The Iron Age 1944-09-14: Vol 154 Iss 11

VAN DEVENTER and Editorial Directer BAUR General and Advertising 100 42nd New York 17, Johnson, Market Research Bour, Typography and Layout ° Regional Business Managers New York New York East 42nd St. 100 East 42nd Cleveland Pittsburgh 1016 Guardian 428 Park Chicage Bidg. 1134 Otis RAYMOND KAY Los Angeles 2420 Cheremoya Ave. and Published HILTON COMPANY (Incorporated) Executive Offices and Séth Sts. Philadelphia 39, Pa., U.S.A. OFFICERS AND DIRECTORS MUSSELMAN, President HILDRETH GEORGE GRIFFITHS EVERIT TERHUNE WILLIAM BARBER, Treasurer BLAIR MOFFETT, Secretary CHASE THOMAS KANE HARRY DUFFY CHARLES Vice-President Vice-President Vice-President ° Member, Audit Bureau Member, Associated Business indexed the Industrial Arts Index. America, South America and Possessions, Foreign, $15 year. Single cents. ° Vol. 154, No. The IRON AGE Editorial Great Technical Articles Designing Rubber Press Coining Heavy Gage Extending Life Industrial Truck Climb Milling With Single Carbide Blade Non-Ferrous Alloy Specifications Features Fatigue Dear Editor This Industrial Week News and Markets Scrap Market Analyzed Colmer House Postwar Report Machine Tool News Iron and Steel Scrap News. Iron and Steel Scrap Non-Ferrous Metals News and Non-Ferrous Metals Prices; Scrap Prices Finished Iron and Steel Steel and Warehouse Prices Semi-Finished and Tool Steel Prices Steel Pipe and Tubing Wire Products Pig Iron and Coke Prices Railroad Material and Stainless Steel Ferroalloy September 14, 1944 123 124 129 182 184 185 186 187 188 189 190 191 192 193 194 195 196 120 The EXPERIENCE and EQUIPMENT handle any assignment One section aspecial geor case fabricated and assembled its entirety Mahon men and machines. THE DETROIT Methods developed Mahon have set new standard the production welded steel plate products all sizes, shapes and weights. These methods call for vast amount spe- cialized modern equipment. Without the enormous production that goes through our plant each day would utterly impossible. The forming roll (shown above) for example, but One item long list tools com- prising flame cutters, saws, power brakes, auto- matic welding machines, positioners, anneal- ing furnaces, sand blasting apparatus, and vast array other all essential the handling, shaping and fabricating heavy steel plates volume. Our DESIGN ENGINEERING SERVICE proving helpful like yourself. First: determining whether your product adaptable plate fabrication. Second: assisting you re- design that may produced practically and economically. 46—THE IRON AGE, September 14, 1944 <= | | abricators Machine Bases and Frames and Steel Plate ction geor ESTABLISHED ° ° ° Sept, 14, 1944 ° ° VAN Presiden? and Editorial Director BAUR DIX Monager, Reader Service ° © ° Editorial Technical Editor........ OLIVER Associate WINTERS TRUNDLE ALBIN JOHN ANTHONY BARMASEL Editorial Assistants SCHIEN WILLIAMS VAN CAMP MUNZER MILLER News and Technical LLOYD Pittsburgh 428 Park Chica 1134 BROWNE EUGENE HARDY Press Bidg. MacDONALD 1016 Guardian 7310 OSGOOD MURDOCK Francisco St. Editorial Correspondents ROBERT McINTOSH Cincinnati DEAN Buffale FRAZAR Boston HUGH SHARP Milwaukee SANDERSON Ont. RAYMOND KAY Los Angeles JOHN Birmingham ROY EDMONDS St. JAMES DOUGLAS Great Expectations nice have great expectations you have definite program fulfill not then it’s better learn and earn than sit back yearn, That’s what too many are doing today. emerge into new and better world where everyone press buttons, metaphorically speaking, and some mysterious auto- matic way receive filet mignon, colored television sets, laborless dish- washers and other attributes higher standard living. Fairy stories have been written that theme. The story Alladin’s Lamp was one them. But least Alladin had use some elbow grease before the genie appeared his bidding. Pethaps this rosy aura hopefulness and wishful thinking helped along election year the political promisers who have advanced from the stage kissing babies for votes that promis- ing mythical Rolls-Royces hopeful housewives. Plus plenty gas with which run them. (The Rolls-Royces, not the housewives.) All this reminds story. Once upon time young farmer who had labored hard and successfully for number years build home and barns had the misfortune have his house and barns burn down. sympathetic neighbor came him and said: “Friend, just think the much better buildings you will have when you get your insurance.” But the farmer replied: haven’t any insurance. But going have those better buildings nevertheless.” friend, wondering, asked him where was going get them from. going get them from the same source that they came from originally,” said he. “And what that?” queried his neighbor. “From hell lot hard work, which where everything comes from,” said the farmer. The world has been conducting the biggest bonfire that ever was. Probably trillion dollars—a thousand billion other words—would not begin measure the destruction material values that have taken place all countries the world during the past five years. Are you going emerge from that into better standard living for every- body without, the farmer said, hell lot hard work”? don’t think so. that were the way raise the scale prosperity, should hold annual bonfires all our communities and burn our possessions. Frankly, don’t you agree with that this thought about silly the idea that country can become prosperous increasing its debt year after year without remission? Creation, not destruction, makes wealth. The sooner get that into the heads everyone the better will for and for the rest the world. And hard work the the creation values. It’s sounder basis than WPA’s lend-lease. | | 7 ; F 7 ry q : | ¢ 4 q Forming shells) for expendable tanks which are dropped from fighter planes when empty. Sometimes they are used incendiary Expendable Gas Tank “Skins” Made Inland Steel Today, thousands fighter planes are being flown direct from our airplane fac- tories distant battle areas, hundreds them are giving fighter protection our bombers long range bombing raids. Helping keep these fighters the air longer, are expendable gasoline tanks made from Inland Cold Rolled Sheets. Thousands tons 0.024” gage, 144” cold rolled sheets already have been shipped Inland Mills Industries, hicago, where these tanks are formed 750-ton, triple-acting press. Each 165- gal. tank consists two identical half sections sheet fed into the press, where first gripped the for- mation two corrugations extending along each side. The draw 14” the deepest point. After the skins are formed they are trimmed and then sent the assembly line where internal structural bulkheads are installed. After air and gas lines have been put place, the half sec- tions are chemically treated prevent rusting, dried, aligned and seam welded. Each tank then pressure tested, per- fectly balanced, and finally painted in- side and out. Continuous production these expend- able gasoline tanks tells the story again Inland service and the fine drawing qualities Inland Cold Rolled Sheets. INLAND STEEL COMPANY Sales Offices: Cincinnati Detroit City St. Paul pack blas cra: jet pos acc yea air til ‘ Br — Front September Output tin mill products this year will reach 3,000,000 tons, against average 2,500,000 tons yearly. All-time peak was 4,000,000 tons 1941. tin are looking for some form tin allocation for about the war ends. Plans are being laid tow dredges Australia they will hand when the Japs get kicked out the Far-Eastern tin fields. Although WPB allocated 7,000,000 aluminum the can companies for the quarter for can production, customers far have shown great because the higher price and because they have contracted for other types containers. Practically none the aluminum will used this quarter. about month the Government suit against all stainless steel producers should full swing Trenton and Newark, The companies have been given Over during the past year attempt flush undesirable pricing and patent practices. The stainless companies are somewhat the dark about the whole thing, but are cynically conscious the precise pre-election timing the court hearings. Batcheller was literally shanghaied back the WPB. Faced with lot postwar problems his own the Steel Corp. twice turned down pped twice return, only faced with newspaper story that had been named, intends put 50-lb. packages welding rods for sale farmers, assorted sizes and for different purposes. Another package lb. lb. assorted sizes will sold garages and the like. These welding rod packages will supplement the five models welding equipment currently directed farms, garages and small industry. Glasgow Corp. has announced intention using foamed slag blocks from nearby blast furnaces for the construction postwar houses the Glasgow area. The English have built and are experimentally flying airplane. The craft conventional monoplane, which second wing may attached biplane. After getting heavy load into the air, the upper auxiliary wing jettisoned. The extensive cutbacks contemplated follow the defeat Germany will make possible for industry produce civilian goods equal the volume output 1939, according WPB's new acting chairman, reach the 1939 level, civilian production would have rise per cent year. Cutbacks are expected fall follows: Army Ground Forces, per cent; Army aircraft, per cent; Navy, per cent, and the Maritime Commission, per cent time. Navy and Maritime reductions are expected tapered. Transfer automotive technicians civilian jobs will formalized the Sept. meeting the Automotive Industry Advisory Committee and the WMC All companies will authorized transfer engineers and other specialists time production preparations. The preparatory stage will fairly well developed the end the month. Two major problems confronting the auto industry are the for plants government equipment and the machine tool situation. recent debate the British Parliament touched off the question why British and Scottish steel workers are being laid off while imports steel ingots and semi-finished steel from the United States are the increase brought light the tremendous task British inland transportation moving men and materiel Allied armies Europe. With all its transportation occupied, British steel mills have had reduce since they had means shipping fabricators. Helicopters are now service Burma with the American Third Tactical Air Force. The pilots, all volunteers, were trained the Sikorsky factory. 4 : : 4 Rubber Press Tools Accurate forming sheet metal the hydropress can accomplished consideration given the dual action the frictional and fluid properties the rubber when compres- sion. Based this analysis rubber pad action, design standards have been established together with the development unusual form and other rubber press tools. Elimination -of hand finishing illustrated novel uses dams, undercuts, punches and other tool elements. the second and concluding part the article, these tools are applied form flanges, and some new shapes. The data are from Eastern Aircraft Division, General Motors Corp., Linden, present task the rubber press too] designer results from the necessity for more accurate methods producing sheet metal air- craft parts imposed the trend the war. This trend toward greater size and diversity the planes built and greater economy and refinement design. consequence such development familiar tooling problems for which approximate solutions were formerly considered adequate are now frequently found require more pre- cise treatment, and the same time greater speed producing new tools imposed. order keep pace with the rapid research program techniques was started last year Eastern Air- more specifically, test exist- ing designs and establish stand- ards design and their limits ap- plication and also develop new de- signs. This article contains all the information utilized from previous sources well the results the research program the present time. The general physical arrangement hydropress equipment shown Fig. plate the press bolster supports the form block. The metal formed placed the form block and held place locating pins thin nesting blocks. Fastened the press ram cast steel alloy case into which the rubber blanket fit- RUBBER CONTAINER FORM BLOCK 50—THE IRON AGE, September ments proc- ess forming sheet metal the hydropress. PLATEN BOLSTER ° ° ° ALBIN ted, see Fig. the press closes, the platen fits into the mouth the case and forms closed chamber con- taining the part formed, the form block and the rubber. apply- ing this high pressure the rubber forces the sheet metal against the form block. Most this primary forming ac- complished the mechanical strength the rubber resisting deformation. The finished flange results from side pressure caused the fluid flow the rubber under high compression and close confinement. indicated tests, described subsequently, the compressed rubber does not act com- pletely fluid but the force ex- erts combination mechanical and fluid properties. The press shown Fig. 2500-ton press used for rubber form- ing many the parts illustrated this article. Four moving tables make continuous operation possible. Load- ing done outside the press will not stand idle while changing parts. The press can operate strokes per and form average six parts per stroke producing over 1000 parts per hr. The size the platen in. and the pressure obtained the press 1827 per sq. in. This figure obtained dividing the ton- nage the area the platen square inches. 2500 tons 2000 Three 2-in. layers rubber cemented together form the pad. Generally 6-in. thick pad limits the designed height form blocks in. high. However, there are some instances where blocks in. high may used. When blocks over in. are used, the life the rubber pad greatly reduced. form block height in. best suited for 6-in. thick pad. 1827 lb. per sq. Straight flanged parts are the type work that can done the hydro- PART loses, the con- the ubber the ac- ength side icated the com- ex- anical form- make Load- will parts. per parts parts This ton- sq. in, ally high. used, reatly thick type LEFT case shown over formed parts. Note the perfora- tions and cuts the sur- face the rubber caused the work. ¥ BELOW hy- dropress. Work loaded tables outside press. press without the use special form block construction guide the com- pressive force the rubber about the flanges. Straight flanges can accu- rately formed without quent hand-finishing. When certain sections part must stretched increased area, drawing operation being approached. Fig. shows parts con- taining curved flanges which stretching the metal. These parts can formed rubber action but the operation more limited and re- quires close study the form block. construction. Very high pressures ap- forming. Sharp corners, generally speaking, cannot formed rubber action alone. Parts having shape that rubber will flow into without severe distor- tion can formed with rubber acting the punch. They will generally shallow, have well rounded corners end edges, but may reasonably sharp the draw ring radius. The parts shown Fig. have been drawn and formed with rubber. Parts having sharp corners where high local Pressure concentrations are required made with solid punch and pressure pad. Aluminum Sheet Tempers Rubber forming medium generally applied aluminum alloy sheet metal parts. Before consider- ing the action the rubber, nec- > - i a 4 é THE IRON AGE, September P t FIs. 4—Examples curved flanges formed the hydropress. 5—A par- tial drawing operation ac- complished the hydropress forming curved shapes such these. 52—THE IRON AGE, September 1944 es: ca 4 ‘ ° ° ° if at le essary understand the three physi- eal conditions which aluminum formed. Briefly the types aluminum may worked one the three tempers, namely, SO, and SW. Aluminum alloy specified indicates that the metal the annealed condition. This means formed most readily rubber. Straight flanges parts 0.125-in. thickness are readily formed SO. Drawn operations likewise can pro- duced thickness 0.064 in. Subsequent heat treatment obtain the condition warps the parts which turn requires hand straight- ening operations, thus the original the part lost. The aluminum alloy the con- dition, meaning that physically hard tempered, not easily formed rubber. However, success- ful straight flanges can produced this condition stock gages 0.051 in. The aluminum alloy this condition not suited drawing operations. Forming, when possible, the condition requires the least number operations. Aluminum alloy the condi- tion indicates that either the the sheet has -been solution heat treated and remains the soft state for short period time. This pe- riod softness lengthened keep- ing the material refrigerated tem- peratures well below the zero point. While the soft condition, form- ing operations must completed. After forming, the material hardens room temperature and becomes ST. When severe distortion likely take heat treating mate- rial after forming, advisable form the con- dition, allowing the part age-harden after has been formed. Where this procedure lowed hand straightening the part necessary. must also under- stood that forming tion requires ex- tensive amount refrigeration equip- ment and close watch material handling order keep the parts soft and uniform temper before forming. For this reason, most the forming described here has been done with stock. knowledge the composition will help toward understand- ing how acts. All grades are com- 1G. durometer for measuring rubber hardness. ° ° posed crude rubber, sulphur, plas- ticizer, anti-oxidants Crude rubber coagulated from latex, the juice grown plantations and the basic mate- rial all natural rubber compounds. Other materials are added knead- ing between two powerful rollers giving the rubber desirable physical properties. When sulphur and heat are added becomes vulcanized. heated this state, will scorch burn, but will not get soft. un- vuleanized rubber heated, be- comes soft, thermoplastic. Unvuleanized rubber compara- tively easy compound and proc- ° 7—Test show that slippage rubber slight.. Dots paint block are transferred intact pad above. ess forming molding. Then, after has been formed the proper required stiffness and me- chanical stability. Plasticizers are added reduce the hardening with age, and anti-oxidants are added prevent the surface the rubber from cracking due the action the oxygen the air. Fillers are used cheapen rubber but give mechanical properties not obtained pure vulcanized gum rub- ber. oxide, chalk, silica flour, carbon black and other pigments are used. Carbon black increases the rubber, gives good wear resistance, tear and cutting resistance with reasonable elongation. Rubber with this type filler used for rubber forming. Hardness rubber fairly well standardized and measured with Shore durometer shown Fig. The scale shows can force the penetrator into the rubber. Hardness defined the resistance deformation. This resistance part the force used form. metal and will greater for hard rubber. Forming usually done with 50-to durometer rubber but harder grades can used. Rubber blanking employs durometer develop high forces shear the metal. can used for forming thick metal but breaks down quickly. Grades harder than durometer cut and tear easily and have low elongation. Action Rubber Pad The shear factor rubber most important studying the forming ac- tion rubber. The ability com- form sheet metal part depends upon the rubber’s tance deformation to. where rubber begins shear. ultimate shear the pressure concen- trations very ‘the sheet not correctly. The frictional properties rub- ber have the Since rubber commonly used dry little slipping. the slipping the rubber the increases, the me- form the part decreases.. THE September 14, 1944—53 3 : 7 pis 8—Diagramming the internal flow the methods measuring flange widths. tion rubber rubber press have considered the rubber act entirely having very little me- chanical strength and being able into almost any opening. Experiments have shown that the mechanical strength the rubber and its frictional properties are just important the smal] amount fluid flow which takes place. the rubber pad approaches form block, the rubber first touches the highest points and the friction holds the sur- face this position even after the press maximum pressure. Rub- ber travels down the edge block the form curve extending be- tween the block and the platen the press, stretching taking place the free surface. very slight amount slip takes place vertical edge but none the top block. Tests were carried out show ac- curately what happens inside the press. Small dots chrome yellow oil pigment were placed form block which was placed under the press. When the block was removed showed that the dots spread slightly and smeared the radius the block where the rubber slipped. This test has shown that very little slip- ping takes place, see Fig. Another experiment determine the surface elongation was prepared 54—THE IRON AGE, September 14, 1944 FLANGE MEASURING FLANGE LENGTH placing dots paint the form block regular intervals. ber pad was then placed over the form block. When removed from the press, was observed that the dots paint were transferred gether the rubber pad. rubber pad forced down over form block, its mass displaces rub- ber from the area over the top and across the edges the block the space the side, see Fig. This dis- placement internal flow the rubber and not surface action. Rubber compressed above the block and forced sideways. This force, com- bined with compression the rubber the side, pulls the rubber around the edge the block causing high compression and pulling force. RADIUS FLANGE FLAT METHOD MEASURING FLANGE FLAT PARTS FORMED RUBBER HYDRO PRESS SIDE UNDERCUT LIP. Many articles the subject rub- ber press work present the idea that rubber will flow under flange unless the space between the end the flange and the platen the press kept below in. Now tests show that more efficient form blocks can signed keeping this height above in. increase stretching. Form block height should pendent flange width much possible, even for narrow flanges. The measurements should from the platen the press the radius since all the work accomplished that point. wide flange can produced block much easier than narrow flange. rubber does not flow under narrow flange, will Flange Widths order study flange widths, method measuring the results must established. The common practice measure the width from the face the material the edge the flange formed rubber the force which bends the radius produced the flat surface extending from the flat surface the edge the flange. side cut prevents lip caused work hardening. RUBBER FLOWING INTO UNDERCUT CAUSES TENSION undercut construc- effective for narrow flanges. HIGH PRESSURE FROM COMPRESSION RUBBER AND FORCE TRANSMITTED TENSION RADIUS PREVENT CUTTING RUBBER a : ° ° ° rub- that unless the that de. above inde- uch es. The the since that than not will iths, must ractice face the When force ced the The term flange flat will used here indicate this dimension, see Fig. For one set conditions any flange width can produced down certain size. Below this width flange flat, complete deg. flange does not always form. This minimum width which will called the critical flange flat width, measure the ability the rubber form flange flat. The narrower the flange flat, the more effective the force rubber. Even though flange angle not deg. there will always flat the edge. Different bend radii may affect the critical width because the metal stretched more radius and will work harden more, thus increas- ing the critical width. common failure forming flanges has been observed when ex- tremely thick stock formed over sharp radius. The metal seems form natural curve larger than the radius the form block. This due work hardening the metal 15—Control rubber pressure exercised dam. imum bend radii are observed and thin beveled top plates are used, this effect reduced but not eliminated. More distortion resulting from work hardening takes place sharp nar- row radius than wide radius. certain short flanged parts lip forms. This sometimes caused the failure the rubber complete the flange. But most often the cause the lip due work hardening. Work hardening caused shear fracturing the metal. This work hard- PART MUST END BOTTOM ANGLE DISTANCE MUST LARGE supported undercut vertex angle. the radius bending proceeds. Since the metal will bend more easily where has not been worked, the bending will progress toward the edge the flange producing curve which not true radius. When min- 1G. 12—Wall form block re- tards flow rurbber, preventing completion flanging. WALL FORM BLOCK PREVENTS FLOW RUBBER VIEW BOTTOM FORM BLOCK ening can removed burring the part. Oftentimes the work hardening too far into the part and amount burring will remove this condition. side undercut form block will allow rubber flow into undercut not take place under acute angle. FLOW RUBBER FORCED INTO CAUSES WEDGING EFFECT ANO HIGH SIDE SURE OBTAINED causing pressure concentration that point and will draw the lip (see Fig. 10). The minimum bend radii ob- served for sheet metals, including steel and magnesium alloys addi- tion aluminum alloys are carried Table Undercut Form Blocks Several types form blocks have been used produce flanges. Since one design will not all jobs, the ad- vantages and disadvantages each design should determined they can applied properly. Narrow flanges can produced effectively the construction shown Fig. 11. Rubber flows around the edge the metal and starts under the flange. the pressure increases, stretching caused the rubber flowing into the undercut pulls the rubber out from under the flange and the same time produces pressure concentration the flange. When rubber not pulled out from under the flange, the condi- tion shown Fig. the result. The undercut form block very good for flange that has large radius, with narrow flange flat the edge and also short flange flat with small radius. Near the vertex acute angle rubber flowing un- der the plate from each side will meet underneath and the necessary stretch- ing cannot take place. The result shown Fig. 13. Along with this con- dition high concentration pres- sure formed the top plate. This pressure great that beyond the elongation limit the rubber and thus causes tear. Parts having acute angle can formed form block that has supported undercut the vertex the angle, see Fig. 14. This design prevents the rubber meeting the sides and also prevents the rubber elongating too much. Nev- ertheless, only suitable the acute angle the part not too severe and the two ends part are not too close. ends part were close together rubber dam should used. THE IRON AGE, September 4 ° ° OAM ° ° ° ° ° caused ITTED Metal thickness radius and metal 0.040 graph holds true 0.100 0.200 0300 0.500 0.600 Minimum flange flat width for minimum flange flat lengths for different metal thicknesses aluminum. variation the slanting undercut shown Fig. one where the undercut horizontal. This may con- structed top plate steel over Masonite base, the edge the top plate extending be- yond the base amount AST 18—Equations for blank size from in- side outside mold line. RAD. that one-third the height the block for blocks in. height. Utilizing Dams The dam, Fig. 15, another excellent means controlling the action the rubber. straight flanging the action 17—Graph for minimum flange flat lengths for different metal thicknesses aluminum. Metal NOTE: obtain length minimum Flange add radius and metal thickness 0.160 Flange This graph holds true per Flange flat shore durometer hardness rubber 0.120 block 0.100 0300 0500 0600 0800 Minimum flange flat width 56—THE IRON AGE, September 14, 1944 SPRINGBACK ALLOWANCE useful design that provides 1G. 19—Equation giving width and radius allowance and the spring- dam can analyzed consisting three factors—one which causes high pressure concentration the ra- dius the form block, another which reduces the pressure the side the block, and third factor which stretches the rubber, Narrow flanges may produced the high pressure concentration the radius and the stretching action keeps rubber under the flange. Dams will increase the accu- racy wide flanges be- cause more bending Lower pressure the edge the flange will reduce the tendency bend where the flange back angle. should remain order get the the dam, its shape and dimensions must determined for the erubber hardness and pressure which will used. The ef- fect width was studied forming narrow flanges block in. high with 2-in. (dam) placed vari- ous distances. Best results were obtained with 1-in. Rubber flowed into the opening about 1.3 in. the dam This test was out Lake Erie press with 0.220 | | | ac | | 0.200 three which ressure the ra- block, side which rubber, nay high tration the keeps Dams accu- res be- radius, the ney flange ind flat. the shape must the and was block vari- Best cing. into 1.3 less. rried ton with Shore durometer rubber 1827 per sq. in. and the results are true only for these conditions. The change width the flat top retainer block dimension which has only slight effect the width flange. Grouping form blocks that one acts retainer block for the other has many advantages, such saving large amount space, giving all parts the advantage the dam which results greater accuracy, stopping the pulling effect and lessening strain the rubber. narrow form blocks, narrow dams may more efficient because they allow the main mass rubber drop lower and thus permit high pressure concentration on.the radius the form block. This, how- ever, may also cut bruise the rub- ber; which case, rubber pad placed over the narrow and narrow retainer block will pre- vent tearing the rubber pad the press. The combination dam and un- perhaps the best method achieve the maximum concentration pressures. This design suited for short flanges alumi- num and heavy gages the alu- minum. Maximum strain the rub- ber produced whenever this design used that pad rubber should placed over the form block. The block and dam should constructed Kirksite steel. The dam should securely doweled and screwed steel base minimum ness. The maximum depth under- cut should more than 7/16 in. else the high pressure concentrations the radius the form block will tend bend the top plate. the thickness the top plate reduced, TABLE Minimum Bend Radii for Sheet Metal, Inches ALUMINUM ALLOYS STEEL MAGNESIUM AND ALCLAD STAINLESS Low 11317 M-111 Ht. Treated Formed Carbon 24ST but Formed Before and Thick- 0.091 2364 332 «teen ave 0.187 For Bends deg. only. the depth undercut should pro- portionately made shallower. Flanging Data The minimum width flat flange that can made with different type blocks shown the graphs: Fig. for material, and Fig. for material. rubber press work are generally not satisfactory graph determined from actual tests. Too many variables*are involved and the action metal cannot pre- dicted accurately. However, equations, see Fig. 18, blank size from the inside outside mold line, are accurate and simple formulas that should used. Another equation, see Fig. 19, which does have practical use, gives the width and radius allowance from the bend radius and the spring back angle. When metal having high spring back bent over large radius the width allowance will very large. many, this appears failure the rubber completely form the part. Closer observation will show that not failure. The formula shown Fig. may used calculate the correct size predetermined width when the spring back known. [In the concluding discussion next week, the forming flanges and other shapes will described.] Density Metal Powder Particles PPARENT density, flow, particle size blend and particle shape are characteristics which are currently being used define the properties metal powders. late, those working particular problems involving metal powders have posed the question, “What the actual ticles?” Upon referring methods estab- lished the A.S.T.M. for cement and pigments, Hardy Metallurgical Co., New York, found that this prop- erty could determined two ASTM Standards 153-39, page 771 ASTM Standards page (both the 1942 ASTM Book Standards) Average Solid Particle Apparent Density Density Density Electrolytic iron 7.87 7.80 2.2 Electrolytic iron 7.87 7.75 2.3 Reduced iron 7.87 7.49 2.1 Electrolytic 8.93 8.86 2.3 Tentative density determinations these methods, shown the accom- panying table yielded the following comparative the Hardy laboratory. known that the porosity individual particles has contribut- ing effect the compressibility metal powders and the study the average particle may throw light the properties required metal powders for powder metal- lurgical use. THE IRON AGE, September a ¥ ‘ < « COINING Heavy Gage Stampings OINING close being cross between forging and stamping. The metal han- dled cold, stamping, and flow metal achieved, forging. The result usually low cost manufac- turing operation which employed produce parts which not only are within fairly limited tolerances, elim- inating need for machining, but which also achieve higher hardness, thus often by-passing need for furnace treatment. The major task satisfactory coin- ing operations usually the develop- ment dies reach the desired end- result. Inasmuch cold flow metal involved, the dies must fulfill number requisites. Primarily, Coining heavy gage stampings closely akin cold forging upsetting. The term implies accurate sizing and work hardening the material higher strengths. Some the possi- bilities the process are found examples taken from practice the Detroit Stamping Co. ° STANLEY BRAMS course, they must direct the metal along preferred flow lines, and this suitably overlapping stages the job complicated. These lines flow must developed that the granu- lar structure the metal strength- knuckle action press commonly used for the great compres- sive stress de- velops. Note the considerable bulk the die the press. ened rather than ondarily, the dies have built process enough pieces justify their cost. Experience obviously impor- tant making coining dies. Coining tolerances are not uncom- monly held within 0.0015 in. The coining process well suited for ir- regular round counterboring, two more surface thicknesses some part gasket flat surfaces, close tol- erance stamped parts, burr removal and edge radius. Customarily, such finishing small parts achieved grinding other forms ma- chining. Coining large areas less practical due the tremendous pressures required. knuckle action press erable, Fig. provide the tremen- dous compressive stress necessary flow the cold metal, and allow time for this flow during the rather long dwell the bottom the stroke. Speed, consequently, necessarily slower than for blanking drawing. This generally holds true for coining work done crank toggle presses. Massive Dies Dies are made from tool chisel steel, air oil hardened, depending the work: done, Fig. Ex- perience and experimental work dic- tate the amount heat treatment necessary. best practice coining dies are usually quite bit bulkier than comparable stamping dies, made thus provide extra margin strength against the stresses imposed the form. this respect, the practice De- = ; : “tae | $l | | : ] | | | ° a j ° ° ° work possi- uilt their ncom- The ‘or ir- two some tol- moval such ma- ndous pref- time long wing. ining hisel Ex- dic- nent ning nade osed De- troit Stamping Co., an.active producer coined stampings, often shrink ring collar onto the die strengthening agent. Where ring not used, the die made with con- siderably larger surface surrounding the work area than otherwise cus- tomary. The Detroit concern has enlarged its coining work since the war began and has abundant file case his- tories prove the point that the method major means reducing costs. has done work small ob- jects like simple washers requiring special edge surface conditions, and has also cold processed parts from stock heavy in. Cost savings are sometimes star- cent over more orthodox machining and manufacturing operations are means uncommon. One-Third the Cost Illustrative the work done this plant the spline lock ring, Fig. starts washer blanked from 0.078 in. chrome molybdenum steel. The rim coined 250-ton press thickness 0.035 in., and the contour then trimmed. no- table by-product the process, Rock- well hardness the edges raised per cent. Normally this part would 2—Typical dies for coining are shown. Left view the punch with coining grooves machined surface and the right the die platen, which may ground irregu- lar correct for flatness. machined from stamping, but coining costs are about third stamping and machining cost esti- mates. more complicated application valve limit retainer, Fig. made with sequence die which provides progressive piercing, coining, trim- ming, repiercing and blanking. soft cold rolled steel, 0.050 in. gage, the medium, and the process ten- sile strength raised the limit lug per cent, increasing wear qualities the point that heat treat- ment unnecessary. The limit lip coined within tolerance 0.002 in. during the reduction gage from 0.050 0.020 in. Previously this part was machined from stamping; coin- IG. 3—A spline lock ring coined two steps from the first operation being the coin- ing the rim and the sec- ond being the trimming the contour. Costs are third those stamping and machining. ing reduced costs per cent. Coining heavier piece exem- plified crankcase oil sealing base, Fig. made in. hot rolled pickled steel into which six grooves are coined into the sealing area around the bolt holes. This base coined flat the same time, the proc- ess eliminating expensive grinding operation and providing improved seal against oil seepage. The grooves 4—The progressive development valve limit retainer shown this illustration. left the strip steel comes the coining stage, three holes having been pierced it. The center lift then coined; three additional holes are then cut out and tongue end trimmed; and the third step the finished piece, shown right, blanked out the strip metal, leaving the scrap skeleton shown. ° ° ° THE IRON AGE, September ABOVE 5—This crankcase oil sealing base, produced from the die shown Fig. has grooves coined depth 0.015 in. operation which flattens the base the same time. the face are coined depth 0.015 in. through rectangular area measuring about in.—an oper- ation which would manifestly ex- pensive, not impractical, other means. Coining reduces about half the cost producing similar piece machined from casting. Coining Reverse Sometimes the coining art has reverse its general line approach. example the engine recessed spline locking ring, Fig. this piece the metal has made flow toward the inside during coining the outer diameter thickness—just the opposite most coining, and much more difficult than flow the metal from the center toward the outer cir- cumference, where can cut off. The thickness the this piece 0.093 in., and the thickness base and curved inside fingers has been reduced 0.060 in., dimension held plus minus 0.0015 in. Made chrome molybdenum cold rolled steel, the piece was formerly produced from bar stock, machined and milled several operations. Coining 400 ton press, followed heat treat- ing and pressed metal re-sizing, has reduced the cost this previous method about per cent. Adaptations for war and peace alike abound this shop. One the for- mer classification bomb fuse head, Fig. Formerly made product and then machined forging, this head was finally converted cold coin stamping, lowering costs third from the pre- 60—THE IRON AGE, September 1944 6—In producing this engine recessed spline locking ring, the metal has flowed the center section which then pierced out and discarded. Flange thick- ness held 0.093 in., while the adjoining base section and the curved fingers have been reduced 0.060 in. coining. Cost about per cent that previous production methods. vious most economical method. Three separate operations are involved this head: Blanking, coining and trim- ming, with need for annealing machining. The piece produced has convex, cone-tapered face the one side with conical extruded flange the other, meeting sharp edge coined down 0.020 in. thickness. The material used SAE 1010 strip stock sheared from sheets 0.203 gage steel. For peacetime uses, the adjustable support bracket for truck chassis, Fig. indicative. Used now military trucks, this hot rolled pickled steel piece must have serrated ends withstand excessive loads without los- ing adjustment. The coining the pads each end the support re- places milling two directions, and work hardening sufficient elim- inate any need heat treatment. Costs are about per cent less than milling. Limitations Discussed Naturally, coining not panacea which can away entirely with ma- chining, milling and grinding opera- tions. Shapes must observe fairly definite limits size and thickness and comparatively simple dimensions. The higher costs dies set job indicates that work loose tol- erances might done more econom- ically other means. Furthermore, the tricks technique involved not lend themselves improvisations tool rooms unfamiliar with such work, the ordinary stamping shop. Nevertheless, study the method may produce worthwhile and econom- ical applications for small parts pro- ducers and users. 7—Steps the production bomb fuse head are shown from left right. left the slug 0.203 in. steel after blanking from strip. center shown the convex taper side produced from this operation, waiting trimming. right the reverse side the head, coined conical shape with extruded flange, after trimming. 8—Serrations the ends this chassis support bracket were coined, reducing milling and, by-product, hardening the work sufficiently eliminate need heat treatment. | } = ‘ Three ved trim- ling has one nge edge ss. The stock istable hassis, OW on nds los- the and elim- than nacea ma- fairly kness tol- more, not work, shop. nom- pro- Extending Life Industria Truck Tires COOK Vice-President, Elwell-Parker Electric Co., Cleveland FIG. rubber tires drive wheels in- dustrial power truck before and after turning. machine tool builder finds that turning grinding down the lumps and removing the flat spots actually adds about four months the normal life industrial truck tires, thus not only conserving vital rubber but adding the life the truck. the plant Warner Swasey Co., Cleveland, effective methods making repairs power truck tires have been developed the elec- trical maintenance, industrial truck department. These conservation mea- sures have resulted longer useful life for the tires and better operating efficiency the truck. Maximum ser- vice obtained making repairs before the tires have become too badly worn, Vibration due lumpy tires cuts down material sometimes operator fatigue and sometimes causing damage the loads. Also, tires which are out round will wear out very much faster; and travel vibra- tion does the truck itself good. These are all good reasons for keep- ing watchful eye contours well thickness, particularly plants where floor conditions tend accel- erate the rate wear. The principal causes tire wear are: (1) The effect oil grease, (2) the effect imbedded chips and (3) the effect hard smashes obstructions and pitted floors. Oil weakens the surface rub- ber tire changing the rubber com- material. With the resilience and strength gone, pieces are separated from the main body the tire, caus- ing hole. are also caused chips shocks. Whatever causes hole develop, the condition ag- gravated the wheel turns over tire before grind- ing. (Center) Similar tire after grind- ing. (Right) Auxiliary steel rim used share load heavily loaded truck tires. 2 under heavy loads, increasing the compression the surrounding rub- ber, which must take the extra, work. The result wasting away the rubber the weak point. Tires which are subject these excessive service conditions are seldom worn smooth. Larger pieces are dis- lodged from one section the tire than from another and the wheel goes out round. When the wheel be- comes flat one spot this flat spot continues grow larger, rather than have the corners rounded off might expected. When this condition has developed the extent several flat spots, truck running miles per hr. subject excessive vibration. The truck handles like automobile with bad shimmy, and the operator natu- rally reduces the speed order preserve normal control, well avoid the fatigue induced the more difficult handling. Turning Tires One satisfactory method which has been developed Warner Swasey THE IRON AGE, September r ° ° ° ° ° yht. the for reconditioning lumpy tire remove the high spots turning lathe, making the circumference true with the center the wheel, Fig. Life the remaining rubber pro- longed the smooth contour and more uniform distribution load; and the efficiency the truck re- stored enabling handle nor- mal speed. The rubber not wasted because usually has been injured that has value. This reconditioning can done chucking the entire wheel with the tire, pressing off the tire and replacing with spare while the reconditioning being done. The average time required remove wheel, press off the tire, press spare tire, wash out the bearings, repack with grease and replace the wheel, hr. Imbedded chips should removed hand, provided this can done without leaving large hole. Spiral turnings, the other hand, are likely tear out too much rubber, cut “biscuit.” Experience has indicated that the turning tool will usually flip out such chips with least damage. Thin Cuts Taken The cutting tool should ground with considerable rake clearance, and should present fairly sharp edge compared tool used for turning steel. should very rigid- clamped into the tool post. The sharp edge fed into the tire upward angle. Cut should 1/16 in. deep less, using slow feed with the lathe chuck turning between 300 and 500 r.p.m. Due the wide range rubber compounds encoun- tered, and variations the condi- tions the tires, the tool angle, clearance, feed and speed are best determined experience. Synthetic rubber tires can reconditioned the procedure just described, but de- tails will have modified suit the material each case. The top worn layer rubber cut more easily than the subsurface layers, and chips give little difficulty, especially the bad ones are removed before turning. warning usually given that chip going make trouble, the tool ticking against before engages solidly. Sometimes chip caught the tool edge and remains there, scoring the rubber. this case the lathe must stopped immediately and the chip removed. The lathe operator should, course, wear safety goggles for this work. the Warner Swasey plant trucks are used three shifts seven days week, and tires have normal life one year. After turning they run about four more months before needing further attention. After the first treatment difference noted the performance the tire. After second cutting the tires feel little more solid; and third cut possi- ble still more pronounced effect solidity noticed. Reconditioning has been estimated add per cent the life the tire. Care always taken replace tires pairs having the same outside diame- ter, keep the truck level position. Especially this advan- tageous the drive axle, reducing wear the differential. Wheels smaller diameter, such are used beneath the platforms lift trucks, are usually not easy recondition turning because the lower peripheral speed. this case hub may turned and chucked centered grinder, and the rub- ber ground off, using very fine in. diameter wheel turning high speed (See Fig. 2). Plenty water must used wash the rubber out the pores the grinding wheel. grinding small tires. Auxiliary Steel Rims Some trucks have cluster four wheels under the platform. These have molded-on tires which are very difficult replace. This situation was met installing steel rims relieve the wear the rubber when the truck loaded. Two steel wheels, one right and one left, are provided with two rubber wheels, the steel wheels being turned in. smaller outside diameter. The rubber tires, being larger, carry the truck when empty loaded lightly. When heavy load placed the platform, the rubber tires are compressed and the steel wheels take part the load. When lightly loaded the truck runs noiselessly and the riding quali- ties are much better for the operator. Until spare tires become more read- ily available, tire conservation will important, both for obtaining long- life from tires and for assuring that the trucks operate the highest efficiency. Good housekeeping and maintenance smooth runways will help more than anything else con- serve the rubber, but when adequate measures this respect cannot taken, the life what good rubber remains damaged tires can prolonged removing the lumpy sur- faces restore smoothness and round- ness. Climb Milling With Single Carbide Blade changing milling with multi-blade high speed steel shell end mill climb cut- ting with carbide flycutter, produc- tion milling the lug shoulder forged nickel chrome alloy steel rocker used aircraft engines (top) was increased from 110 pieces per hr. and the finish the work pieces was appreciably improved. making the switch carbides, old multi-blade high speed steel shell end mill in. diameter, which had previously been used low cutting speed this job, was converted into flycutter tipping with single blade Carboloy grade No. 78-B. The tool had deg. helix angle (bottom). The 62—THE IRON AGE, September 1944 speed was increased 550 ft. per min.; feed in. per min. was used, and maximum depth cut in. was taken. When the direction rotation the cutter was reversed use climb milling, the finish ob- steel rocker forging which lug milled. BOTTOM: High speed shell which was converted single bladed, car- bide tipped fly cutter. tained was materially improved. addition upping production more than 300 per cent, climb cutti