The Iron Age 1942-09-10: Vol 150 Iss 11

46.55 The unpleasant fact that not scrap being col- there chance building backlog for the winter J dies, parts, etc. remain frozen, and cannot move without check your entire plant, giving orders everything Time short the need please act now be- 44.00 fore winter sets 2.00 PILING RAILS TRACK REINFORCING BARS HESE will one day announce our arrival door-step. Meanwhile, these projectiles are being heat-treated with the help these Hoskins Alloy-502 Fixtures that are light but strong. The fixture about ft. weighs and carries projectiles that are in. dia. ides in. long. The picture shows how these are mounted which also available rolled rod. you need heat- ° ost e con ors Hoskins Manufacturing Company, Detroit, Michigan. for HOSKINS ELECTRIC HEAT TREATING FURNACES HEATING ELEMENT ALLOYS TRON AGE, published every Thursday the CHILTON CO. (INC.). Philadelphia under act March 1879. Entered second class matter November 1932, the Post Office yearly North America and South America, Foreign $15. Vol. 150, No. 11. — ROMIUM SEPTEMBER 10, 1942 This Weekin... VOL. 150, NO. VAN DEVENTER President and Editor BAUR Vice-President and General Manager ° ° or, ROWAN Editorial OLIVER Associate Editors Every Cloud Has Silver Lining JAMES VAN MacDONALD WINTERS Editorial Assistants . BUTZNER 3 S. H. BARMASEL Resident District Editors Forging Aluminum Alloy MOFFETT CAMPBELL Cleaning and Burring Cartridge Belt Links Washington Pittsburgh i DONALD BROWNE PHAIR Abrasive Cut-off Wheels Chicago BRAMS Reclaiming Tin Detroit OSGOOD Drilling Square and Hexagon Holes Ss Francisco Surface Roughness Standards Cincinnati FRAZAR RAYMOND KAY Vestibule School Boston Los Angeles . HUGH SHARP JOHN McCUNE New Equipment Milwaukee Birminaham onte St. Louis BACON Seattle Features Assembly Line Washington Advertising Staff West Coast ion Clevela Fatigue Cracks Research Mar. duct Mo This Industrial Week News Industry Personals and Obituaries Non-Ferrorus Metals Machine Tool Activity Scrap Markets Iron and Steel Scrap Prices Comparison Prices Owned and Published Finished Steel Prices CHILTON COMPANY (Incorporated) Warehouse Prices Executive Editorial and Advertising Offices OFFICERS AND DIRECTORS MUSSELMAN, President Index Advertisers A + o + < ¥ Copyright. 1942. by Chilton Company vv A o ® + ¢ | | Art vi. q } ° ° ° | Emerson Fin Raymond Kay, 2420 Cheremoya Ave., Los Angeles, Cal. Peirce Lewis, 7310 Woodward ° Ober, 100 East 42nd New York O. L. Johnson, Ma } Member, Associated Business Papers lished every Thursday. Subscription Price Possessions, $8; Foreign, year. 146 adel ph 3. Po. = New York. N. U.S.A. 205 Ac SEORGE GRIFFITHS Vice- J. H. VAN DEVENTER Vice- i JOHN BLAIR Secretary HARRY V. DUFFY CHARLES J. HEALE ABE: fice at > T’S long way from raw steel finished tools war—from plates, structurals, bars and sheets—to planes, tanks, ships and guns! Helping keep steel moving quickly and smoothly all the thousands that must come ahead final assembly Ryerson’s part the war production job. Ten big Ryerson Steel-Service Plants, conveniently located serve the nation, provide reliable source for emergency steel quickly available keep arteries war production flowing. This the vital function these steel warehouses are performing. And, spite today’s emergencies, when required stocks are not always immediately available, Ryerson engineers, laboratory technicians, and steel-service men from RAW the BATTLE LINES! But Ryerson Cuts the Corners usually find way supply industry’s war needs. Time and again, Ryerson stocks and Ryerson ingenuity, have been able supply steel vital the steady flow war production when first seemed impossible. Whatever your steel requirements line with the WPB system—the experience and resources this cen- tury-young steel-service organization are yours com- mand. Phone, wire write the nearest Ryerson plant. get quick action once. Joseph Ryerson Son, Inc., Chicago, Milwaukee, St. Louis, Cincinnati, Detroit, Cleveland, Buffalo, Boston, Philadelphia, Jersey City. ; - ™~ * THE IRON AGE ° ° ° SEPTEMBER 10,1942 Every Cloud Has Silver Lining expressed some optimistic views about our prospects for after-the-war recovery. They were based upon our nation’s experi- ence after the Civil and the First World War, which indicated that war stimulated additions our inventory plant, equipment and labor skills and always provided springboards from which jump higher activity levels.* Evidently Dr. Hans Elias, Middlesex University, Massachusetts, does not agree with me. For the Associated Press reports him recently predicting that the post-war world will poor that women will have return their grandmothers’ spinning wheels and that men will have build their own houses. “There will cars, radios, washing machines refriger- ators the world that will exist after the said Dr. Elias. “The masses people will impoverished the burdens which the war imposes upon far trade between nations concerned, there just won't any, according the eminent educator. “There will practically export industry because the countries abroad are already completely exhausted. There will practically import trade because whatever the destroyed countries produce they will need for themselves and shall longer wealthy enough buy more than need.” the professor has been correctly quoted, there least one ray hope his last sentence above. indicates that may able buy what need, even though more. And that leaves con- siderable latitude and longitude. course, with cars, radios, washing machines refrigerators will have scrap most our plants and equipment, for there will not much left for machines do. And herein emerges corner the silver lining, for then would not have worry about scrap collections. And course going back the Stone Age would have its advan- tages, too, the form automatic world disarmament, because you cannot make modern weapons without modern machines. would have settle our international quarrels with shillalahs and brick- bats, which would break for the The professor has not convinced any means that right. But has clearly demonstrated the fact that the expounding crack- pot views will bring newspaper headlines. After the War,” The Iron Age, Aug. 1942. q | | q | q | t 4q 7 Time have war the cen- | com- 4 | | | Contribute $1,500,000 Get Scrap Sales Offices: Companies The seriousness the scrap situation perhaps best indicated the extent which the steel companies themselves are going desperate attempt obtain more scrap. are contributing $1,500,000 (other industries $250,000 be- cause other metals, rubber, etc. are included) total fund $1,750,000 for nation-wide educational program sponsored the War Production Board and over the signature the American Industries Salvage Committee. The steel companies have also converted very large portion their current advertising the subject scrap collection. addition the promotional campaign large number steel men have been assigned the task scouring the country for scrap cooperation with scrap dealers. Here Inland are making substantial contribution the general cam- paign and are also devoting major portion our own advertising the task getting more scrap. But the scrap situation critical that are taking many other steps effort keep our furnaces operating top capacity. Inland lake freighters are breaking records and extra freighters have been leased bring down more ore from our mines the north. New blast furnaces are being rushed completion that will able make more pig iron and use less scrap. But the situation still remains critical. cannot urge you too strongly recheck your scrap situation—not just production scrap but the frames old buildings, old machines, tools, dies, parts, etc. only with this additional material that can make enough steel assure Victory. Please act today—tomorrow may too late! INLAND STEEL COMPANY MILWAUKEE DETROIT ST. PAUL ST. LOUIS KANSAS CITY 40—THE IRON AGE, September 10, 1942 | all the fabricating proc- esses employed the pro- duction aluminum parts for the sinews war, probably less has been written about forging than any other. For this apparent neglect forging literature, how- ever, there eminently valid reason. The forging aluminum new industry. recently 1939, forging out- put represented only about per cent new aluminum production. 1941 had increased per cent the total, and demand has continued surge rapidly up- ward. reasonable estimate that now about per cent the new metal produced will go- ing into forgings, and that con- siderably greater number fabri- cators will producing them. The problems which arise the making aluminum forgings dif- fer certain details from those in- volved forging steel. Steam and air hammers, board drop hammers, upsetters, mechanical and hydraulic presses are employed working both these metals, but considerable variation the power required, the design dies, pre-heat- ing and heat treating procedures, finishing and inspection must made for aluminum. The power requirements for forg- ing aluminum are approximately the same for strength alloy steel—or about per cent more than for common low alloy steel. The reason that the vield strength aluminum alloys Forging Aluminum Alloys ... Forging types aluminum alloys are discussed this article, well the principal factors covering die de- sign general. later articles the same subject, press forming aluminum alloys, upsetting and heat- treating and aging processes will taken greater detail. Much the material has hitherto been un- published. their proper forging tempera- tures, higher than the yield strength low alloy steel its proper forging temperature and strength high tensile alloy steels their proper forging tempera- tures. peratures aluminum may have lower yield strength and hardness, and relatively high elongation when compared with some the high strength alloy steels, obvious that room temperature properties not govern during the forging operation itself. the respective “proper forging temperatures,” the forging properties aluminum al- loys and high strength alloy steels are more less similar—at least relation power required. true, course, that billet tem- perature during forging operations aluminum alloys declines some- what due cooling and that this has effect upon the plasticity the material. Obviously, the metal cools temperature below the proper forging range before the forging operations are completed, reheating the proper temperature indicated. course, the size the alu- minum forgings that can pro- duced any particular forging equipment also depends upon the design the part and the special TABLE Nominal Composition Principal Forging Aluminum Alloys Percent Alloying Elements Alloy No. 11S 5.5 14S 4.4 0.8 0.8 0.4 17S 4.0 0.5 0.5 18S 4.0 0.5 25S 4.5 0.8 0.8 32S 12.5 1.0 1.0 0.6 53S 0.7 1.3 70S 1.0 0.7 0.4 0.5 0.5 2.0 0.9 0.25 0.25 10.0 impuritie THE IRON AGE, September 10, q | ; Remainder aluminum plus normal characteristics the alloy being used. The different aluminum al- loys vary forging characteristics and such physical and chemical properties strength various temperatures, thermal expansion, and resistance corrosion. The aluminum alloys commonly employed the manufacture forgings include the following: 17S, 18S, 25S, 32S, A51S, and The nominal compositions these alloys are given Table The choice alloy for partic- ular forging job should made only after careful consideration the manufacturing volved using the various alloys, well the conditions under which the finished forging used. The physical properties are shown Table One the first alloys employed principally for forging was 25S, and used today large ton- nages for many purposes. Mechan- ically, its properties are essentially similar those 17S (see below), but elevated temperatures more easily worked. Alloy 14S also was developed pri- marily for forging purposes. re- cent years the use has in- creased rapidly because higher mechanical properties than any the other well-known forg- ing alloys and finds applications where maximum saving weight desired. For aircraft structural parts and pipe fittings, alloy 17S widely popular because has somewhat better resistance severe corrosive conditions (such water) than 25S, and readily machinable well. Forged radial engine crankcases are usually made from alloy Such forgings would difficult produce any the harder alloys, and the properties A51S are otherwise satisfactory should specified, where possible, for most large and intricate forging jobs. Ease forging this alloy increases the life dies considerably and, flows readily, forgings can made closer tolerances. Produc- tion time also materially reduced. Where retention strength elevated temperatures essential, alloys 32S and are best suited for use forged parts. The co- efficient thermal expansion 32S also lower than that any TABLE Minimum Specification Values other wrought aluminum alloy, and this factor additional advan- tage the manufacture such items pistons. superior resistance certain kinds corrosion the first con- sideration, alloy 53S often spe- cified. Where machining costs are the deciding factor, the use alloy 11S promotes economy. Alloys (pure aluminum) and (1.2 per cent Mn), because their desirable welding characteristics and resist- ance corrosion, are also occasion- ally used for forgings requiring such properties. Forging Stock Aluminum forging stock must first cut into billets the proper size. This can done cutting with band saw, shearing (where the stock not more than in. means abrasive cut-off wheel. Where the finish the cut end important (as where this end large part the forged surface) the abrasive wheel most efficient, since the desired forged finish can still attained without polishing the cut end. preparing the billet, the most Mechanical properties Heat-Treated Aluminum Alloy Forgings Typical Values (not guaranteed) Tension2 Hardness2 Shear Fatigue Density Yield Ultimate Brinell, Shearing Endurance Strength Per Cent 500-kg. Load Limit! Lb. Per Sq. Per Sq. In. In. 10-MM. Ball Lb. Per Sq. In. Lb. Per Sq. In. Lb. Per Cu. In. 34,000 55,000 12.0 31,000 0.101 50,000 65,000 10.0 125 45,000 16,000 0.101 30,000 55,000 16.0 100 15,000 0.101 25S-T 30,000 55,000 16.0 100 35,000 15,000 0.101 40,000 52,000 5.0 115 14,000 0.097 A51S-T 34,000 44,000 12.0 32,000 10,500 0.097 30,000 36,000 14.0 24,000 11,000 0.097 50,000 16.0 37,000 21,000 0.105 1These properties apply forgings in. diameter thickness. grain flow. and hardness values determined from standard %-in. values tension. (1) For all alloys, wrought and cast, the following data GENERAL NOTES diameter test specimens. Long axis test specimen taken parallel direction Values compression least equal for Testing Materials specification for methods tension test- apply: (a) Young’s modulus elasticity 10,300,000 Ib. per sq. in. (b) Modulus rigidity 3,850,000 Ib. per sq. in. (d) Bearing strength equal 1.8 times the tensile strength provided the edge distance, the direction stressing, not less than twice the diameter the hole. (2) Yield strength the stress which produces permanent set 0.2 per cent the initial gage length 42—THE IRON AGE, September 10, 1942 and specimen. (American Society (3) Shearing strengths are single shear values obtained from (4) Endurance limits are based 500,000,000 cycles com- pletely reversed stress using the Moore type machine (5) Elongation varies with the form and size test specimen. When round specimens are used the gage length for the mea- surement elongation equal four times the diameter the reduced section the specimen. 6 ‘ and advan- such certain spe- sts are alloy 1.2 per sirable resist- ‘asion- must proper wheel. end disa rface) ficient, can ishing most lest- from com- chine men. mea- f the advantageous grain flow should considered order achieve maxi- mum strength the forging points heaviest loading. Die de- sign and control fabricating methods are also important items considered with respect grain flow. For some large forgings, the bil- let starts ingot which worked into wrought structure and partially shaped hydraulic press. The flat dies used the press for this work have corner radii about in. prevent tear- ing and cutting. The distance the squeeze such press limited the die radius. Presses used for this work range from 1500 3000 tons. Some landing gear parts, wing beam sections, and crankcase sections for air-cooled aircraft en- ABOVE alloy aircraft propeller blade being forged one the larg- est steam hammers the country. Note the large amount lubricant being used. RIGHT alloy forgings are made from rolled, extruded, ingot stock. Here stock pile showing round and square billets ready sawed proper length for forging. 3 i gines are examples forgings pro- duced from ingots. Dies for Forging designing forging dies for use with aluminum alloys, care must taken insure correct draft, shrinkage and mismatch tolerances. When natural draft provided the final shape the forged part, 7-deg. draft must normally allowed. the forging made press, however, draft angle approximately 0.25 deg. usual- sufficient. For parts produced upsetter, draft angle allow- ance about deg. correct. (See Table IV.) Shrink the contraction forg- ings (in all directions) caused the cooling the metal. Mismatch caused improper alinement the forging dies. The result shift one part forging from its relative position the other part the forging along the part- wae i d 2 ° ° ° TABLE Heat-Treating Cycles for Aluminum Alloys Required Attain Physical Properties Given Table Heat-Treating Ageing Temperature, Alloy Deg. Hours Deg. 930 340 940 10-12 Room 960 10-12 340 25S-T** 960 10-12 340 930 10-12 340 340 A51S-T 960 10-12 340 70S-T 960 340 *For maximum hardness and tensile strength, age hr. deg. **Propellers heat treat 12 hr., age a minimum of 15 hr. TABLE Draft Angle Tolerances for Aluminum Alloy Forgings Tolerance Inside holes and TABLE Drop-Hammer Forgings Nominal Plus Nominal Upset Forgings Plus Angle, Deg. Minus, Deg. Deg. Shrinkage Tolerances for Aluminum Alloy Forgings Shrinkage Length Width, In. Plus 0.004 0.012 0.014 0.020 0.024 Each Additional Inch, Add 0.004 For Example: 0.096 0.144 0.192 0.240 In. Minus 0.062 0.004 0.006 0.008 0.010 0.012 0.002 0.024 0.036 0.048 0.072 0.096 0.120 When designing a forging, metal should added take care shrinkage and mismatch (see Table VI). Calculation tolerances for shrink and mismatch must be made in conjunction with each other; Which ever greater allowance given direction never the sum the two. these requires govern, 44—THE IRON AGE, September 1942 Weight, Lb. TABLE Mismatch Tolerances Forgings Net Weight, Mismatch Lb. Upto 2.50 6.25 8.50 15.00 20.00 25.00 and TABLE VII 0.015 0.018 0.021 0.024 0.628 0.032 Thickness Tolerances for Drop- Hammer Forgings Minus 0.250 0.010 1.00 0.015 1.01 4.00 0.032 4.01 0.032 17.01 0.032 24.01 0.032 Tolerance, In. Plus 0.032 0.032 0.045 0.062 0.078 0.093 Tolerance, ing line. When designing forg- ing, metal should added take care shrink and slight amount VI.) extra stock for machining the metal allowed for shrinkage and mismatch. Most dies use present are made alloy steel containing 1.00 1.50 per cent nickel, 0.50 0.80 per cent chromium, 0.25 0.35 per cent molybdenum, and 0.50 0.60 per cent carbon, normalized, tempered, and drawn about Rockwell This type die has given good service and attained fairly long life use. For the up- setter forging press, slightly harder die block necessary. the dies for small hammers are found fuller, edger, bender, blocker and impression. The fuller and edger draw out and shape the metal roughly the proper size. the finished forging such that bending required, may done this point. the time the metal reaches the blocker, should such shape will fill the blocking die completely. Use the blocker gives the metal ample opportunity flow easily, and fill the die much possible. The final impres- sion much the same the block- ing impression, except that the radii and corners are well defined and the forging brought exact size. course, not always employ all the above operations. large work (such the forg- ing crankcases) the blocking die the finishing impression are the same die block. prop- designed blocking die will aid the production clean, well-de- fined, and completely filled final forgings with shuts” other irregularities. Die design must also allow for the proper distribution and flow metal into what constitutes the flash. little flash should produced the making good forging. The attainment proper grain flow imperative many high com- pressive strength desired. Thickness Tolerances hammer-forging aluminum al- loys, small thickness tolerance permissible. This allowance applies the overall thickness the forg- ing (in direction perpendicular the parting plane, parallel the direction which the ram travels), and proportionate the forg- ing’s net weight. Any deviation Hours 10-12 12-20 12-15 10-15 8-10 forg- take mount and hining nkage are 0.50 alized, has ained up- fuller the size. that metal exact ways forg- die are al- plies the els), org- from the listed tolerances will ne- cessitate the use coin press dies complete cold restriking die. Thickness tolerances (see Table VII) should applied separately and independently any other tol- erance. Die Lubrication Important, too, forging opera- tions the prevention excessive ° ° BELOW HERE are shown the upper and lower dies used produce the forged spray-gun handle shown. The billet shaped roughly the fuller the right, using light, quick blows give proper distribution the metal. Rough forging done the die impression (at left, uppermost die block shown) called the blocker. the right-hand die impression the same block, the forging receives its final shape. Afterward, flash cut off trimming press. ABOVE MALL sized stock cut into billets shear, here. Larger stock cut with band saw abrasive wheel. polished end -desired, the abrasive wheel best. sticking, and various lubricating media are used for this purpose. Graphite oil, salt water, melted beeswax are the most com- mon. Comparative shown beeswax the most effi- cient where ease operation concerned. Hence almost ex- clusively used the forging press. Cost prevents extensive use bees- wax other forging operations, however, except when there distinct gain expected. Proper lubrication dies, addition prevention sticking, produces After the proper alloy for job THE IRON AGE, September 10, 1942—45 — ment 2 TABLE _Maximum Forging Temperatures Alloy Deg. 14S 840 17S 840 18S 820 (Upsetter 880-900) 25S 860 32S 800 (Upsetter 880-900) A51S 880 53S 880 70S 840 73S 820 cut and prepared, ready heated the correct forging tem- perature. Table VIII indicates the maximum forging temperatures normally employed. often de- sirable work temperatures considerably below given, however. Metal worked tempera- tures above the allowable maximum forgings and said “burned.” Obviously, therefore, heating stock must closely controlled. attain the maximum physical properties aluminum alloy forg- ABOVE FTER interme- diate inspection, workmen remove folds, checks, other defects before the forging under- goes final hammer operations. ° ° LEFT SMOOTH face dies important pre- venting aluminum al- loys well providing smooth surface the forged product. large die for forging crankcase section for aircraft engine. ings given Table II, they must undergo heat treatment. This consists heating the forgings temperatures which much possible the hardening constit- uent the alloy dissolves form solid solution the aluminum. (See Table III.) Heating followed quenching medium which, effect, produces supersaturated solution. For certain aluminum al- loys, the quench followed an- other step called precipitation hard- ening aging, which the alloy held for period tempera- ture much lower than the first step heat treatment. This pre- cipitates the hardening constituent finely divided particles, and brings about greater hardness and greater strength but less ductility. they This ‘orm able solid al- an- ard- era- first pre- lent and and ity. Cleaning and Burring Cartridge Belt Links tridges were fed into 0.30 caliber machine guns canvas belt. the present war, with faster machine gun firing and the need for more dependable cartridge feeding, the canvas belt has been replaced ingenious metallic link belt. These links are made progressively forming process which produces hinge similar that used door. The cartridge itself acts bolt hold the links together, forming contin- uous belt any desired length. Links for both 0.30 caliber and the newer 0.50 caliber machine gun cartridges are formed the same manufacturing process—the only difference between the two links being one gage and over-all di- mensions. First roll cold- rolled strip steel fed into auto- matic punch press, which eight progressive operations turns out formed links. Next these are put through annealing furnace and then are tempered provide suit- able springiness they must with- stand 120-lb. pull without losing their original form. They are then blast cleaned, with fine grit abrasive remove scale, dirt and burrs. From this cleaning process the links pass through zinc plating tanks where they are galvanized. some plants Parkerizing em- ployed instead zinc plating. In- spection and packing follows. The assembly the links with the car- tridges takes place the govern- ment arsenal. World War car- cleaned metallic belt links ready for unloading from the Wheelabrator Tumblast airless abrasive blasting machine. Several years ago when one the arsenals was developing this method producing links high production basis, exhaustive tests were made determine the proper equipment for satisfactorily clean- ing the huge quantities links manufactured. Numerous re- quirements were demanded the blast cleaning machine, among them being the following: (1) must remove all scale encrustations re- sulting from the heat treating processes, and remove any burrs remaining after the punching op- erations; (2) must thoroughly roughen the surface the links serve bond for the zine Parkerized coating; (3) must not break damage the links dur- ing cleaning, and (4) must capable maintaining high pro- duction schedule. the result the tests con- ducted, the in. Wheelabra- tor Tumblast, airless abrasive blast cleaning machine equipped with rubber apron conveyor, was found fulfill all cleaning and pro- duction demands. Two these machines were then ordered for this purpose. Loads cartridge links are fed into the blast cleaning machine means automatic loader. short period all links are sub- jected the abrasive grit stream thrown the overhead Wheela- brator unit. Inspection the load links being cleaned may made any time during the cleaning cycle stopping the abrasive blast wheel, opening the machine door, and test- ing few the links for complete cleanliness. longer cleaning time needed the operation can resumed immediately. result the successful per- formance the in. Wheel- abrator Tumblast the arsenal, this machine used, with few ex- ceptions, most manufacturers for cleaning cartridge belt links. THE IRON AGE, September 10, 1942—47 | og | ° ° LL Abrasive Cut-Off Wheels— thin abrasive cut-off wheels are used: (1) the foundry for removing sprues, gates and risers; (2) the stockroom production line cut stock length; (3) the toolroom for many purposes; (4) productive departments for slotting, slitting and other operations. Any material—ferrous, non-fer- rous, non-metallic—that can sawed, sheared flame-cut, can usually cut off more rapidly, often more cheaply, and always more accurately with wheels than other methods. However, does not follow that abrasive wheels should substituted for other methods cutting-off all jobs. low cost more im- the metal working industries, 48—THE IRON AGE, September 10, 1942 portant than high production, accuracy and finish are moment—some all which are true great many jobs—other cut-off methods are often prefer- able. The use cut-off wheels lim- ited only the size the stock. The limit most cut-off machines though one will cut off in. diam- eter solid material, any section which can inscribed 6-in. circle. One machine will cut in. diameter tubing re- volving the stock. gray iron foundries still the common practice knock off the sprues with hammer, and then snag off the stubs with snagging wheels. However, some foundries have found that pays cut them off with thin abra- sive wheel. Usually this can done close the casting and the finish often good that snagging needed. One steel foundry enjoyed saving one-third time when switched from flame cutting abrasive wheels. The heated the castings that hours were required for cooling before they could handled for snag- ging. using cut-off wheel, the cooling time was eliminated and the amount snagging needed reduced— sometimes eliminated. Great savings are the rule non-ferrous foundries when abra- sive cut-off wheels are substituted other extreme Fountain pen points are slotted with abrasive wheels thin 0.005 in. BELOW MAN-SIZE job —Parting steel mill roll necks with large abrasive cut-off wheel. ‘ f a? = | pays the vhen ours nag- heel, ging ed— ibra- are in. ~ Where and How Use Them for other methods. Sprue cutters rule leave lot material which must snagged off, and they often tear the casting. Hack and band saws are not only slower cutters, but dull quickly when cut- ting the tough non-ferrous metals. For example, one foundry has remove risers from certain man- ganese bronze castings which av- erage sq. in. cross-section. With saw took more than hour cut. These same risers are removed with abrasive cut-off wheels sec. Another foundry brass mallet heads ten the mold. The cross-section the gate about sq. in. the casting. They are cut off the rate five per min- ute with abrasive wheel. About tons castings are handled per wheel. Instances are record where the cost cutting off non-fer- rous foundries has been reduced much per cent. the stockroom the pro- duction line where materials any shape cross-section have cut length, the abrasive wheel not only usually saves time and cost the cutting operation itself, but frequently cuts the cost of, eliminates subsequent oper- ations which were needed when using other cutting-off methods. First consideration speed and hence cost cutting. Here are some actual production figures against which you can check your present performance. One concern cuts various sizes heat-resist- ing alloy. This the perform- ance: Diam. Cuts per Stock, In. Hr. Another shop cuts 7/16 in. chrome nickel steel round bars sec. each, the total cutting and handling time for 100 piece lot being hr. in. wheel used. After cutting 100 pieces the wheel diameter 3/16 in., when transferred another machine and used down in. diameter. UPPER Engineer, The Carborundum Co. ° ° ° the first part two-part article, the author dis- cusses applications where abrasive cut-off wheels show best advantage, both from the point view pro- duction time and elimination subsequent finishing operations. pins his argument down with specific data wheel performance. Other typical production times are given the accompanying tables and II. When cutting-off small sections simple fixture which will hold more than one bar, that several can cut each feed the wheel. Thus, one concern cuts in. diameter 0.035 in. wall, SAE 1025 steel tubing two time, sec. for the two—a production increase per cent over the former method. Another company cuts six bars in. cold chisel stock time. There are many cases where cutting time with wheels 1/40th TORCH won't work here. Abrasive saws are well suited cutting off risers non-ferrous castings, such the manganese bronze piece shown. THE IRON AGE, September 10, 1942—49 | ee ee . that with other methods. case the time cutting stainless steel 1/325th the former time. Another advantage due the fact that abrasive wheels can readily and rapidly cut materials which are hard that other method could used. Many alloy steels which cannot sawed until they have been annealed pre- sent difficulty wheel. One concern formerly bought valve stock annealed condition, sawed it, and then had harden cost 1c. per lb. now bought the hardened state and cut with wheels. average $15 ton the one saving forge shop since has been able cut blanks from hard- ened steel. also saves 0.3 lb. stock per cut due the wheel being only half thick the saw formerly used. Second consideration cutting the cost subsequent operations. Because the good finish left the ends piece cut off wheel, and the great accuracy length and parallelism attainable, the time required for subsequent operations can always cut and often Whether the piece sawed, sheared flame-cut, always necessary, anything approach- Table Cutting-Off Wheel Performance Size, In. Wheel Size, In. Time, Sec. Wheel Monel metal hex. bars 15% 400 min.) Steel—Chrome nickel stainless, sq. 20x 300 min.) TUBING: Table Cutting-Off Wheel Performance Cutting Cuts Per Material Size, In. Wheel Size, In. Wheel Bronze, manganese gates and risers. 16x Cutting Cuts Per Material Size, In. Wheel Size, Time, Sec. Wheel Soft laid knives with Hardened 50—THE IRON AGE, September 10, 1942 ing precision manufacture, fin- ish the ends grinding. prop- erly selecting the cut-off wheel, possible the cut-off operation get nearly any degree finish required, that subsequent grind- ing rarely needed. The same true for accuracy. not all difficult hold length and parallelism 0.002 in. Holding them 0.005 in. usual practice. short, when the piece the ends are concerned. These savings practically always amount more than the extra cost the wheel over other methods, even when such quick method shearing used. This was shown automotive plant which sub- stituted abrasive cutting-off for shearing valve stems. The over- all cost now far less. Some cutting-off methods cause air hardening the material which slows subsequent ma- chining operations. This was true job which was threaded. The threading time sively long until abrasive cut-off wheels were adopted, when the ab- sence air-hardening greatly de- creased the threading time. Incidentally, the accuracy abrasive cutting-off saves mate- rial, which may well worth while dollars and cents with many modern materials, aside from the angle material con- servation. making new tools, bars the hardest tool steels are quickly cut length with abrasive wheels. Then the same wheel can used rough out the approximate angles required. This much quicker than grinding the angle back with ordinary wheels. The same statement true badly chipped tools, which are cut back the solid metal with cut- off wheels. Wet grinding saves the temper the tool. When cemented carbide tools are badly chipped best cut them back, using regular alu- minum oxide cut-off wheel cut through the steel shank, and diamond cut-off wheel cut through the tip. When cutting-off with diamond wheels more pressure should used than needed let the cut freely. force the cut nearly sure break the wheel. safeguard, use only machines that provide constant pressure. ~ ey i { q fin- el, ation inish rind- racy. hold in. ‘hese the even sub- for over- erial ma- true xces- it-off ab- de- nate- vorth with aside con- the cut used mate nuch ingle cut cut- the Campbell No. Cutalator wet abrasive cutting machines being used cut alloy steel large bar Diamond wheels are always used wet. When composite tools can longer used and are sell the whole tool. Instead, cut off the high-speed tips from the shanks and sell them separately. The increased price received for the tips considerably more than pays for the time and wheel use. Cut-off wheels are also used the toolroom for grinding chip break- ers—aluminum oxide carbide for steel tools, and dia- mond wheels for carbide tools. Abrasive cut-off wheels have many strictly production uses. The following are typical and should suggestive ways which they can used the production departments many shops. maker commercial cutting knives uses wet cut-off machine cut large knife blades. The blades are made two grades steel—one for the cutting edge, the other for the body the blade. The method formerly used was knick, crack off, and then grind the ends. They are now cut size with smooth finish the ends single cut-off operation. manufacturer electrical apparatus cuts transformer tubes the radius. aircraft manu- facturer cuts slots hardened tubular valves the same way. Many concerns use cut-off wheels grind slots rapidly and accu- rately, instead machining them methods. mill. The ends forged shells are trimmed machine equipped with attachment which rotates the shell the wheel moves down- ward, that the wheel need pass only through the wall the shell, instead through the entire diam- eter. The job done better faster than the former method. aircraft engine manufac- turer uses automatic cut-off machine equipped with special fix- tures for cutting off the ends forged crankshafts. The job for- merly required considerable set- time for cutting off the ends with cutting tool. the abra- sive method the shafts are put the fixture with overhead hoist, locked place roller car- riage and moved into cutting posi- tion. The special alloy shaft cut off min.—5 min. floor floor. Ed. Note: concluded next week’s issue. user this horizontal wet abrasive cutting machine reports successful sectioning alloy white cast iron (700 Brinell), manganese steel, all types abrasive resistant irons and heat resisting alloy steels, without burning checking the surface. THE IRON AGE, September 10, ¢ | ¥ Fig. view the Bullard-Dunn descaling units, showing the various process tanks. baths used cleaning metal parts the Bullard-Dunn process the Peoria, plant Caterpillar Tractor Co. has been developed the point where sav- ings are being made per cent previous new tin re- The descaling process specialized method electrolytically removing scale from used the Peoria plant replace sand shot blasting for the re- moval heat-treating scale. This cleaning method licensed the Bullard Co., whose engineers discovered that under certain cur- rent conditions sulphuric acid bath containing about 0.1 oz. tin 52—THE IRON AGE, September 10, 1942 per gal. solution, scale would selectively attacked and removed while the exposed steel would plated with tin. The tin-plated steel rendered passive further attack, while the moved. Because this absence etching embrittlement per- manent nature results when this precess used. The thin coating tin which deposited not suf- ficient interfere with subsequent assembly except the case ground surfaces. The descaling machine consists set six arms, see Fig. capable rotating through five tanks. automatic timer causes the hydraulic lifting device raise the charges out the tanks and index them progressively from the loading the unloading stage. usual practice, takes cycles min. duration per tank take care the scale removal the ex- tremes condition experienced this plant. When the scale has been removed, tin course plated on, but again removed second cycle necessary for the elimina- tion more resistant scale. the repeated cycle that tin stripped from the work the alkali bath. Such tin represents eco- nomic loss unless reclaimed the new method described this article. When this cleaning process was originally put work here, the tin | . the and the take the ex- iced been ted on, second tin alkali ned this 3S was the tin was stripped the alkali tank and sheet steel electrodes were used for accumulating the tin deposit. was quite difficult remove the tin deposit from these sheet steel elec- trodes mechanical means, and, for the most part, the electrodes with the contaminated metal con- taining about per cent tin, were discarded for ultimate recla- mation. Now, however, trodes have been substituted the stripping tank. When these elec- trodes are coated sufficiently with tin, they are simply transferred the acid descaling tank, and made available for solution the tin the bath. method, substantially 100 per cent the tin deposited from the stripping tank claimed. The necessity for periodic cleaning the electrodes, which operation when done mechanically, has also been eliminated. There some tin deposited the sludge which accumulates the alkali tank, but from the stand- point the small amount tin lost, this negligible. Tin Use Cut Per Cent has been the experience this plant that this method rotating MARTIN Caterpillar Tractor Co., Peoria, the electrodes reduces new tin re- quirements about per cent. The average monthly new tin require- ments one unit, operating hr. day, days week, before the rotating practice was developed, amounted 416 lb. Requirements amounted only 245 lb. after this practice reclamation was insti- tuted. Each descaling unit this plant provided with special fixture, Fig. for changing coated elec- trodes from the alkali the acid tank and for the return the stripped electrodes from the acid the alkali tanks. The electrodes shown hanging the fixture Fig. are coated electrodes transferred the acid tank for reclamation the tin the de- posited material. Bullard-Dunn machines this plant are operated using elec- trodes the alkali tank and the acid tank. The cycle rotation the electrodes follows: FIRST MONDAY MONTH—Elec- trodes Nos. and are transferred from the alkali tank the acid tank, and three electrodes are returned the alkali tank from the acid tank. SECOND MONDAY—Electrodes Nos. and are transferred the acid tank and exchanged. THIRD MONDAY—Electrodes Nos. and are transferred the acid tank and exchanged. Fourth Monday—Electrodes Nos. and are transferred the acid tank and exchanged. When there are five Mondays any month, electrode changes are made the fifth Monday, and the cycle resumed the first Mon- day the following month. IG. 2—Fixture (indicated arrow) used transferring stripped elec- trodes from the alkali the acid bath and vice versa. Fixture made round steel, properly insulated and shellacked. supported work arm machine and anchored against the trusswork immediately above. THE IRON AGE, September 1942—53 | 54—THE IRON AGE, September 10, 1942 Drilling Square and Hexagon Holes Because the need for eliminating strain aircraft engine parts and other vital machine parts, this ex- planation the Watts method drilling square and hexagon holes metal presented means avoid- ing these reactions punching broaching. need for the elimination punching broaching square hexagon holes critical aircraft engine and other armament parts resulting increased use the Watts method for drilling angular holes. This method pro- duces more strain distortion than the drilling ordinary round holes with twist drills, and the work can done standard lathes drill presses. typical application this method for drilling angular holes has been rocker arm shafts for airplane engines. Failure such part would disastrous that specifications provide that these holes must drilled rather than punched broached. The method, developed the Watts Brothers Tool Works Wil- merding, Pa., uses relatively simple set tools. guide plate with hole the shape the one drilled fastened over the work. drill, which three-cornered cutting square hole mild steel bar. hole in. deep was drilled min. ° ° ° PARMITER Chief Metallurgist, Firth-Sterling Steel Co., McKeesport, Pa. ° ° ° the case square hole and five- cornered the case hexagon hole, fastened special float- ing chuck. This chuck keeps the axis the drill perpendicular the work but gives sufficient freedom movement the the drill reach the corners the angular hole being drilled and then retracted the corners the drill move across the straight sides the hole. The guide plate controls this movement the drill the work rotated, the case operation drill press. During the course rotation, the centers the cutting lips the drill not follow circle, but curves whose chords are parallel the sides the hole being drilled. Since all the cutting done the end the drill, similar end mill operation. This means that there little wear the guide plate only sub- jected friction when the drill started into the metal. After the drill started leaves the walls the guide plate and follows the walls the opening made, thus assuring that the lands the drill also are subjected little wear. Guide plates outwear three four angular drills. The drills are pro- vided lengths which permit ex- tensive regrinding. The drills, which are made Firth-Sterling high often last for several thousand holes when drilling mild steels and give 800 1000 holes high carbon steels. the case the rocker arm shafts for airplane en- gines, mentioned above, the appli- cation being SAE 6150. this case pieces are produced between re- grinds. The guide plates are made Firth-Sterling Invaro oil hard- ening die steel. drilling steels and other hard metals, round lead hole ad- visable but this not necessary ° ° Steel five- the ular ifficient ich the being cted le. The vement drill lips but allel drilled. done similar This ear drill ter the walls the thus drill wear. four nit ex- steel, ousand steels high the en- appli- severe, case re- made hard- hard ad- essary when drilling brass, copper other soft metals. Drills, guide plates and equip- ment necessary for their use are available sizes from in. 2in. Holes resulting from tools in. have tendency cut 0.002 0.003 in. oversize. larger sizes the tolerance increases slightly proportion the size the hole being drilled. im- portant that tools ordered slightly undersize where resulting holes must finished exact size. Except when working ex- tremely close tolerances, finish- ing work necessary the holes. The depth the holes limited, the maximum depth being twice the distance across the flats. Thus, drill will drill in. deep. The drills provide and inexpensive method drilling blind angular holes. The bottoms blind holes are finished flat. Other applications include die work, production socket wrenches, and counter-boring for bolt heads. The drills are not intended take the place broaching where produc- tion sufficient volume justify the installation broaching equip- ment where the strain the metal from the broaching operation not important consideration. They offer substantial advan- 2—Assortment Watts drills and plates for drilling varied types angular holes. Top center guide plate for square hole with sharp corners. right, sharpened drill for this hole. Guide plate and drill for 3/32-in. hexagon hole are lower left. lower center guide plate for square hole with standard SAE corners; the corresponding drill Smaller drills are for 0.387-in. hexagon oles. tages over broaching where produc- tion limited small quantities where the elimination strain important. The principal commercial de- mand for tools drill square and hexagon holes. The drills also can provided for octagon holes. Within certain limitations, drills can provided cut slightly filleted corners, rounded special types corners. Heating Units Remove Aircraft Skin Wrinkles MAJOR difficulty encountered riveting aluminum “skin” over ribs and spars cover air- craft wings has always been the buckling and wrinkling the skin under the impact riveting ham- mers. This deformation, even though slight, interferes with the flow air over the wing and im- pairs the efficiency the plane. system heat treatment de- vised Harry Kneische, assis- tant factory manager the Glenn Martin plant, solves the problem expanding the skin and then shrinking the wing. The new process also reduces overall assem- bly time. The sheets aluminum that make the skin Martin wing are riveted together wooden frame that has the shape the wing. The skin, now full buckles and wrinkles, laid the wing the ship, and electric heating units are placed top the skin. These large sectional units, shaped the contour the wing, are brought temperature 140 deg. This amount heat, thermostatically maintained, causes sufficient expan- sion the aluminum rid all wrinkles and buckles. Heating re- quires only few minutes, and while the skin expanded stitch riveted around the edges and along the ribs. Considerable experi- mentation was necessary develop the treatment the point where shrinkage cooling just suffi- cient produce smooth skin without overstressing the metal. ¢ 4 heating units eliminate wrinkles from the wing skin Martin bombers. The skin riveted into unit jig and laid over the wing frame, with the heaters top it. temperature 140 deg. removes the wrinkles and stitch riveted place this temperature, that will cool smooth and taut. THE IRON AGE, September 10, 1942—55 f 4 4 { Surface Roughness Standards HERE widespread need the present time for practical, rapid and reliable method for the designation ma- chined surface finishes from both the design and production view- points. This particularly impor- WALTER MIKELSON General Engineering Laboratory, General Electric Co. the root-mean-square (r.m.s.) American Standard Roughness, B-46, surface roughness height the surface irregularities whose peaks are closer together than 1/32 in.; and surface wavi- ness the height deviations ant time when subcontracting machined parts widespread. The successful completion manufactured product having par- ticular surface finish requirements depends considerable extent upon clear understanding surface finish requirements between manu- facturers, and between engineering, designing, and production groups any one manufacturing plant. approach this problem that the past, but its value has become par- ticularly apparent today. The performance machined surface from the finish viewpoint depends upon the dimensional char- acteristics the surface irregu- larities. These characteristics can vary considerably and depend both upon the material and upon the method finishing used. The most important characteristics are: Surface roughness Surface waviness whose peaks are farther apart than 1/32 in. The other terms are be- lieved self-explanatory. Instruments are now available which can used measure some these characteristics and these should aid materially obtaining much needed data surfaces and their behavior. these, the most widely used are stylus needle- type instruments which measure surface roughn