The Iron Age 1944-05-18: Vol 153 Iss 21

Repre- and uralite fea- ended. CENTERS VAN DEVENTER President and Editorial BAUR General Manager Editorial and Advertising Offices Eas? 42nd St., New York Johnson, Market Research Baur, Typography and Layout. ° ° Business Managers 100 East 42nd St. 106 East St. ROSERT BLAIR FITZGERALD Cleveland Pittsburgh Sidg. Park Bidg. Chicago PEIRCE LEWIS WARR RAYMOND KAY Los Angeles 2420 Cheremoya Ave. Owned and Published CHILTON COMPANY (Incorperated) Executive Offices and Sts. Philadelphia 39, Pa., U.S.A. OFFICERS AND DIRECTORS MUSSELMAN, President JOS. HILDRETH Vice-President GEORGE GRIFFITHS EVERIT TERHUNE Vice-Presideat VAN DEVENTER Vice-President BAUR Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary CHASE THOMAS KANE HARRY DUFFY HEALE Member, Audit Circulations the Industrial Arts Index. Pub- every Subscription Price North America, South America and Possessions, $8; Foreign, $15 year. Single Copy, cents. ° ° ° The IRON AGE Vol. 153, No. May 18, 1944 Editorial Jobs for Everybody ° ° Articles Hyper Milling vs. Fly Cutter Eliminating Cracking Heavy Forging Dies X-Rays Made Mass Production Basis Hand Drilling Operations Speeded Surface Protection Aircraft Parts. Cost Meehanite Castings vs. Welded Structures Safety Color Code for Industry New Equipment Features Assembly Line Washington Personals and Obituaries 100 Dear 104 This Industrial Week 106 ° ° ° News and Markets Non-Ferrous Metals News and Developments 170 Non-Ferrous Metals Prices; Scrap Prices 172 Iron and Steel Scrap News and Prices 174 Comparison Prices Year. 178 Finished Iron and Steel 180 Steel and Warehouse 182 Semi-Finished and Tool Steel Prices 183 Steel Pipe and Tubing Prices.......... 184 Wire Products Prices 185 Pig Iron and Coke Prices............... 186 Railroad Material and Stainless Steel 187 ° ° Index Advertisers 295 Member, Associated Business q 7 q { q IRON AGE, May 1944 YOU DARE CUT INVENTORIES? here safe method that works! Out the maze talk and conflicting state- ments regarding war contract cancellations and seems reasonable conclude that large-scale production curtailment ex- pected until after the successful invasion Europe accomplished fact. However, ordnance schedules are constantly being ad- justed account changing needs and im- proved designs. This has resulted recent cut- backs for many metal-working plants. Also, reserve stocks certain war material have al- ready reached point where has been found advisable cancel further deliveries. Due this situation, many manufacturers may overnight confronted with the task disposing steel overstocks. Too often these stocks are not easily converted other pro- duction uses. valued inventory can quickly become white elephant. urge you try avoid this loss. Keep your inventory practical working level without excessive reserves. believe this entirely safe and practical today—and can done without incurring undue risk continu- ous production. There was time when ware- house stocks were rather bad shape and manufacturers, self-defense, built high steel inventories. But the WPB has seen the folly each company carrying big inventories meet all eventualities, and has permitted reasonable build-up general warehousestocks, which serve everyone. Thus the overall ton- nage idle steel may reduced, and the cut- back and cancellation blows are cushioned. Stocks most steel distributors are good shape meet all reasonable demands. Reli- able trade sources report that these warehouse stocks are now more than 100% over the low 1942. Ryerson, particular, has large and complete stocks bars, shapes, plates, sheets, stainless steel, alloys, tubing and other vital steel products—ready for immediate shipment. Call any one the eleven conveniently-located Ryerson steel-service plants for your day-to- day emergency steel requirements. Prompt, personal service assured. JOSEPH RYERSON SON, INC. Steel-Service Plants Chicago, Milwaukee, St. Louis, Cincinnati, Detroit, Cleveland, Buffalo, Boston, Pittsburgh, Philadelphia, Jersey City ESTABLISHED May 1944 VAN DEVENTER President and Editorial Director BAUR Vice-President and General Manager ° DIX Manager, Reader Service Editorial Staff Technical Editor..... Associate Editors WINTERS LLOYD BARMASEL Editorial Assistants SCHIEN GS. B. WILLIAMS ROGERS Regional News and Technical Editors CAMPBELL Pittsburgh 428 Park Bldg. POST Chicago 1134 Otis Bldg. MOFFETT DONALD BROWNE EUGENE HARDY Washington National Press Bldg. MacDONALD Cleveland 1016 Guardian Bldg. BRAMS Detroit 7310 Woodward Ave. OSGOOD MURDOCK San Francisco 1355 Market St. Editorial Correspondents ROBERT Cincinnati PENLEY Buffalo FRAZAR Boston HUGH SHARP Milwaukee SANDERSON Toronto, Ont. RAYMOND KAY Los Angeles JOHN McCUNE Birmingham ROY EDMONDS St. Louis DOUGLAS Seattle OLIVER Jobs for Everybody AMES SCOTT, president the National Machine Tool Build- ers’ Association addressing meeting this group last week, put some important thoughts into plain words. telling you,” said Mr. Scott, “that after this war, cost cutting going just about the biggest problem the entire industrial field. You know that wages aren’t going down. And you know too that prices keep going up, American industry won’t able get the mass markets needed sustain high level postwar employment. industry can’t sustain high level postwar employment and today’s workers are out work just when the boys come back from the other side looking for jobs, who going step save the situation? You know the answer. Government will provide the jobs. Government will say: ‘Obviously, industry can’t take care this situa- tion. What need this country more deficit spending.’ What Mr. Scott told the tool builders goes clear down the line and across the boards not merely one industry but all. The kind prosperity that financed deficit spending fictitious one. the nature things cannot last, since eats itself like the mytho- logical worm. The creation enough wants and the means satisfying them and thus maintaining employment job that Government cannot under- take and that should not wished upon it. The responsibility for doing multilateral and rests upon the shoulders every man and woman having any part productive enterprise. not something that can assign Uncle Sam, the employer the labor leader. More goods for more people means more jobs which what hope have after the war. means turning out more useful things than have ever had before. means turning them out faster, cheaper and better. means stretching our dollars the only means that dollars can successfully made farther, namely cost reduction. Everyone has part play this big job making things cost less which another term for job building. The employer does providing better machinery, the worker increasing his own efficiency, the labor leader discouraging slow downs and promoting harmony. Government too can play big part helping reduce production costs private enterprise easing the tax burden that rests all | * } | | ° ° effort. Sales Offices: For Finer Consult Inland when plans are started for parts products which must have the strength, utility, and beauty that can come only from steel sheets and strip. Inland was among the first install modern continuous mills. [ts engineers and metallurgists have contributed many notable advancements sheet and strip One the Inland cold reduction mills, which strip precise thickness and produces lustrous finish Steel production methods and quality control —resulting unsurpassed uniformity, workability, and finish. Inland experts are ready help you select the right steel for finer products and economical fabrication—whether the products are for wartime use, for the markets that will follow Victory. Sheets Strip Tin Plate Bars Plates Floor Plate Structurais Piling Rails Track Accessories Reinforcing Bars INLAND STEEL COMPANY Cincinnati Detroit Kansas City Milwaukee New York St. Louis St. Paul runn: thee. the pend emit powe used the San this News Front MAY 1944 From India reverse American military forces received $35 Canadian manufacturers are negotiating with the Soviet Union for the sele generating equipment for the rebuilding the Dnieper Dam. Soviet may exceed $25 million. for three continuous bloom heating furnaces. New military programs has stepped machine tool demands that tentative requirements for the last three quarters the year now reach $400 $16 million although when forging equipment, heat treating furnaces and necessities are included, the dollar estimate may soar $150 million. The new stainless steel air cargo plane has been put into full scale illion which nearly half was represented petroleum products. date total from the British colony amounts $149,512,000. Russia has also awarded Rust Furnace Co. contract for design and critical The War Department's heavy shell program will require 2000 new machines valued the Edward Budd Mfg. Co. For the first time considerable scale, welded stainless steel will utilized instead riveted aluminum alloy sheets. plane two engine transport ft. long, with wing spread 100 and capable transporting 10,400 lb. cargo over range 650 miles. processing, eliminate the need for acid cleaning. Glass applied near the end the rod rolling operation, and cracks off about 400 deg., pulling light surface oxides away the same time. According Franklin Johnson, American Exporter, there are Hawaii many large and work, unlike the situation California. camp the S., his son the Army, and his wife daughter the store. Twice, recently, purely Chinese firms gave luncheon parties and invited some fof Muller Phipps Japanese salesmen. Hawaii there tremendous inflation services. One laundry recently offered $500 month for good laundry presser. And, Waikiki's well-known Wagon restaurant advertised recently that would "closed all day Sunday for the wedding our head pantry girl our chief cook. Open for business usual Monday." jet airplane will carry the designation P-59. Rumor that will the "Airarocket", but this not quite true. least four other manufac- turers, other than Bell, are working jet aircraft. According the Berlin radio, the RAF employing small radio set pended from balloon. This, when dropped over the target, guides the bombers emitting note. The Northrup "Black Widow", the new secret fighter, powered two 2000 plus hp. double Wasp motors, and Swedish says fitted with radar equipment for locating enemy airplanes. 16-2 stainless steel, although known for many years, has only recently been this country. Aircraft manufacturers are now learning that weight can saved using this type substitute for 18-8 when heat treated 175,000 per sq. in. tensile strength. Although corrosion resistance inferior that 18-8, the short life the modern aircraft wartime service has accelerated its approval the armed forces substitute for more corrosion resistant steels. For the duration and six months thereafter, Western Pacific and Southern Pacific railroads have volunteered carry finished steel from Geneva, Utah, San Francisco Bay for per ton. However, Utah industrialists still feel that this rate too high and order assure the Geneva mill's competitive future arate tidewater must not over $6. | Es i ‘ ous % 7 a 7 | Hyper Milling vs. Fly Cutter Milling Among the advantages cited the author favor single- point fly cutter milling over multi-tooth face mills with negative rake angles are the lower power requirements, reduced cost and ease maintenance. cutter body described which the fly cutter can mounted one several slots various negative helix axial rake angles suit the particular operating conditions. the early GAYLORD THOMPSON part No- Manufacturing Engineer vember, 1943, Joshua Hendy Iron Works, Sunnyvale, the president Cal. prominent car- bide tool manu- facturing concern gave lecture be- fore group engineers the Joshua Hendy Iron Works, Sunny- vale, Cal. This lecture was supple- mented moving pictures showing hyper milling cutter machining steel the rate 3500 ft. per min. and better. peculiar fact connection with this remarkable performance was that when the peripheral speed came into the range 5000 6000 ft. per min., and became neces- sary sharpen the hyper milling cutter—now load this—the cutter sharpened grinding away the body the cutter from around the carbide tips. (In this spe- cial cutter, the carbide tips were brazed directly the body.) were not for the scientific correct- ness this grinding procedure, its very essence goofiness would create gobs humor for tool engineers. When some new outstanding per- formance carbide tools revealed ° ° ° was IG. from above cal multi-tooth hyper milling cutter horizontal boring mill. Note the clean chips. the trade, tool engineers, ics and other personnel the and shop become more convinced carbide tools are unpredictable chicken the roadside front your speeding car. small cant clearance angle, positive tive, may mean the difference total failure the tool its success. Machine tool designers and facturers have been forced into asperating pursuit the fast travel. ing manufacturers carbide cutting tools. Machine tools that wer| built the area high speed just did not have the power and speed give carbide tools good workout Too slow speed definitely mental carbide tools. Manufacturers engine lathes, turret lathes, boring mills and planers have done good job designing machines that put them into neck and neck race with carbide tools. ing machine manufacturers, however, have had the worst handicap over. come. While their products, which also include horizontal boring milling machines, were built oper. ate speeds high 400 ft. per involving ordinarliy fast enough for efficient production performance with tools, now they are confronted with this new steel devouring glutton the milling cutter world—the hyper milling cutter. Just like chasing have the “bloomin’ thing” make big jump ahead them again. There however, many milling machines horizontal boring mills late design use throughout the country that can operate hyper milling cutters very economically because being able attain peripheral speeds the range most suitable carbide tools. The Joshua Hendy Iron Works one plant which considerable perimenting has been done and ence obtained with hyper milling cut ters. This work brings new slant economic production with milling ters. This new slant involves the tion which the more ical hyper milling cutter use—the multi-tooth type with inserted carbide carbide tipped blade used cutter. Example Cited ventional multi-tooth hyper milling connecting rod for steam engine. drawing the cub ter head shown Fig. negative helix angle the slots equivalent 10-deg. negative rake str this for attai thele ume vere place with spon | ° ° ° rake angle ground tool placed straight slot. Since the machine feed in. per min., equaling 864 graph the hyper milling cutter that this picture was comparatively light ft. per min. producing operation order reveal the glossy finish for the rugged action imposed the that formerly took hr. with produced the cutter face off hyper cutter, the highest cutting speed high speed steel cutters. However, the rod. The finish produced was ex- attainable was 690 ft. per min. Never- this speed could not maintained cellent—a characteristic all hyper s q theless, this operation was completed steady production because over- cutters. Oftentimes questions 1.8 min., whereas min. was the machine and motor. have been asked whether the sumed when high speed steel cutters The speed was lowered 289 r.p.m., work was ground. were used. maximum depth cut in. and Now then, come the subject This same hyper milling cutter was feed 3.1 in. per min. This rear- hyper fly cutter milling. This type nto placed another heavier machine rangement provided peripheral milling was first adopted the with greater permitting speed 730 ft. per Hendy Iron Works when the in. face spindle speed 330 r.p.m., corre- the range efficient carbide tool per- frame similar that door sponding speed 864 ft. per min. formance. casing had milled. This facing steels Fig. 2—Details the cutter shown Fig. Body Meehanite. signing neck owever, which ft. per efficient carbide tton hyper ising aff only big ere are, and design very able range and orks ble ex- experi- slant cut- se—the carbide toothed milling 4Holes- through Material: Meehanite grade > ~ E Material 4/40 heat treated stock Blades are set deg. negative helix angle, deg. radial rake. Holes Chore deep The slots back Machine all over allowing grinding stock back face draw 730° 750°F, finish grind back face and pilot holes THE IRON AGE, May | 4 | / / \y 4 ae 22295} 7" Section A-A ZA — 3 4 ABOVE 3—Another view the hyper milling operation shown Fig. illustrates the fine finish characteristic this work. the left the author this article. With him George Bowman, chief tool engineer, Joshua Hendy Works. BELOW Fig. 4—Fly cutter tool used special milling body horizontal boring mill. 4 62—THE IRON AGE, May 18, 1944 operation necessitated extending the in. diameter spindle the horizontal boring mill out about ft. from the front main bearing. The material milled was fabricated boiler plate steel and naturally, when small H.S.S. milling cutter was at- tached the end the spindle for this operation, the chattering and vibration due the extreme ex- tension the spindle made this oper- ation impractical. Fly Cutter Application experimental hyper fly cutter head was made shown posi- tion the horizontal boring mill, Fig. This head has four slots hold in. square shanked carbide tipped tool one four positions. The slots were cut the head 10, and deg. negative helix angles shown the drawing the head Fig. The reason for providing for different angles because the peculiarities carbide tools. Often- times, the carbide tool will not per- form satisfactorily one angle posi- tion whereas will “go town” one the other angles. Especially this true where intermittent cut- ting involved. this particular instance, the face milling the “door frames” was ac- complished without any chatter vibration. The fly cutter tool was set the deg. negative angle slot which proved the best perform- ing position and one which produced excellent finish. The speed used operating this in. hyper fly cutter was 250 r.p.m. —590 ft. per min.; feed, in. per min. 0.010 in. per rev., and depth cut, 0.005 0.250 in. The photograph, Fig. shows an- other view the hyper fly cutter used vertical position for milling hori- zontal faces. This photo gives ex- cellent view the tool set the deg. negative angle slot. The heavy chips the foreground were produced the roughing cut while the finer chips were produced the finishing cut which happened 0.008 in. deep this instance. Note the smooth finish the work, the gloss which makes appear that coating oil water lay the surface. The fact however, all hyper milling, whether with multi blade single fly cutter, done Experimental Cutter Tool photograph the hyper fly cut- ter tool shown Fig. and drawing the same shown Fig. Incidentally, order avoid the possibility the fly cutter tool being clamped the wrong slot, the = 4 ‘ fe be | luced finer shing in. 100th vhich oil fact itter, cut- avoid tool the / Wedge bore, Yor piece 4/40 Heat treated stock Required -Q2000" body Web carburize and harden Holes-No.F Chore for piece No./2 Fig. 5—Details the cutter body pictured Fig. The single cutter can held either 10, deg. negative helix angle. angle setup for which the tool de- signed stamped the top face the tool shank, together with the tool number which identified the tool crib. The tool the photograph shows the tool number X-236 while the number signifies the slot angle the head for which the tool deg. matter information, the tool used the hyper fly cutter was Ken- nametal Grade KM, style No. 11-T-50, standard tool ground modifica- tions shown the drawing Fig. very gratifying result obtained the hyper fly cutting operations with cutter positioned shown Figs. and representing two differ- ent setups the same weldment, was the fact that the job which formerly took allowance 140 hr. com- plete was whittled down actual consumption hr.—a reduction almost per cent machining time. This saving hr. can best ap- preciated when known that involves $85,000 machine whose overhead charges plus the labor two mechanics present sizeable fig- general foreman another de- partment, upon witnessing the per- formance the hyper fly cutter re- marked, been using hyper milling cutters job depart- ment that should made-to-order for this fly cutter head. You see, got only one carbide cutter head for the present until others are made. use for couple hours and then sharpened. the meantime use high speed steel milling cutters which takes about ten- times long the job. How about using hyper fly cutter the job?” This foreman, Bill, got his hyper fly cutter with all the trimmings ex- plained the foregoing paragraphs. The job setup was solid and close the main bearing the machine from which the spindle extended—a setup that near perfection for economi- cal performance carbine tools interrupted cuts. The cutter was started 250 r.p.m. in. feed per min. with from 1/16 5/16 in. depth cut. This speed was gradually stepped 380 r.p.m. and the feed in. per min., but Bill’s enthusiasm for speed was toned down the superintendent maintenance 298 r.p.m. with 3.2 in. feed per min., which equivalent approximately 0.010 in. feed per rev. The former speeds and feeds were too much for the machine and motor. Practical Viewpoint few hours later Bill remarked: “You know, Thompson—I was never sold them damn carbide tools but when seen the way that hyper mill- ing cutter and that hyper fly cutter THE IRON AGE, May the ontal oiler Wwedge- ering : oper- “Se. cut- face slot 732R ri / Af / orm. this per lepth an- used hori- the 7 worked—well, I’m sold. But listen— that one tool the hyper head lasts just long, not longer, than the hyper head with cutters it—and the beauty that when the cut- ter gets dull don’t have send the grinding room for precision grinding which takes hr. time. All the guy has got now put new sharp tool when one gets dull and keep producing. Yes, 5 wi? q q af? q ABOVE view the hyper fly cutter ver- tical adaptor clearly shows the deg. negative helix angle which the single point tool mounted. when the fly cutter type hyper mill- ing cutter was placed the operation the only change required was that the feed, which was reduced 3.2 in. per min. because only one tool do- ing the cutting. The question might asked, “Why was not more feed used the multi- toothed hyper milling cutter? you can take 3.2 in. per min. feed single tool, you should able take RIGHT standard carbide lathe tool ground form hyper fly cutter blade. Note the marking the tool shank. sir!—that hyper cutter setup dulls only one tool time while the other dulls 15! Think what that means time saving and tool ex- pense!” When the speed for the multi- toothed hyper milling cutter was set 298 r.p.m. the feed was set 6.3 in. per min. with depth cuts not exceed in. The limitations were found necessary order avoid the possibility machine breakdown and motor trouble because excessive speed and constant strains. Now then, 64—THE IRON AGE, May 1944 in. per min. cutter with blades.” Speed Limitations This reasoning logical and partly answered the opening para- graphs. The limitations are due the lack capacity the machine operate high speeds required carbide tools—especially when from one eight tools may cutting si- multaneously. Two expensive break- downs were experienced more from unusually high speeds than from strain pulling cuts. Bearings froze the geared heads, stripping gears and bending shafts such extent that weeks valuable production time were lost the two machines. Not wanting this occur again, the main- tenance superintendent set limitations speeds and feeds. spite these limitations, how- ever, the speeds are ample for carbide tool performance and the production surpasses that high speed steels such extent that caution could afforded. The battle between the multi-toothed carbide tipped hyper milling cutter and the single-toothed hyper fly cutter could doubt controversial. the examples quoted above, the hyper milling cutter 6.3 in. feed per min. has the advantage almost two one the hyper fly cutter 3.2 in. per min. But, let take actual example. The multi-toothed hyper cutter never exceeded steady production run hr. with one sharpening. mat- ter fact the average life between grinds was hr. And remember, this case there are tools involved. The hyper fly cutter tool shown the photograph, Fig. and the drawing, Fig. made record run constant performance starting with the day shift 4.00 p.m. and con- tinued throughout the hr. swing shift and finally had taken out for sharpening 2.00 a.m. the graveyard shift—a run solid pro- duction for hr. And only one tool had sharpened! Not 15! Some- thing think about there! One fact that might explain the superiority the single fly cutter tool over that the multi-tooled cutter the grinding—and remember—this the heli hav the tool anc deg neg grec 7 far the most critical moment the life carbide tool. standard carbide tool set deg. negative helix angle the cutter head would have front clearance deg. plus the usual deg. the standard positive clearance which very exces- sive. Since only deg. front clear- ance actually needed the point the tool and the tool set deg. negative, this means that front negative rake deg. must ground the tool point reduce the excessive clearance caused the posi- tion the tool the deg. negative slot the cutter head. See Fig. and compare with the appearance the point the tool shown the photograph Fig. Blending Angles Now where come the critical phase the grinding the that makes superior performance the tools the multi-cutter head. This critical moment the grinding opera- tion the blending the negative rake the front the tool, into the positive clearance the side the tool. If, grinding the small radius the point the tool, the deg. negative rake carried around the tool point too far, negative clear- ance created the side the tool where positive clearance required the machine grinding the multi-tool hyper cutter, the negative front rake and the side cutting edge angle can ground accurately, but when comes blending the nega- tive front clearance deg. around the point and gradually coming into positive clearance the cutting side the tool—it just can’t done the present type milling cutter grinders. Because this, the ma- chine-ground hyper milling cutter tools are forced get along without Chamfer ° ° ° 3° the hyper fly cut- ter bit shown Fig. Because the angle which the tool mounted, the front clearance an- gle deg. nega- tive with respect the top face. Front radius Section the desired support under the small radius the very point the tool The hyper fly cutter tool more fortunate this respect that there machine commercially available for grinding each cutter individually exact duplicate form with blended positive and negative relief angles around the nose the tool, thus giv- ing the weakest part the tool maxi- mum support. This machine the Bura-way grinder* made For description this unit, see New Conception Grinding,” Iron May 21, 1942. James Donaldson Co., New York. this unit provision made for the angular setting the tool ver- tical plane, heavy, but freely moving tool holder which can slid hand upon the surface pivoted table front the wheel. The angu- lar setting this sine bar table, called because the method used set angles precisely, determines the side clearance relief angle the tool since governs the tilt the tool shank when presented sidewise the ai wheel. the other hand, the com- bined angular setting tool holder and table determines the front relief angle the tool. Duplication the form the tool obtained cam the base the moveable tool holder that rocked oscillated against flat cam bar below and behind the grinding wheel face. When used grind lathe tools the machine gener- ates relief surface around the nose tool that constant the direc- tion feed, thus giving uniform wear around the cutting edge. For grinding the tool shown Fig. the sine bar table the Bura-way would set deg., providing the positive side relief the side cutting edge chamfer its independent holder, the tool would tilted with its shank upward angle deg. (negative) that when the tool presented straight onto the face the cup wheel effective relief angle deg. negative deg. ob- tained. When the tool holder slid around present the side cutting edge the wheel face, this negative angle blended around the nose into deg. positive relief angle governed the sine bar table setting. Improved Explosive Rivet improved explosive rivet that fits itself the hole has been developed the explosive depart- Co. Although its present application expected have many postwar uses the fabrication such products radios, refrigerators, automobiles and buses. The original rivet, introduced two years ago, was expanded the end the shank lock place. Im- provement the rivet, made alumi- num alloy, was accomplished em- bodying small auxiliary explosive cavity and modifying slightly the explosive charge. The auxiliary extends from the main chamber the shank toward the head the rivet. Detonation the charge expands the entire shank. This leeway makes possible more rapid insertion the rivets. After insertion, the new rivet, like the original, may expanded one man contrasted with per min. for most “blind” rivets. The new rivets will available diameters 5/32 and 3/16 in. the modified brazier types, and perhaps other types. The new explosive used has the nontoxic and high stability properties. The explo- sive charge usually detonated with electric riveting iron which fires the charge the cavity when heat applied the head. THE IRON AGE, May 18, ent Not ons Section ion hed ter ter per ver at- er, ed. the ith yn- iminating Cracking in| TEELS for drop forging dies are supplied steel works number qualities, an- nealed heat treated condition. The strength the steel influences the performance the dies very greatly. However, certain economic considera- tions, such machinability, limit the strength the material which sup- plied 90,000 lb. per sq. in., and usually lower tensile strength some 70,000 lb. per sq. in. used. For very large dies with deep re- lief this strength generally ade- quate. flat dies, strengths are desirable prevent the early wear the tool, particularly when they are_used for forging hard materials. customary buy die steels also for heavier tools the an- nealed condition and heat treat them after machining the required hardness. Frequently the hardening process unsuccessful and the tools fracture during hardening after more less protracted period use. Die breakage frequently due unfavorable stress distribution hardening, occasioned temperature differences between the surface and the core arising out the heat treat- ment. This effect occurs during heat- ing hardening temperatures, during quenching and tempering and par- ticularly pronounced heavy dies. But, possible suitable steps the heat treatment heavy dies successfully harden the material with little risk. Heating rates for harden- ing for tempering should ad- justed that pronounced tempera- ture differences and stresses are re- duced minimum. Data concerning minimum heating rates function the die dimen- sions are not available the litera- ture. Therefore the heating periods hardening and tempering tem- peratures were calculated and corre- sponding curves sketched. has been rendered elsewhere regard- ing this work. (Haerterei-Technische Mitteilungen, Band bei den Vor- traegen des ums.) Herein only the more essential data are reported: 66—THE IRON AGE, May 1944 ¥ Heat conduction, Below 930 deg. transmission can convection heavier and IG. cracks owing too rapid heating. One-fourth natural size. radiation. convection and over- head radiation are the predominant modes heat transmission. surface heated first and the core rises temperature heat conduc- tion. Obviously the corners the die which are exposed three sides the heat carrying medium (convection radiation) and the edges exposed two faces heat much more rap- idly than the center areas. This tem- perature differential between surface and core result sizable stresses which may cause cracking the core The more accentuated the tempera- ture differential between surface and core, the The die heavier the stresses set and the greater the danger tearing. This temperature differential must for this calculation, alloy steel drop forging dies in. square and hard- ening temperature 1592 deg. were assumed. The influences (a) the furnace temperature, (b) the rate driving the furnace, (c) the die size, and (d) the heat conductivity the die steel the temperature gradient between surface and core the die were calculated. (a) increase furnace tem- perature increases the temperature differential between core and surface. According Fig. the hardening temperature 1592 deg. can reached after hr. furnace temperature 1832 deg. F., but only after 10% hr. 1724 deg. This not permissible view the pos- sibility tearing overheating the die, particularly corners and edges. This danger increases with the fur- nace temperature which should there- fore not chosen unnecessarily high. Drop forging dies usually furnace, which the rate heating will more rapid owing the im- mediate flame contact. Particularly rapid will the heating when “driving flame” used, for example, when special burners are used. (b) increased rate driving the furnace using flame” allowed the die surface reach the hardening temperature after hr., while needed hr. normal heating. maximum temperature differential between sur- face and core about per cent greater under the “driving flame.” (c) The influence the size the die was calculated and was found that the temperature differential be- tween core and surface die in. square multiple that existing in.a die 3.9 in. square which about 212 deg. (d) The influence heat conduc- tivity naturally according the definition that term. The calculations agree with the practical experience. The temperature differential favors stresses and there- increases the danger tearing. Therefore, abl anc ful Lor de} all di: ° ° th le a n | weg Heavy Forging Dies must kept minimum suit- able direction the heating process, and definite minimum heating periods must allowed for each die size. The heating rate particularly dependent the temperature difference between furnace and die, the temperature conductivity the die and the rate heat transmission. secondarily dependent the relation between fur- nace size and die size. the various shops these factors vary greatly and will difficult arrive gener- ally valid conclusions, but the fol- lowing shown way which the problem may tackled: During heating three steps can distinguished: Heating 932 deg. F., heating from 932 deg. the hardening temperature, the period penetration equalize temperature differentials between the core and the surface the die. 932 deg. heating must particularly slow and thorough order keep the temperature differ- ential between surface and core low possible. The steel unable absorb considerable stress this tem- perature range. Therefore, best heat the die with the furnace. case should the furnace hotter than 392 572 deg. F., since other- wise, owing the rapid heating the die surface, interior cracks would unavoidable (Fig. 1). Frequently the mistake made that the hot fur- nace cooled mere opening the furnace door and charged too early. The pyrometer and the surface the refractories actually register low temperature, between 392 572 deg. F., but the refractory bricks have stored much heat that the die heats very rapidly when the fur- nace door closed again. Should the tool charged hot furnace about 392 572 deg. F., then under circumstances should further heat- ing started immediately. The die block should first given oppor- tunity absorb approximately the furnace temperature and then further slow heating may begin. Above 932 deg. possible heat rapidly with “driving flame.” this temperature range the steel HAUFE Dr. Eng. Dusseldorf These German suggestions for the proper handling heavy drop forging dies during the hardening and tempering cycles are interest that they indicate thoughts this important problem that country. The ideas put forward may serve stimulate the preparation heating curves for stee!s and conditions other than those considered herein. This translation article that appeared fur praktische Metallbearbeitung, March, 1943. can absorb even fairly heavy stresses without tearing. When the hardening temperature reached the furnace should turned off and held there for some time. The calculation results for different drop forging die dimensions alloyed steels are given Fig. func- tion the heating periods which have proved successful two different works. This comparison shows good agreement with the calculated heating periods. The replies questionnaire sent number firms showed that the ranges given for alloyed and unalloyed die blocks are valid for the determina- tion the heating period harden- ing drop forging dies the semi- muffle furnace. The dies must always heated slowly 932 deg. Only from this point may “driving flame” used. Quenching Drop Forging Dies Water, oil and air are used quenching media the hardening dies. Water offers the most rapid the surface ° and air the slowest quench action. the quenching process the heat removed from the outer areas the part more rapidly than from the core. Particularly rapid the quench action exerted the corners and edges which are surrounded two or, three sides the quenching medium. hardening larger dies the more rapid quench action corners and edges compared with the center areas the die can clearly ob- served. While center areas are still dark red, corners and edges are al- ready black. Owing their more rapid cooling, the outer layers tend contract but they are inhibited the warmer core which under pres- sure from all sides. Since the steel core cannot yield this pressure, the colder layers must bulge out they are still sufficiently warm and ductile. However, the plasticity becomes too low with decreasing temperature then the surface will crack. further cooling the core looses its volume. Since the core held the outside layers turn will now exposed + furnace > | vo furnace tem- ing rate. Difference surface and core Heating THE IRON AGE, May the F, (a) rate die em- ace. lace the res. igh. ally iffle im- irly ple, ing ure 900 800 ent the ind ces tensile and the surface layers pressure stresses. now possible for the core disintegrate loosen itself from the outside. The temperature differential between sur- face and core parallels the magnitude the heat stresses. The influences (a) the hardening temperature, (b) the die size, (c) the quenching medium, and (d) the heat conductivity the die steel, the temperature differential between sur- face and core the die has also been calculated. (a) The hardening temperature was chosen 1436 deg. and 1544 deg. for water hardening, and 1526 deg. and 1652 dg. for the oil hardening material. Water hardening die steel begins rather rough grained 1544 deg. Its toughness thereby reduced and the danger cracking increased. the more rapid water hardening, the hardening temperature should way higher than absolutely necessary obtain evenly hard and sufficiently deep hardened layer. hardening dies alloyed steel may become necessary harden the upper hardening temperature limit for adequate tem- per stability. The hardening tempera- ture must case high that the toughness the die suffers the occurrence coarse grain. (b) The influence the die size upon the temperature course and tem- perature differential were calculated for die sizes 3.9, 7.8 and in. square. material, carbon steel and uniform hardening temperature 1472 deg. were assumed. The tem- perature differential between surface and core reaches maximum, accord- ing Fig. for all die sizes after short interval, and then decreases extraordinarily rapidly for the small die sizes. With increasing die size this maximum differential retained for increasingly long periods, for example drop forging die in. square retained for several minutes and de- creases slowly thereafter. was expected, the maximum increases with the die size, since the heavier dies are hardened the upper hard- ening temperature limit and tempera- ture differential increases with the hardening temperature and_ these temperature differentials are further accentuated. (c) order understand the effect the quenching medium uni- form hardening temperature 1472 deg. was assumed and the cooling curves for die in. square car- bon steel air, oi] and water were LEFT time for drop forging dies dif- ferent sizes. BELOW Influence drop forging calculated. The temperature differen- tial, according Fig. far the greatest water hardening. air cooling comparatively small. The temperature differential air, oil and water quenching related the present example about 1:3 and 6:8. The stresses will, therefore, similar relationship. practice the hardening temperature consider- ably higher oil hardening and par- ticularly air hardening than water hardening. When the practical hardening temperatures were allowed for with 1490 deg. for water quenching, 1616 deg. for oil harden- ing and 1652 deg. for air cooling, then the temperature differentials for air, oil and water quenching are re- lated 1:3 and 4:7. (d) regards the influence the heat conductivity, Fig. shows that the temperature difference between surface and core increases with de- creasing conductivity. Since the heat conductivity increases with increasing alloying constituents, are particularly sensitive quench- ing, and the rate quenching should, therefore, not greater than the hardening requires. permissible conclude that the temperature differential between surface and core hardening, and, therefore, the temperature stresses, increases with increasing quenching temperature, die size, quench action the quenching medium and decreas- ing heat conductivity. Temperature stresses are further enhanced stresses the crystal lattice which are caused hardening. hardening, space increase takes place when compared with the annealed condition which connected with stresses. water hardening steels the critical cooling rate affects only the outer layers heavier sec- tions. Therefore only the outer areas die size the lly hardened (Fi are actually hardened (Fig. 7). These ing through such steels occurs only | | | Hardening temperature 850deg.C. 68—THE IRON AGE, May 18, 1944 Dimensions, sq.mm. 400 between surface and core when the sections are thin. oil hardening steels the critical cooling rate attained also heavier cross- sections and air hardening steels even reached with very large sec- tions. Fig. shows schematically the connection between the critical cooling rate and the deep hardening effect. Fig. shows the hardness readings forging die air hardening CrNiMo steel. There practical difference between the core and the outer layers the die. The hardening effect takes place the action stresses imposed space increase the lattice harden- ing. These stresses are particularly pronounced their surface hardening effect and decrease with increasing penetration the hardening action. the heat stresses chromium steel in. and 9.8 in. diameter (Treppschuh, Arch. huttenwes. 13, 1940, No. 10, found tensile stresses 114,800 and 107,800 lb. per sq. in. respectively ex- isting the center. logical that heavier dies water hardening steels frequently break quenching. Since stresses this magnitude are close exceed the limit tensile strength the material, only very slight and hardly perceptible change hardening conditions enough cause increase the temperature structural stresses and breaking the die. This effect offers also the explanation for the phenomenon that the hardening number dies under seemingly identical treatment, the one the other breaks without explanation becoming evident later examination. How possible reduce the which are caused the quenching process the harden- ing that hardening becomes fully successful? The forgings determine the size the drop forging die. The heat con- ductivity determined the steel used and cannot influenced. The Influence quenching agent the cool- ing rate. Drop forging die ° ° RIGHT Influence heat conductiv- ity the cooling rate. ° hardening temperature depends steel and die size. All these factors are invariable. water hardening, the hardening stresses can reduced quenching water into jet with the engraved face first. The jet prevents the for- mation steam bubbles the en- graving and takes care even and adequate quench action. The die then pulled out the water re- peatedly about two-thirds its volume and whenever the back takes color plunged again into the water until the back remains dark. great mistake leave the dies the quenching medium until they are completely cold. this procedure tensions and the danger cracking are unnecessarily increased. Dies should rather warm that they transferred into tempering furnace while they are 482 deg. F., that oil water can still evaporate. This method hardening being applied with success experienced heat treaters. The time for “catch- ing” the tool the correct tempera- ture matter experience. The core temperature the die should little lower than the projected tem- pering temperature when the tool removed from the quenching medium. must therefore quenched for definite period. Should the core tem- between surface and core perature still too high then the quench incomplete and possi- ble that tempering action occurs and the desired strength ultimately not attained. the dies are left the quenching medium for too long the temperature stresses are again magnified and the purpose “catch- ing” not attained. The theoretical time necessary for “catching” various drop forging die sizes was calculated, permitting the core drop temperature 572 deg., 752 deg. 932 deg. oil hardening and 392 deg. 572 deg. kcal water quenching. The results are shown Figs. and 10. using these data the influence the engrav- ing the die thickness should allowed for. Tempering Drop Forging Dies All drop forging dies must tem- pered immediately after hardening relieve heat stresses and attain the required tensile properties. The per- high degree the choice the most favorable tensile figure. This strength determined the material the die, its size, the type and shape the engraving, the process which used and the plasticity and forging temperature the mate- rial worked. The choice the correct strength, therefore, presup- poses very considerable experience. But can said generally that drop forging dies with flat engraving, par- ticularly when hard materials are worked, require very high tensile strength order avoid early wear the breaking off any rap- idly cooling ridges which the die face may have. Thus small dies, usually made from water hardening steels, such those that are used for the manufacture small steel parts such scissors, are used hardness about Rockwell-C and tempered THE IRON AGE, May 1944—69 | 200 ° ° } > Air stee/ Stee/ LEFT Influence Critical cooling rate cooling rate depth hardening. about 302 deg. For flat engravings drop forging dies medium size, tensile strengths 105,000 per sq. in. have proved successful. Thus the drop forging motor pistons increase the strength the die from 98,000 105,000 lb. per sq. in. caused increase production from 4000 6000 7000 pieces per die. such high tensile tools bending and notch stresses must avoided spe- cial care the construction and sign. Drop forging dies with deep en- gravings have the suitable strength about 91,000 lb. per sq. in. since here the toughness the tool the greatest importance. the engraving exposed heavier notch actions then necessary reduce the tensile strength 77,000 lb. per sq. in. more deep hardening steels. Fig. shows diagram the rela- tionship between strengths and tempering temperature for water hardening, oil hardening air hardening drop forging dies. RIGHT Hardness suited for the tempering dies. should taken guide for the approximate heating rate. Here are given the periods which are used minimum heating periods for dies various sizes reach the temper- ing temperature 1022 deg. with- out setting considerable tempera- ture gradients between core and sur- face. this heating period which values (Brinell) across large drop forging die 19.5 in.) Cr-Ni- steel. respect. Hardened steel does not ex- pand evenly heating but 212 deg. 527 deg. contraction oc- curs which favors the formation heat cracks. Hardened dies must, therefore, heated especially slowly and carefully tempering order prevent the formation cracks. Muffle furnaces which the rate heat transmis- sion comparatively slow are well 100 LEFT time oil for core temperature 350 450 deg. and 550 deg. ro (662 deg. 842 deg. and 1022 deg. F.) 300 350 400 450 After hardening, the die steels have very great hardness, but are corre- spondingly weak toward notch im- pact stresses. Furthermore must observed that the heat conductivity depends the structure and re- duced hardening. Heat conduc- tivity particularly poor alloyed steels but with increasing tempera- ture this difference becomes less pro- nounced that higher tempera- tures alloyed and unalloyed steels exhibit marked difference this IRON AGE, May 1944 includes adequate allowance for heat penetration additional time must allowed for the structural reforma- tion which the effect tempering. dimensions below 15.6 in. square While any cooling rate correct for most tool steels after tempering (that after hardening and following tempering high temperatures) and without considerable effect their properties, certain steels lose tough- ness slow furnace cooling than cooled more rapidly. Such steels are referred being temper-brittle, and and Cr-Ni steels are particu- larly temper-brittle while steels con- taining are not sensitive to- ward temper embrittlement. The temper-brittleness bound tem- perature range ab