly made and given ex- haustive tests under laboratory con- ditions. The results obtained showed con- clusively that the new design was superior any other current use, but was felt that laboratory tests were not true indication, since con- ditions were too carefully controlled. the other hand, shop tests were usually resented the machine op- erators because they tended slow down production, and the operator objected having engineer look- ing over his shoulder while was work. Arrangements were therefore made place pair the new cutters regular production job along with two other pairs more conventional design. The operator was notified that test was being conducted, but was instructed run his machine normal manner, paying more than ordinary attention the tools. 1G. operation wing hinge. Cutter has solid cemented- carbide blades located the body 15° positive radial rake angle. The job was run piecework basis, and the only requirement was that record kept the number pieces made each cutter between grindings, and that the cutters re- moved before they had worn ex- Wear 1/32 in. the peripheral land was used in- dication dullness requiring cutter replacement. duplex operation set typical application employing car- bide tipped face-milling cutters. The workpieces, aircraft wing hinge forg- ings SAE 4340 steel normalized 200 Bhn, were milled shown figs. and The first cut was ap- proximately in. long, in. wide, and 5/16 in. deep while the sec- ond cut was approximately in. long, in. wide, and 13/32 in. deep. Comparative tests were run pieces the same lot avoid, wherever possible, differences the THE IRON AGE, November 22, workpiece material and size. Both cuts were performed Milwaukee Duplex driven 10-hp motor, standard equipment with the machine. Before this investigation dertaken, cutting speed 524 sur- face fpm was established stand- ard with feeds ranging from in. per min. Feed rate was usually constant during any one test and was governed chiefly the available machine power with the resulting feed per tooth agreement with good milling practice. The cutters shown figs. and were designed according general recommendations for negative radial and axial rake angle cutters. They were two distinct types—one, fig. was the brazed-tipped design which: the carbide tip was brazed directly the cutter body and one, fig. which solid carbide blades were mechanically held the cutter body wedges. The third cutter, fig. incorporated the design features mentioned above, namely the use solid carbide blades, held the face the cutter body. wedges, set positive secondary radial rake angle with negative primary radial rake angle imposed the peripheral cut- ting edge. the first two types cutters, figs. and negative radial and axial rake angles were used. The third cutter, fig. was provided with 15° positive secondary radial rake angle with 10° negative primary radial angle 0.025 in. wide imposed the peripheral cutting edge. From the tabulated test data, table 56—THE IRON AGE, November 22, 1945 1G. 2—Dimensions cut milling sides wing hinge. Depth varied from in. 5/16 3—Dimensions cut milling hinge end. Depth 13/32 in. can seen that the double radial rake angle cutter usually produced the greatest number pieces before 4—Ten-inch face-milling cutter with brazed cemented-carbide cutting tips. Radial rake angle negative. Axial rake angle nega- tive. varied from in. dulling, and resulted minimum power consumption. There little variation between brazed and mechan- ically held carbide face milling cut- ters provided with negative radial rake angles. Workpieces produced be- fore dulling were approximately equal for the two latter types cut- ters but considerably less than the combined-angle cutter production. Since the work completed the face-milling cutter with solid cemented-carbide cutting blades. Radial rake angle negative. Axial rake angle nega- tive. two cutters about the same, choice between brazed tipped and mechan- ically held blades would based several factors not including tool life between regrinds. Among these fac- tors would the following: Initial cost brazed tip cutter less than the cost cutter designed with mechanically held blades; brazed tip cutters are often affected detri- in. | | \ 6—Ten-inch face-milling cutter with solid cemented-carbide cutting blades. Radial rake angle 15° positive. negative face and 0.025 in. wide provided the peripheral cutting edge. The wedge the back the blade provide uninterrupted chip space. are not excessive. graphical analysis these tests presented fig. order provide complete pic- ture the advantages the various types cutters tested, continuous check was kept the amount carbide used, repair, resetting, and resharpening time required for each cutter. this respect also, the com- bined-angle cutter proved su- perior. Because the machine operator was piecework incentive rate pay, was interested producing many pieces possible with one set cutters. Since the cutters shown Fig. and failed more quickly than that fig. the tendency the part the operator was run the former cutters longer than was advisable realize the maximum number workpieces between cutter changes. Because the combined-angle cutters stood well, they were usually removed from the machine when the land showed 1/32 in. wear, the machine operator feeling that satisfactory number pieces had been produced with the cutter. Before the cutters were returned the grinding department for re- sharpening they were inspected the type wear was noted shown the last column table After the data were evaluated, they helped settle number questions con- cerning comparative tool life, regrind- ing, repair, and economy the cut- ters tested. Besides the particular data ascer- tained these tests the following points were observed: Production tests, although they will not show uniform results labora- tory tests, are more convincing the shopman. Production milling tests have bet- ter chance succeeding run after laboratory tests have established the soundness and practicality new principles. Machine operators, those working piece rate basis, will co- operate investigation does not interfere with their earning capacity. Milling cutters should resharp- ened before they have completely failed; otherwise the expense re- conditioning them will higher than any advantage gained machining greater number workpieces. The cutter, fig. with solid carbide blades wedged into the cutter body 15° positive radial rake angle and provided the cutting edge with negative face small width: (1) Machined substantially more workpieces between grinds. (2) Used cemented-carbide material more economically. (3) Operated with and deflection workpiece. (4) Consumed less power shown its ability take heavier and deeper cuts without stalling the machine, and (5) Always produced acceptable finish leaving objectionable burr. ACKNOWLEDGMENT The cooperation Messrs. Wm. Guin- toli, Barczak, also the assistance Roubik and Bunce, all the company, following and evaluating these tests gratefully ac- mentally the brazing operation and grinding into the body regrind- ing operations, factor not en- countered cutters provided with mechanically held blades; blades are more easily and quickly reset for re- grinding, replaced the cutter with mechanically held blades. After analyzing these factors apparent that the cutter with mechanically held adjustable blades the less expen- sive long production runs. From the test data, table wide variation the number work- pieces produced with each set cut- ters can noted. This occurred despite the fact that the workpieces were made the same material and subjected the same heat treatment. Whenever possible two types cut- ters were applied the same lot workpieces. several instances only single set, but more often two three sets, cutters were necessary finish lot about 200 pieces. However, those familiar with produc- tion will agree that these variations NUMBER PIECES PER CUTTER FIG. 7—Graphical representation test results. RADIAL AXIAL RAKE ,CARBIDE TIPS BRAZED BODY 140 120 RGH MILL SIDES MILL HINGE THE IRON AGE, November 22, 1945—57 be- the the | / 4 the numerous brands tool steel that serve the require- ments modern industry, the group that used cold-die applica- tions vies with the cutting tool group for the place greatest importance. Not only they enter into great many manufacturing processes, but they are vital factor mass pro- duction. The metal-stamping industry repre- sents one large field for die steels, used for blanking, drawing, and form- ing punches and dies. Starting big way with the mass production automobiles, metal stamping enters into the production parts for air- refrigerators, washing ma- chines and other household appliances, tractors, farm implements, business machines and many others. The heavier stampings have replaced forg- ings castings many instances. Die steels have made possible volume production the manufacture tin cans and other types containers. Similarly, the cold heading up- 58—THE IRON AGE, November 22, 1945 setting process for making bolts, cap and numerous allied products, long tool life vital success, An- other application where much ex- pected dies the way long runs and size accuracy the production laminations silicon steel for the electrical industry. Runs these dies are often the millions. From the standpoint variety, mentioning only few, cold-die steels enter into the production collapsible tubes, photographic film and paper, pharmaceuticals, jewelry and some plastics. The principal groups die steels for cold work may divided into four groups follows: (1) Water-hardening steels (car- bon and carbon-vanadium). (2) Manganese and other low-alloy oil-hardening die steels. High carbon-high chromium steels. (4) Air-hardening die steels. Some factors affecting the selection the proper die steel include the na- ture the operation, material work- ed, production required, size change expected after heat treatment, and the cost the tool steel and its fabri- cation. The nature and physi- cal properties the four groups die steels used for cold work are de- scribed this article, along with factors affecting their selection for specific jobs. Carbon and die steels: The original material was straight-carbon tool steel (carbon approximately 1.00 pct) melted the crucible furnace. Since about 1925, the crucible process for melting tool steels has been replaced the elec- tric furnace process. spite the advent numerous alloy die steels, straight-carbon tool continues used large quantities. While some cheaper grades high-carbon steel are melted the openhearth and used tool steel, the better grade, which preferred for dies, electric furnace melted from good raw mate- rials. has wide hardening range —which means that although usually hardened about 1450°F, may heated high 1500° 1550°F without excessive grain coarsening. When hardening, carbon tool steel requires rather drastic quench water brine most cases. Except small sections, carbon tool steel after quenching develops hard case limited depth with softer core. This duplex structure gives the de- cided advantage absorbing more shock which harden through the section. the other hand, readily apparent that dies and tools redressed grinding, the number regrinds limited the depth case. account requiring rather drastic water quenching, warpage and relatively large change dimensions hardening are often problems with this grade. the case intricate shapes, there may considerable haz- ard cracking. These hazards, to- seq the | | | range. Die Steels For gether with the volume production required are the principal factors that determine whether water-hardening steel will used for die. Conditions vary greatly different plants. Some are partial the use water-hardening steel and get with jobs where another would use oil air hardening. general, medium deep-hardening carbon tool steel desired for die work this means more grinds before the hard case removed and there less chance soft spots. the other hand, there are jobs where shallow hardening steel preferred large sections order keep distortion minimum. The carbon-vanadium type closely allied the straight carbon its properties. will develop high de- gree hardness quenched, but used mostly where less hardness and great toughness required. Con- sequently, usually drawn back considerably after quenching. This type has the advantage remark- ably wide hardening range owing the fact that vanadium resists grain growth. This makes suitable for cold-header dies and others that give best results when hardened tem- peratures considerably over the criti- behaves just like straight carbon. Resistance shock and fatigue one its most important properties. Manganese oil-hardening die steels: die work grew more complex and exacting, the need for steel that Work would less subject warpage and deformation that straight carbon be- came more This led the development one the first alloy tool steels—usually known the manganese oil-hardening, non- shrinking non-deforming type. The analyses made the different mills vary somewhat, but all carry approxi- mately 0.85 0.95 pet carbon. Man- ganese the principal alloying ele- ment and ranges from low 1.00 With the lower manganese content ap- proximately 0.50 pet chromium and tungsten are carried with without vanadium. With the high manganese there may small vanadium molybdenum content. The oil-harden- ing property largely due man- ganese and result the less severe oil quench, fewer hardening cracks and less warpage are encoun- tered than with many other types tool steel. Being eutectoid composi- tion, the simple carbon-manganese steel hardens comparatively low temperature. This very desirable the lower the less scaling and change dimensions. With man- ganese the only alloy, the tempera- ture range for proper hardening limited. mainly widen the hardening range from which refined fracture can obtained, that addi- tions other alloys have been made. the same time this has meant that the steel has quenched from higher temperature develop full hardness. WILLS Metallurgical Engineer, Allegheny Ludlum Sieel Corp. When properly quenched oil, this type will become file hard sections ordinary size. The maximum hard- ness thus attained slightly less than straight-carbon steel water brine quenched. will harden deep any the low-alloy tool steels, al- though not deep high carbon- chromium high speed. This steel absorbs heat slowly, and the practice preheating intricate large dies dull red (1100° either the hardening furnace desirable, be- fore bringing the hardening temperature. The oil bath should ample volume and warm for uni- form quenching. tempering after quenching there very little change hardness with draws 350° 375°F. The de- crease becomes more pronounced with draws 400°F and over. draw about 375° 400°F results the nearest approach the original size. Overheating with accompanying grain growth results increased change dimensions. most the applica- tions for this type require rather high degree hardness, drawing tem- peratures are seldom over 425° These steels have low resistance shock impact, which ex- pected because their deep-harden- ing properties. However, they develop quite high compressive strength. These combinations properties make this type very good steel for plug, ring and thread gages, intri- 4 LEFT - THE IRON AGE, November 22, | q t ial q 25, ls, 3 4 ile on q e, | cate blanking and forming dies, and numerous tools not subject heavy pose oil-hardening steel for the tool room. Although there has been con- siderable development air-harden- ing die steels, large amount man- ganese oil-hardening die steel still Other oil-hardening die steels this group include the low-tungsten- chromium types which are used for much the same applications the manganese types, but their use not widespread. They require some- what higher hardening temperature than the manganese steels and large sections are not apt harden uniformly. other words, the effect mass the hardenability more pronounced. High-carbon high-chromium die steels are later development die steels and were intended meet the increasing demand for better wear and resistance abrasion than the carbon and manganese types. The first steels this type the market had range pet chromium with other alloys. The straight-chromium type with car- bon over 2.00 quite low tough- ness and for the purpose improv- ing this, later analyses have come out with additions vanadium and nickel. Other additions have included co- balt and molybdenum, the latter im- prove the air-hardening property. The types now the market can di- vided into two groups: the oil and air- hardening types. The oil hardening higher carbon content— usually 2.00 2.50 the air hardening runs about points lower carbon. Both carry about the same chromium content. The air harden- ing carry about 0.75 1.00 pct 60—THE IRON AGE, November 22, 1945 RIGHT VERHEATED LEFT ROPER hardened structure car- bon and manganese steel. structure manganese oil-hard- ening steel. 500X. molybdenum and die sections ordi- nary size will harden still air more. These steels are very dense and have resembling high- speed steel and they have rather limited forging range. They absorb heat slowly and because numerous carbides must into solution for proper hardening, they should held for considerable time the harden- ing temperature before quenching. Unless controlled atmosphere fur- nace available, pack hardening recommended which slow heating and the surface protected during the long heating cycle. The oil-hardening types develop high degree hardness quenched, usually least even large sections. The hardness general slightly more than the air hardening for given section. After tempering, the hardness maintained better than with the low alloy tool steels. Even with draws 900° 1000°F, hardness over obtained. The high carbon-chromium are very deep hardening and may counted harden through any sec- tions ordinary size. The toughness impact value these steels low, particularly the size increases. This should taken into account the design dies made from steels this type. ample factor safety should provided with reference the maximum stresses involved. Very large sizes should avoided build- Large drawing forming dies should, general, have heavy back- ing tough steel. These steels are considerably hard- machine, file and grind than straight carbon and the low-alloy die steels, might expected, due their high alloy content. The air-hard- ening steels machine somewhat easier than the oil-hardening types. They are distinguished very high resistance wear abrasion, which roughly proportional the carbon content. This along with their good nondeforming property make them unsurpassed for die work where high production first importance. The applications this type are interest account their variety and the economy effected through the high rate production obtained. Blanking and cold-forming dies perhaps their most general application. The material worked ranges from light-gage silicon sheet steel plate 3/16 thick more. One report comparison this type with carbon tool steel blanking silicon sheets 0.019 0.025 in. thick showed three one production over straight car- bon with die cost per million cuts reduced over pct. Other important clude drawing dies, cold-forming rolls, thread-roller dies, burnishing and trimming. dies. Air-hardening die steels: The air- hardening die steel group represents the latest development steels. these, the high-carbon high- chromium air hardening described previously the original one this group. improvement over the oil-hardening steels that there less change dimension after hard- ening with the less drastic cooling air, greater toughness, and cracking hazard practically nil. The pet chromium and manganese -air-hardening steels that have re- cently come the market are intend- manganese oil-hardening steels and the same time less expensive than the high-carbon chromium steels. From the standpoint, these . Col bee cas ste the « 4 | | | | . i steels are more difficult handle than the manganese oil-hardening types, and they are more difficult machine. The chromium types are hard- ened somewhat similar the air- hardening carbon-chromium, except slightly lower temperature—namely, about 1750°F and not over 1800°F. The manganese air-hardening types have the advantage hardening about the same temperature range many the manganese vil-hardening steels, namely, 1450° 1550°F, which means less scaling and distortion. They are rather deep hardening and develop more toughness than the oil- hardening die steels. All have excel- lent non-deforming quality. resistance wear and abra- sion, they are intermediate between the manganese oil-hardening and high types. This group, being comparatively new, has not yet been widely used the manganese oil-hardening steels although the number applications constantly increasing. Their use _will become more general they are more readily available from ware- house stocks. Large Steel Castings West Coast Plant HEN the war started there were steel foundries the Pacific northwest capable producing large marine castings such stems, struts stem frames. The Columbia Steel Casting Co., Portland, Ore., whose previous experience had been producing relatively small castings, took over the operation foundry facilities provided the DPC. This new work raised the castings capacity the company 1000 net tons per month. the peak wartime demand, many Lib- erty stern cranes were produced per month, more than one day. Most the castings weigh from 20,000 42,- 000 Ib, each requiring 25,000 70,000 liquid steel per casting poured green sand molds. order meet the demands for these large steel castings, two electric melting furnaces wére installed. One melt, the largest electrical furnace the used solely for producing steel for casting. melts about tons charge per hr. Heats from 60,000 90,000 represented the average range, the maximum being slightly over tons. This stand- ard top-charge furnace with swing roof. Instead the usual bucket magnet used for charging. smaller furnace with maximum practical capacity tons was built the plant the Green Electric Furnace Co., from such scrap mate- rials were available. The trans- formers which were built the local electrician from three scrap cases 1500 each have given excellent ser- vice. This furnace charged from the top simply lifting the roof off with overhead crane. functions Electrodes measuring in. diam 5-ft sections are used, electrodes consumption being about per ton charge. Electric energy con- sumed runs about 485 kw-hr per ton charge. The melting cycle, from tap tap, hr. Both furnaces are acid lined. For the most part, steel plate scrap from the shipyards was charged the furnaces, the average analyses steel poured being 0.70 manganese, 0.21 0.24 carbon and 0.40 silicon. The mechanical properties were follows: Tensile strength, 60,000 70,000 psi, elongation and large steel casting, tanker stern-frame center section, made Columbia Steel Casting Co. which formerly had produced relatively small castings. Finishing touches the drag face before casting tanker center section. THE IRON AGE, November 22, | | i | 7 q j § t Ray Standards For Purchasing Castings Agreement castings accepted can greatly furthered interpreting non-homogeneities radiographs accord- ing the criticalness the area which located. ROM the consumer’s, engineer- and purchasing points view, the greatest disadvantages specifying castings are the unpre- dictability internal discontinuities and the limited degree which test bars represent the metal quality the corresponding cast parts. Purchase orders, general, have been based specifications that did not define, satisfactorily, the limits defect acceptability. Such specifica- tions have not prevented arguments arising after the foundry had large investment fabricated castings. fact, some cases there has not been 62—THE IRON AGE, November 22, 1945 agreement even what names use for the defects that were revealed, nor whether they should have any sig- nificance judging the acceptability the article “Controlling Quality Steel Castings” John Juppenlatz 50. the case light alloys, the prin- cipal reason that test bars not rep- resent satisfactorily the quality the actual casting, because, general, the cooling rate the casting much slower than the test bar. Also, the LESLIE BALL Assistant Technical Director, Triplett Barton, Inc., Burbank, Calif. ° feeding conditions most sections the casting are inferior those the gage length the test bar. These dif- ferences become most important when the melt contains excessive amount dissolved hydrogen. With such gassy melts, the physical properties the test bars may well within the specification but the physical properties coupons eut from cast- ings may fall far below the pct al- lowance. Fortunately for the con- sumer, high-quality radiography re- veals the condition the melt re- gard these gas porosity conditions and combination radiographs and ray micrographs can used satisfactory purchasing standard. ray micrographs are helpful bring out details the gas porosity type defect, consisting micro- ing critical from noncritical areas for determining castings acceptance. all regions the cast- ing, other than the enclosed the circles, defects lorger the crit- but smaller than the non- critical standard can accepted. How- ever, any defects that would intersect the face may have read the crit- ical standard. a | | | } ; | | — | standard defect sample mounted plastic shown with its radiograph. The sample piece enclosed the 2-in. rectangular plastic block. The white rectangle corresponds slot the plastic block which the file card the zinc tape used for describing the block can inserted. The example shown propagating defect, identified hot tear. cavities that are sub-visible size. The simplest possible method picking out radiographic illustrations choose certain size intensity defect, independent its location the size function the part which existed. However, two fac- tors make the simplicity the single standard impracticable. The first these factors that casting there are often noncritical areas which not undesirable accept quite large defects. There are also highly critical areas, such at- tachment lugs, which only quite small defects can tolerated. Sec- ondly, common foundry experi- ence that while possible keep defects out specified areas, often not possible eliminate them altogether from certain casting. workable compromise between the complexity multitude static test standards for each part and single standard for all areas all castings, designate the criti- cal and noncritical areas and then pick out sizes intensities defects than can accepted the critical areas and pick out much more gen- erous illustrations that can ac- cepted the noncritical areas. Fig. shows method that has been developed the Lockheed Aircraft Corp. for distinguishing between these critical and noncritical areas. this typical aircraft casting, two bosses shown the side drawings are critical and have free from any but minor defects, while the rest the casting, mod- erate defects can accepted. Fig. illustrates method pre- paring radiographic illustrations for critical and noncritical areas that has been developed the laboratories Triplett Barton, Inc., Burbank, Calif. When the image suitable discontinuity metal quality condi- tion seen production radio- graph, the part obtained and the affected section cut out band saw. For use standard, area, 3—Typical radiographic standard illustration for discrete defect. The image this dross hole characterized uneven blackening and fairly well defined boundary. THE IRON AGE, November 22, Re 7 J | in. sq, containing the discontinuity, cut two spaced milling cutters. One-inch squares sheet metal are attached bring the total thickness standard. Then the metal as- sembly placed cellophane mold and sunlight-setting plastic cast around it. The cast plastic blocks are durable and their size such that they can filed conveniently ordinary filing cabinet drawer. Each piece radiographed and the picture, together with description card attached the piece standard defect sample file. For any particular purchasing problem, for use part gen- When radiography used detect these propagating discontinuities, still necessary have illustrations that the foundryman and the con- sumer will agree that certain radio- graphic appearance actually does rep- resent propagating discontinuity. For general use hot cracks tears, cold cracks, cold shuts and jagged shrink cavities are specified propa- gating. certain alloys, where eutec- tic partially fills tear opened stress, the defect called stress gation also included. Fig. may propagating discontinuity. Discontinuities which consist 4—Typical radiographic standard for dispersed defects. The diffuse globular images distributed over the whole sample area are due gas porosity aluminum casting. eral specification, the available films are studied and pieces are selected and assembled together within standard area. Then ra- diographs are made the assembly. this means one two radiographs are sufficient provide complete standard set illustrations. Most discontinuities that consist sharp cleft the metal are recog- nized just cause for absolute rejec- tion repair casting. the consumer these defects are objection- able because they produce stress con- centration and they are liable cause failure propagating through the casting. Many purchase orders re- quire automatic rejection castings containing propagating defects. 64—THE IRON AGE, November 22, 1945 three dimensional cavities containing gas foreign material mixture both are objectionable either be- cause they show the machined sur- face because they reduce the area the section through which fracture may occur. Such defects occur either singly groups. From the con- sumers’ point view, these defeets are well described the general title discontinuities.” Fig. shows standard for dross hole. The image identified its shape and blackening pattern, but as- sessed mainly the basis its area the radiograph. Dispersed discontinuities consist minute voids scattered throughout all considerable portion the cast- ing. For example, the minute grain boundary cavities known magne- sium microshrinkage and the small pin holes known gas porosity aluminum castings, are types dis- persed discontinuity. radiographs these conditions show peppering darkened pattern. Dispersed discontinuities may occur practically all cast alloys, but only the light alloys that they have assumed position major impor- tance. When melting practice permits hydrogen absorption into the melt, much all light alloy ra- diographic rejections may due these minute voids. Fig. repro- duction standard for gas porosity noncritical areas. this illustra- tion the ordinary radiograph provides satisfactory standard, but other the ordinary radiograph may require very great skill apply be- cause the indications are quite minute. these latter cases that ray micrographs may used pur- chasing standard bring out great detail the limit the condition that acceptable. For use purchasing standard, ray micrographs should pre- pared the following manner. normal casting section any thick- ness representing the maximum ac- ceptable degree for the dispersed de- fect should selected. This selection may based correlation normal ray appearance with strength tests cal section. slice between in. and 0.030 in. thick should cut high-speed cut-off wheel mill- ing cutter. The slice should then grained film and the photographic print made diam magnifica- tion. Where the graphic appearance requires skilled interpretation barely visible im- ages, the ray micrographs are easy judge. The purchasing specification should state that, case disagreement ordinary radiographic rejections heat castings for dispersed defects, final disposal shall depend upon com- suitable slice from representative casting with the standard. course, the purchasing specification could use metallography the same way, but the ray micrograph method more workable because the results are al- most independent preparation tech- nique and exact slice location. | | | | | | | | | | | | | | | Blasting Cylinders ALBIN Associate Editor, THe meal, ground apricot pits, cracked wheat, clover seed, and plastic powders are some the mate- rials which American Airlines engi- neers have been testing the main overhaul base, Guardia Field, New York, new process blast clean- ing and polishing cylinder heads, pis- tons, baffles, and miscellaneous parts. Which the best grit and the most economical are questions that further testing and trials will supply an- swer, but the materials and process engineers American Airlines are greatly intrigued with the possibili- ties coffee. With very altera- tion available sandblasting equip- ment and using cleaning grit the coffee grains which result waste product extraction process, Gil- bert Brower and his staff have been able boost their production pet, and found that they could meet cylinder maintenance requirements with only one half the manpower for- merly occupied sandblasting. Cylin- ders and pistons (from cylin- ders per engine) are completely overhauled and inspected the Guardia base after every 800 flight. view 300 pct increase the number engines expected ovedhauled within the next months, great emphasis being grounds, coconut shell process. The great advantage soft-grit Soft-Grit critical surfaces and parts cylinders with rubber gaskets and plugs, great time-consuming opera- tion, was abandoned American Airlines when changeover was made from sandblasting soft-grit blasting. Coffee grounds, among other soft grits, are being used former sandblast equipment American Airlines remove carbon de- posits from airplane engine pistons and cylinders. increase production amounting pct using only one-half the manpower when sandblasting has been attained this method which mini- mizes abrasive damage critical surfaces. blast cleaning the control the abrasive action that damage crit- ical surfaces avoided. The hard carbon and oxide deposits relinquish their hold the piston surfaces with almost the first pass the blast hose. Unlike sand, there scratching the precision ground cylinder liners, valve guides, the softer alloys the pistons. Hence the first great sav- ing time that formerly required masking parts and openings from the abrasive action the sand. This en- tailed protection rubber gaskets and plugs (fig. 1), job that had done with great care certain that none the fine sand would dam- age areas subject abrasion sand. Before the parts come for soft- grit blast cleaning they are given pre-soak solvent solution which attacks the resins that bind the car- bon the surfaces. Formerly, when sandblasting pistons the soaking pe- riod lasted hr, but with the soft grits, the soaking period has been re- duced somewhat. The removal oily occlusions helps prevent contamina- tion the grit. Cylinders are placed the same fixtures used for sandblasting (fig. 2). The blast chamber and operator’s equipment are also the same. The lighter material sucked off the exhaust fan the upper portion the chamber. Air pressure applied varies between psi and psi. Mesh sizes vary between and 60, depending the type grit used. the case coffee, mesh the THE IRON AGE, November 22, 4 j a = XY N —_ 4 q | 2—Blast cleaning with coffee grounds the Guardia field overhaul base American Airlines. Note the exposure openings and stud posts the action the soft grit which easily removes carbon deposits but does not abrade the critical surfaces. Equipment formerly used sondblasting average. ground size for American Airlines after obtained waste product from coffee ex- traction and concentration factory. Further investigation may reveal that this source may supplemented quantities unuseable coffee grades South America. fig. shown the pouring the soft-grit material into the suction receptor. American Airlines correlating its findings with the results received from other sources testing such materials. Considerable data being amassed that based the following charac- teristics grit materials: (1) Explosion hazards IRON AGE, November 22, 1945 nition characteristics. (Cracked wheat, for example, requires special precautions.) (2) Storage properties; vermin and water effects. (3) Service life and economy; breakdown grit; pounds per unit cleaned. (4) Particle size; dust and sieve analysis, before and after cleaning. (5) Particle shape; grinding shape and size. Granular and sharp outline sought rather than shreddy and round. Retention shape after cleaning compared with shape particles before working. (6) Contamination; presence oily residues, sand the original material. (Sand derived usually the course gathering some products.) Furthermore, application affected the pressure and volume the air, particle size distribution and shape, and the moisture content which counts factor line clogging. Price these new grits im- portant factor that may balance ad- vantages experienced time and la- bor saving. this respect, American Airlines find that soft-grit products vary from 50¢ per One dis- advantage the case coconut, one the least expensive materials, that sand may sometime get attached the fibers the shell they are picked off the ground. The coconut meal appears furnish good results altho