The Iron Age 1945-12-27: Vol 156 Iss 26

VAN DEVENTER President and Editorial Director BAUR Vice-President General Manager LEONARD Assistant General Manager HAYES Advertising Manager Reader Service and Market Research BAUR, Production Manager CLEARY, Technical Research and Promotion Manager Executive Offices Chestnut and Sts. Philadelphia 39, Pa., U.S.A. Editorial and Advertising Offices 100 East 42nd St., New York 17, N.Y., U.S.A. ° ° ° Regional Business Managers New York New York 100 East 42nd St. 100 East 42nd St. ROBERT BLAIR GIBBS Cleveland Pittsburgh 1016 Guardian 428 Park Bidg. Philadelphia Chicago Chilton Bidg. 1134 Otis Bidg. PEIRCE LEWIS WARREN 7310 Woodward Ave. Box RAYMOND KAY Los Angeles 2420 Cheremoya Ave. ° ° ° Owned and Published CHILTON COMPANY (Incorporated) OFFICERS AND DIRECTORS MUSSELMAN, Chairman JOS. HILDRETH, President GEORGE GRIFFITHS Vice-President EVERIT TERHUNE Vice-President J.H. VAN DEVENTER Vice-President BAUR Vice-President FAHRENDORF Vice-President JULIAN CHASE Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary BUZBY HARRY DUFFY KANE CHARLES HEALE WILLIAM VALLAR, Asst. Treas. Chilton Editorial Board PAUL WOOTON Washington Representative Member, Audit Bureau Circulation Member, Associated Business Papers the Industrial Arts Index. Pub- lished every Thursday. Subscription Price North America, South America and Possessions, $8; Foreign, $15 per year. Single Copy, cents. Review Number $2.00. ° ° ° ° ° ° Copyright, 1945, Chilton Company The AGE Vol. 156, No. December 27, 1945 Editorial ° ° Technical Articles Fabricating High-Strength Aluminum Automatic Roto Shaving for Fine Weldability Factors for 18-8 Finishing Spur Gears for Aircraft ° ° Features ° News and Markets Machine Tool 100 Nonferrous Market News and 102-3 Iron and Steel Scrap News and 104-5 Comparison Prices Week and 106 Finished and Semifinished Steel 108 Warehouse Steel and Pig Iron Prices 111 Ferroalloy Prices 112 Future Metal Seen 116 Urges Creation Patent 122 Manpower Seen Problem 130 Plans Power Plant 134 Material Holders Free Disposal 134 Contract Terminations Reach $1.5 Million 136 Granite City Steel Drops Divided 136 Welding Suppliers’ Group Formed 137 Mexican Foundrymen’s Group 138 ° 7 | . | | Forgive reminisce little, while wish you the merriest Christmas possible, and the best New Years. But our company was started 1842, little two-story building Chicago, and the Christmas Day just ahead will our 103rd. How much has happened since that first Christmas! The raw little town Chicago has grown into metropolis only day’s journey from London air. Four great wars have come and gone. The telephone has become unnoticed convenience. The radio almost always present—sometimes when would rather were not. Television just about here. Business tempos have speeded immeasurably. Swift trucks hurry through streets where once horse-drawn drays leisurely carried our steel. Ladies’ skirts which once swept the wooden sidewalks are— well, higher. The motor car has made the farmer almost city dweller, easy for him back and forth from his farm. And now atomic power! But much has changed 103 years, the spirit Christmas remains just what was—cheery good will all men everywhere: May this spirit continue with the years come. JOSEPH RYERSON SON, INC. Steel-Service Plants at: Chicago, Milwaukee, Detroit, St. Cincin- nati, Cleveland, Pittsburgh, Philadelphia, Buffalo, New York, Boston. 36—THE IRON AGE, December 27, 1945 Preside Vice-Pres Editor News Machine Europe Canada Regiona | 1 — sy . — ESTABLISHED December 27, 1945 VAN DEVENTER BAUR ° Editorial Staff CAMPBELL LINSLEY News Markets Editor Machine Tool Editor...H. ° ° Associate Editors WINTERS ALBIN JOHN ANTHONY BARMASEL Editorial Assistants SPEAR Editors LLOYD Pittsburgh 428 Park Bidg. POST Chicago 1134 Bidg. MOFFETT EUGENE HARDY ANSBORO Washington National Press Bidg. LLOYD Cleveiand 1016 Guardian Bidg. BRAMS Detrolt 7310 Woodward Ave. OSGOOD MURDOCK WORTH HALE Sen 1355 Market St. Editorial Correspendents ROBERT Cincinnati DEAN Buffalo FRAZAR Boston HUGH SHARP RAYMOND KAY Les Angeles JOHN Birmingham ROY EDMONDS St. Louls JAMES DOUGLAS Seattle AGE President and Editorial Director Vice-President and General Manager ACK SANDERSON Out the Frying Pan approach the end 1945, may appropriate give some thought what has happened America during the most event- ful year the world’s history. has been year sorrow and rejoicing, victory and defeat, tremendous gains and enormous losses. But and large, add the assets and the liabilities 1945, some may think with considerable truth that have stepped out the frying pan into the fire. For example: have stopped fighting the Axis and started fighting each other home. Our scientists have performed miracle that may result blowing everybody into kingdom come. have become the world’s leading financial power; hence, the world’s leading lender without security. have expressed our graduation into internationalism grabbing several foreign relations bulls their tails and may not able let them for many years come. have built the greatest producing machine the world, capa- ble filling innumerable wants, and are progressively hamstringing its operation quarrel over division its undetermined output which becoming thereby progressively less. other words and sum up, have achieved the distinction being the smartest idiots ever. These are not cheerful year-end thoughts. But traditionally, since new resolutions are made January first, this the last chance 1945 consider our shortcomings. What about it? suggestion make 1946 year which pay particular attention minding our own business. Our business, the metal producing and metal working business, get busy and produce largest possible quantity the best possible Doing that would solve the question management-labor friction. all what can do, the results will certainly enough make possible satisfy all reasonable people. And the unreasonable ones couldn’t satisfied anyway. our industry, and management and labor other American industries all that are capable doing, our country will well off that Uncle Sam can afford play Santa Claus wants and needs and want him to. that and the results, after they are known, are what they should be, should able divide the proceeds such way make labor and stockholders happy, far money capable making people happy. think that having work that one likes and con- genial and comfortable surroundings which goes farther than money make people happy, provided you have enough the latter Minding our own business will bring that end much more quickly than trying run everybody else’s business, which what most are doing today. | INLAND HI-BOND* REINFORCING BARS Provide the strongest known grip between steel and concrete. Im- portant reasons for specifying BOND are briefly: Higher Bonding Strength Greater Mechanical Grip Higher Stress Transfer Reduces Width Cracks Greater Resistance Slip Higher Design Stresses Possible Material and Labor Close Cooperation STEEL the early stages, when you start planning job, it’s well keep mind the useful service Inland can render. Through very broad contacts touching many fields, Inland’s engineers and metal- lurgists have become familiar with practically every use and appli- cation steel. They know what steels can do— also the shortcuts profitable. For many years, the building industry has turned Inland for structural and reinforcing steel. From long experience they have learned count Inland’s close cooperation. matter what your construction problem is—bring Inland work with you. Inland Steel Company, South Dearborn Street, Chicago Illinois. Sales Offices: Cincinnati, Detroit, Indian- apolis, Kansas City, Milwaukee, New York, St. Louis, St. Paul. Principal Products: Bars, Structurals, Plates, Sheets, Strip, Tin Plate, Floor Plate, Piling, Bars, Rails, Track Accessories. INLAND STEEL coppe! are cans, tacky some the and tor's obnox than tern Nati prot very duce tice oper ear’ 38—THE IRON AGE, December 27, 1945 NEWSFRONT Dec. 25, 1945 army half million steelworkers recruited 80,000 women and girls crane drivers and laborers scrapyards and steel plants. may not significant the political color the British Labor ment, but several programs reconstruction and modernization that have been nounced, including steel and railways, are identified plans. During the war the Germans were able substitute phenolic nated woven hemp internal bearing surface for ball bearings. They roughened the inside surface steél roller and held the hemp against inserting fitting aluminum rod. When heating cure the resin, the differential expansion the aluminum exercised the pressure needed bind hemp steel. The polymides plastics used for connecting belts motor driven equipment Germany during the war are reported have lasted times the life leather belts. The plastopals were used baking and lacquers for coating tin cans, wires, railway cars and machinery. Polyvinyl hammers are used place lead, rubber wood hammers forming copper, aluminum and light metals the automobile and aircraft industries. They are reported have much longer life, times. They are made placing sheets 10-12 mm. thickness steam bath 100°C. for hour produce tacky condition, then placing them press for hours. While immediate British auto production models identical prewar cars, some small firms are redesigning their products completely. typical example, the Jowett Javelin breaks away from conventional body design for airplane styling, and features horizontally opposed four cylinder engine. Discarded military flamethrowers are now being used the Louisiana sugar cane fields burn out weeds growing between the rows young cane. The tor's skill handling this wartime innovation measured his ability kill obnoxious growths without scorching the growing cane. Shot peening aluminum sand castings results better corrosion resistance than sand blasting. Also shot peening obscures any small cracks porosity surface casting. Recent comparison test fully killed acid bessemer steel pipe and hearth pipe shows bessemer steel have higher yield strength and tensile strength however, elongation slightly lower. New simple procedure for determining thickness and coating composition terneplate has been worked out the Tin Research Committee laboratories. new machining process, called photo shaving, has been developed the National Broach and Machine Co. for high quality finish. The Germans contemplated and designed rocket propelled missile which had maximum speed 1700 mph 100,000 ft. There were also designs and prototypes rocket guided the infra-red rays emitted bomber motors. For photographic reconnaissance, they produced powered glider intended for very high altitude operations. striking similarity production methods has been noted among German pro- ducers tool and special steels. All manufactured products the form rolled and forged bars, cold drawn and ground bars, wire, plate and sheet. tically all these steels were melted electric furnaces, yet all producers had openhearth capacity for carbon and low alloy steel production. new development which may take around 30,000 tons magnesium annually the cathodic protection steel pipelines. Where they come into contact with earth water, possible slow corrosion diverting the electrical action from the pipeline magnesium anode buried the ground. | Fabricating High-Strength Precipitation hardening aluminum alloys which are replacing unaged 24S-T new aircraft designs can fabricated with minimum shop difficulties. Their mechanical properties, heat- treating operations, effects cold work, well problems con- nected with forming, attachment, machinability and finishing are included this article based paper presented before the SAE, Los Angeles, Oct. the new high-strength alumi- num alloys are alloys that are aging heat treatment, subsequent the solution heat treatment, develop their maximum mechanical proper- ties. These alloys, the aged condi- tion, are characterized relatively low elongations, reduced impact resis- tance, increased notch sensitivity, in- creased ultimate strength, and yield strength that much more nearly equal the ultimate strength than true with conventional unaged alumi- num alloys. The problem presented before the research department the Consoli- dated Vultee Aircraft Corp., San Diego, Calif., was how best fabri- cate aircraft components from these alloys take full advantage the superior mechanical properties these materials. result this study the following shop fabrication procedures have received prominence: (1) That cases where design dictates the use precipitation hardening aluminum alloys, the de- tail parts formed, whenever the as-quenched solu- tion heat-treated condition. (2) That the high-strength alu- minum alloys not joggled, dim- pled, formed reworked when the precipitation hardened condi- TABLE tion unless accurately controlled heated-tool methods are used. These alloys, due the chief alloy- ing constituent used, divide naturally into two groups, the copper alloys consisting 14S, 24S, and R301, and the zinc alloys consisting 75S and Each can aged successfully aging cycles, but general the zinc alloys respond best relatively low temperature, long-time aging cycles, whereas the copper alloys respond best relatively high temperature, short-time aging cycle. One the important differences between these two groups that the zinc alloys are not affected their response the aging heat treatment amount cold work which they have been subjected, whereas the mechanical properties the copper alloys, most cases, are greatly improved cold work prior the aging heat treatment. The mechanical properties and rec- Mechanical Properties and Recommended Aging Cycles for High-Strength Aluminum Alloys Material Aging Cycle Designation Clad sheet Clad sheet Clad sheet Clad sheet Forgings Forgings c=} ? o Mechanical Properties Shear, Ultimate on Bearing Strength 2 232 Notes: All values with grain. Not approved Navy and CAA; see Material solution heat treated and aged user. Except that Army approved 62,000 psi for this Not approved Navy and CAA, Values shown are for rectangles in. less, squares in. less, and rounds in. diam less. modul Not approved Army and CAA, modulus 10,500,000 psi. Thermal coefficients expansion are: 24S, 0.000013; and 75S, 0.0000144. 40—THE IRON AGE, December 27, 1945 Primary Where the material clad, the secondary modulus 9,500,000 psi. The rigidity 3,900,000 psi. According NACA TN966, 0.10 the case 24S-T, and 0.11 the case very and sheet has ever shov cond the ing ten: stre 75S val Heat 1.5 Diameter 2.0 in. Diameter Treat ature, on, perature, Aluminum Alloys ommended aging cycles for these alloys, more especially the great in- yield strength, makes them very desirable for aircraft structures. will noted from table and fig. 75S-T has the best ultimate tensile and shear strengths the various sheet materials, though 24S-T86 sheet has the best yield strength. Forgings, course, should 75S-T wher- ever possible; otherwise they should made 14S-T. Viewing the mechanical properties shown table these are for the materials the artificially aged condition and are attained immedi- ately after cooling from the aging temperature. The properties the condition, i.e., after completion the solution heat treatment and prior the aging heat treatment, are also interest. fig. are curves show- ing the values the elongation, tensile yield and tensile ultimate strengths for 14S-W, 24S-W, and 75S-W. These data were obtained from 0.064 sheet and are typical values. The bearing values shown table should noted, are for the mate- Yield new high strength aluminum alloys. Elong rial bearing bolts protruding head rivets, and may used de- termine the strength joints not critical shear the bolt rivet sheet adjacent the hole, occur- rence with sheet that relatively thin with respect the diameter the bolt rivet. determining the strength the machine countersunk riveted joints, the effect the head must also considered. fig. shown typical curve the strength riveted joint plotted terms the sheet thickness. The impact strength aluminum alloys is, general, reduced the precipitation heat treatment. This means, course, that they are more sensitive notch effects and the rate application load the aged than the unaged condition. understood that the impact strength 75S-T somewhat better than that the series materials. The relative merit these mate- rials with regard fatigue resis- tance not yet well established. The few data available indicate that aging tends reduce slightly the endurance Shear ° ROY MILLER Chief Structural Research Engineer, and MAX TATMAN Chief Metallurgist, Consolidated Vultee Aircraft Corp., San Diego, Calif. limit the unaged material, but, general, the overall endurance limit these materials not improved the aging treatment and may slightly reduced some instances. Heat Treatment and Cold Work The recommended solution and pre- cipitation heat-treatment cycles for these materials are shown table except that the time temperature for the solution heat treatment not shown, function of, and in- creases with, the thickness mass the part. Reference should made the applicable specification for this information. The recommended solu- tion heat-treat temperatures should carefully adhered but the precipi- tation aging treatment may ac- the case the copper alloys the time required obtain maximum ties decreases with the increase temperature though the practical low limit the case 24S considered and the safe upper limit fig. are shown curves which illustrate the aging character- Extrusions Forgings THE IRON AGE, December 27, J | | Clad sheet Tensile stress, psi 0.1 Elongation, pct. 100 1000 Log normal room temperature aging time Iday properties 14S-W, 24S-W and 75S-W after the solution heat treatment and prior the aging heat treatment. istics typical duraluminum type alloy several different tempera- tures. Although these curves actually represent 24S-RT material, the curves for the other tempers 24S would quite similar. The aging cycle shown for 14S and table are recommended, and result ma- terial that meets the specification re- quirements. However, data hand indicate that the resultant mechanical properties clad 14S-T sheet in- crease slightly the aging cycle va- ries toward lower temperature with longer time. would appear that 340°F for might the most practicable one for bare and clad, and for R801. the case the alloys containing zinc, the recommended cycles give the best properties, but appears that the time temperature may ma- terially reduced without appreciable loss strength. This may seen readily from fig. which shows the aging curves R303-W several temperatures, and also represent the trend for 75S-W material. should noted that aging these alloys above 275°F would undesirable. Tests in- TABLE Fabrication Data for High-Strength Aluminum Alloys Material Spot Welding Strength Forming Characteristics Welda- Compar Bend General Form bility Clad Sheet Clad Sheet Clad Sheet Clad Sheet Sheet Clad Sheet Clad Sheet Clad Sheet Clad Sheet Clad Sheet Clad Sheet Clad Sheet Clad Sheet Clad Sheet Extrusions Extrusions Extrusions Dimpling Forming Very poor Very good Good Very poor Notes: Army requires that the edges primed. Denotes clad that has been solution heat-treated and stretched The bend radii for the condition are for material with normal room temperature aging. Spot welding this material not recommended. 42—THE IRON AGE, December 27, 1945 dicate that there little difference between the interrupted and the pro- gressive aging cycles. Both the copper and zinc alloys are sensitive the rate cooling from the solution heat treatment, but are affected differently. Slow cooling has marked tendency reduce the cor- rosion resistance the copper alloys and lesser effect reducing the strength. the case the zinc al- loys tends reduce the strength and has little any effect the corrosion resistance. Forming, joggling, dimpling, and reworking materials are shop oper- ations, but they also merit careful consideration designers. The aging heat treatment greatly increases the yield strength the amount spring-back from forming and sim- ilar operations greater, and greater loads and better tools are required the work. shown for the mate- that these operations performed these materials the unaged con- dition. Considerable work being done develop technique very short time applications elevated temper- ature the material the condi- tion just prior the forming, jog- gling, dimpling operation. Some the experiments show promise and in- dicate that 300°F the minimum bend radii shown table may substantially reduced and without any appreciable reduction mechanical properties. Until such technique thoroughly proved, however, should not assumed when planning de- sign. Instead the material formed should obtained either the annealed condition (solution heat treated) condition, depending upon the part question and the ma- terial concerned. Pressed parts can readily made 24S, R301, 75S the annealed condition, restruck after the solution heat treatment, necessary, and then aged. Parts made 24S-T81 and 24S-T-86, course, must made from as-received stock, since their final strength de- pends considerable extent upon the cold work they receive prior aging. Parts 24S-T84 material are formed the annealed condition, so- lution heat treated, stretched, and aged; but joggling required, should done before aging. any case they should not reworked otherwise cold worked after the aging operation. The aged alloys may joined suc- cessfully the same method conven- tionally used with unaged material, than sheet the: bon dor the tre Designa- tion Finishes Good Lower Very good Very good Very good None Good Same Good Good Good None Good Higher Fair Fair Fair None* Good Higher Poor Poor Poor None* 24-RT Good Same Fair Fair Fair None Good Higher Very poor Very poor Very poor None* Good Same Poor Fair Fair None Good Higher Very poor Very poor Very poor None* Good Lower Very good Very good Very good None Very good Same Good Good None R301-T Very good Higher Poor Poor Poor None Good Lower Very good Very good Very good None ery goo gher ery poor ery poor one and prime and prime and prime riveting, bolting, spot welding, and in. shank the spot weldability the aged alloys 1400 very good and the shear strengths the welds are somewhat greater sheet. Care should exercised 1000 riveting since the increased notch sen- sitivity these materials may result cracks when riveting done near al- deep scratches notches. The min similar cements will not appreci- ably reduce the mechanical properties corrosion resistance any these aged alloys; however, Metlbonding 200 may not done prior aging any these because the aging temperatures involved are too high for the Metl- 002 0.06 018 bond material. Spot welding may Sheet thickness, in. done prior aging, desired, since the aging temperatures not affect 3—Typical curve the strength riveted joint. Rivet head thick- the welds adversely. the case ness 0.070 in., rivet diam 3/16 in., drill size in., edge distance 3.27 rivets driven prior the aging heat treatments, none them (A17S-T, 17S-TA, and 24S-T) are af- necessary desirable, note should taken the fact that number 80,000 materials customarily found aircraft assemblies will not satisfac- torily withstand the aging tempera- tures used with 24S, and R301 alloys. These are plastics, rubber, rubber substitutes general, units with fiber inserts, bearings containing lubricant, all fuel tank sealants, and all cements such Metlbond and over-aged and would have consid- 50,000 erably reduced strength. Aluminum ging slightly reduced strength. Unclad FIG. 4—Mechanical properties clad aged several temperatures. 24S-T sheet should not used has reduced resistance 7 fected appreciably by the 250°F tem- compared with the aged clad sheet. perature used with 75S material. The Finish requirements are not higher temperatures used with the copper alloys, however, tend re- 80,000 duce the shear strength A17S-T rivets much pct, not par- ticularly affect the strengths 17-S-T and rivets, and in- crease the strength 24S-T rivets much pet. The corrosion resis- tance these rivets not affected. Admittedly rather small amount experience has been had ma- chining aged materials, but in- dicated that they machine readily unaged material and that 75S-T machines easily 24S-T. Machin- psi Tensile and yield strengt ing, possible, should done the unaged condition and, the case 75S-W, soon after the solution heat treatment possible that straight- ening difficulties may kept minimum. the event that assembly aging Aging time, hr. FIG. properties clad R303-W aged several temperatures. THE IRON AGE, December 27, _ | i Yield 4 changed the aging heat treatment, noted, however, that the copper alloys, under-aged, have reduced corrosion resistance the core material; over-aged, the corrosion resistance re- mains satisfactory. The inspection these aged alloys is, present, serious problem be- cause there known nondestruc- tive test whereby the exact degree hardening may determined. The conventional Rockwell testers will not work the readings appear function the ulti- mate strength and aging. Heat treatments crease the yield strength, the increase ultimate strength being within the scatter the hardness readings. Etchants have been developed where- not the materials 24S and 75S have been subjected the aging tempera- ture; but their action not sufficient- precise make known the degree aging. For example, the etchant reaction for 24S-T86, when aged hr, the latter being the required time this temperature. These etchants, however, combination with close attention furnace control and suit- able tension test specimens for each furnace charge, may used with confidence classification, when necessary. satisfactory spot test has also been suggested and available differentiate between 75S and alumi- num alloys containing zinc. The spot test applied the surface the clay alloys, whereas the etchants are applied the core material. Close furnace control particularly impor- tant, not only certain that the furnace completes the proper cycle with each charge but that the tem- perature distribution throughout the furnace uniform. addition tension samples, green red lac- quer may used, the case material differentiate between aged and unaged material, since the aging cycle will cause either color turn dark mustard color. This color change, with the etchant test, not precise, but does show that the material has been subjected tem- perature near the aging tem- perature and with appreciable ex- There are many types furnaces that will accomplish artificial aging the new high-strength aluminum alloys satisfactorily. Since the tem- ‘perature very critical, especially when high temperature, short time cycle used, the temper distribution throughout the loading area the furnace must uniform. The control equipment also must very good, the on-off temperature sweeps must small, the order 20°F less. The overall spread tem- peratures from all sources during the aging cycle should within 50F. The Quality Terneplate usual methods for determin- ing the thickness and coating composition terneplate involve either the complete dissolution the specimen dilute acid, stripping the coating hot concentrated sul- phuric acid, and subsequent analysis for tin and lead. These methods are lengthy and inconvenient and sim- pler procedure, where number rou- tine determinations are made, has been worked out the labora- tories the Tin,Research Committee. was found that all hot-dipped tin- lead alloy coatings steel could dissolved, without attack the base metal, Clarke’s solution (cold. hy- drochloric acid containing antimony trichloride), used for pure tin coat- ings. The reaction terneplate considerably slower than with tin- Bessemer Steel ESSEMER still many considered brittle, and conse- quently its use frequently has been restricted largely structures parts which this property not important. However, decided im- provement has been made this type steel, that modern variety may now obtained having properties vastly superior those the older type. This improvement been brought about largely controlled deoxidation the steel during its 44—THE IRON AGE, December 27, 1945 plate, taking about min for each coating per basis box. The recommended method may briefly summarized follows: Select sample known area give coating weight not more than 0.8 degrease, dry and weigh. Attach nickel wire and immerse 100 the stripping solution. When the coating dissolved, quickly remove the loose deposit, keeping the speci- men immersed. Remove the clean steel, wash, dry and weigh. Transfer the solution with the deposit and washings conical flask, connect supply carbon dioxide and boil for min. Cool, dilute with 100 water and add pct starch solution and pct potassium iodide solution. Titrate with N/20 po- tassium iodate. The iodate should standardized against mixture tin and lead, approximately the same proportions terneplate, dissolved the stripping solution and treated above. ,By this method the weight and composition tin-lead coatings Other suggested applications the method are for measuring the distri- bution coating thickness and com- position over the surface sheet terneplate; for analysis electro- deposited tin-lead alloys steel; and for the determination tin tin-lead solders (after rolling foil). Alloys containing more than tin may analyzed the same way dissolving suitable quantity lead with the sample. for High Pressure Steam Piping manufacture. Many the mechanical properties these fully-killed acid- bessemer steels are similar those openhearth steels and they may used interchangeably some appli- cations. the request the United States Coast Guard, George Ellinger and Morgan Williams the National Bureau Standards, metallurgy divi- sion, recently completed comparison test fully-killed acid-bessemer steel pipe and openhearth steel pipe the type used for high temperature, high- pressure steam service merchant ships. The yield strength and tensile strength the bessemer steel were somewhat higher than those the open-hearth steel, whereas the elonga- tion was slightly lower. Notched-bar tests (using special subsize Charpy notch specimens) the temperature range 925° 50°F indicated that the impact properties the fully-killed bessemer steel were good better than those the openhearth steel. 4 4a #3 H ee ing wi ‘ ¥ | i LEFT AND BELOW sand casting after being subjected shot peening (left). right, the sand-blasted casting before the peening operation. groove was sawed this cast- ing and piece bent over such manner form crack varying width. Other saw cuts are the lower portion. Shot Peening Effect Aluminum Considerable surface differences are observable American Aviation, Inc., show slightly greater cor- the effects aluminum sand castings shot resistance following shot peening, which gives ing compared with sand blasting. The results darker appearance the casting and obscures any test the production development laboratory cracks porosity visible the surface. BELOW 1G. 2—Crack after shot peening, magnifi- cation 12X. Hollows lend overall darker appearance. f = minum castings after being subjected 120-hr salt spray test North American tion. The sand-blasted specimen corroded slightly faster and more and also had — more red corrosion products, not apparent the photograph. THE IRON AGE, December 27, Finishing Spur Gears for ODERN aircraft engines rep- resent culmination knowl- edge and skill handling design, materials, and manufacturing techniques that has resulted high reliability under extremely severe op- erating conditions. Tomorrow’s com- mercial aircraft engines will show not only high reliability but also long use- ful life together with high efficiency regard fuel consumption and the elimination excess weight. obtain high reliability and acquire, addition, long useful life and high economy commercial air- craft, requires optimum design each component part the engine, and the incorporation devices that increase the safety and efficiency operation. These devices have resulted the extensive use gearing modern aircraft engines. While the most elementary form the four- cycle aircraft engine requires only one pair gears, cam gears, present units benefit from the use reduc- tion gearing, gear chargers and many other gear driven auxiliary devices. The development and application gearing the aircraft engine has gone along hand hand with the growth the engine whole. De- sign techniques have improved with the years, and tremendous strides have been made metallurgical de- velopment. But without modern gear methods, neither de- sign nor metallurgical developments could exploited for extensive use. well designed gears minimum weight and size, compromise can made with accuracy without court- ing structural failure. Type testing may indicate that modifications are necessary, but once the necessary deviations profile and lead are es- tablished, close tolerances tooth form, spacing, and lead must held. hold these extremely close tol- erances two major methods are avail- able the manufacturer. These in- volve the use either tooth grinding tooth shaving. Shaving has been the aircraft field for but short time, having been developed the automo- tive field, but now competing strongly with tooth grinding. Contro- method are continuous. However, time alone can tell which the better method; and both will, all prob- ability, used for some time come. For other articles gear shaving and grinding, see THE IRON issues Dec. 24, 1942, Aug. 1943, and April and April 19, 1945. The extremely hard working sur- face the majority aircraft en- the two-wheel, non-reciprocating type generating gear grinder, using flat dressed wheels inclined the pressure angle the basic rock. 46—THE IRON AGE, December 27, 1945 gine gear teeth, obtained case cannot machined the use cutting tools. Tooth grinding has permitted the manufacture case-hardened gears extremely close tolerances since tooth grinding can applied after hardening, thus limiting the accuracy the precision the grinding machine alone. exception this the case the gear with extremely thin cross-sec- tion which the relieving surface stresses grinding may introduce distortion. There are two distinct methods available the manufacturer the tooth-grinding field. These are the generating and the forming methods. The generating method makes gen- erous use the fact that the basic rack the involute system straight sided. grinding wheel can easily dressed conform the shape such basic rack. Once this form has been dressed, the grinding machine needs only pass the gear the wheel, and provide rolling motion which duplicates the roll the gear with the rack. the grinding wheel represents only one tooth part tooth the rack, some means indexing from tooth tooth the gear must provided. Variations the types grinding wheel geometry have resulted dif- ferently designed tooth-grinding ma- chines. the grinding surface the wheel dressed passing diamond over direction normal the axis rotation the wheel, plane surface the wheel results. The axis the wheel must then tipped with respect the path relative motion between the gear and wheel the pressure angle the basic rack. customary use two grinding wheels such machine, one for each side the tooth. The plane surface the wheel lies the plane the tooth surface the imaginary basic rack. Relatively large-diameter wheels must used reduce the arc effect. The arc effect results deeper grinding the center the tooth face than the outer ends, owing the curvature the outside the wheel. gear with 1-in. face width, ground with 20-in. flat dressed wheel, the wheel will grind 0.013 in. deeper into the the ential width, this duction ing which wheel relativ grindi wheel the and with order the cated. ing thus there whee with has sing’ wher cup prir Oth era met spa too for <j rack - + - - . i Age “4 the root the center the face than the outer ends. The depth differ- ential increases rapidly with face width, thus putting limitation this type machine. The rate pro- duction, however, high. second application the grind- ing wheel incorporates single wheel which grinds both sides the teeth time. The axis the grinding wheel lies plane parallel the relative motion the gear and the grinding wheel. Each side the wheel dressed the pressure angle the basic rack. The grinding sur- face the wheel conical shape and consequently has only line contact with the surface the basic rack. order grind the full face width the gear, the wheel must recipro- cated. This results constant grind- ing depth across the face the gear, thus eliminating one the objections the flat-dressed wheel. course, there reason why the flat-dressed wheel could not used conjunction with the reciprocating head give constant grinding depth, but then has advantage over the simpler single wheel conically dressed. Some other variations grinding wheels are found, but they are little used this country. These are seen reciprocating and non-reciprocating cup type wheels which are the same principle the flat dressed wheel. Other variations are conceivable. Contrasting sharply with the gen- erating method, the form-wheel method tooth grinding. The axial section grinding wheel dressed correspond the form the tooth space, and then passed through each tooth space, imparting the wheels form the work. indexing device, course, must used move the wheel from one space the next. Two problems unique this method are encountered. First, the wheel must dressed accurately the form the tooth space; and second, the wheel must fed into the work exactly the right amount properly position the tooth space radially. common method accurately dressing the grinding wheel pass diamond over involute path controlled master cam. The mas- ter cam usually six more times ° ° SIDNEY CORNELL Gear Engineer, Pratt Whitney Aircraft Economy operation, together with light weight, are impor- tant factors the engines modern commercial aircraft, and gearing plays important part bringing these into being. this article the author discusses the merits both the grinding and shaving methods finishing aircraft spur gears, and describes the principles upon which each process operates. larger than the involute the gear being ground, and the motion the cam follower reduced through pantograph mechanism that the motion the diamond scaled down the proper amount. Other methods controlling the path the diamond have been are being used. One these depends the underlying prin- ciple the involute curve, and con- trols the path the diamond the use mechanism which duplicates the action string unwinding from base ¢ylinder. Another uses cir- cular cam the profile which not involute, but the angular rotation which imparts involute path the diamond through suitable mecha- nism. entirely new method dressing the wheel for form-tooth grinding being tried, which the wheel dressed without the use diamonds. Crusher rolls are used which roll the surface the slowly rotating grinding wheel and crush the involute form the roll. Just what results production will ob- tained have not yet been estab- lished. The task positioning the wheel radially analogous the old prob- lem the proper depth cut for form-tooth milling cutters. the cutter grinding wheel not fed deep enough, the result will tooth form with high bearing. fed too deep, low bearing ob- tained. Once setup has been estab- lished, however, production can run with only minor adjustments allow for diamond wear. The rate production with form tooth grinding compares favorably with that the single-wheel generat- ing method. has the disadvantage that somewhat more skill required operation. However, the form- wheel method lends itself internal work, whereas the generating method does not. Also, the present time, the form-wheel equipment the mar- ket permits the use much smaller 2—Principle the single-wheel generating gear grinder, using reciprocating wheel conically dressed conform the shape the basic rack. THE IRON AGE, December 27, | e | : | | \ | ‘ 4 | | wheel than the generating type machine, This means that gears with shoulders close the end the gear teeth can often handled with the form wheel grinder, where the gen- erating wheel grinder with its larger wheel would unable operate helical cutter spur work, spur cutter helical work will all give slippage depending the difference helix angles. This difference helix angle commonly referred the crossed axis angle and the angle which the tool set the without striking the shoulder. There reason why the generating type machine could not developed use small wheel for grinding shoulder gears, and some develop- ment work along this line being Tooth Shaving shaving tool cutter used to- day looks something like master gear with serrations the working surfaces the teeth, and the question often asked, makes cut?” That does cut evident from the fact that the chip pan shaving machine production must fre- quently cleaned pounds fine chips. The shaving tool, most cases, has helix angle which differs from that the work from 20°, with the majority the 12° 15° range. This difference helix angle results relative motion slippage between the cutter and the work direction which gives cutting action the serrations the working surfaces the shaving tool. This slippage exists even the helix angle the cutter the work, but not both, zero. other words, helical cutter helical work, 48—THE IRON AGE, December 27, 1945 ABOVE 3—Grinding air- craft gear recipro- cating head grinder with conically dressed wheel. RIGHT Princi- ple the form-wheel type grinder which the wheel accurately dressed the form the tooth shaving machine. good shaving job shows tooth surface with high quality cut finish and little evidence burnishing. shaving cutting operation, must done before case harden- ing the teeth. some aircraft en- gine splines, and few gears, are not case hardened, they lend themselves the possibility shaving after final heat treatment. instance splines such materials AMS 6260, AMS 6294, AMS 6274 hardnesses higher than Re. When necessary shave the range than normal tool life obtained. When gears are shaved before final heat treatment, the best results ap- pear obtained the range from Re, although this some- what lower than that recommended for ordinary steels. Minimum distor- tion heat treatment obtained shaving the gears after carburizing and before hardening, but tool life poor that not practical method for production appreciable quantities. Furthermore, although the distortion from heat treatment somewhat greater when the shaving done before both carburizing and form nature and can allowed for the shaving operation itself. This, course, applies only the gear blanks themselves are such na- ture that they can open tank quenched without warping going out round, that they can kept from warping the proper use quenching dies. The distortion which must allowed for appears increase tooth thickness and “weakening” the involute. heli- cal gears there tendency for them unwind. Methods for allowing for these distortions are obvious. The first use which shaving was put aircraft engine gears was gears such design that they could not ground. Although shav- ing cannot done without certain amount clearance between ob- structing shoulder and the end the gear teeth, can used where there much less clearance than would cutt \ shot axi cro bet the a ¢ ' 4 / \ AAA er \ WwW li fs — = fi required the smallest grinding wheel available. use shaving cutter gears that have little shoulder clearance, requires reduc- tion the crossed axis angle from the usual 12° 15° range. The less the clearance, the lower the crossed axis angle must be. The lower the crossed axis angle, the less slippage between the cutter and the work and the less cutting action obtained. Be- fore shaving was used any extent aircraft engine gears, crossed axis angles less than were almost unheard of. Because the great need for improving the quality gears which could not ground, the manu- facturers shaving equipment did development work which enabled the use cutters designed work with crossed axis angles little 1%°. The low crossed axis angle resulted very little cutting action compared with the tendency the tool burnish the tooth sur- face. Although the ideal high quality finished cut surface was not obtained, acceptable, partly burnished, part- cut surface resulted. Parts proc- essed this way were definitely superior those processed any other method available. Later, shaving was used gears which could ground but which were not for use points where large amounts power were transmitted. Shaving has not been applied exten- sively heavily loaded gears that can ground because the required quality, least the present state development, can more easily LEFT 5—Form grinding larger gear, opera- tion not possible with either the two other methods shown figs. and BELOW grinding internal gears the form wheel grinder the only type currently available. LOWER RIGHT 1G. principle gear shaving which the angle between the axes obtained grinding. obtain quality equivalent that pre- cision ground gear shaving, re- quires extreme care pre-shaving (that is, roughing out the teeth for shaving), shaving, heat treat- ment, and relocating reference sur- faces. Constant vigilance must maintained discover and correct the effects dulling the tool the involute profile produced. Further development the field shaving heavily loaded gears urged forward several factors. Shaving much faster than tooth grinding, and use this method consequently requires less equipment handle given volume given time. Since stock removed from the tooth surfaces after carburizing and harden- ing, the problem maintaining ade- quate case depth critical areas the working surface the tooth and the highly stressed root fillet are eliminated. Surface decarburization does present problem here, ap- preciable stock removed from the working surface the gear after hardening. However, proper precau- tions protecting the surface the hardening operation will reduce this hazard minimum, Another method shaving now the market depends the reciproca- tion the shaving tool for cutting action. The crossed axis angle zero. This usually referred “parallel axis” shaving. best adapted present internal work and has marked advantage over the crossed axis method applica- tion, that little shoulder clearance, often found internal work, required. Non-conventional methods heat treatment are being extensively in- vestigated. These methods usually sub- ject the part less severe quenching conditions with resulting lower overall distortion. They open possibilities for successfully processing with shaving any gears with intricate blanks, the distortion which could not entirely con- trolled quenching dies. Indications are that local distortions involute and tooth thickness are not re- duced these new meth- ods. the many gears aircraft engine that are shaved before carburizing and hardening, all present routine problem cleaning after hardening. many angle S/ippage ; L / / \ \ \ THE IRON AGE, December 27, methods cleaning that are avail- able, the most commonly used for cleaning shaved gears are light sand blasting, sometimes followed lap- ing, the Bullard Dunn process (pat- ented), and wet abrasive blasting. Light sand blasting with pressures about psi does not damage the involute profile but leaves much desired surface finish. Some impove- ment obtained lapping the teeth after sand blast, but surface finishes are still not good before the heat treating operation. The Bullard Dunn process electrolytic process which attacks scale and stains. The loosened scale subsequently removed wire brushing operation. The parts eliminate hydrogen embrit- tlement. After processing, the parts appear they did before heat treat- ment, and show change surface finish. third method cleaning the teeth subject them wet- abrasive blasting. This similar sand blasting that the parts are wet-abrasive blasting, however, the abrasive much finer and suspend- water. Results obtained show complete removal scale and stains, together with good surface finish. Teeth which are ground angle gear with little shoulder clearance. ° ° ° usually are roughed out leaving from 0.004 in. 0.008 in. stock for grind side. The amount stock for shaving usually less than 0.0015 in. side. Roughing for grinding for shaving done either hobbing erating process using crossed axis principle and having action simi- lar milling. the fastest method roughing gears for grind- ing where speeds can pushed the expense finish and accuracy, Slower speeds production must used when roughing for shaving (called pre-shaving), accuracy and finish must higher quality. Hobbing limited that cannot used gears with little shoulder clearance. Gear shaping the Fel- lows gear shaper can used gears with very little shoulder clear- ance and consequently used exten- sively gears shaved, al- though also widely applied gears ground. Gear shaping also uses generating principle, and with reciprocating cutter shaped like involute pinion. Gear shap- ing cannot pushed hard hobbing, and consequently not fast for roughing prior grinding. special problem encountered preshaving. Clearance the form undercutting the root the tooth must provided order avoid shoulder the root shav- ing. This clearance provided the use special preshaving hobs Fellows’ cutters which have pro- turberance the tips their teeth. Universal Bender for Pipes and Shapes ONSTRUCTION nance work usually necessitate great deal bending work, whether this pipe, tubing, structural shapes, and four general bending machines are customarily em- ployed, each having its own character- istics and applications. All the features the four types namely compression, tension, roll and ram types, have now been combined into single machine, according 50—THE IRON AGE, December 27, 1945 announcement made Pedrick Tool Machine Co., Philadelphia. The new machine compr