The Iron Age 1943-05-27: Vol 151 Iss 21

| tor shaft for turbine driven generator Grand Similar shafts have been furnished Mesta for many the largest dams, including Boulder and Bonneville. The complete from the hot ingots poured the Mesta Open Department. forg le! t i 4 3 you run into oversized under- sized diameters? Are you ever troubled with pole” “‘Chinese-writing” finishes? Ever have the start cut? Ever cuss the re- ground cutters? YHE Warner Swasey Single Cutter Bar Turner sees more service than any other tool used turret lathe setups for bar work. Job studies this tool action plants all over the country disclosed our field men the urgent need for better knowledge the mechanical details the tool itself, and better understanding its usage. Many operators were not getting the best per- formance from the tool because simple adjustments were overlooked, cutters were improperly ground wrongly positioned. This reflection upon these operators. Even the master machinist veteran setup man can learn things about this important tool that probably didn’t know before. Robe That’s why 32-page booklet about the Cutter Bar Turner has been written and offered increased production. Use the Handy Cou- nde pon Mail Today or . . P Will Bring the Single Cutter Bar Turner Manual Promptly. Warner Swasey Service Bureau, Cleveland, Ohio Please send booklet, Performance from Name Address City State ; the press will ate with AB f \ HAR | irner need per- Even learn ingle and nd, Ohio ‘om MAY 27, 1943 VOL. NO. VAN DEVENTER President and Editor BAUR Vice-President and General Manager Managing Editor, LIPPERT News Markets Editor, JAMES Technical Editor, OLIVER Art Editor, WINTERS Associate Editors Editorial Assistants BUTTERS Regional News and Technical Editors Washington Pittsburgh Washington Chicago Cleveland Detroit OSGOOD MURDOCK San Francisco Editorial Correspondents Buftalo Cincinnati FRAZAR RAYMOND KAY Boston Los Angeles HUGH SHARP JOHN McCUNE Milwaukee Birmingham ROY EDMONDS St. Louis SANDERSON Toronto, Ontario BACON Seattle ° ° DIX, Manager, Reader Service ° ° Regional Business Managers Robert Blair, 629 Euclid Ave., Cleveland Fitzgerald, 428 Park Pittsburgh Herman, Chilton Bldg., Philadelphia Hottenstein, 1012 Otis Chicago Raymond Kay, 2420 Cheremoya Ave., Los Angeles, Cal. Leonard, 100 East 42nd New York Peirce Lewis, 7310 Woodward Ave., Detroit Ober, 100 East 42nd New York Johnson, Market Research Mar. Hayes, Production Manager. Baur, Typography and Layout. ° ° ° Member, Audit Bureau Circulations Member, Associated Business Papers Indexed the Industrial Arts Index. Pub- lished every Thursday. Subscription Price North America, South America and Possessions, $8; Foreign, year. Single Copy, cents, Annual Number, Cable Address Y." Owned and Published CHILTON COMPANY Editorial and Advertising Offices 100 East 42nd St. Executive Offices Chestnut and 5éth Sts. Philadelphia, Pa. New York, OFFICERS AND DIRECTORS MUSSELMAN, President JOS. HILDRETH, GEORGE GRIFFITHS, EVERIT TERHUNE, VAN DEVENTER, Vice-President BAUR, Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JULIAN CHASE, THOMAS KANE, HARRY DUFFY CHARLES HEALE Vice-President Vice-President Vice-President This Week in... Editorial Repeated Technical Articles Properties Hardened Menaso Makes Landing Gear Struts Soldering Aluminum Alloys Arc Welding Speed and Costs Figured. Induction Brazing Carbide Pits Gear Features Assembly Line Washington West Coast Fatigue Cracks Dear Editor News and Markets This Industrial News Personals and Machine Tool Activity Non-Ferrous Metals Scrap Iron and Steel Scrap Prices Comparison Finished Steel Index Advertisers ° ° hes Copyright, 1943, Chilton Company The demand for welded steel plate fabrication show- ing spectacular upswing—as more and more indus- tries become aware the advantages this superior construction. wide diversity parts and products great variety sizes and shapes today are fabricated from steel plate. The advantages are many. Welded steel plate construc- tion stronger and lighter. requires less machining and finishing. eliminates pattern expense and scrap. presents smoother, finer appearance. And, nearly all instances, parts and products can pro- 4. Another Industry Served Mahon duced quicker time and very attractive cost. Mahon, skilled metal workers and welders, backed modern production facilities, are turning out vast volume steel weldments every day. They are equipped produce any type size product that adaptable steel plate fabrication. your requirements, let Mahon engineers give you the benefit their long and varied experience. From design delivery, you will have the advantage expert advice and assistance. Estimates furnished request. Designing Service—To assist you conforming your part product welded steel plate fabrication, Mahon maintains staff experienced design engineers. The services these experts completely your disposal. THE DETROIT Machine lany Welded Plate Products COMPANY 2 4 i | | | MAY 1943 ° ESTABLISHED 1855 Repeated Request Senator Kilgore, West Virginia, has introduced Senate Bill 702, proposing the appointment administrative agency mobilize (?) our scientific and technical resources. Under this authorization, research and invention would administered and controlled Government. this looks like attempt cross the New Deal donkey with the Technocratic mule. What Nature has found impossible may perhaps accomplished those who rush where angels fear tread. that may, this proposal has brought number requests reprint editorial published some years ago when the late but unlamented Committee National Resources proposed take all future inventions under its wing. Here is: would the proposed National Board for the Forecasting and Control Inventions, proposed the Committee National Resources, handle the case the zipper, assuming that had not yet been invented? The zipper, you know, that clever little device which takes the place buttons and other fasteners. The zipper really has very large social impli- cations, reverberations and repercussions; larger, perhaps than have steep airplanes house trailers. Thus the zipper would probably come under the jurisdiction such board. Let sit into imaginary board meeting, consider the yet (as- sumedly) unthought zipper. Chairman Whoozis: “Gentlemen, are here discuss the social impli- cations involved doing away with buttons. Some guy may think this some day and should prepared say ‘yes’ ‘no’.” Prof. Whyzis: the nudists and the infants who are still the safety-pin age, have 115,000,000 people this country using buttons. conservative estimate buttons per person, buttoned and unbuttoned once each day and average time required sec. for buttoning un- buttoning each button, arrive the astonishing total 57,500,000 man hours per year for buttoning and unbuttoning our buttons. Since one the main objectives the New Deal increase leisure among our people, for any invention which will save any considerable part this tremendous amount time. looks like open and shut Prof. Howzis: “Considering this subject fundamentally from its impinge- ment upon the sociological pattern related technological involuntary displacement, desire enunciate and emphasize the indisputable fact that 12,000 our citizens are now gainfully employed the manufacture buttons; 14,000 individuals are employed the correlated and adjunctive occupation constructing button holes; 6,500 members genus homo Ameri- canus are occupied attaching buttons garments means thread other fastening devices and 4,800 additional persons gain livelihood through associated activities such the manufacture, collection transportation the miscellaneous and diversified materials from which buttons are customar- ily fabricated. If, therefore, buttons were abolished, the resultant would eventuate gross maximum technological displacement aggregating 65,860,000 man hours per year premised upon the hypothesis mean, average, secular, interseasonal, integrated, progressive, occupational working week trend stabilized hours. Since one the main objectives the New Deal restrain the increase unemployment, against any possibility such would concomitant with the invention under consider- ation. me, appears open and shut proposition.” Mr. Lewzis: “Representing the great masses American organ- ized labor whose throats are even now exposed the cruel fangs heart- monopolistic employers, would remiss duty did not tell you that votes votes. Since one the main objectives the New Deal and keep the votes, against any possibility such this, which ikely alienate them. looks like open and shut proposition and therefore move, Mr. Chairman, that the future shall prohibited law.” invention any such device 1 } | are hat you ‘om ALY eie*e 2, Canadian and British manufacturers use Inland Ledloy speed war production, 25% Less Scrap 22% More Production 50% Longer Tool Life Inland lead-bearing, faster machining, low steel. This only one the many remarkable many parts for war equipment—result- war records being made Inland Ledloy. faster production, lower unit the case history Ledloy used for and great savings critical cutting the manufacture mm. shell tools. Canadian munition plant. When peace comes Inland Ledloy will Experiences like this led rapid in- available for general manufac- crease demand for Ledloy before the turing use—helping produce finer war. Today, all the Ledloy that lower cost—products that makes going into millions shell and priced attract the most buyers. SHEETS STRIP TIN PLATE BARS PLATES FLOOR PLATE STRUCTURALS PILING RAILS TRACK ACCESSORIES REINFORCING BARS “Foreign LIMITED, Cannon Street, LONDON. Wi? Yyy UM sig Properties Steels ° ° ° ° ° ° Not great deal known about the physical properties very hard steels and their reactions service. Herein are great deal correlated data this subject. ARDENED are never specified ordinary Table based results reported which are placed terial will do. Swift. Numerous instances are with surface hardness true that wear-resistance in- record confirming the practical 500 Brinell more. this condi- creases with hardness, but also value Swift’s ideas, and the re- tion they are practically unmachin- true that certain combinations his results. able and, finished all, must the softer materials have excellent ground, lapped, otherwise prepared qualities. This indicated Properties (A) Hardness: The tween the carbon content and the maximum attainable hardness steel shown Fig. 1.' Note that this hardness depends largely upon car- bon, being practically independent alloy content. The effect alloys chiefly produce hardenability; that is, the ability attain maximum hardness with slower rates cooling. Mc.Quaid (B) Wear Resistance: The curves and Jeffries Fig. from Rosenberg, indicate Grossmann the influence carbon, and hard- ness, upon the wearing qualities plain carbon steels. (C) Strength: Fig. shows the relation between tensile strength and 040 060 O80 090 100 Brinell hardness. Note that the rule, Per cent carbon “Tensile Strength 500 Brinell use Maximum hardness Rockwell for service. Steels which are hard- ened, whether plain alloyed, may (1) Case-hardening (mild) ABOVE 0.25 per cent carbon be- HARDNESS (2) Tough-hard (medium) tween carbon content 0.50 per cent carbon and the maximum (3) Hard able hardness steel. Ss 1.00 per cent carbon Potentially, hardened parts are brittle, and may become source Therefore the greatest care de- RIGHT carbon, and hard- Sharp notches, unbalanced upon the wearing and “stress-raisers” all kinds have plain carbon much more destructive From upon hardened parts than upon those ms. per work ards Journal Research, made from softer materials. September, 1931. Hardening increases the cost and Therefore hardened steel should Carbon content, per cent Wear,g THE IRON AGE, May 27, ay Works Laboratory, General Electric Co. Schenectady - | he } | | | WEAR hardness,” holds good rela- tively high hardness values, provided the material not brittle. Most steels containing more than 0.55 per cent carbon and which are over 600 Brinell hard behave brittle man- ner the tensile test. This fact often taken show that the tensile test value connection with hardened steel. How- ever, even though the tensile may low, this may all the more reason know exactly what is. The methods stress analysis described demand that the tensile properties known, the basis sound engi- neering design. The same true the shear properties. tests two kinds case-hardened steel. the Vanadium some data the torsion (shear) properties tool steels. Aside from this, though, this much-needed infor- mation virtually non-existent. Fig. shows the relationship be- tween hardness and compressive strength hardened steel. Naturally, this curve represents samples which were hardened uniformly throughout. The compressive strength case- hardened articles will vary, depend- ing on: (1) The nature the load applied. (4) The hardness the core. This further discussed later under “Relation Case-Depth Core Properties.” Tensile, bend, and Charpy impact tests were made, using notched and unnotched samples representative case-hardened, tough-hard, and hard steels. The test specimens used are shown Figs. and Table II. The bend and impact tests are cluded for the sake comparison. Table was prepared from data collected over period years, for the purpose presenting compara- tive picture these three steels, and indicate which tests were significant and which were not. perhaps unfortunate that some the steels given are not representa- tive those general use today. However, they are believed rep- resentative their class, and was comparison classes and not indi- vidual analyses that was intended. The “reduction obtained from the ordinary tensile test room temperature was used the measure “cold is, the abil- ity the steel bent, formed, drawn cold while the annealed state. “Hot plasticity” taken the “reduction when the test conducted temperatures approaching those used forging. that the results compare with forge shop experience. Most measurements have involved the force energy necessary effect certain deformation. However, the writer this factor unimportant. The reason that, with modern presses and hammers, limited power can brought bear, the principal limitation ability the metal deform with- out rupture. “Machinability” indicated the The “hardenability” results are ex- those who are not familiar with the terminology used, can stated that the symbol means that hardness Rockwell was ob- tained distance 13/16 in. from the quenched end the Jominy test bar. looking another way, this means that all sections smaller than in. diameter, when oil quenched would develop Rockwell better the surface. The mechanical properties results will become evident son the results with the different test specimens. explanation the bend (mod- ulus rupture) test may Sample specimen size may in., the load being midway between the supports set 3.5 in. apart. (2) The hardness the case. those who may doubt the value 3—Relation between tensile strength and Brinell hard- 4—Relation between hardness and compressive ness. strength hardened steel. 1000 900 900 800 ZONE 800 with 500 400 400 300 200 200 100 Tensile strength, sq.in 40—THE IRON AGE, May 27, 1943 Compressive strength, sq.in _- orge the } - =! with un- the WW | from Notched- Pag R. test 4.Notched- Sharp "V" way, erent middle, the modulus 5—Tensile test pieces, hardened steel. Test pieces rupture (S) That is, the modulus rupture (S) and are the same the standard 0.505-in. calculated for this specimen times the tensile specimen, except for the notch. breaking load (P) the formula de- breaking load (P). allowance was scribed the text. made the for the » tween TABLE Wear Metals Sliding Contact vol. 131, June 19, 783-785) WEAR SPECIMEN Nitralloy 1.4 3.7 0.70 4.3 0.65 1.2 0.65 0.5 0.70 0.75 290 0.75 330 8800 0.50 100 0.60 Notes: (1) specimen 0.001 in. per million feet travel. Determined loss weight specimen every 28,000 feet. Tests run for 350,000 700,000 feet. Speed 80r.p.m. 120 ft. per min. (4) Lubricant none. THE IRON May 27, | , | | | | | 800 Fig. 7—Charpy test pieces, hardened steel. 8—Section friction driver showing pit. Note the relation between the pit and the sulphide inclusions. The steel SAE case hardened (cyanide process) notched specimens, since all cases the areas above the notch for the notched specimens, and the cross-sec- tional area the unnotched samples, were equal. true that the formula applies strictly only the elastic limit ductile materials and the break- ing load only for very brittle mate- rials (zero ductility). 4 4 4 7 For steels with appreciable duc- tility, such the tough-hard, the formula gives fictitiously sults. one the purposes this table demonstrate this fact. (Com- pare tensile and bend results for the different steels.) the writer’s testing tool steels, the tensile test used hard (0.50 steels and the bend hard (1.00 steels. During the tensile and bend tests LEFT 9—Showing pit case hardened part subjected heavy rolling (bear- ing ball) pressure. RIGHT Cold- drawn steel, bent depth 0.005 in. the case hardened samples, par- ticularly those not severely notched and with the “light” case, was easy see and hear the first crack, and subsequent ones, the case the specimen broke. All the unnotched tensiles, cyanide case hardened, were filled with parallel, evenly spaced, circumferential cracks the case after rupture. Unfortunately, when the tests were first begun, the significance this was not realized and the values not recorded. the author’s opinion that the stress the first crack the case, for such samples should taken the true point failure, rather than the stress. One the main purposes this compilation was show the utility the ordinary tensile and bend tests compared what may well the more elaborate and significant magnetic powder method. she imp beg has cal ma fre 42—THE IRON AGE, May 27, 1943 par- ched easy and ched were aced, case were this not inion ilure, pture this tility tests the ficant LEFT and RIGHT cracked cold bending and then case hardened. This shows structure along the side walls and the root the crack. Heat impact and fatigue tests. From the beginning, the effect notches was strongly emphasized impact fa- tigue testing and almost disregarded the more simple tests. Experience has convinced the writer that Gensa- mer right—the simple tension and shear tests properly applied and in- terpreted are capable results much more significant and reliable, and fraction the time and expense. Importance Soundness and freedom from physi- cal defects are particularly important Pipe seams, flakes, and other gross de- fects cannot tolerated. Certain items not ordinarily classed defects may cause trouble hardened parts. High sulphur steels such SAE- X1112 X1315 contain manganese sulphide inclusions which give them their free-cutting qualities. Under ordinary conditions, these steels make excellent case-hardened parts. Uuder extreme pressures, however, the sul- phide may cause trouble. case point illustrated Figs. and which show how pitting took place localized weak spot due sulphide inclusion. Figs. and show part made from cold-drawn steel, bent cold. This treatment was ening cyanide, min. 850 deg. C., then water quenched. Beginning crack left; end crack right. BELOW cracked failure re- move surface seams prior hardening. a = formed crack the inside the bend. The crack was fine that was almost invisible the naked eye (until revealed the magnetic test method). The part was later case- hardened. This rendered brittle that snapped when thrown the floor. Note how the cyanide has pene- trated the root this crack. The effect much like putting scratch piece glass. Yet such parts not cracked before case-hardened, will take considerable abuse without breaking. Next improper grinding, surface seams probably ruin more hardened parts than does any other cause. The trouble that such seams are ex- ceedingly difficult see, unless de- tected the magnetic test method, some equivalent method. Cracking Due Surface Defects The following finish allowance for hot rolled forged material should eliminate all surface seams and other defects, the material has been prop- erly made. Figs. and show large pivot which broke hardening because failure remove the surface. Pres- ence the seams was proved the dark (oxidized) areas seen Fig. 13. possible, however, that originally these were not deep shown, but were “opened up” the process heating for hardening. surface hardened articles, the desirable case depth will depend upon THE IRON AGE, May 27, 1943—43 LEFT pivot cracked hardening. Presence seams prior hardening shown dark heat-colored areas fracture. RIGHT case hardening experiments with machine steels. Heat treatment: 825 875 deg. C., oil quench, tem- pered 175 deg. for min. Cyanide content, per cent. Etchant, per cent Nital. 100 diameters. the working pressure well upon the hardness the core. For ex- Minimum Finish ample, when using steel which de- Diameter Thickness One Side velops relatively soft core, such necessary than when the base mate- Over in. in. rial develops more hardness. Over in. Rockwell Over in. in. Case depth 0.004" Fig. shows case depth obtained under production conditions, when samples representing three common trouble bearing surface. machine steels were exposed the originally made from SAE1020, cyanide bath for various periods case-hardened for ten minutes time. Note how the Rockwell hard- 9-13), these bearings operated ness value changes with depth case perfectly. However, when SAE 1112 the different materials. was substituted for the above, using The foregoing study was made be- same cycle, (-6)), the Rockwell 37-38 Case depth 0.010" LEFT Representa- tive curves showing relation time and temperature carbon penetration. All carbu- rizing done gas retorts using gas (95-98 per cent methane) the car- burizing agent. All mea- surements made tri- angular test pieces. Carburizing hours Case depth 0.013 44—THE IRON AGE, May 27, 1943 vider > gees 0.140 = lA | | | PF. * 0.0 | - | | | | — > 3 | | | | ; «J SAE SAE X1315 Minutes 120 Minutes THE IRON AGE, May 27, ~ 0.005 0. | , 0.013 Name and Specification PROPERTIES HARDENED STEEL TABLE Case-Hardening Properties Hardened Steels Tough- Carbon Tool Hard (A4119) (SAEX1315) (A9255) (SAE4140) Steel Tool Steel Modified (Steel (1) Chemical Analysis 0.19 0.17 0.56 0.40 1.05 Vv 0.15 ma (2) Mechanical properties, annealed Machinability (SAE 1112) 100 per cent 92°; 55% 31%, Good Poor Possible Possible Possible Possible Brazing Good Excellent Excellent Possible Good Possible (3) Normal hardening range, deg. F.. 1600-1650 Normal quenching Oil Oil Oil Oil Water Air Normal hardness expectancy, Brinell,* surface 636-854 636-854 655-716 513-636 636-854 636-820 hardness expectancy, Brinell,* core. 170-400 150-300 400-716 300-636 301-513 636-820 5-8 5-8 9-10 5-8 8-9 9-10 Jominy distance specified hardness, J58 J60=12 J50=7 J65 Air Hardening Largest diameter develop specified hardness “Safety,” size change, warpage, Good Good Good Poor Best (4) Mechanical properties, hardened Surface hardness, Brinell 763 763 695 546 805 763 Wear resistance factor 1.10 1.00 0.46 0.37 1.00 1.00 Tensile strength, Ib. per sq. in. 190,000 347,000 282 ,000 203 ,000 Sharp notch 175,000 147,000 221,300 Unnotched Unnotched Bend strength, modulus rupture, per sq. in. 206,000** 229,000 596,400 400 ,000 230,000 in. notch 124,000** 182,000 295,050 178,600 Sharp notch 148,000** 170,000 228,900 91,350 Unnotched 214,000** 222,000 310,000 Charpy impact, 10.3 161 150 6.5 9.1 14.0 in. notch 6.0 6.7 Sharp notch 5.0 1.5 5.0 u Pack carburized 1650 deg. F., hr., 142 in. case. Direct oil quench. Stress first audible crack case. Cyanided. 1550 deg. hr., in. case. Oil quench. Limit. 46—THE IRON AGE, May 27, 1943 bea the ing Sel ming bearing balls sank into the surface, and “froze” there, ruin- ing the operation the device. The relation case-depth time and temperature shown the Time, Temperature—Carbon Penetration Although the curves Fig. are based upon gas carburized samples steel, has been the writer’s experience that, for most practical purposes, the same curves may used for the pack-carburizing and cyanide case-hardening processes, and for all kinds steel well. Naturally, proper allowance must made for the time required heat the steel the carburizing tempera- ture. spite numerous claims and counterclaims, has also been the writer’s experience that the wear re- sistance, strength, and other physical properties cases produced the different case hardening processes, whether gas carburized, pack carbu- rized, cyanided, one the nu- proprietary when all else equal, equivalent. the Therefore, choice process should depend more upon the depth case, the production requirements, facilities available, and upon econom- ics, than upon the rather mysterious “advantage” claimed for certain pro- prietary equipment, processes, and materials. Summary and Recommendations (A) The applications the three classes hardening steels are best (B) Case hardening steels are out- standing for ease manufacture— forging, machining, cold plastic work- ing, welding, brazing, Further- more, they combine high wear-resis- tance with very desirable resistance weakening (C) Tough-hard steel would appear develop maximum tensile and elas- tic properties unnotched mildly- notched designs. (D) Hard steel indicated only for parts such bearing-balls, which are subjected compressive loads be- yond the capacity case hardening tough-hard materials. (E) Close co-operation between de- signer, planner, production man, and heat treater essential for success with hardened Finally, drawings, well plan- ning and production arrangements, should leave doubt to: (1) Material. (2) how much, but where. surface hardened. (4) Allowance for warpage, size change, and decarburization (finish allowance). (5) Special requirements, any. References Hardenability,” Burns, Moore and Archer, Trans. A.S.M., 1938, 14. 2“The Marked Similarity the Tensile Properties Several Heat-Treated Alloy Steels,” Janitsky and Bae- yertz, Metals Handbook, 1939 edition, pp. 515-518. Metals Under Combined Maxwell Gensamer, A.S.M., Cleveland. Parts Under Fatigue Stresses,” Woodvine, British Iron and Steel Inst., Carnegie Scholarship Memoirs, Vol. XIII, 1924, pp. 197-236. Physical Properties Hard- ened Tool Steel,” Proceedings A.S.T.M., vol. 31, 1931, 47; also “Some Physical Emmons, Trans. A.S.S.T., February, 1932, 289. Steel Data Book,” 1941, Vana- dium Alloys Steel Co. A.S.M., 1939 edition, Fig. 1041. 19, 1939. Electron Microscope Improved Siemens electron microscope has recently been improved ac- cording the German “TZ fiir pro- ktische Metallbearbeitung,” and said that the instrument has now reached such degree perfection that marked further improvements cannot expected. The microscope can operated the layman after short instruction period. All spe- cial fixtures are one cabinet and not need serviced. All nec- essary manipulations can formed the observer the operat- ing stage without endangering him- self working near high tension The presentation the object has been greatly facilitated new ob- ject stage, consisting particularly transparent material, special collo- dion films about 0.02 (0.00002 mm.) thickness. Three electro-magnetic lenses are used instead the former two. The principle the lens shown Fig. Direct current flows through the coils, considerably increasing cur- rent energy. Since the lens body has been kept circular, this current energy has the effect concentrating the invisible electron radiation and ing through the fine opening be- tween the pole shoes the lens where- the magnetic lens formed. changing the strength the current, the focus the lens can adjusted and the degree magnification varied wide limits. op- eration the electromagnetic lense the electron microscope. using such lenses series magnifications 40,000 diameters can obtained. The magnifying power the. mi- croscope has been increased 40,000 diameters, and can adjusted down 4000. (The optical microscope has maximum magnification 2000 diameters.) Photographic magnifica- tion clear electron picture can enlarge the size the original ob- ject 200,000 diameters. Optical Magnetic field lines Flectron paths | | | | | ° ° THE IRON AGE, May 27, 1943—47 = 4 te q 4 § RIGHT done semi-automatically this Monarch lathe especially fitted with cam bar the rear place the regular taper turning attachment. slide carries follower rol- ler which held against the cam air piston and toggle action. Cemented carbide used turn this alloy steel forging. J these and following pages are shown sampling some the tooling and special machinery installed the Menasco Mfg. Co., Burbank, Cal., for the production oleo land- ing gear struts for the P-38 Lockheed Light- ning fighter plane. With few exceptions, the equipment brand new inasmuch machine tools for the production light aircraft en- gines, the former product, could not readily converted for this special work. LEFT the solid forging for the main strut has been cen- tered and rough turned, drilled from the solid this Barnesdril No. H-4 Hydram inverted drilling machine. The hole being drilled over in. diameter and in. long. The huge drill remains stationary and the work both rotated and fed down over the drill. Head with chuck and lower steadyrest are fed hydraulically. The entire machine over ft. high. Makes Landing q 4 dle und ing 48—THE IRON AGE, May 27, 1943 ABOVE the main shock strut cylinders John Barnes hydraulic boring machine. Note the elaborate type sad- used grip the outboard end the workpiece. large volume coolant under pressure pumped through the bor- ing bar and carries the chips out through the base the pedestal the left. RIGHT THE most elaborate milling machine jig the plant the one used for supporting the main strut while the up-lock attachment lugs are being straddle milled this manu- facturing type Milwaukee miller. This intri- cate forging rested the pedestal until end plug screwed into position with the handwheel the left. Radial position- ing obtained with the V-block and toggle clamp shown the upper left. LOWER RIGHT THREAD milling operation plug cap for the main strut. This done Lees-Bradner thread miller. ABOVE HEEL attachment fittings and yoke lugs are arc welded the piston tube this elaborate positioning jig, which as- sures correct location the lugs with re- spect each other. The entire fixture rotated about trunnion bearings. MENASCO MAKES LANDING BELOW HOCK strut attachment lugs being drilled intricate trunnion jig mounted the bed Carlton radial. After the operation shown completed, the carrier ro- tated deg. counter-clockwise and locked with index pin. Then the whole fixture moved forward few inches its base, location being the index plug shown the central foreground. matic relativ eter, rear. many but — 4 ABOVE all machining operations the strut bodies and pistons are completed, the forgings are hardened. This view shows two the electric fur- naces which bring the work the quenching tem- perature. the rear may seen one the hoods into which the work hoisted prior transfer the oil quench tanks. The furnace atmosphere fills these containers and keeps the work from scaling during the transfer interval. LEFT hardening and sand blasting, the first operation the strut cylinder cylindrical grinding, performed this dis unit. Note the liberal use steady rests all the important diameters. — : ING the inder Lan- ters. BELOW TTACHMENT lug holes are accurately sized and finely finished with this Micro- matic Hydrohoner. Because the holes are relatively shallow compared their diam- eter, the stone holder piloted front and rear. The complete cycle automatic. Like many other toolings Menasco, this simple but sturdy jig excellent example arc welded construction. ABOVE RINDING packing gland side diameter the tary type grinder. The work clamped rigidly the special fixture shown tudinal feed motion only. RIGHT interior the strut cylinder shown being honed this John Barnes horizontal type honer. Similar operations also performed Barnesdril vertical type machines. = 1 { il ] ESPITE the advances the usage, advancement methods joining has not always gone ahead with the alacrity, the British Light Metals points out discus- sion the theory and practice joining light metals. The most com- mon methods have been riveting, bolt- ing and flame welding, and, lesser degree, arc welding. Resistance weld- ing, particular “spot” welding, has now attained sound position that inspires confidence, but has taken long time gain this state when com- pared with the same process for the steels. Soldering has not yet acquired the universal importance that has with the majority metals, particularly the coppers and brasses. The real problem soldering light alloys concerns natural oxide film upon their surface and its elimination. technical prob- lem and supposed objection the formation bimetallic joint be- tween the highly electropositive alu- minum and the usually electronegative “solder.” many cases, this the real objection, but often the ex- for failure solve the practical problem efficiently. However, order always accurately judge this, felt that what meant ing” requires definition and that ac- cepted practices soldering other metals justify examination. The term “soldering” generally im- plies process joining two metals metallic components using molten metal “cement.” Metallurgically, little more than this required; the molten joining metal must wet the complete area both mating surfaces and must alloy, least superficially, with the parent metals. The strength the junction that the joining metal, except exceptional cases where the joined surfaces are in- timate contact and mere film joining metal alloys with the two sur- faces simultaneously. These excep- tions are becoming the rule some modern processes, for example, fur- IRON AGE, May 27, 1943 Soldering Aluminum nace brazing steel parts with cop- per which enters the junction cap- illarity and the extension the prin- ciples this mode assembly soft soldering and silver brazing brass and other alloy components. all cases will noted that the solder lower melting point than the metals joined. Soft soldering uses binary alloys tin and lead, although these may modified with additional alloying ele- ments small percentage, for ex- ample, antimony, They generally melt within the range 350 480 deg. F., with operating temperatures 430 660 deg. Hard soldering and various braz- ing processes use higher melting point alloys. Brazing brass the oldest and most typical, with melting point about 1110 deg. although today various silver solders are widely em- ployed. These are chiefly alloys silver and copper, silver, copper and zinc, melting between 1290 and 1920 deg. Lower melting alloys. down 570 deg., silver and tin are also used bridge the range be- tween soft solders and brass brazing alloy. Copper itself used for fur- nace brazing steel controlled atmospheres. Flux Compositions Used Active fluxes are used with all these alloys. Flux must completely re- moved after soldering separate washing operation, otherwise virulent corrosion occurs with early failure joint. When such washing cannot applied due the nature the as- sembly, either modified flux less corrosive propensities must used and the risk from some corrosion ac- cepted, non-corrosive flux must employed. this work sur- faces must have been pretreated, usu- ally prior assembly, render such mild flux effective removing superficial oxide films. Apart from strength and working temperatures determining the type solder used, practical factors base metal composition, surface condi- tion, actual composition within given type range, flux com- position, method application and working temperature have studied relation one another, and the correct balance conditions ob- tained. important note these factors, because recent researches have estab- lished their inter-relationship the case aluminum alloys. brief resume soldering facts shows: (1) The existence wide range solders and soldering (2) Choice solder depends upon the job and the requirements ser- vice. (3) Low and high melting solders are both used for all metals indepen- dent the melting point the latter (except, course, this cannot below the soldering temperature). (4) Fluxes have used. (5) Ordinary fluxes are strongly corrosive and must washed free. (6) Special non-corrosive fluxes are used, but general can only con- veniently used conjunction with preparatory precautions. (7) Bimetallic junctions result practically every case. (8) Broadly speaking, outside the light-alloy series, assumed that most metals can soldered with all types solder, and conditions are found for precise solder compositions, flux and operating conditions duce efficient, serviceable junction. The aluminum alloys are admittedly more difficult proposition than the brasses and steels, despite the fact that, under normal conditions, they not readily corrode, and they reach the soldering stage cleaner con- dition than the general run ferrous and non-ferrous work. The trouble that the natural oxide film difficult remove than from non-ferrous rust from ferrous metals. But can simply removed preparatory treatments developed for ele flu rc SE solder com- and and ctors, estab- the facts range upon ser- olders latter °S are with ilt that all are itions, pro- ttedly fact they reach con- ible more arnish moved for Alloys electroplating (for example, nickel dips, sodium-zincate treatments, etc.). Further, aluminum more highly re- active than the other metals soldered, and more readily ruined retained fluxes. Again, electroplating practice shows that retained chemicals can washed free. For similar reason, alu- minum more prone failure from bimetallie contacts, but long service from soldered joints under arduous conditions, even domestic utensils, such tea-pots which spouts are soldered, establishes that least some solders are reliable. Bimetallic Corrosion Problems this subject cor- rosion, naturally the truest results are obtained from service experience only, and the closest prediction test can only hoped for closely sim- ulating service conditions the test set up. Some information can ob- tained from electrode potential values. Those given Table were measured deg. artificial sea water with the metal against normal cal- omel cell. “safe” combination metals contact usually regarded one giving disparity potentials not exceeding 0.25 volt. The table set out show the potentials the nor- mal basis materials and the principal ingredients the alloys used for jointing; also shows similar data for the light alloys. can seen that for the steels the soft solders should but that these solders are beyond the border line for the copper and solders, without tin, are the border line for the steels, but with- limits for the copper alloys; the same applies copper the brazing material. Regarding the light alloys, the rea- son for the choice soft solders becomes obvious. While tin low for potential value, the higher alloys should com- pensate this large degree, but straight alloys should This British discussion the theory and practice joining aluminum light alloys refers particularly soft soldering. Brazing aluminum also investigated, well progress made dip soft soldering. The extreme emphasis laid the past corrosion dangers questioned. prove nearest the ideal. With the hard solders, alloy somewhat lower melting point than the alumi- num alloy joined has se- lected and difficulty from the po- tential angle should arise. This consideration potentials has been only superficial, but sufficient evi- dence has been presented show that normal soldering spheres bimetallic junctions are involved and electro- chemically the disparity between the metals such junctions may quite marked. With aluminum soldering, the disparity need greater and many cases smaller. Consequently, the seriousness this point must not junction must not assumed condemn aluminum soldering with- out first giving the actual combina- tion serious consideration. Methods for soldering aluminum- base alloys are similar those for other metals with the marked excep- tion that dipping not yet satisfac- torily developed, least insofar dipping molten solder concerned. The oxide film difficulty accounts for this; found that friction, fric- tion plus flux, with the solder in- timate contact with the base metal, alternatively, special temperature flux. has been found practicable use the latter dip bath, the surfaces joined being held to- gether with the joining solder, and then immersed the molten flux. Brazing Alloy Flow systematic study the flow the brazing alloy aluminum joint- ing has been made Aluminum Re- search Laboratories, New Kensing- ton, Pa., Miller, results which were presented the Alu- minum Welding Society, Philadelphia, October, 1941. The following in- cludes résumé the work carried out. The practical work determined the extent flow of, and the form taken by, liquid brazing alloys various capillary conditions, the capillaries consisting aluminum tubes ar- rangements aluminum plates parallel angle one another. From these data, calculations sur- face and interfacial tensions were made for the liquid alloy contact with solid Thence, design data have been accumulated. was realized that impossible wet the aluminum aluminum- alloy surface properly with brazing alloy unless the oxide film com- pletely removed, and that this cannot those involved, but removed only means efficient flux. This flux has serve several functions: (a) The complete removal oxide film, well other incidental impurities, from both the base metal and the brazing alloy; (b) the provision protective blanket coating prevent further oxidation during brazing; and (c) the modification surface and in- terfacial tensions the brazing alloy order promote its free-flowing characteristics. achieve these aims successfully, the flux must molten little below the brazing temperature; must sufficiently mobile enter the jointing interstices ahead the mol- ten brazing alloy; must capable dissolving aluminum oxide with- out adversely affecting its own physi- cal characteristics and without having unduly adverse influences upon the alloy, corrosive attack, pitting and the like, and must stable under these application conditions. Aluminum Soldering Fluxes The fluxes used fundamentally com- prise mixtures halides the alkali and alkaline earth metals. One for- mation mixture equal parts potassium chloride, lithium chloride, sodium fluoride and beryllium fluoride, while another comprises one part three parts calcium chlor- ide and six parts potassium chlor- THE IRON AGE, May 27, 1943—53 | | ide. chloride the base, with additions sodium and ammonium chlorides and potassium fluoride, with chlorides potassium and ium and sodium fluoride, again with chlorides ammonium and stannous tin, affords another series. The -fluxes are produced formly mixed fine powders. For fur- nace brazing they are applied pastes water industrial meth- ylated spirit, whereas dip brazing they provide the liquid bath. The im- — — TABLE homogeneous fluid obviously portant the last case. im- Soldering with Brazing Alloy The position the brazing alloy was also given consideration. both furnace and dip brazing, conditions are similar, and may differ funda- mentally from torch brazing iron soldering. these latter, the jointing alloy can large degree forced where required. the two first methods, the brazing alloy has preplaced, and positioning must Electrode Potentials Volts Artificial Sea Water deg. against Normal Calomel Cell. Values for Various Basis Metals and Alloying Elements Solders Illustrate Possible Corrodibility Dissimilar Junctions. BASIS METAL JOINTING MATERIAL Metal Potential Type Ingredients Potential Pure iron 0.46 Solt solder 0.50 Mild 0.59 0.40 Medium carbon 0.42 Lead 0.60 Silver steel, 1.1% carbon 0.50 Copper Brass 0.26 Silver 0.02 Phosphor bronze 0.22 Silver solder Copper 0.25 High tensile brass 0.26 1.05 Aluminum bronze 0.26 Tin 0.40 Nickel 0.24 Brass 0.26 Monel 0.24 Copper 0.25 (70-30) 0.22 Zinc 1.05 Nickel silver 0.24 Copper 0.25 | | | LIGHT ALLOYS LIGHT ALLOY SOLDERS Aluminum. 0.80 Soft solder (tin-zinc alloy) Tin 0.40 0.62 Soft solder (tin-zinc-cadmium Zine 1.05 alloys) Cadmium 0.76 Hard solders 0.60 0.82 (aluminum with one more Aluminum 0.80 the following:—silicon, copper, zinc) Copper 0.25 1.05 TABLE Miller's Values Apparent Surface and Interfacial Tensions Brazing Alloys Aluminum Tubes j | Radius Height Distance Tension Tension Type Tube Between Dynes Dynes Aluminum Brazing Brazing Tube Rise Plates Width Per Per deg.* 1.181 0.073 0.170 | deg.* 2.000 0.039 0.080 635 Correction not made for angle spread. 54—THE IRON AGE, May 27, 1943 designed order that flow where required, and not haphaz- ardly. Surface tensional forces, capillary, alone fundamentally deter- mine where the braze will flow and the form will take, although these may accelerated gravity, suction pressure. For furnace and dip-brazing methods, the brazing filler material may present the raw material. That is, filter-coated sheet, coated one both sides, may employed, which case de- sign component must take care design for joining from the outset, and the filler material will already present the mating surfaces. ternatively, will applied the form wire, washer strip much the same way usual with copper for furnace brazing steel. these cases, application will dur- ing after assembly the parts that have brazed,.and the volume filler material needs fairly accurately calculated and its position correct relation the junction. These factors must, necessary, predetermined trial. metal surface also important, known bitter experience all those concerned with dip tinning mass assemblies metal terminals using soft solder and resin flux. Tele- phone switch banks which may use terminals brass, bronze nickel silver are outstanding example. With lightly burnished terminals, rumbling with steel balls and leather mousings, difficulty encoun- tered wetting the brass with the solder, flow not ready, and there strong tendency for the solder “ball-up.” The same principles apply aluminum and its alloys. Surfaces roughened light abrasive blasting, treatment, etched acid immer- sion, favor wetting by, and spreading of, the molten filler alloy due the capillary effect contributed all the pores and cavities the metal sur- face. Smooth and polished surfaces are unfavorable account the adverse surface tensional qualities. Brazing requires close control time and temperature because the jointing alloy closely similar com- position the base material itself, and the difference solidus melting temperature small. Close similarity alloys means that temperature too high, and/or time the tendency alloy preference brazing the main function increas- es, and proper flow may not se- cured, but pitting and damage sur- faces may result some degree. for prac lows was sus] the fur tem tou bri tel co ve ce h 0 a eter- and vity, and the ides, eady Al- the with dur- ition tion. hose sing use and oun- the here pply aces. acid ner- ding the the All these factors were taken care the experiments that Miller made for determining surface tensions. The practical procedure adopted fol- lows: The capillary shape tested was fluxed brushing the flux paste dipping molten flux. was suspended furnace controlled the correct temperature. the same furnace and, therefore, the same temperature, was small reservoir molten brazing alloy, free from oxide virtue thin flux coating. When the shape was lowered that its end just touched the flat surface the molten brazing alloy. Instantaneously, the brazing allowed flowed into the cap- illary reach the height and take shape characteristic the size and form the capillary and the surface tension the alloy. The mass was then quickly solidified means cold-air blast directed onto the out- side the capillary shape and onto the reservoir alloy. The assembly was then cooled and washed free from flux, and sectioned. Sectioning was vertical for round tube for two parallel plates, and measurements could made capillary width and height flow. For abutting plates, sectioning was horizontal. These sec- tions are shown diagrammatically Fig. For measurements height rise and radius tube, width and distance apart plates, and from density values the materials ex- amined the liquid state, surface tension values were calculated. Tension Values Miller’s values for surface tension X.716 brazing alloy when molten, density 2.53 gm. per c.c., flow tempera- ture 582 deg. C., are approximately 690 dynes per sq. cm. Values ilar order were obtained between abutting plates, whether vertical angle, and whether the alumi- num alloy was 2S, 61S. flux-dip brazing, interfacial ten- sion between the liquid flux and the brazing alloy moment well the individual Miller’s approximate value for the surface tension value No. flux determined 1080 deg. where its density 2.2 gm. per 185 dynes per sq. em. simulating the con- ditions flux-dip brazing his ex- periments, found the interfacial tension X.716 brazing alloy against No. flux about 250 dynes per sq. em. The flux and brazing alloy code numbers refer proprietary prod- ucts the Aluminum Co. America, many which are patented. Miller’s results these very diffi- cult experiments showed close con- sistency and are reproduced Table They were calculated substi- tuting the form measurements from the sectioned test pieces appropri- ate formulas for round and flat plate capillaries respectively. should borne mind that these results apply specifically only the solid and liquid phases taking show- ing arrangement for Miller's surface tension test. vertical tube; (B) sec- tion oblique tube; (C) abutting plates; (D) section AA; section BB. part the experiments; would seem unwise base too wide general- izations upon them. The distance flow values given can prove useful guide design and production planning for predicting