The Iron Age 1944-05-04: Vol 153 Iss 19

VAN DEVENTER President and Directer IRON AGE 42nd St., New York 17, Vol. 153, No. May 1944 Johnson, Market Research Hayes, Production Manager, ° Baur, Typography and Editorial Regional Business Managers ROBERT BLAIR FITZGERALD Technical Articles 2420 Cheremoya Ave. Broken Taps Disintegrated Applying Carbide Tools Automatic Screw Aluminum Welding With Liquefied Gas Chestnut and Sts. Philadelphia 39, Pa., U.S.A. OFFICERS AND DIRECTORS Features MUSSELMAN, President News Front Vice-President ° ° ° ° ° Member, Audit Bureau News and Markets Non-Ferrous Metals News and 156 Member, Business Papers Non-Ferrous Metals Prices; Scrap Iron and Steel Scrap News and 158 Finished Iron and Steel Prices 161 Steel and Warehouse Prices 162 Semi-Finished and Tool Steel 163 Steel Pipe and Tubing Prices 164 ° ° ° | ° © ° | — | | | Steel Cut Close Tolerance. Experienced crews working with modern high-speed friction saws, giant shears, powerful hack saws and other metal-working machinery can turn out steel quickly—cut, formed otherwise prepared your requirements. Steel that cut exact size and specification eliminates scrap and frees your man-hours for more production. Any Shape Expertly Flame Cut. Skilled ators and modern equipment—combined with ever- present stocks all types steel—assure quick, accurate flame cutting and prompt delivery. Al- most any shape, matter how intricate, can fashioned from steel plates shapes. You save the time and expense forging casting and gain the added strength rolled steel. Complete welded and riveted assemblies are also fabricated Help For Steel Problems. Our staff engineers and metallurgists are expe- rienced serving customers every branch industry. These men have displayed genius solving problems pertaining steel heat treating and fabrication. Theirs the prac- tical type know-how and you can depend them work with you whenever difficulty arises. é Speedy Delivery Without Expediter. Every man and woman our eleven strategically-located plants knows the meaning the word rush! The Ryerson organ- ization geared getting your steel delivered the shortest possible time. Write for your copy the Ryerson Stock catalog steels stock for im- mediate shipment including: bars, shapes, plates, sheets, structurals, tubing, carbon and alloy steel, tool steel, Allegheny Stainless and many others. JOSEPH RYERSON SON, INC., STEEL-SERVICE PLANTS AT: CHICAGO, MILWAUKEE, ST. LOUIS, CINCINNATI, DETROIT, CLEVELAND, PITTSBURGH, PHILADELPHIA, BUFFALO, BOSTON, JERSEY CITY. 44—THE IRON AGE, May 1944 ESTABLISHED 1855 May 1944 VAN President and Editorial Director BAUR Vice-President and General Manager ° ° ° DIX Manager, Reader Service ° Editorial News, Markets Editor...D. JAMES ° ° Associote Editors WINTERS LLOYD BARMASEL Editorial Assistants SCHIEN WILLIAMS BUTTERS Regional News and Technical Editors CAMPBELL Pittsburgh 428 Park POST Chicago 1134 Otis Bidg. MOFFETT DONALD BROWNE EUGENE HARDY Washington National Press MacDONALD Cleveland 1016 Guardian BRAMS Detroit 7310 Woodward Ave. OSGOOD MURDOCK San Francisco 1355 Market St. Editorial Correspondents ROBERT PENLEY Buffalo FRAZAR Boston HUGH SHARP Milwaukee SANDERSON Toronto, Ont. RAYMOND KAY Los Angeles JOHN McCUNE Birmingham ROY St. Louis DOUGLAS Mistakes Become Big Blunders NDIVIDUALS and institutions alike are “typed” the public mind more little things than big ones. salesman who comes into your office chewing gum and telephone operator recep- tionist who either impudent high hat are “typed” the outset those who meet them. Some people might say that these things are picayune and should not influence opinion broad minded circles. But they are not picayune. The gum chewing salesman reflects the ineptitude the sales manager who hires him and the company who employs such management. And the impudent incapable subordinate who the company’s first point contact, types the organization, from president down, the minds those exposed him. There long tradition and good authority back this habit judging little things. goes back the Biblical advice that: “By their works shall know them.” Notice that this injunction mentioned “works” not theories, promises protestations. have mentioned before this page, the fact that the American public had been given the “works” the form the atrocious Lincoln penny. Why this amateurish and confusing product thoughtlessness and ineptitude should named after one our clearest thinking presidents beyond imagination. Just within the last few days, have received from the Stanley Steel Co., Ltd., sample the new Canadian cold rolled steel nickel. shows what can done administration that looks before leaps when faced with the problem substituting one coinage metal for an- other. one could possibly confuse this new Canadian coin with any other denomination the Dominion. both practical and attractive. Not content learn their mistakes, our New Dealers have perpe- trated another colossal blunder. refer the new blue and red ration tokens. the two months which have elapsed since these tokens were in- troduced, more than 12,000 them have been put into the slots transit company fare boxes, according the American Transit Asso- ciation. They have also been found cigarette and candy vending machines, postage stamp dispensers and even automatic War Savings Stamp vending machines. the date issue the statement, last week, this practice had already cost transit companies alone something like $30,000. have fair these matters and perhaps the public has been last given break. After shrinking the value the dollar cents, our New Dealers have now given the public chance get even passing pennies for dimes and fiber tiddle-dy-winks tokens for trans- portation fares. little mistake course excusable. But when multiplied these are hundreds millions, you arrive big blunder. ‘ ™ 3 Spheroid Another Wartime Use Inland Steel Guarding America’s great harbors small Navy within the men and tenders who handle the antisubmarine and antitorpedo nets. These nets, often more than two miles long. are supported spheroid floats. great number these floats. which are in. diam- eter, are made welding together preformed segments that are cut from plates. The plates shipped for this purpose Inland not only measure specifications. but they are delivered schedule. assuring uninter- rupted production. low manufacturing cost. and on-time delivery floats the and Sheets Strip Tin Plate Bars Floor Plate the Navy. Meeting manufacturing schedules Inland tradition, which have done our best maintain even the face the heavy demands and changing needs wartime production. This principle punc- tuality begins when order taken—and follows through the order department, the metallurgical department. modern and the traffic department. Inland. order calls not only for high uniform quality but for cooperative service well. When you need steel invite you call Inland. Structurals Piling Trock Accessories Reinforcing Bars INLAND STEEL COMPANY Dearborn St., Chicago Ill. Soles Offices: Cincinnati Detroit Kansas City Milwaukee New York St. Louis St. Paul regu. redu food resu neth has usec reac raic alr News Germany has always favored the liquid cooled in-line motor for military aircraft. ago, however, the new came out with radial air-cooled motor, and unique feature which was power driven fan improve cooling. Now, one the largest makers American motors has announced motor with integral driven fan, and: the French Gnome-Rhone concern has announced four row, radial engine 3700 hp. This motor also will use the fan assisted cooling, patterned after that employed the German BMW 801. Many American military aircraft motors will soon carry water injection equipment water can squirted into the cylinder give per cent more increase engine power for short spurts time, when the pilot serious difficulty. Reversing the trend toward heavier and higher powered fighter aircraft, designers showing interest very light-weight and small fighter planes, made perhaps and carrying air-cooled in-line motor power under 1000 hp. Regardless the actual supply picture, West Coast allocations appear firmly entrenched ever. sore point the material allocations situation iron and steel scrap which continues under allocation while there exists this area apparent scarcity. The West Coast chemical industry appears postwar money maker evidenced the recent purchases Pont the Chemical Co. plant Tacoma Monsanto Chemical Co. Laucks, Inc.; Seattle. Shot the arm for the machine tool industry are the Army programs for heavy artillery and shells, truck axles, changes aircraft and new landing craft. These all require new machine tools quickly and the Army appears poised release three-quarters billion dollars worth new machine tool orders for 1944 delivery. reduce financial risks, the steel industry sees need for legislation regulations permitting payment for raw materials, including ores the process reduction and metal process being rolled. Present termination regulations are silent the subject. Beer carried into the Pacific fighting front fighter plane belly (gas) tank. It's nice and cold when the plane lands. Glenn Martin says, private conversation, that the postwar transportation food will employ huge cargo planes flying the substratosphere. openings will result freezing the cargo transit, resulting economies time and money. the request the late Secretary the Navy Knox, General Motors Corp. and Steel officials will assist the Navy making study designed improve its nethods handling materials and supplies. Through Mexican corporation now being formed, Continental Can Co., will modern can manufacturing plant the six months since its previous audit, the United Steel Workers America has gained more than 200,000 members and increased its net worth $766,844 $3,313,077. Dropping streamers tin foil German aircraft over England has received several newspaper notices. The method was originally devised the British and constantly them: The function the tin foil give large radar indicating many more planes particular point than actually are there. This accounts for the uncertainty regarding the numbers involved recent German England. Negotiations are reported underway whereby one two open hearth men from Fontana sent Caracas, Venezuela, supply technical information and advice problems small open hearth furnace there. proposal make free port the Kaiser shipyards Richmond, Cal., being bandied postwar possibility. Catapult armed merchantmen are disappear from the merchant fleets the United Nations, there are now enough escort carriers give the convoys fully protective air cover. | ENTRIFUGAL casting was utilized originally method for making simple pipes. Prog- ress technique and changes de- mand have since made possible the production complicated shapes and multiple castings. Generally, castings made centrifug- made the centrifuged method, should diametrically balanced about the axis rotation. long the central hole the axis rotation and symmetrical the bore the cast- ings may include some irregularities such outside slots, flanges and projections. Most types tubes and circular castings lend themselves read- ° ° ° 1G. castings. The cast- ing left gray iron. The 85-5- 5-5 alloy right had the sprue poured statically and was then spun; note com- plicated vancing. ily this process, whereas, pieces having extended offsets must counterbalanced weights. cen- trifugally casting these types, ideal condition exists when solidifica- tion progresses from the outer the inner wall the casting. This re- sults product with definite out- line and sharp detail not restricted the pads fillets the static proc- ess. For other articles centrifugal cast- ing, see THE IRON AGE issues April and 22, May and 20, and Dec. 1943; also, March 30, 1944. Two considerations determine the initial manufacture metal parts— the quality required and the cost manufacture. Still another feature— availability—presents itself, and cur- rently particularly important. The chief concern this article outline the factors which deter- 48—THE IRON AGE, May 1944 ompetitive JOHN PUTCHINSKI Centrifugal Casting Department Allis-Chalmers Mfg. Co., Milwaukee mine the cost manufacture the comparative costs related the process completing part cast- ing from the raw material. The basic limitations the proc- ess cannot well defined, since, with enough expenditure, equipment and research work may possible spin any castings method that could called centrifugal. However, until some such experimental work done, the following limitations are realized. Materials should suitable for the process. Most metals such pure copper, alloys, aluminum and manganese bronzes, variety copper-tin-lead-zine alloys, cast iron and steel are practical with some few exceptions the ferrous and non fer- rous groups. Among these restrictions the non-ferrous groups are high- phosphorus alloys which wet the mold and stick badly; high leaded alloys containing per cent over which tend “centrifuge” alloys which are not suitable the application with- out further heat-treatment (cast iron permanent molds); alloys which are hot-short and may possibly crack high speeds (thin walled sections silicon bronze which need dinary control temperature and metal handling.) However, with good judgment and experience, most the alloys can handled favorably. fact, metals lacking ductility malleability which cannot extruded rolled, may successfully cast centrifugal. ly. Among these are high antimony, high bismuth and high tin alloys. Due centrifugal force, combina- tions metals may realized. some instances composite gray iron and brass has been made, and, the ferrous field, high-chrome steel ring cast with lower grade backing. With progressive design im- provement placing wear resisting material where its quality required, extensive developments pated. Suitability size and shape another consideration centrifugal Size single considera- tion principally determined the speed-range, strength tion the mechanical equipment available. Parts weighing from three- quarters pound several tons have been cast successfully and eco- nomically. casting. considering the economy the Counter- Casting 2—A weight used coun- terbalance when the casting has some irregularity. process also set bottom limit size. present centrifugal cast- ing some difficulties are still enced where “cast size” “no ma- chining” are specified, particularly plate castings thin sections and very large diameter. not cal make ordinary plate simple cover casting centrifugal- ly, simply for appearance sake. For unless exacting conditions are tained, good appearance will not result. Shape factor prime impor- haracteristics| 2 cons basi usa} the the por sho abo sor wei N : tre its lov the né pl traor- and and metals ability rolled, fugal. imony, grade im- sisting antici- sidera- the nstrue- ipment of the has imit ma- arly and practi- rifugal- For main- impor- tance. Though its definition may vary considerably, should contain certain basic features for the most desirable usage. Continuity adjacent parts the basic element. Centrifugal force lessens the difficulty filling heavy sections through thin wall. Symmetry necessary because the excessive stresses produced when unbalanced load swung about the machine axis. The stress pro- portional the load and the square the speed. Preferably, the casting diametrically balanced about the axis rotation, should some irregularities become evident weight used counterbalance this effect (Fig. 2). Non-cylindrical slotted bores uncored openings have not, yet, been successful centrifugal cast- ings. These are represented Fig. Pressures developed the mold ex- tremities centrifugal force pre- scribe come limitations true cylindrical bores. For example, imag- ine casting propeller blade with its hub. certain speed would calcu- lated for the bore avoid the parabola formation; then the force the end the blade would beyond the lim- its the machine (Fig. 4). Minimum size the spun holes another important feature. Bores be- low in. have not been very practi- cal. losses are realized the handling the metal, through spillage (in the flush out method where excess metal emitted through the cover for cast size and nearly Fis. 3—Non-cylindrical slotted bores uncored openings have not, yet, been successrul cen- trifugal castings. completely oxidized), or, the length time the metal held the fur- nace. probable solution this prob- lem spin the castings solid. practical, several pieces should placed about the axis rotation with gate. Where quality and its linking features are unnecessary, Centrifugal Castings What metals and what products can cast centrifugally centrifuged? What are the factors which determine the cost manufacture centrifugally other methods? These are the questions dealt with herein. may better cast these small jobs statically. Ring blanks having heavy cross- sectional area tend shrink the center the inside bore. This par- ticularly true individual pieces large diameter with small heights. order overcome this natural shrink- age, becomes necessary add large amounts stock the bore in- sure sound, clean casting (Fig. 5); or, the metal pouring must started rapidly, then tapered off. Castings with vertical bore and outlying details right angles have definite limitations the non-ferrous fields because dross entrapment (Fig. 6). This difficulty trapping corner sections minimized steel castings where the metal not rapidly disturbed oxygen. possi- ble procedure for overcoming this de- fect inject neutral gases inside the mold previous the introduction the live metal. The shrinkage metals from the mold wall aids the extraction cast- ings and the repetition the casting process. After one casting spun but matter seconds before the mold can adjusted and prepared for the next casting. Still other restrictions are noticed the use cores. Hard surfaces, high tensile strengths and high dry strengths are required for the outside cover cores. Cored center openings present production problems. The dif- ficulty exists chiefly anchoring the core permanent semi-perma- nent mold. Cores, colloquially termed, “splash cores”, have cessful. Where cored openings are neces- sary reliefs permanent mold equipment, gain inside contours, collapsible center cores must used due the contraction. This neces- sary, casting pulley for example, where the outside rim may level higher than the hub. The metal not able collapse the materials be- tween its constricting areas. Special care must also taken tying these cores. Where necessary insert pin cores the area the surface for bored holes (Fig. preferable use the centrifuged method sta- tic casting. the metal poured while the mold rotating, the metal washing these pin cores invariably will wash the core away show flow lines detrimental the casting. Another limitation characteristic centrifugal casting the requirement that the cored cast hole must near the axis rotation insure progressive shrinkage feeding use centrifugal force. Previously, machine design has been characterized heavy construction. This was necessary because failure obtain maximum physical proper- ties casting. Generally, the proc- ess streamlining equipment and making more compact has increased the demands for improved smaller type casting—one which occupies minimum space with maximum efficiency. Where metal density and IG. 4—A certain speed mcy calculated for the bore avoid the parabola formation (right), and this speed the force the outer end the blade may beyond the limits the machine. THE IRON AGE, May ° ° ° Vs. nbina- a gray and, 6 Shrink cavity 5—Ring blanks having heavy cross-sec- tional area tend shrink the center may necessary add large amounts stock the bore (shaded area, right) insure sound, clean casting. the inside bore. RIGHT 6—Castings with ver- tical bore and outlying de- tails have ferrous fields because dross entrapment (dark areas). 8—Where necessary insert pin cores the area the surface for bored holes, preferable use the centrifuged method static pouring. Top view casting left; side view right shows position pin cores. compactness size are required qual- ities, centrifugal casting may the only solution for some engineering problems and the comparative costs may not factor. Parts that have been cast success- fully are legion. gray iron: variety gear blanks, pulleys, stick castings, sleeves and bushings. non- ferrous metals: blanks and bushings all sorts, squares, hexagon and octagon shapes and many types sleeves capable withstanding hy- draulic pressures high 3000 lb. per sq. in. (Fig. shows some variety among the smaller types; much larger types based the same principle have been made.) steel: cluster gears, gear blanks, valve bodies, inside flanges, airplane landing gear parts and axles are com- mon castings. Steel lends itself more readily centrifuged castings than 50—THE IRON AGE, May 1944 definite limitations the 7—Where cored open- ings are necessary reliefs permanent mold equipment, gain inside contours, col- lapsible center cores must used due the contraction, the metal will crack (wavy lines). Flow lines the non-ferrous alloys because the easy removal the gates with cutting torch. Due its directional qualities, cen- trifugal casting challenges forging some fields. The resultant castings are uniform, closer size, compare favorably density with high per- centage yield the casting and machining operations. many in- stances the casting has only boring threading operation and can then immediately applied the job; whereas comparative instances free forgings the latter may have trued, then milled, turned, bored and threaded. Frequently such forg- ings require more expensive equip- ment, more machining and more high- trained mechanics. (Fig. 10.) Price much debated question. Static casting with its “gang” molds offers competition certain types 9—A variety centrifugal castings. small, individual pieces jobbing lots. Often arising this question— more economical spin indi- vidual pieces with further opera- tions necessary before machining, flask, considering the cost such ad- ditional operations cutting gates, handling the sand, well extra equipment repair other necessary overhead? understood, course, that special physical characteristics high tensile strength density are required. The cost molds mold material not much different than the cost good sand pattern equipment. The use molds for bushings minimizes cleaning costs, eliminates the center core and re- duces extra metal handling. Centrifu- gal casting, due its higher yield and lower scrap percentage proves more favorable the non-ferrous field be- cause there comparatively lower overhead through lack risers and accompanying costs. higher yield results, not because personnel but because better metal pressure and control through feeding that cannot accomplished static casting. The higher yield the outstanding fea- ture the foundry the machine shop. Another consideration can nized the machining costs. all, would found defective the first machining roughing opera- tions; gas holes spongy structures are readily noticed. the other hand, this does not hold true for static casting, where inherent defects may still exist. For example, static casting heavy bushing, shrink gas hole may confined some place within the wall and not uncovered the ma- the press But centr sent ance ance. with mana balan only for and what but sated able holdi large per that quire ing Whit are hoist safe use anent aning re- trifu- and more lower and yield but and annot fea- chine the pera- tures other for hole the ma- chining. This job may sent into the field for use and placed under pressure, with resultant leakage. But after the final machining centrifugal casting, the part may sent out the job with good assur- ance its soundness and perform- ance. comparative cost can seen with the layout all the predominant managerial factors arranged balance sheet. comparison find only small space necessary for cen- trifugal casting with large building for static sand casting; less skilled and highly trained personnel needed; for centrifugal casting some- what more equipment necessary, but the higher initial cost compen- sated the higher yield, with vari- able metal loss through oxidation and holding furnace that favors the larger centrifugal casting; production per man reasonably higher than that static casting. Altogether, though, the initial cost centrifugal casting may higher complicated jobs which may re- quire cores special mold equipment. The finished cost will usually simi- lar less than casting. Therefore, centrifugal casting should considered even the less obvious With these principles mind, ean concluded that centrifugal casting desirable because the fol- 10—This centrifugal casting shown cast (left) and machined ready for application (right). lowing advantages: (1) High quality the casting. (2) Greater yield. (3) Savings machining costs. (4) Limited equipment needed. (5) Maximum production with lim- ited space. Self-Limiting Hoist Drive Developed NEW electric hoist drive for cranes, the important feature which exciter embody- ing cross-flux principle, was de- Whiting the General Electric Co. meeting the American In- stitute Electrical Engineers. The new drive system not only automati- cally “weighs” the load that hoisted and lowered the maximum safe speed, but also prevents the han- dling dangerous overloads. This accomplished without the use me- chanical relays similar devices. Although the first successful ap- has been two high speed, high lift cranes the TVA Fontana dam, North Carolina, which place the rate almost tons amin. Mr. Whiting pointed out that the drive believed equally suitable for application high grade, heavy duty indoor cranes steel mills and heavy machine shops. The equipment consists gen- erator, cross-flux exciter and or- dinary constant-voltage exciter driven synchronous d.c. motor. The hoist motor the type which standard for high speed crane hoist installations, except that has non- standard main field for variable separate excitation. The cross-flux exciter designed and connected the system that increase load the hoist, either motoring hoisting, regenerative lower- ing, reacts the field the exciter, causing strengthen the hoist motor field and simultaneously weak- the generator field amount de- pending the magnitude the load. Since the generator supplies the power the hoist motor armature, weakening the generator field reduces the voltage impressed the hoist motor armature and reduces its speed. Also, strengthening the hoist. motor field reduces the motor speed. ad- dition, strengthening the motor field corrects the ill effect armature re- action and prevents any trend toward instability. decrease hoist motor load, either hoisting lowering, has the opposite effect, thereby increasing the speed the hoist motor. this case, however, there necessity for armature reaction correction since the decreasing load automatically re- duces its effect. This effect from the cross-flux ex- citer, Mr. Whiting explained, partly brought about energizing one its fields series turns through which the current the hoist motor arma- ture flows. Since this current flows the same direction whether motoring regenerating, the effect the hoist motor field and the generator field the same both cases. The method interconnecting the motor field, the generator and the cross-flux exciter armature also important produc- ing these effects. THE IRON AGE, May ion— indi- pera- or ingle ad- other | Numerous methods transferring engineering information onto tooling and fabrication materials are being used aircraft manufacturers, and since two companies have precisely the same requirements many plants have developed new techniques alter- ing their photographic equipment. The author reviews the various methods now use and makes recommendations based upon the ability any process fulfill particular requirement. the first considerations discussing any method template parts reproduction its adaptation existing system design and fabrication. Some com- panies have revised their customary systems around the advantages of- fered particular method re- production. Others have found that they benefit more introducing new method for shop use only, such duplication existing templates, etc. For the purpose comparison, template reproduction may classi- fied into three groups: Projection methods using photo- graphic materials Contact methods graphic materials graphic chemical means transfer. discussing the various methods evaluate properly the advantages of- fered each. The most effective way determine the value any particular process attack the problem from the standpoint abil- ity perform the greatest number services expedite the entire han- dling part. using photo- Projection Methods The projection method general makes use the standard copy tech- nique long used photographers for making duplicates, with refinements 52—THE AGE, May 1944 dictated the need for accuracy, the handling very large sheets, and the reproduction onto metal instead the conventional printing-out paper. The aluminum steel about 0.051 0.064 in. thickness which has been sprayed with several coats fine grained matte lacquer. The lines are put with pencil sharpened chisel point. The width the line largely de- pendent the condition the chisel point the pencil. all reproduc- tion work very important have clean dense line; the quality the final prints depends the uniform- ity coverage the graphite over the area defined the edges the ° ° ° THOMAS MILES Template Reproduction Engineer, Consolidated Vultee Aircraft Corp. line. Fig. illustrates the difference. The camera set and calibrated standard set size reductions, usually either one-quarter fifth. The master layout placed vacuum-frame easel which holds the layout firmly the flat plane the easel face. sensitized glass plate placed the negative holder, the master layout then illuminated, and the plate exposed. The plate then developed extreme contrast de- veloper, fixed acid fixing bath, washed thoroughly and dried. This negative retouched with opaque block out unwanted details, and then put back into the holder for pro- jection positive reproduction the original master layout. This done blacking out the easel side the camera, replacing the master layout with sheet photographi- cally sensitized metal, moving the lamphouse behind the negative, turn- ing the light source and making the exposure before. The latent image the sensitized sheet then developed and fixed, washed and dried, dense lines are important making good reproductions. The best lines are made with pencil sharpened chisel point. tions glow and duced cent The nicely duced the scale making shrink hand versing ent right print. quantit variety thickne rr Reproduction | | ° metal the nethod ions, one- the the the then bath, This aque pro- side aster aphi- the turn- aking atent then dried, lines AFTERGLOW PRINTING 2—Cross-sec- tions reproduction and ex- both pro- duced X-ray ac- cent the reproduction checked for distortional effects. The projection method lends itself nicely such things making re- dueed scale transparencies cut jown sizes blueprints made from the master layouts, making reduced sale templates for wind tunnel mod- other testing purposes and making scale templates shrink templates for alloy dies. Right hand templates may made re- the negative, provided the negative made superior grade plate glass free from irregularities. entire contour may developed fom either half matching the right and left hand images single print. not practical attempt the variety materials having different thicknesses the projection method. metal negative The tem- first activ- exposure and then negative merely sheet with the activ- layout the shown. template repro- from the are made X-ray exposures. x ¥ This particularly when many different thicknesses are printed from single negative, since the pre- cision changing the easel requires considerable time that might spent making templates these areas standard gage template stock. One objection that has been raised method has been the tendency for lines widen when printed upon sensitized surface backed with white lacquer. This because the halation light that through the emulsion and reflected back from white surface tends spread and expose larger area than covers upon incidence with the emulsion surface. The use tinted base lacquers and shorter exposures will remedy this difficulty. The glass negatives used are very permanent PRIMARY EXPOSURE all effects except violent careless handling. X-Ray Methods preclude many the obvious dimensional and operational difficul- ties found projection methods two processes known the X-ray tem- plate reproduction methods are One these uses fluorescent lac- quered sheet activated X-rays expose photographically sensitized sheet, and known the “primary exposure” method. The other uses the phosphorescent X-ray activation fluorescence ex- pose the sensitized material and known the method. The two methods (Fig. each have their specific applications. The pri- mary exposure method best suited reproduction the many rela- ° tal 7 @ “U: THE IRON AGE, 1944—53 tively small parts found the fabri- cation and tooling for experimen- tal aircraft. The after-glow method best suited the large scale repro- duction drawings ranging size from in. and over. However, either both methods are applicable any size sheet, ft. being the largest now use. The after-glow method printing, Fig. eliminates the slight back- ground fog prints made the primary exposure method. The X-rays not absorbed the fluorescent layer will expose the film and give pearly gray background positive prints, particularly those given prolonged X-radiation. Since the activation ex- The phosphorescence thus obtained sheet template material, the two sheets being placed vacuum frame insure good contact. The ex- posed template sheet then devel- oped customary photographic solu- tions. The print has black lines white background, and read mirror image unless the scribing done also mirror image. obtain left hand and right hand reproductions match either half contour together make one complete contour, the lines are scribed through masking lacquer applied thin plastic sheets. Reproductions may then made either hand printing, when from the white areas Light posure X-rays the layout much longer for after-glow than pri- mary exposures, necessary use X-ray unit higher energy out- put and mount overhead lead lined chamber. The layouts are placed the copy carriage and rolled into the chamber. The 200 250 kv.-peak X-ray unit turned and activa- tance ft. from the layout. The activated layout then removed vacuum frame and after-glow vacuum contact with the sensitized material. Masking Phosphorescent Method The phosphorescent method reproducing templates, parts, etc., applies the use phosphorescent paint. drawing made sheet metal sprayed with phosphorescent lacquer and overcoated with black masking lacquer. scribe used remove the masking lacquer along the areas reproduced, care being taken not scribe into the phosphorescent layer beneath. When the drawing complete, the exposed phosphorescent uniformly activated with ordinary lighting fluorescent lamps. 54—THE IRON AGE, May 1944 The original frame photo-sensitized surface metal, paper, etc. Transparencies also made. Reflectography Another method reproduction comprises making reflex negatives contact and printing back positive any desired sensitized ma- terial. This method, called reflectog- raphy, now use many air- craft companies but limited the ft. The drawing reproduced made the same manner that used for the photographic process, namely pencil lines white lacquer. The negative prepared laminating sheet translucent based, very high contrast, reflex paper glass plate some cases, plastic sheet. When the cement dry, the sensitized glass, emulsion side up, put into glass- topped vacuum printing frame, the drawing reproduced placed face down the sensitized surface, vacuum blanket placed over the sandwich and the lights turned for few seconds. The light passes through the emulsion without giving sufficient exposure produce strong latent image but when per cent reflected from the white areas the drawing and back the emulsion, the increased exposure will make developable high density. The black pencil lines not reflect enough the light ma. terially increase the exposure already made the passage the (Fig. 4.) The process holds lines very nicely with appreciable widening. Nega. tive prints, right hand, can made printing the negative positive another piece negative stock, and after processing, resultant transparent positive back negative, right hand layout, any desired material. Working from these two transparent plates sible print entire contour from either half placing registration points the original drawing’s cen- ter line and matching the two parent plates printing one half, locally developing points, matching the second these points and printing again. The same procedure followed the projection method splicing very long images recommended. Dry Offset Printing Perhaps the simplest method re- producing templates the dry offset printing method. The only requisite that the original templates are scribed good template lacquer wood. The process consists inking the original template scribed lay- out with relatively fast drying printer’s ink and placing template the bed proof-press type machine with sheet white lacquered tempiate stock equal dimensions. rubber surfaced sufficient circumference cover the longest sheet normally used rolled across the inked template and across the white painted template stock. The resultant print with white lines but not image. Although not practical attempt the various refinements and special applications handled some the more elaborate methods, dry offset printing far the most efficient and productive method produce from existing cut-out tem- plates from other scribed lines. accuracy entirely dependent the quality the roll used and the workmanship the printing bed. Electrolytic Reproduction Another method lines from scribed sheets employs electrolytic etching process. The ginal sheet body steel gal- spraye ing throug The alumir face phate, contac has insert total applie copy tive Many from racy conta times ing ror type whicl limite alloy sphe das Frie unde diox deg. fluer sect. tem) tent was dec: hen mal inc! act White to ma- light, nicely Nega. made Ositive stock, ack from from tration trans- tration these same jection mages offset quisite uer sanded inking drying inked white equal d roll cover sed and black mirror actical most re- tem- lines. and bed. erring the gal- yanized sheet upon which sprayed coating special insulat- ing template paint. Lines are scribed through the paint the base metal. The transfer made cleaned sheets body steel, galvanized sheet aluminum flooding the scribed sur- face solution ferrous sul- phate, placing the contact with and applying pressure means large press. The press has rubber platens into which are inserted flats copper establish electrical contact each sheet. total power about kw. then applied over about sec. The etched copy washed, dried and tive clear lacquer finish applied. Many copies may made this way from the same original. The accur- racy high because metal-to-metal contact. The line quality some- times inclined poor, especially the template lacquer chips away gets into scribed line, thus insulat- ing the two sheets that point. Mir- ror image reproductions are the only type available, and the materials upon which reproductions may made are limited metallics. This method best suited the duplication ex- isting templates. Electro-Etching Method The process template reproduc- tion carried one step further method electrolytically cutting out the reproduced template. This elimi- nates all but few minutes hand- work finishing the edges the template. The original either template lines scribed metal layouts. This original linked with print- er’s brayer, placed large proof press and grained acetate sheet laid over it. roller exerting total pressure 1000 passed over the two sheets and the ink thereby transferred the acetate sheet, giv- ing negative. The negative dusted with lampblack hasten drying and increase the opacity the image. The template stock degreased and pumiced give tooth and then sen- sitized whirling centrifuge with colloid containing solution am- monium dichromate. The sheet dry placed with the negative glass- topped vacuum frame where ex- posed are lights for min. After being exposed flooded with de- veloper which dissolves the unhard- ened gelatin min., flushed anhydrous alcohol 200 deg. inked with etching ink. The ap- plication cool water washes away the colloid and leaves the ink. After drying with chamois and air blast, the sheet dusted with Dragon’s Blood etch resist and the back also coated with resist. baked for about min. 500 deg. F., and then placed solution sodium chloride and electro-etched, using the sheet the anode and lead the cathode. Five minutes etching will give depth 0.005 in. which time the sheet removed paint over with asphaltum varnish all the lines but those etched through. the etching tank for additional min. will etch the template free from the surrounding metal, leaving only fillet filed off. The image stopped the varnish very durable shop use and the accuracy the process 0.005 in. for any given line. Reproductions may also made blocks. Malleabilizing With STUDY the reactions during the decarburization alloy and alloy-free irons with mixed carbon-monoxide/carbon-dioxide atmo- spheres described “Archiv fur das March, 1948, Friederichs. Decarburizing investigations were undertaken white, chilled cast iron mixed carbon-monoxide/carbon- dioxide atmosphere temperatures between 950 and 1050 deg (1742 deg. and 1922 deg. F.), and the in- fluence controlling factors such sectional thickness, time heating, temperature and gas composition, also the influence the carbon con- tent the original cast iron, well that manganese, nickel, chro- mium, vanadium, molybdenum and sul- phur the speed decarburization Was investigated. addition, the diffusion constants carbon iron were determined, and the mechanism the reaction occurring during the decarburizing process was compre- hensively clarified. The results obtained may sum- marized follows: (1) The speed decarburization increases with rising temperature; the much greater during the initial first hr. the heating than after further hr. heating, and plotted against time, the curve hyperbolic function falling from the relatively high initial decar- burization speed. (2) Volatilization the carbon oc- curs within practical limits only the surface the specimen being treated. The carbon required main- tain the decarburization migrates from the interior the outer surface. The velocity the determined the speed this car- bon migration. The work demon- strated the tenability Ledebursch’s theory the decarburization reac- tion. (3) The rule, established the case steels, that the amount carbon within given period time proportional the initial carbon content the material, may applied without qualification hypo-eutectoid white cast iron. In- clusions primary cementite appear after short period heating, which increase amount with increasing carbon content the material, and this depresses the speed diffusion the carbon and consequence the velocity decarburization. After further heating, this preliminary re- tardation, however, becomes scarcely noticeable. (4) Manganese, nickel, chromium and vanadium have litte influence small additions, and with larger amounts these elements, un- favorable influence exerted the decarburization velocity. Only molyb- denum was found raise the speed 950 deg. C., the effect this element similar the others being un- favorable. Sulphur also appears un- favorably affect the decarburiza- tion. (5) With low velocity the de- carburizing gas atmosphere, optimum speed decarburization occurred with gas mixture about per cent CO, and per cent CO. (6) Carbon-dioxide contents above about per cent gave rise sealing the iron and also reduc- tion the decarburizing speed. (7) White cast iron can decarbu- rized without scaling taking place with broad range gas compo- sition, corresponding the composi- tion the former, provided that certain carbon limit not exceedéd. THE IRON AGE, May 1944—55 FIRST OPERATION SHAPING AND MACHINING PUNCH FOURTH OPERATION POUR MOLTEN KIRKSITE and the large volume different jobs encountered manufacture often create emergen- cies where almost impossibil- ity produce tooling for sheet metal parts through ordinary channels. these instances such slow operations sawing, routing cutting with snips generally must employed. Every aircraft plant does some this work part its but certainly not considered good practice. overcome this handicap and pro- duce sheet metal blanks that are needed emergency, the North American Aviation plant Ingle- wood, Cal., began experimenting with Kirksite blanking dies.* While first attempts were rather crude, they For production blanking dies from rolled material, see “Mass Production 70. did indicate that the method had defi- nite possibilities. These dies have since proven very successful and sev- 56—THE IRON AGE, May 1944 SECOND OPERATION LOCATING PUNCH MOLD OPERATION REMOVE MOLD SEPARATE PUNCH DIE eral thousand have been date. many 14,000 parts have been blanked one die, which showed dural sheet has been blanked success- fully, but figures are available the ultimate life the die. Two different types cast Kirksite dies were worked out: One blanking die for parts temporary nature, the other blank and pierce die for longer runs. the latter case, the method. casting the die onto the backing plate not practical for tem- porary tooling since requires sep- arate shoe for each die. For tempo- rary tooling, use made universal mounting plates which can utilized with any punch and die combination made this manner. There doubt, however, the minds North American Aviation methods engineers that this type die can also used for permanent tooling under system proper tooling control. Fig. outlines the procedure for Kirksite blanking dies the former type. First the punch laid out placing the part template Kirksite THIRD OPERATION CLAMP MOLD TOGETHER AND HEAT SIXTH OPERATION ASSEMBLE KIRKSITE for casting Kirksite blanking dies. The punch forms its own nest the die casting the zinc alloy around it. piece chrome molybdenum steel in. boiler plate and scrib- ing around it. The punch cut out band saw and filed size the same manner the template. important that the edge the punch kept deg. angle with the face the punch. clearance needed and not necessary sur- face grind the punch. advantage the straight sides that when the cutting edge the die wears (gen- erally after 400 500 parts have been blanked), the die may in- verted and the life the die doubled extra cost. The mold for the Kirksite dies must constructed that even heat obtained throughout entire area. This very important since any unevenness heat will result bad casting uneven shrinkage. Success casting depends on: properly designed mold. 2—Correct and even heat mold. placing the punch relation the contour and cutouts. 4—Proper cooling. The mold rectangular shape, in. tions plate riveted Fig. allow rately flared molten must excess punch, cast. mold, contact sprayec ide) site there mold, coating The mate | Ss ~* in. thick and made two sec- tions out in. hot rolled steel plate with narrow in.) filler strips riveted three edges one plate, Fig. The mold made separable allow the punch placed accu- rately and one end left open and fared act pouring gate for the molten Kirksite. The size this gate must not large that will cause excess Shrinkage away the punch, around which the alloy cast. Before the punch located the mold, the surfaces which will come contact with the molten Kirksite are sprayed with ferrous oxide (red ox- ide) prevent the punch and Kirk- site from sticking the mold. there moisture present this spray utmost importance that all this moisture driven the mold, leaving only the dry protective coating the interior surfaces. The punch placed the approxi- mate center the mold that uni- Cast alloy dies are being used successfully with steel template blanking punches North American Aviation, Inc. For temporary tooling, both halves the set are screwed universal die shoes. Pierce and blank template dies are made casting Kirk- site onto keyed backing plate. This modification the tech- nique making pierce, blank template dies out rolled Kirksite. form mass Kirksite will surround the punch. Otherwise distortion likely result when unequal masses the same body metal cool. Care must exercised when placing the punch that all the air the mold will escape gradually when the mol- ten metal enters prevent blow holes forming geyser type erup- tion taking place. When the punch place, the side plate the mold tightly held against with wedges driven through slotted pins, Fig. important that the assembly held tightly prevent flash forming the die. Pouring the Die the foundry, the mold and punch heated gas-fired torches until quite hot. This heating utmost importance. has two-fold pur- pose: First and most important, drive out all moisture which entered when the red oxide was sprayed the mold, and secondly raise the temperature the mold point where will not absorb too much heat from the molten Kirksite, caus- LEFT 1G. 2—The Kirksite mold made hot rolled plate. The main body, left, has flared lip act pouring gate. BELOW 3—Assembled mold, showing use clamp wedges slotted pins. THE IRON AGE, May 1944—57 = > 18 3 a ing solidify before could reach the extremities the mold. Although requires only about min., the heating must performed with care, because upon depends the quality the casting and safety the workers. After the Kirksite poured, the min. for partial cooling. can then handled w