The Iron Age 1944-11-09: Vol 154 Iss 19

ype Cast chonteric Inc. ate design are ced the machining. duct plons. NEW YORK ILLINOIS VAN DEVENTER President and Editorial Director Vice-President General Manager Editorial and Advertising #00 42nd St., New York Johnson, Market Research Hayes, Production Manager. Baur, Typography and Layout ° Business Managers New York New York East 42nd St. 100 East 42nd St. ROBERT BLAIR GIBBS Cleveland Pittsburgh HOTTENSTEIN Chilton 1134 Otis PEIRCE LEWIS WARREN Detroit Hartford Conn. RAYMOND KAY Los Angeles 2420 Cheremoya Ave. ° ° Owned and Published CHILTON COMPANY Offices Chestnut and Sts. Philadelphia 39, Pa., U.S.A. OFFICERS AND DIRECTORS MUSSELMAN, President HILDRETH GRIFFITHS TERHUNE BAUR WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JULIAN CHASE THOMAS KANE DUFFY CHARLES HEALE Vice-President Member, Audit Bureau Member, Associated Business Papers the Industrial Arts Index. Pub- every Thursday. Subscription Price North America, South America and Possessions, $8; Foreign, year, Single Copy, 1944, Chilton Company Vol. 154, No. Editorial The Empty Technical Articles Equipment and Material for Precision Casting Drawings Printed Metal With Layout Paint Supersonic Measurement Metal Thickness. Tiny Internal Cam Miller Devised What Quenching Oil Not Adjustable Racks Speed Aluminum Anodizing Gear Mfrs. Discuss Hobs. Approval Precision Thread Rolling Practice (Part High Speed X-Ray Camera Benefits Ballistics Indirect Lighting System Provides Ft. Candles New Equipment News Front Assembly Line Washington West Personals and Obituaries Fatigue Cracks Dear Editor This Industrial Week News Industry News and Markets Russian Tool Orders Threaten Domestic Light Gage Metal Invades Lumber Field American Can Forms Research Group Canadian Steel Output Trends Downward Norman Foy Leave German Metals Immediate Sales Surpluses Urged. Aluminum Killed Steel Extra Vulnerable Alloy Steel Branch Dissolved Machine Tool Market Developments. Non-Ferrous Metals News and Prices Iron and Steel Scrap News and Prices Comparison Prices Week and Year Finished Iron and Steel, Steel Prices Warehouse, Semi-Finished, Tool Steel Prices Steel Pipe, Tubing, Wire Products, Prices. Pig Iron and Coke Stainless Steel and Ferroalloy Prices Index 101 103 103 104 104 107 108 112 112 152 154-155 156-157 158 159 160-161 162-163 164-165 166-167 233 | 7 | 4 101 ° ° | | | ° ° ° q q Mahon Hydro-Foam Dust Collectors have done outstanding job assisting industry achieve truly amazing war production record. Take, for example, the installation shown above—part huge battery Hydro-Foam units—used effectively and economically remove the dust from machining operations aircraft propellers. Because working areas have been kept clear dangerous aluminum dust, production has been greatly accelerated. The health workmen has been protected. vital importance, also —from strictly dollars-and-cents point view—is the fact that monetary loss incurs. This same dust-collecting system can converted peacetime operation—without delay —and with but minor expense for possible changes duct work. assistance Mahon engineers available any plant now operating Mahon Hydro-Foam Dust Collecting System adapting after-the-war production—or any plant that requires superior dust collecting mechanism for both immediate use and for peacetime operation. Mahon Hydro-Foam Dust Collectors manufactured standard units ous capacities which can used singly multiple meet any requirement, ply Units Hydro-Foam Dust Collectors—and Units ro-Foam Dust Collectors—and Units Production Equipment—including Complete Finishing ESTABLISHED 1855 VAN DEVENTER President and Editorial BAUR Vice-President and General ° ° ° DIX Manager, Reader Service ° Editorial Staff Associate Editors WINTERS ALBIN JOHN ANTHONY JACK HIGHT BARMASEL Editorial Assistants SCHIEN WILLIAMS O'CONNOR MILLER News Technical Editors LLOYD Pittsburgh 428 Park POST Chicago 1134 Otis MOFFETT DONALD BROWNE EUGENE HARDY Washington LLOYD 1016 Guardian Bidg. Detroit 7310 Woodward Ave. OSGOOD MURDOCK San Francisco 1355 Market St. Editorial Correspondents ROBERT SANDERSON Toronto, Ont. .RAYMOND KAY Angeles JOHN McCUNE Birmingham ROY EDMONDS Louls JAMES DOUGLAS Seattle Cincinnati Buffalo FRAZAR are Boston used singly Milwaukee The Empty Chair HERE are some four million empty chairs the tables American homes today; chairs which not long ago were occupied our be- loved sons and brothers. And already, though the second front still come and have hardly begun fight offensively, many these chairs will never again occupied. There real democracy these empty chairs. They are found the homes the rich and the poor; the employer and the laborer. But sheer arithmetical weight numbers, there will far more these permanently empty chairs the homes labor than all other categories. For today have over million workers our labor forces. And that means per cent all the men and women between the ages and 59. Each one us, matter what his station life may be, respon- sible for doing everything his power help win this war. respon- sibility not merely equal that the soldiers and sailors who are going abroad fight for their country but one that even greater. greater because they are risking their lives and many instances will lose them. greater because they are subject established discipline while must depend self-discipline. Self-discipline not easy thing exercise democracy that has been based upon individual freedom. Yet must attain here home our daily work hope match the totalitarian efficiency the Axis powers. have not yet achieved that self-discipline here. had, would not hear per cent absenteeism some our war production plants. Can you imagine such things this happening the war production plants the Axis powers? Can you imagine German Japanese mechanic machine operator taking day off from work each week be- cause happens feel bit under the weather because big wages are burning holes his pockets? This not problem that management can solve. personal prob- lem for labor. perhaps, some instances, for labor unions. The American public, which labor such large part, will cheer- fully without meat coffee gasoline. will buy bonds the limit and undertake tremendous tax burden. will even resign itself the drafting our 18-year olds, most whom seem like babies their fathers and mothers. But the American people have the right expect that every man will his duty. And home that duty put every possible working moment. It’s not too much ask view our established working week. Remember, friends, empty place the bench machine may mean empty chair after this war somebody’s home, perhaps yours. This editorial appeared originally the issue Oct. 29, 1942. repeated for two reasons—first, because cabled copy for current editorial had not been received from Mr. Van Deventer press Mr. Van Deventer enroute from England this country. And sec- ond, because slowdowns due over-optimism give the editorial even greater significance than had two years ago, when was written. Time necessitates only two changes. “Four million empty should read “eleven million empty chairs,” and “54 million workers” should read “61 million.” j 4 ; Nov. 1944 q | Poy by q 1 7 q J q { il ilte od Air: : nishing Round-the-Clock Carloading Inland Carloading and prompt dispatch cars from the mill are important Inland because they are im- portant Inland’s customers. These round-the- clock jobs have been intensively studied, resulting improved packaging and carloading despite full rolling schedules, shortage some types railroad equipment, scarcity bracing, etc. When order ready for shipment, cars suitable types are ordered into the mill. Cars loaded with the product one mill are spotted that mill. When carloads are composed products from two more mills, loading speeded spotting car one mill and trucking the products other mills the Throughout each hour the twenty-four, expediters keep steel flowing loading points and soon cars are loaded, they are switched the railroad yard where they are assembled for quick dispatch our customers. invite you confer with Inland ship- ping specialist. will gladly study your loading, unloading, and shipping problems, giving you all available assistance under the conditions war, and helping you plan for speedier and more convenient delivery steel for use time peace. Bars Floor Plate Piling Plates Rail Reinforcing Bars Sheets Strip Structurals Tin Plate Track Accessories INLAND STEEL COMPANY Dearborn St., Chicago Illinois Sales Offices: Cincinnati Detroit Kansas City St. St. Paul : News November 1944 Automobile companies are beginning place orders for steel and parts for passenger car production. Deliveries schedules have been weeks mfollowing Some shipments will made two weeks after which ably will shortly after the defeat Germany. Between the automobile, stove and refrigerator manufacturers about half million Mdollars worth business has been placed. One company placing these orders for and parts has specified that prices will the same those charged other manufacturers for the same quality and quantity. odd aspect the Japanese war that there are known Jap air aces. Perhaps are aces. Despite many propaganda broadcasts from Tokyo, Jap pilots are name Americans fighting the Pacific. The British Government will have about thousand factories turn over after the war. Like the American plan, disposal many these plants now being arranged without regard exact time the properties will available. the American plan, the British procedure involves ten-year leases with sales. Government crutches business England after the war will far more pro- nounced than this country. council has been set help industry design and another being formed keep constant check retail variables. through flue, the furnace gases are withdrawn through permeable wall tories. sparring nail down export outlets continues occupy much the attention various groups England and the Great Britain now exporting the amount billion and quarter dollars compared with three billions for Thus: Great Britain doing larger commercial export business today than S., based per capita basis. But, even though many American exporters think they are being stung, the British business man equally convinced getting The drafting British civilians work coal mines has its difficulties. 18-year old boy was sentenced two months' imprisonment for refusing the pits, and expressed preference for the prison sentence. But, after quick visit the prison changed his mind and went the mines. The Russians are not limiting their machine tool purchases new equipment but are now going through midwestern plants, looking pieces already installed but not very much demand and buying them for immediate shipment the U.S.S.R. ip- The extra ton medium gages aluminum killed steel, now well lished Detroit, will probably result considerable haggling when passenger car production resumed. Automobile companies will take the position that prewar days such extra was never charged, that mills should able deliver ing sheets the same quality prewar, and that after all there way their being able tell whether they are getting aluminum killed steel simply ordinary low carbon deep drawing sheet. The steel companies can counter that the residual alloys likely present Steel for some time after the war make stabilizing the metal absolute necessity breakage deep drawing not rise prohibitive levels. this they will have practical proof back them because purchasers steel may find breakage unprecedented proportion. The War Department has announced that battlefield scrap iron and steel will longer returned from overseas theaters because the improved domestic supply because the considerable labor involved has resulted some cases delays ship= time. Two furnaces unusual design have been use England for sufficient time promise notable fuel savings. Instead the products combustion being i $4 > q 4 F 4 § : q 4 : Equipment and Material for YEAR two ago when indus- trial firms first began make use the precision technique (“lost wax”) process for ferrous and non-ferrous metals, they often had devise their own equipment because existing apparatus had been developed primarily serve the manufacturers jewelry and dentures who had been using the process for years. Within recent months, however, great deal casting equipment especially de- signed for industrial applications has been placed the market. Some the centrifugal casting machines rep- resent adaptations dental machines which have been greatly increased size and capacity and have been mo- torized. The original dental units were spun spring motors such are used phonographs. What perhaps even more signifi- cant that industrial equipment mak- ers totally unknown the jewelry and dental trade have appeared the picture. Among them are manufactur- ers induction heating apparatus. Melting small batches metals was “natural” for induc- tion heating because its speed and cleanliness. Several companies this field supply not only the crucibles, in- ductor coils and generators but the centrifugal casting machines well. the other extreme, least one maker large centrifugal casting machines for general foundry work soft metal mold, using Kerr “Rapid the left, Rapid Stone poured above modeling clay matrix retaining the master part; right, mold inverted and the collar with plunger are placed hydraulic press and perma- nent matrix made the soft 52—THE IRON AGE, November 1944 has brought out smaller unit for precision casting heated refractory molds. The readers THE IRON AGE may refer the case histories two man- ufacturers who designed much their own equipment, the cision Castings Turbosupercharger Buckets,” issue Feb. 10, 1944, and “Industrial Precision Casting Manufacturing Jeweler,” issue Sept. With the equipment about de- scribed metal parts weighing from ounces lb. more are being cast shape within few thousandths inch size, the tolerance depend- ing the size the pieces. Before describing and illustrating the avail- able equipment for this application, will well review the process itself. Casting Procedure Essentially the precision casting en- tails first the reproduction the piece wax, which accomplished in- jecting melted wax into mold made either soft metal steel having cavity the exact dimensions the piece. steel mold used large runs wax patterns can made with higher degree accuracy than possible with soft metals. Each wax pattern then utilized refractory invest- molding material called the ment. After the patterns are sprayed with what amounts facing sand, the procedure pour the invest- ment mix over the wax patterns at- tached central gate wax. some set-ups the gate set onto rubber base, called having annular ring for holding flask made heat resistant alloy steel. After the investment has hard- ened will have encased the wax pat- terns intimately without compression distortion. The rubber base then removed. Elimination the wax without residue accomplished placing the flask cold oven and heating gradually 1300 deg. over vaporize it, inverting the mold over steam table and thereby melting the wax out. After the molds are cooled down lower temperature proper for cast- ing the particular metal, they are placed centrifugal casting chine which sends the molten metal into the cavity originally occupied the wax. should noted, however, that since the molds are poured temperature roughly two-thirds that the melting point the alloy, the flasks are sometimes raised tem- perature high 1600 deg. the case non-ferrous, refractory al- loys like Vitallium metal, almost uni- versally used for turbosupercharger buckets. The castings are separated from Electrically heated machine for in- jecting wax under air pres- sure into mold, through the needle valve nozzle cated lower plate. prayed sand, invest- at- ax. onto holder, ding alloy hard- pat- ression then and and own cast- are ma- metal that oy, the tem- al- uni- from for in- air pres- through plate. Precision Casting the investment dipping water steam pressure after stripping the flasks. When the procedures are properly controlled, the castings come out with sharp edges, good surface and high accuracy. reproduce the wax patterns models large quantities and having the dimensional accuracy for preci- sion work, the steel mold the best answer, although soft metal molds are still being used some the largest production jobs. the experience one casting firm, many 60,000 wax patterns can made before signs wear are apparent the steel mold. Steel molds will withstand higher pressures that may used inject the wax, especially the case hydraulic machine. Because the steel sectional mold makes demands the greatest ingenuity and skills the toolmaker, the bottlenecks cast- ing production are often located here. Soft Metal Molds The soft metal molds suffers amount distortion after repeated injections wax. But its construc- tion fairly simple compared that steel mold, and also certain prac- tices help overcoming the distor- tion degree. The customary prac- tice make mold the master part two pieces soft metal, which becomes the die into which the wax forced. Soft metal molds are gen- erally made the hobbing process which has been used for over years the manufacture plastic molding dies. producing the latter, the hob made tool steel the dimensions the part molded and hard- ened. The hob then mounted the upper platen press and forced into the soft steel die blank which soft metal (bismuth alloy, Woods metal, Cerrobend, Cerrobase, type metal, etc.) dies similar that the master piece becomes the hob and forced into the metal the parting line. Where the end product circu- lar, the master may turned lathe and polished. then sunk its center line form each half the wax mold. The Kerr Dental Co., 6081 12th Street, Detroit employs technique ° ° ALBIN ° Products offered manufacturers—among others—that have typical uses precision casting the “lost wax" process are described the first two-part article, which contains great deal hitherto unpublished data details the technique. for making soft metal molds that based the use its “Rapid Stone” similar artificial stone. Through the use Rapid Stone temporary holder, the scratching the master part overcome, hazard which liable occur the process mak- ing the soft metal mold directly the hobbing process. Accordingly, the bottom half the part put ordi- nary modeling clay pliable wax which can easily leveled off and scraped clean without scratching the surface the part. The part and modeling clay base are placed circular frame collar serving chamber for the pouring, see Fig. Rapid Stone then poured into frame. This product like plaster, but much smoother and harder. soft paste formed mixing 100 grams vacuum chamber remove air; vi- bration hastens the elimination the air bubbles. After this operation, the mixture retains proper consistency for pouring for period min. After the Rapid Stone has hard- ened (in min.) the combina- tion inverted and the modeling clay removed. The chamber, composed the collar wall and the hardened Rapid Stone with the imbedded part, now filled with low fusing metal. Immediately preheated plunger placed over the metal, hydraulic pres- sure about 10,000 Ib. per sq. in. applied. When the metal has hard- ened, ejected from the frame and mold has been formed one half the part. The foregoing steps are repeated accomplish the other half the mold, except this time the Rapid Stone removed and the first half serves base for the second pour. Before pouring the second section, 3—Flasks for retaining molding material and wax patterns. Diameters flasks shown vary from in. Soft rubber sprue holder lower left used hold wax models mounted central gate sprue. THE IRON AGE, November 1944—53 Percentage expansion | | | indented identification marks are placed the first half the mold and land surfaces are thoroughly cleaned with emery cloth. The master pattern left place during this cleaning process and the surfaces are worked down the parting line. also advisable indicate numeri- cally, the outside surface the side wall the first section, the dis- tance from top bottom. Otherwise, after the second section the mold the parting line. Separation the surfaces obtained using pow- dered graphite parting medium. Plugs steel brass are inserted undercuts, holes, etc., or, when necessary, undercuts are blocked off covering them with Rapid Stone. When more than two-piece mold indicated, additional sections are made the same manner. Pattern Waxes Much research has gone into the de- velopment the wax that used for making pattern model the item cast. Because essential that the wax possess definite characteris- tics, the correct pattern wax has been developed blend out number commercially available waxes, each which contributes its peculiar use- fulness. many six types wax into the blending some the pattern waxes now available. One the essential characteristics required the wax that can evaporated from the investment with- out any residue. When the flasks containing the investment and correct pattern wax are heated tem- perature 1300 deg. and above, 54—THE IRON AGE, November 1944 ° ° ° LEFT ex- pansion age curve the invest- ment material, balite. RIGHT 5—Vacuum pump with removing air bubbles from the poured investment. Note the spring support the table for impart- ing vibration. QE ° ° ° deposit should remain. The presence such deposit might, course, contaminate certain metals. The wax, next, must possess low shrinkage upon solidification. must have sufficient tensile strength and hardness surface withstand bench handling without breaking chipping. The rate solidification important. hardens too rapidly, the pattern might break removing from the mold. Hence, the wax must the kind that chills uniformly. Waxes now developed hardly cause erosive wear the steel mold. the experience one fabricator, signs wear the steel mold began show only after many 60,000 patterns had been formed. The Kerr Dental Mfg. Co., Detroit supplies two pattern waxes. The dark green Kerr “Precision Pattern Wax” may injected into the mold lower temperatures than usual. The correct injecting temperature for this may vary from 145 deg. 170 deg. depending the bulk shape the pattern. When forming small thin patterns which chill more rapidly than large thick patterns, preferable raise the temperature the wax. This higher temperature will assure complete fill-in with very thin patterns, and since these small patterns have shorter chilling time, they should removed from the molds sooner than the heavier patterns. Large, thick patterns have longer chilling time than the smaller pat- terns; hence the chilling time should extended for such patterns and, for the same reason, patterns should not removed from the molds until the wax has become set throughout. The Kerr light green pattern wax used harden re- duce the chilling time the precision pattern wax. Both waxes blend with- out any difficulty, and mixing ommended fit particular require- ments. Although always preferable invest the wax patterns soon possible after they are produced, they may stored provided low room tem- peratures are avoided. Storage tem- peratures between and deg. are recommended. aid having the wax reach all surfaces and metal molds, Kerr Debubbilizer serves lubri- cant. sprayed brushed the mold and then blown dry. Pure, color- less castor oil, diluted with alcohol, using per cent each, can also used. Best results are obtained using the lubricant sparingly. For making sprues and for similar purposes where soft, sticky wax needed, Kerr’s “Utility” wax avail- able. Zophar Mills, Inc., 112—26th Street, Brooklyn 32, supply molding C101, which was originally developed satisfy the requirements jew- elry ring manufacturers, but now finding use industrial precision casting firms making components for ordnance and aviation equipment. combination with blending waxes, this material contains which supplies the hardness factor, especially important for casting ob- jects having fine detail such the prongs rings. common with other industrial casting waxes, Zophar’s C101 wax characterized low shrinkage, the extent which 1.3 a fying” re- ecision with- rec- equire- able they tem- tem- leg. ach all molds, lubri- the color- also similar wax avail- Street, wax, reloped jew- now ecision its for nt. this wax, factor, the other low ich brought out the fact that necessary lubricate the metal mold with light oil order remove the wax pattern without bending distortion. The American Cyanamid and Chemi- cal Co., Rockefeller Plaza, New York, manufacture four types cast- ing waxes, each type being subject modification depending the require- ments the particular mold being employed. allow for carving corrections such burrs, where necessary, include conformation detail not possible incorporate the mold. Type wax possesses hardness and flex- ibility for producing good definition outline and for withstanding ordinary handling. Type III extremely hard, yet flexible. does not deform fracture subjected severe han- dling impacts. Type wax suitable for large castings where vol- ume involves the cost factor. Com- pared Type III, relatively low cost wax. All these waxes possess broad period thermoplasticity that they may injected with mini- mum shrinkage. the application where the molten wax poured, the Cyanamid Company special waxing having very low coefficient contraction. For gating mounting wax patterns, No. very soft and adhesive wax available. Where desired, waxes are color coded order that they can readily distinguished for the par- ticular application. machine, Fig. especially de- signed inject melted wax into metal Waage Electric Co., New York, and distributed Alexander Saunders Co., Bedford Street, New York. the top plate located the valve lever which controls the needle valve nozzle the bottom, mercury thermometer with scale from 0-300 deg. F., and compressed air regulator and gage. temperature regulating dial found the thermostat the side wall, means which the wax may main- tained constant temperature. The maximum air pressure but the model can equipped for greater pressure desired when larger and bulkier pieces are cast. The standard machine has capacity qt. There are two models, one for use a.c. and the other d.c., both 110-125 volts, 1250 watts. Alexander Saunders Co. also dis- tributor for Waage electric storage melting pots with capacities from pt. gal. centrifugal casting, the patterns are mounted angles about central rod riser sticky wax obtain the optimum metal distribution. This rod, which forms central gate for the casting, set into rubber base sprue holder. Plasticine, similar molding material, then used seal the crack between the outer wall the flask and the sprue holder pre- vent leakage the poured investment. Typical flasks and sprue holder are shown Fig. refractory material this technique the “investment” mold- ing sand should possess the kind properties that will lead the produc- LEFT furnace for completely evap- the wax from the investment. The above furnace usual- supplied with me- tallic hearth. The flasks are charged trays which are then slid and out the furnace. Photograph courtesy American Gas Furnace Co., Elizabeth, ° ° ° RIGHT 7—Pot furnace for melting non-fer- rous Photograph courtesy American Gas Furnace ° ° tion smooth and accurate castings. should readily removable from the casting, and contain corrosive acid producing ingredients which are detrimental the castings, the flask the furnaces. Likewise, after the investment. has been poured around the wax patterns and has so- lidified, distortion compression the patterns should occur. Non-Ferrous Investment investment material suitable for non-ferrous metals which prepared the Kerr Dental Mfg. Co., Detroit, from siliceous mineral the same name. special characteristic Cristobalite the achievement high thermal expan- sion relatively thin mix which will not crack. This thermal expan- sion higher than that quartz. the thermal expansion and shrinkage curve, Fig. the rapid expansion dur- ing the early stage heating evident. The wax patterns can set very closely each other without any danger the Cristobalite breaking down between them when the casting made. important, however, that sufficient thickness investment left the end the flask. This thickness should normally about in., but should in- creased when relatively large bulks metal are cast (anything above oz.). order break the surface ten- AGE, November 1944—55 4 ‘ sion the wax that the investment can flow freely the surface the pattern, the mounted patterns should cleaned prior investing. The Kerr Dental Mfg. Co. provides prod- uct known Debubbilizer for this purpose. The patterns after they are mounted the sprue holder are simply immersed for instant. The excess solution gently shaken off. The proportion water Cristo- balite not critical. thinner mix (50 water 100 grams Cristobalite) ideal for casting pieces with fine detail, particularly when the vacuum pump employed draw the air from the investment. heavier mix (44 c.c. water 100 grams Cristobalite) recom- mended for bulkier pieces. For thor- ough and fast mixing the Cristo- balite with water, some firms make use mixer similar baker’s mixer. interesting practice connec- tion with the pouring the invest- ment the use 1/16 in. asbestos lining within the flask, which serves cushion for the expansion the investment during its setting and heating phase. The liner generally cut off about in. short each end allow the investment seal se- curely. For the purpose investing, vac- uum pump recommended draw out the absorbed air. -The mixture Cristobalite and water should vacuumed first while the mixing bowl and also immediately after the investment has been poured into the flasks, completely covering the wax patterns. The application vibration the mixing and the flasks dur- ing the vacuuming will hasten elimi- IRON AGE, November 1944 i & nation air from the mix. The Cristobalite should allowed stand for least hr. before placing the flash into the furnace. Once the wax patterns have been invested, the flask may stand indefinitely before burning out. The length time for burning out the wax will vary with the size the flask. Starting with low heat and gradually increasing until tempera- ture 1300 1350 deg. reached, the flask should held this tem- perature until the wax vaporized (carbonized) and the heat uniform throughout the flask. obtain dense castings essen- tial allow the flasks cool before The cooling should grad- ual and rate approximating the heating rate. The proper tempera- ture the flask for casting depen- dent upon two factors, the metal used and the bulkiness the pieces cast. First, the temperature the flask relative the melting temperature the metal. For example, the metal used melts temperature be- tween 1700 and 1800 deg. F., flask temperature from between 800 and 900 deg. The sec- ond factor that determines the tem- perature the flask the bulk the castings involved. the castings be- come progressively heavier the flask temperature should lowered. extremely heavy pieces the flask tem- perature should lowered between 500 and 600 deg. The flasks may cooled recommended without any danger the Cristobalite cracking. the metal used permits plunging the flask while hot into water, re- 3 1G. 8—Detroit rock- ing electric furnace, type GMS, showing panel and transformer with external tap changers. Photograph courtesy Bay City, Mich. moval the investment from the flask facilitated. Brushing and ex- posure steam pressure effi- cient means for removing the invest- ment from the castings. High Temperature Investment For casting stainless steel, Haynes Stellite, Vitallium and other alloys having high melting points, special heat resisting investment required. place the usual investing mate- rial containing amount plaster paris which breaks down under high temperatures, investment contain- ing siliceous powders together with binder known silicate can used. product the Carbide Carbon Chemicals Corp., 42nd Street, New York 17. ester slowly hydrolized water water and sil- icie acid which turn dehydrates adhesive form silica. The properties pure silicate given below; the commercial prod- uct, condensed silicate, dis- tinguished brown tint but its properties are practically the same the pure product. Specific gravity 20/20 deg. 0.933 0.938; boiling range (760 mm.) below 160 deg. not more than per cent; below 170 deg. not less than per cent; available silica not more than 0.05 per cent; color, water white; odor, mild, non-residual; average weight deg. C., 7.78 Ib. per gal. Before mixing with the siliceous powders, preliminary solution the ethyl silicate needs made follows: furnace, owing tap tesy ich. the ex- effi- laynes alloys special juired. mate- high with Street, slowly sil- ilicate prod- dis- its (760 more not silica color, .78 iceous the Mix volumes silicate with volume water and volumes denatured alcohol (or synthetic sol- vent such Synasol). least hr. must elapse before this prepara- tory solution ready for modification. This done mixing volumes the solution with volume water and little acid giving completely hydrolyzed solution that ready for use. The preliminary partially hy- drolyzed solution may stored for indefinite period and the completely hydrolyzed material for least month without the change viscosity deposition silica. Deposition silica occurs evaporation the water and solvent. get consistent results the time elapsed between the preparation and use should always the same. may noted that the hydrolysis the silicate solutions are hastened the addition minute quantities mineral acid such hydrochloric acid. The speed the reaction will depend the quantity acid added and can thus varied meet par- ticular needs viscosity speed setting. The solvent, Synasol, also prod- uct Carbide Carbon Chemicals Corp., and consists 100 parts ° ° ° type drying oven for eliminating mois- ture from large size flasks. circulation with ex- ternal heater em- ployed for rapid heat transfer and uniformity. Flasks have been put racks which are be- ing placed into the oven lift truck. Courtesy Despatch Oven Co., 190-proof (denatured), parts ethyl acetate and part aviation gasoline, The approximate price densed silicate 55c. per f.o.b. South Charleston, Va. The pure variety sells for 70c. per Kerr Dental Mfg. Co., Detroit, preparing water setting investment which will suitable for ferrous use and other metals high melting point. Vacuuming the Investments During the mixing the investing material and water, amount air entrapped the mixture. Unless this air removed before the invest- ment solidifies about the investment— and the time element important be- cause fast hardening the case the investment used for non-ferrous such casting may lack smooth surface. Tiny excrescences will cover the cast- ing due the impingement air bubbles about the wax. The vacuum method for removing the air recom- mended two steps. First, after the investment material has been mixed with water, the mixture poured from the mixing bowl into jars con- venient size and placed under bell jar. Vacuuming repeated immedi- ately after the investment poured into the flasks containing the wax patterns. unit developed for quickly elimi- nating air entrapped investments distributed by. Alexander Saunders Co., Bedford Street, New York 14, and illustrated Fig. oil sealed vacuum pump having free air capacity cu. ft. per min. at- tains barometric pressure equal in. mercury. rubber mat ce- mented steel plate measuring in. The inside dimensions the bell jar are in. diameter and in. height. The pump pow- ered hp., phase, 220 volt, motor. smaller unit also available for experimental use, which operated hp. motor and em- ploys in. bell jar. Heating the Investments Heating the flasks containing the investments for the purpose evapo- rating the wax and bringing them the appropriate casting temperature generally accomplished conven- tional batch type oven furnace. These ovens are heavily insulated with high grade modern insulation firebrick and have special hearth ma- terials which promote quick heat THE IRON AGE, November ° x 1400 deg. about min. and 2000 deg. about in. shield the operator from the hot brick facing, insulated, slide pivoted door desirable, embodying tight seal and providing evenness heating. One type oven furnace for heating in- vestments shown Fig. Pyrometers and automatic temper- ature regulators are essential for pre- cise control. Since the casting temper- ature for the same metal varies according the bulkiness the cast- ings, pyrometer controlled arrange- ment ovens permits accurate con- trol the heating cycles for batches flasks. contrast the batch type oven, there the conveyor type oven util- ized the Austenal Laboratories, Inc., and described the article “Pre- cision Castings Turbosupercharger Buckets,” THE IRON AGE issue Feb. 10, 1944. excess moisture before the flasks are placed the oven furnace for vapor- izing the wax, special drying oven can used advantage when larger flasks in. more diameter) are used. Temperature should main- tained about 140 deg. prevent generation steam which may cause flaking cracking the investment. These ovens should recirculate the air order achieve fast drying and uniformity temperature throughout (see Fig. 6A). excess moisture before the flasks are placed the oven furnace for vapor- izing the wax, special drying oven can used advantage when flasks in. more diameter are used. Temperature should maintained 140 deg. prevent generation steam which may cause flaking the investment. These ovens should recirculate the air or- der achieve rapid heat transfer and uniformity temperature throughout. Melting the Metal large number industrial fur- nace manufacturers supply melters that are finding application the typical precision casting plant. should therefore sufficient indi- cate the general types pot furnaces and electric furnaces. The induc- tion heating furnace, the other hand, more recent facet metal especial interest because the greater speed and higher temperature attainable. Furthermore, the applica- tion heat through the agency easily movable tubular coil permits compactness. Doubtless, the design integral induction furnace and centrifugal machine goal some equipment manufacturers. For melting aluminum, copper, brass alloy, tin, lead and cast iron (but not recommended for steel), the gas oil fired pot furnace gen- erally satisfactory. Illustrated Fig. small gas fired furnace which will take No. crucible capable pouring approximately metal. This furnace has swinging cover lifting assembly. Better adapted for melting (and non-ferrous metals well) the electric arc furnace, such the furnace illustrated Fig. which has capacity lb. The trans- former for this furnace connected 220 440 volt power line and requires kva. single phase capacity. smaller are furnace lb. capac- ity also provided this facturer. This article will concluded next week with description induction heating furnaces and centrifugal casting machines. Drawings Printed Metal With Layout Paint ATERIALS for simplified method printing working drawings directly metal have recently been announced the Eastman Kodak Company. These are Kodak layout paint and Kodak layout paint primer. the name the latter implies, acts subbing base for the layout paint. The new applicability for the production products involving flat metal parts. Kodak layout paint sprayed room light directly vir- tually any primed metal surface with conventional spray gun, after the surface has been cleaned reasonably free loose dirt and grease. Drying takes place rapidly and the prepared metal ready for immediate use can safely stored for reason- able time dark place. The drawing which has been pre- viously prepared with black ink transparent translucent material next laid contact with the prepared surface and exposure few minutes’ duration made arc mer- vapor lights. The drawing removed and the metal flooded with warm, weak ammonia water. vigor- ous spray tap water follows which 58—THE IRON AGE, November 1944 GENTLE water spray removes all Kodak layout paint which has been light-struck, leaving only the lines and figures the original drawing. washes away the entire exposed coat- ing, leaving only white lines where black lines appeared the drawing. Another thin spray coat layout paint primer protects the finished product. marked are accurate the original drawing. metal, the new layout paint withstands bending, shearing and punching without showing any tendency loosen, and will actually resist the application cutting torch the point where the molten metal carries away, provided that the metal does not scale. The new method said have distinct advantage over the scribing method because operators’ instruc- tions which are inked the drawing are transferred the part fabri- cated. Reductions scrap loss are forecast that layout can pre- pared include parts for sev- eral products. doing maximum use metal can achieved. There are critical steps involved and inexperienced operator can learn the process. expected that the new process will boon all fabrica- tors who work with sheets metal having uneven oxidized surfaces. vA applica- permits design ace and some copper, cast steel), gen- Fig. which metal. cover steel well) the which trans- mnected ine and apacity. capac- next nduction casting coat- where lrawing. layout finished original layout shearing ing any actually cutting molten led that have instruc- drawing fabri- loss are pre- for sev- There and earn the the new fabrica- metal surfaces. Supersonic Measurement Metal Thickness the highly stressed parts High frequency sound waves have been utilized the Soni- modern airplanes the complete in- gage measure the thickness metal sections where one the spection section thickness after inaccessible. The instrument which was first designed final machining important. the inspection hollow steel propeller blades requires con- inspection becomes difficult problem with only one surface the object and little operating skill, some finished parts where the making readily adaptable other testing procedures. This inner surface wall not acces- paper, describing the instrument and its operating principles, was sible. some cases, instrument first presented before the National Aeronautical Meeting the requiring only external contact the Society Automotive Engineers held Los Angeles Oct. part necessary. The Sonigage, which was developed particularly for the inspection the eral microseconds. turn about hollow steel propeller blades made measurement microsec. Compli- General Mo- such small time General Motors Corp., Detroit cated electronic tors such device. High frequency intervals involves circuits are also in- sound waves, that is, supersonic vi- the use compli- determine the thickness the ma- terial. With the Sonigage only necessary have contact with one surface the section being mea- sured. The problem measuring thick- ness surface contact somewhat similar that measuring the depth the ocean, inasmuch the ocean bottom not easily accessible. 1921 Behm suggested measuring the ocean’s depth sending supersonic pulse down through the water and into contact material being measured and then tuning the oscillator dial the resonant frequency the work. The quartz crystal converts electrical energy into mechanical vibrations. sound would the bottom and re- turn sec. when the depth one- half 4700 ft. This echo easily separated from the original pulse until the depth becomes less than 100 which case the time interval only few hundredths sec- ond and hence difficult measure. Still shorter intervals are measured with modern radar equipment which determines distance the reflection time radio wave. Short time in- tervals are involved because the veloc- ity such wave 186,000 miles per sec. and thus even distance few miles equivalent only sev- supersonic wave can used would suitable for reutine measure the thickness metal parts production inspection should simple the echo method. However, with operate and inexpensive build. thin sections the time intervals in- These requirements have been met volved are extremely short. This Sonigage. due the high velocity sound The simplicity the Sonigage metals, for example, about 250,000 in. arises from the fact that does not per sec. steel. Therefore, piece measure time intervals directly but steel in. thick, the echo will re- rather the frequency which the ; THE IRON AGE, November work set into resonant vibration the thickness direction. Since this resonant frequency plates given metal directly related the thickness, the measurement fre- quency determines the thickness. The Sonigage, therefore, consists only simple varjable-frequency electronic oscillator and quartz crys- tal for converting electrical energy into mechanical vibrations. Operation this instrument requires only the pressing the quartz crys- tal into contact with the material and then tuning the oscillator dial the resonant frequency the work shown Fig. Due internal damping the metal, power re- quired maintain this resonant thickness vibration. This power supplied the oscillator. power output meter serves indicate the resonant frequency the work much the same way “Magic Eye” radio serves indicate tuning resonance with particu- lar station frequency. This resonance point very sharp and the oscil- lator detuned little per cent the indicated power amplitude greatly reduced. sharpness makes accurate thickness measure- ments readily feasible. The Crystal: small flat piece quartz crystal used the Sonigage. Quartz cut this manner changes thickness when electrical potential applied its facets. The action reversible and instantane- ous that when high frequency alternating potential applied the quartz plate faces, the crystal changes thickness rapidly that frequency. This forced mechanical vibration can transmitted any material placing one face the quartz plate contact with it. Since the ampli- tude this high frequency motion ordinarily only few billionths inch, good coupling such that provided oil film between the 60—THE IRON AGE, November 1944 ° ° ° 2—Typical Sonigage crystal holder and cable. the unit shown here the quartz about in. square and 0.06 in. thick. silvered one side form an_ electrode while the work serves the other electrode. The quartz crystal cemented bake- lite button which can move and down between stops the holder. crystal and the work required. Brushing the work with oil before testing sufficient. typical Sonigage crystal holder and cable shown Fig. this unit, the quartz about in. square and 0.06 in. thick. silvered one side form electrode while Fis. 3—Simple one tube varia- ble-frequency lator used the Sonigage. using efficient coil and good insulation, power losses are kept low that normal plate current small. the work serves the other electrode. The crystal cemented bake- lite button which can move and down between stops the holder. For stable seating the work, the holder has tripod arrangement. coil spring presses down the sil- vered crystal face keep the quartz contact with the work. This spring also applies the voltage from the shielded cable center conductor the silvered The grounded cable shield connected the holder and thus through the tripod, the work grounded. The Oscillator: The oscillator simple type shown Fig. Its power output indicated d.c. milliam- meter its plate circuit. using efficient coil and good insulation the oscillator power losses are kept low that the normal plate current small. The variations this no- plate current encountered the oscillator frequency range are com- pensated adjusting the special loading plate the tuning condenser. The small constant plate current then balanced zero the meter the bridge circuit which the meter connected. With this arrangement the meter will read only the addition- external power output the oscil- lator which drawn the crystal when the work resonance with the oscillator frequency. perhaps well point out that quartz crystals have their own natu- ral resonant frequencies which de- pend the thickness the quartz. These fixed frequencies are some- times used control fixed frequency oscillators but the Sonigage has variable-frequency oscillator which the frequency controlled its coil and tuning condenser. The Sonigage oscillator controls the forced vibration the quartz and the crystals used are always chosen that their natu- ral resonant frequency higher than the range used for measurements. Then, even crystal wear does occur, the quartz thickness would smaller but its resonant frequency still suf- OSCILLATOR WORK ficiently high that crystal res- onance would observed. single crystal sensitive over about 2:1 range thicknesses that Sonigage oscillators are built cover single 2:1 frequency range. Additional ranges changing coils, crystals seales. Because the low cost and extra inspection capacity separate units such multi-range models have been built. The oscillator tuning condenser dial calibrated frequency but for any one metal can calibrated read thickness directly, since the product the resonant frequency and the thickness will equal one-half the velocity sound. For any one metal this velocity constant and, there- fore, the frequency and thickness are inversely proportional. Work Vibration: For steel the rela- frequency kilocycles per second, inch, and 125,000 one-half the velocity sound steel inches per . 7 | fe) ° ° “a CABLE CRYSTAL: idenser. rrent meter ddition- oscil- crystal with that natu- ich de- some- equency has which its coil onigage ibration used natu- than occur, smaller tal res- over SSeS built range. require dial ost and eparate have ser dial icy but ibrated nee the and alf the metal there- ess are rela- the cond, the hes per second. Fortunately the velocity steel not appreciably affected ordinary alloy content, hardness heat treatment, one calibration holds for all common steels. The amplitude resonance indi- cated the oscillator meter may less the c