The Iron Age 1940-03-07: Vol 45 Iss 10

VAN DEVENTER President and Editor BAUR Vice-President and Ceneral Manager Managing Editor News Hditor Editor Emeritus Machinery Editor Art Bditor Vetallurgical Editor Associate Editors Washington Editors Resident District Editors Pittaburgh Chicago D. R. JAMES W. F. SHERMAN Cleveland Detroit Editorial Correspondents Ropert G. McIntTosH London, England Cincinnati FRAZAR Boston Hamburg, Germany MEYER CHARLES Post Milwaukee San Prancisco SANDERSON CLYDE ENNIS Toronto, Ontario Birmingham LEROY ALLISON Roy Newark, N. J St. Lowis TURNER, Ruffalo A. H. DIX, Manager Reader Service {DVERTISING STAFF Emerson Findley ? go Robert F 621 Union Bldg., Cleveland B. L. Herman, Chilton Bldg., Phila H. K. Hottenstein, 1012 Otis Bldg.. Chicago H. E. Leonard, 239 W. 39th St.. New York Peirce Lew!s. 7310 Woodward Ave., Detroit C,H. Ober 239 W. 39th St., New York W_ B. Robinson 4s > ldg ritts Ib. ©. Warren. P. O. Box 81, Hartford, Conn Don F. Harner. 1595 Pacifie Avenue, Long Beach, Cal Member, Audit Bureau of Circulat'ons Member, Business Papers Indexed the Industrial Arts Index. tion Price United States and Po sessions, Mexico, Cuba, $6.00; Can ada, $8.50; Foreign, $12.00 a year Single copy. 25 cents Annual Nu ber $1.00 Cable ss, * Tronave, Owned and Published by CHILTON COMPANY (Inecorporat. d) Fditerial and Publication Office Executive Office. Chestnut and 56th Sts 239 West Soth St Philadelphia, Pa., U.S.A New York, N. Y., U.S.A OFFICERS AND DIRECTORS ©, A. MUSSELMAN, President JOS. S. HILDRETH, Vice-President GEORGE GRIFFITIS, Vice-President EVERIT B. TBRHUNE, Vice-President J. H. VAN DEVENTER Vice President 8. BAUR, Vice-President WILLIAM A, BARBER, Treasure JOHN BLAIR MOFPFETT, Secretary JULIAN CHASE, THOMAS L, KANE, G. BUZBY, P. M. FAP RENDORF HARRY V. DUFFY Contents 1940 Process Control Aircraft Spotwelding Molding Sands Air Hardening Die Steel Metal Cleaning Mechanical Means Open Hearth Slag Control Casting Temperatures for Non-Ferrous Alloys Industrial Radiography Plant Service Apparatus the Assembly Line Washington News THE NEWS BRIEF Weekly Ingot Operating Rates Rate Activity Capital Goods lant Expansion and Equipment Buying Free Industrial Literature Just Between Two Products Advertised Index Advertisers Copyright, 1940, Chilton Company 102 113 113 132 136 169 170 202 2 = Ne 3 is | the right reproduced unretouched photograph Welded Steel Machine Base produced Mahon for Krueger Co., Detroit, Michigan. Above illus- trated the completed Krueger Feedex Power Indexing Ma- chine for which the base was built. 40—THE IRON AGE, March 1940 Produced Skilled Crafts- men Unexcelled the Art Welded Steel Machine Frames and Bases are not only smoother appearance but can produced with greater accuracy and with less bulk and weight than castings like dimensions. That why many alert machine manufacturers are today turning welded steel con- struction. The Mahon Company now producing welded steel frames and bases for many the leading machine manufacturers throughout the country highly skilled craftsmen, and ultra modern, elaborately equipped plate shop make available you new standard quality workmanship this field. you demand machine bases exceptionally fine finished appearance and accuracy—bases upon which you will proud place your com- pany’s name, send your blue prints Mahon for quotations. THE MAHON COMPANY DETROIT, MICHIGAN Machine Frames and Bases and Many Other Products. 4 ‘ a ESTABLISHED 1855 THE IRON AGE ... MARCH 1940 Vol. 145, No. “Informa tion, other day had the pleasure meeting comparatively young man who was the recipient Carnegie Medal. And that, the way, quite distinction, because these medals are not handed out indiscriminately. This particular hero had plunged into the waters off Rockaway Point rescue two non-swimmers whose boat had sunk under them. brought them quarter mile shore and safety, one each arm. For this voluntary and heroic piece work, our friend received Carnegie Medal and $1000 cash. All which would seem indicate that society puts certain minimum value human life, this case, $500 per unit. Now have become accustomed, industry, accept this principle that life and limb are worth saving, even the expenditure considerable money. Witness the safety devices which all modern industrial concerns adopt prevent accidents. imagine accounting were made their cost, would probably aggregate least $500 investment per employee. For safety alone. course, impossible arrive any financiai evaluation American life, terms its value the state community. But can say that one them con- sidered worth least $500, the basis the market value established above. minimum, course. Contrast this evaluation what worth conserve life peace time, you please, with what paid take life war time. The World War cost the United States $40 billions round figures, according Treasury Department figures. That meant cost $317,000 for each American casualty. Expensive business, any way you want look it! Maybe cost less, the last war, kill Englishmen Frenchmen Germans than did kill Americans. don't know. But there does seem large discrepancy between society's appraisal value $500 life saved and its appraisal value several hundred thousand dollars investment taking one. Maybe that what makes war expensive. Can someone answer this question? For dead man worth five six hundred times much live one, why have Carnegie Medals safety devices industry? | | kas ADOPTS New Inland lead-bearing, open hearth steel Factories France are humming today top feed the guns—to win the war. That why this advertisement appears leading French industrial paper. French factories, and English factories too, are finding what many American manufacturers have already learned—Inland Ledloy bars and plates production. Work goes, the words the man, trés grande vitesse. This remarkable new Inland development—a bearing, free-cutting steel—greatly increases production while retaining all the desirable qualities good open hearth steel. Ledloy made all open hearth carbon steel analyses. Cutting speeds are increased 60% —tool life, 200%. Actual savings, available for increased profits, are often high $50.00 more per ton steel machined. You should familiar with the possibilities important new machining steel. suggest that you call write for Inland Ledloy Bulletin No. 50. SHEETS STRIP TIN PLATE BARS PLATES FLOOR PLATES STRUCTURALS PILING RAILS TRACK ACCESSORIES REINFORCING BARS grande Cette piement Ces sous : \TES equip- ment meets its most se- vere test aircraft manufac- ture. What the requirements are, the welding variables, time current dwell, diam- eter and shape electrodes, pressure electrodes, con- tact resistance, and current density are all covered herein. POTWELDING gradually emerging from its experimental role production process aircraft manufacture, with from unstressed parts primary structures. course, the change has slow “caution” the keynote was first introduced, that this method joining metals would revolutionize the industry. This has not taken place because, relatively speaking, changes struction are gradual. con- Those who remember the wood and fabric days realize the shift welded tubular construction did not take place overnight. The same was true when the welded tube design was replaced the all metal stressed-skin airplane. Yet vestiges former designs can still found the present models. HIBERT Consolidated Aircraft Corp., San Cal. Fabric still used some surfaces, engine mounts are welded tubular construction, and many other similar examples could cited familiar with aviation. The same true aircraft proc- esses—one process does not displace another, nor departments die out. Although many new processes have come into existence, the aircraft factory still has the fabric, welding, and wood shop. Spotwelding will make inroads riveting, and other forms welding, but likely will never com pletely either. present the spotwelding depart- ment airplane shops consists few machines, and the work diversi- fied materials. Templates and jigs are made gal- vanized sheet, and chro- mium-molybdenum steel. The mate- character and rials used for regular production con- sist aluminum magnesium alloys, stainless steel, and chromium- molybdenum steel. All these mate- rials require different treatment, and therefore will necessary re- strict this article generalities, with special notations applying the vari- ous materials. pendent the accuracy the control the welding variables amount care used the control the process. These points are divided into groups and will covered this article under their respective headings. Welding Control (1) Time current dwell. (2) Electrodes. (3) Pressure electrodes. (4) Contact resistance. (5) Current intensity. Process Control (1) Equipment. (2) Personnel. (3) Design. (4) Supervision. (5) Inspection. The foregoing divisions have beer made with the object outlining satisfactory welding technique for air- craft production. Only all factors are analyzed and understood will possible gage their relative values and importance produce the ideal repetition weld. well organized con- trol essential get results and not alibis, and the object this article outline the type control that essential. assembly completed with faulty welds, which time may virtually im- possible rectify the faults because THE IRON AGE, Mrach 1940—43 rial are ady pen bon for ore this you anodizing some other finish treatment. Perhaps the biggest step welding practice was the development the electronic control for current timing. The making and breaking the heavy kva. necessary weld the non-ferrous metals are rather difficult achieve with mechanical timing device. But, course, for use with ferrous metals there are some excel- lent contactor timers the market. Timing devices should not only con- trol the length time but the amount current passed for each weld should uniform. The difficulty with most mechanical timers that they not cut the a.c. wave the neutral axis—consequently current variation introduced. The d.c. welder an- other story, for here the electronic principle cannot applied and the amount current should rationed according Time Current Dwell Spotwelding stainless steel (18-8) without the addition columbium titanium requires short period time prevent carbide precipitation and deleterious effect the corro- sion resistant properties. Columbium titanium added prevent inter- granular corrosion and this variety stainless said stabilized. Tests indicate that changes time have lit- tle effect shear strength per sq. in., and corrosion, provided the fused zone does not reach the surface the sheet and the area the weld adequate. For this reason, the welding stainless steel there necessity for using excessive time the welding machine has adequate power. Neither necessary use half cycles which will tend build d.c. component the welding transformer. Sufficient increments current adjustment should provided enable low current setting for the thinner gages. length current dwell between and cycles may regarded within this range may used for all gages 18-8 sheet welded for air- craft work. has been believed that short peri- ods current timing are essential for welding aluminum alloys, prevent the zone fusion from reaching the exterior surface the sheet. Further investigation has revealed this not being necessary, and more uniform re- sults may obtained using longer cycles, that cycles the neighbor- maximum The welding 44—THE IRON AGE, March 1940 aluminum alloys differs from that steel, since the former has very short plastic range. That is, actual slug must cast the aluminum alloy sheet, whereas steel has long plastic range and spotweld may com- pared with blacksmith forge weld. For welding steel other than the stainless alloys, period current dwell above cycles appears give better results, which may due the working the weld the elec- trodes while the weld still plastic. Weldability decreases with the advanc- ing carbon content the steel. SAE (4130 and 4140) steels must nor- malized after spotwelding, for the welds are doubt the hardening characteristics the steel and the quenching effect the water cooled electrodes. Shape Electrodes The diameter and the shape the electrodes have always been matter experimentation. represent the bottle-neck the elec- trical sysiem because their neces- sarily small cross-section. The ampere- density extremely high, and for this reason they should water cooled within short distance the welding end. Excessive pickup some cases caused insufficient water cooling, and for any production welding mandatory that all tools and holders should provide for adequate cooling the electrodes. Copper has been used extensively electrode material because its exceptionally good conductivity, but too soft for production welding YSTERY ship 31X spotwelds. The cowling steel, and the nacelle and flaps trance door the side are spotwelded pit furnishings are che aircraft materials. Consistent results cannot attained the electrode material does not retain its shape un- der high welding pressures. Now, various copper alloys are the mar- ket—they have good conductivity and are much harder than copper, and such alloys stand well service. They are sold under several trade names, with manufacturers’ recommendations what materials can welded the various alloys. might mentioned that the search for satis- factory electrode material for welding aluminum alloys still goes on. The with copper alloy electrodes that they tend alloy with the aluminum, the result being pickup and necessity for frequent cleaning. Shape and design tips may vary with the metals that are welded. the case stainless steel, where less current used, not necessary have large diameter tip. also possible sacrifice conductivity the electrode material for higher hardness. Alloys for electrode material are rather expensive and therefore the practice insert diameter rod about in. flush into copper elec- trode. press fit rather than silver solder used hold the insert place. For, heating will cause some these alloys sweat. For aluminum alloy welding the electrode material not expensive, and the tip made en- tirely one piece. Electrode tips should designed that they are standard changeable with any the holders, and this also applies holders well, they should interchangeable with ee 4 ey H = ¥ J ‘ | j i j j i | j | i | ¢ Corp. contains many thousands the nose ring 18-8 stainless The beaching gear door and en- pitot mast and practically all the cheap production method. all spotweld machines. little thought this direction will eliminate con- siderable production tips should provided for frequent changes, and these can stored wood tray drilled receive the shank. The ideal electrode tip would have spherical end, but this shape difficult maintain. Therefore, 3-deg. cone used for steels, and from deg. for welding aluminum alloys. setting the electrodes, the conical tips must line perfectly for best re- sults, and several test welds should made develop the electrode the proper contour. Tips should cleaned with fine sandpaper, but never with file. Clamping weed block wrapped with No. 7-0 sandpaper, similar de- vice, between the tips makes fective cleaning tool, that will not abrade Cleaning tips varies with the mate rial being welded—for steels very lit- tle cleaning necessary, whereas with aluminum alloys the tips cleaned after every welds. times flat tips are used. Such tips eliminate deep depression the work but necessitate higher electrode pressures. With the the tendency splash between the sheets eliminated and results are better regards porosity. flat tip more difficult control, and ence required for sults. Any errors nique are magnified when using one two flat tips. Improper care electrodes causes more grief and poorer results than any other factor single spotwelding. Work must held right-angle the tips for best results, and any skew- ness distributes the effective current over greater area, making for poor welds. Frequent test samples should made during production check electrode conditions and character the welds. the tips are badly worn they should returned the tool room for redressing. Furthermore, tips should changed when the ma- chine setting changed for different gage metal. There are four requirements for satisfactory electrode and any new material considered should meet these: (1) Must harder than the mate- rial welded. Will not alloy with the work. (3) High melting point. (4) Conductivity higher material welded. Pressure Electrodes pressure not critical the other welding variables. may varied over fairly wide range, but when one pressure has been se- lected for the work progress must remain constant. increase elec- trode pressure results contact resistance between the sheets and consequently less heat devel- Therefore, with sures more current must used develop satisfactory weld. Too high pressure necessitates very large welding currents with tendency to- ward shallow welds, whereas too low electrode pressure results porous welds and danger the current arcing oped. between the work, causing blowhole. Low welding pressures will cause ex- cessive pickup the electrodes and pinholes the center the weld. Air pressure dial readings should calibrated read electrode pressure instead the usual reading Ib. per sq. in. air pressure. this done some idea gained where start with machine settings—for with five variables control would better use recommended settings for four variables and leave but one for adjust- ment, namely current. Table gives recommended settings for various air- craft materials. All spotwelding equipment, includ- ing portable tools, should air hydraulically operated. spring operated pressure tools should never used where consistent spot- welding desired. Contact Resistance The amount heat generated when spotwelding expressed the for- mula where equals Joule heat. equals current amperes. equals time the current flows. consists the sum three re- sistances resistance between the electrode and sheet. specific resistance the mate- rial welded. between the two sheets welded. can seen from these factors that the resistance depends first upon the specific resistance the material, second, the condition the sur- face, and third, the pressure used. the resistance the material relatively high, the case with stainless steel, small kva. required for welding. For where the resistance approaches that copper, high amperages are neces- sary. The condition the surface very important, and has been neglected for some time. For best re- sults nothing but absolutely material should welded, and this meant surface that will support film water. has been found that operators touching cleaned alu- minum alloy material with gers will lower test results. The same true the steels perhaps lesser degree. Some materials such aluminum alloys have naturally acquired oxide THE IRON AGE, March 1940—45 + | le S, | Ig 'y A 0 4% n equipment for aircraft spotwelding. This view shows the electronic control cabinet; sequence panel and auto-transformer are contained the second cabinet from the right, and the instrument panel the welding ma- chine. More recently developed equipment has phase angle shift included the electronic control, which eliminates the auto-transformer steps for current adjustment. TABLE Recommended Welding Data for Various Aircraft Materials | Shear Strength, Desizn, lb. Shear Electrode Pressure Time Current Dwell ness, 0.005 150 0.065 4000 690 500 2670 460 330 400 650 | NOTES: (1) understood sheet thickness means the thickness the thinnest gage welded. When heavy sheet welded light gage, use values for the light gage. (2) Pressures given the table are the minimum values used. (3) For current use high enough setting develop welds that will aver- age above the minimum shear strength given the table. (4) Time cycles based cycle current. 46—THE IRON AGE, March 1940 coating high resistance. this would seem result better welds with less current. Nevertheless the oxide coating has been found chemical means. per cent nitric per cent (remainder water) wash makes good cleaning solution for removing the oxide coat- ing from aluminum alloys. This can contained lead lined tank, and parts should rinsed off with running water after 30-sec. dip the acid solution. The parts should then dried and welded soon practicable. Paint, oil and grease acid etch. Aluminum alloys that not contain copper alloying agent need only These alloys have such low specific resistance that difficult effect weld insure satisfactory results the contact resistance lowered fur ther removing the coating from the contact side. course neces sary that such contact surfaces cleaned extraneous material. Steel parts that are scaled must pickled sandblasted before welding. Here again much effort wasted any attempt weld dirty stock. small amount time required cleaning more than offset : f > | | | | | | | | | | | | | | | | § } | | | | | saved electrode maintenance and correcting poor welds. course with materials free oxide coatings, like stainless steel, only essential that they cleaned free grease dirt, This can done using one the many commercial solvents. paint. Wherever should made after spot welding, for the presence flux extraneous material between joint will cause spongy spot welds strength. possible Current Intensity Current intensity required weld the gages aluminum alloys required aircraft supposedly the neigh- 5000 30,000 amp., and 1000 5000 amp. for 18-8 stainless steel. Although secondary current can- not measured directly, assumed product the primary current and turn ratio. The effective current available the electrodes matter conjecture because the variable reactance introduced changes tool set-ups and machine arm positions. efficiently designed machine may rated only few kva. and ac- complish spotwelding heavy gage similar material machine rated much higher kva. other words, kva. ratings are function throat dimensions, power factor, and efficien- cy, and mean nothing far ability spotweld. For the reasons just mentioned, any attempt correlate amperage weld various gages materials would futile. The proper procedure other welding variables and maintain these constant, then adjust current from low setting until the optimum weld obtained, indicated shear- ing tearing tests. Most work spot- welded for aircraft are parts, and weld that will pull slug when rolled apart may considered satisfactory. Current settings will vary from day day, due line fluctuations, differ- ences tool set-ups, and other factors beyond the control the operator. Therefore, test samples should made for every change welding condi- tions, instead relying previous settings. Ed. Note:—Next week the author con- cludes this report with data design spotwelded parts, equipment used, per- sonnel and inspection welds. Large Assembly Jig Magnesium Alloy the most elaborate jigs ever used for assembly line ac- curacy automobile chas- sis probably the one used locate the power plant the frame the 1940 Buick. The fixture used line the center line the crank- shaft with the propeller shaft, thereby assuring that the drive through the lateral center line the ear. The procedure also ineludes means checking determine accu- rately that the rear engine mountings are equal height not with respect the front engine mounts which the engine first bolted. the rear mountings are not properly lev- eled, undue strain placed both engine and frame. The jig gives the means locating the error and making the cor- special rear engine- mounting locating fixture made extruded and cast nesium alloy) and was ricators, Adrian, Mich. Magalloy was selected because pro- proper amount rigidity essential operation this kind while the same time giving extreme lightness. The material weighs only two-thirds much aluminum and approximately one-tifth much steel. Because its size, the fixture handling. Another quality which fitted the material this use that has high abrasion resistance. use, the locating fixture placed over the frame (see accompanying il- lustration), being located the front the engine bolt holes the front engine mountings and the rear gage hole the center the cross- member the kick-up. Plug gages are then lowered into the tapped holes the top the rear engine mount- ings. When the plug shoulders are fully seated, the mountings are cor- rectly placed and are then tightened position. means appropriate linkage, the amount that one mounting lower than the other indicated large dial observable from the top the fixture. The dial graduated show the number spacers in- serted between the engine and the mounting the indicated low side. THE IRON AGE, March 1940—47 { : | | the most important items the production iron castings the mate- rial used making properly shaped containers hold the molten iron until That statement made quarter century ago the late Dr. Richard Moldenke, especially appropriate today when foundrymen are expected produce castings with all the attributes rubber band, the Opening for feeding clay bonded new sand into weigh platform Cement 48—THE IRON AGE, March 1940 PHAIR Associate Editor, The Age Maginot Line and Ann Sheridan—and all price competitive with second- hand newspapers. Foundry technologists throughout the world have given this container problem very serious study over the past decade and many reforms have resulted from these efforts. One mani- festation these studies the devel- opment the Randupson’ process molding with cement sand. The metallurgical and economic aspects this molding method have been discussed previously’ consider- able length, but little attention has been devoted the practical sand Revolving screen Vibrating screen conve receiving bin feeder Farrei- Birmingham's new sand han- dling plant the Ansonia foundry. ° ° ° : This automatic system reclaims both clay and cement bonded sand. Grain distribu- tion control rticularly effective. problems involved conditioning sand reclaiming the sand. noteworthy equipment, the design the casting, for use with this method. illustration this trend the new and time needed mold. This time the early days the process, the sand reclaiming plant (in this article, element, incidentally, perhaps the spent sand, which, after removal from reclaiming will taken cover the chief limitation the cement process. the casting, partly lump form and reclamation, mixing and tempering the maximum, prepared cement partly the form very fine parti- the sand) the Ansonia, Conn., foun- sand can stand for about hr. cles, was either crushed some degree dry Farrel-Birmingham Co., before dehydration has advanced the and used backing material core (Fig. 1.) point where the sand unfit for use. vents, simply thrown away. Very This sand unit unique that The Farrel foundry has set min. little effort was made reclaim it. the first reclaiming the maximum time the sand may stand before using, limit that provides 2—This sand cas- cade, located immedi- ately below the revolv- ing screen unit shown tion sand dedusting apparatus. The sand stream, bouncing from louver louver, ex- posed air stream which moves the fine particles and acts cool the sand. This disposition was obviously costly and inefficient, the refractory value the sand grains not affected use. However, users become more fa- miliar with the process, there have been significant strides the direction for Sand entrance exhaust ‘ ' ' for air volume capable handling both cement bonded and clay bonded sand. The unit also embodies many features heretofore incorporated into sand re- claiming systems, notably the sand cas- cade shown Fig. The output this plant large and varied and nature that requires high degree finishing combined with good strength. Typical products turned out the foundry include machine tool beds and frames, engine cylinders, gears, turbine casings, transmission equipment parts, rolls, presses, The company started using the Rand- upson process experimentally No- vember, 1937, and went into full pro- duction March, 1939. Some jobs are still put the orthodox dry sand and green sand methods, the choice dictated pattern ample safety factor. Previously was the practice the Ansonia foundry discard the used sand, saving only small portion for backing and core venting material. The new sand unit reclaims practical- all the silica content the sand, purposely weeding out the fines which are finally disposed the form sludge. Before venturing into description the new sand unit, would well record some the more interesting experiences the company since the introduction the Randupson process. The use cement sand not prop- osition that effects only the molding department. the contrary, ramifications extended through every phase the plant, even touching upon employee relations. Cleaning opera- tions large castings are substantial- simplified the manner which the sand peels from the castings. many cases the finish the larger castings after shakeout such require little further attention. Ab- sence gas forming elements the mold clears many the small gas scars which too often plague the large casting surface. The Randupson prod- uct surprisingly free skin blem- ishes. The strength cement molds minimizes warping and consequently lowers machining allowances. Un- machined castings excellent trueness, the sidewalls the way channels the 30-ft. grinder bed shown Fig. (On casting this size, the reduction machining allowances economic reactions). The dimensional accuracy the castings turned out cement THE IRON AGE, March + molds appears superior usual dry sand practice. course, cement molds cure-alls, and while they ameliorate some the usual headaches, they give servation would appear that gray hairs are just common using the cement process one us- ing the commoner methods mold- ing. Less Dust Created While true that most cases, the rectilinearity cement molded castings something rejoice in, there are still enough wayward cast- ings require constant surveillance all operations. Yet, judging from the experience this particular the cement process does siderations that not only improve the caliber the castings turned out, but also offer opportunities for improved shop costs. The reduction dust creation, particularly vital concomi- 3—The use the cement sand process makes possible the molding this roll grinder bed strictly production basis. Sections such can seen the crane hook are rapidly produced molding ma- chine standardized core boxes. ° ° ° tant the process, not only offers psychological benefit the plant personnel but also has tangi- effects upon insurance premiums. Large Bed Molding Simplified example the improvement production practice brought about the cement process the Farrel foun- dry its ability produce the com- ponent parts the roll grinder bed shown Fig. bumping, open end, roll-over molding machine, thus converting strictly proposi- tion into production item. The ma- Tabor and built ham, has plate in. and ac- IRON AGE, March 1940 my commodates two sizes standardized core plates. The various sections the mold, such seen the crane hook Fig. are rammed this machine, transferred roller conveyor for finishing, and then stored for curing. The curing, common practice cement molding, takes hours. This machine operated with crew four men—two ram, one finishes and one supplies 4—Batch prep- aration platform. The long rod which the operator's hand rests controls the move- ment the weigh lorry from bin bin, while the levers hanging overhead control the bin gates. Cement con- veyor housing can seen right center. Other castings are also made this machine, but this roll grinder bed perhaps outstanding example one phase the economics involved in. plate. The sand delivered the large machine from the mixer sand boxes carried automatic elec- tric trucks. The sand raised and attached jib cranes either side the machine swung over the core box and dis- charged opening gate the con- Lumps for backing are stored bin front machine and when needed are lifted vertical con- swivel chute, and directed into the core box. Any attempt appraise the value the cement sand process ducing the types castings made the Ansonia foundry confused some- what the fact that the foundry casts Meehanite metal. There some degree overlapping the advantages ac- cruing from the use both the Rand- upson and Meehanite processes and would difficult ascribe any spe- cific characteristic the final product either one the other process. i : the final analysis, production cost and service performance are the practical criteria the value the two meth- ods. Judging from those two stand- ards, appears that the combination indeed happy one, for each process has the facility extracting from the other the fullest measure its capa- bilities. One consideration constructing particular conditioning plant, which not always met engineering such units, that the time limit im- posed the quick setting the mixed sand renders not feasible prepare the sand more than hour advance its actual use. The mixing the sand batches must geared closely their actual use. important this feature that experi- ments are being conducted using both telephone and telautographic commu- nication between molding floor and the mixing platform facilitate the synchronization the mixing and molding operations. schematic sketch the new con- ditioning unit shown Fig. Con- siderable liberty has been taken with the actual dimensions this unit for the sake clarity. This unique unit can handle both clay bonded and cement bonded sand with only minor adjustments the system. Used sand enters the system through the shakeout, which passes all chunks must broken down 3-in. size. From the shakeout, the sand progresses over underground magnetic which removes tramp iron, dis- over pulley charges into vertical boot conveyor, and carried the top the system. The sand then runs into revolving screen where three distinct separa- tions are 3-in. lumps, mesh in. material, and sand below the sieve. The 3-in. and 1-in. lumps are passed into their respective THE IRON AGE, March | = A < bins, while the finer material bumps over the sand cascade, onto veyor, over vibrating screen and into the reclaimed sand bin. When han- dling clay bonded sand, the vibrating screen by-passed and the sand moved into the reclaimed clay bonded sand bin means suitable belt con- the bottom the lump hoppers are series gates and vibrating feeder which permits either drawing the lumps off for backing venting purposes, passing them through the pulverizer which reduces them approximately 20-mesh size. The operater has the option draw- ing off either 3-in. lumps. GRAIN DISTRIBUTION AND PERMEABILITY SAND No.30 JERSEY SAND 0 100 Sieve number From the pulverizer, the sand car- ried back into the vertical elevator and again the revolving screen. New silica sand unloaded the re- ceiving bin and conveyed belts the four storage bins. Cement en- ters the system the cement receiv- ing platform and dumped into storage bin and fed the batches New clay bonded sand enters receiving platform the corner the building and means skip moved into position over the weigh lorry tunnel and drop- ped into the lorry. The entire system operated under slightly negative pressure. a screw conveyor. The handling system was installed Link-Belt Co., and all equipment ex- cept the following was manufactured Link-Belt: two National Engineer- ing intensive mullers, two Jeffery vi- brating feeders, Simplicity shake- out, Stedman pulverizer, magnetic pulley made Magnetic Mfg. Co. and Fairbanks scale. One No. and one No. 36, Type American Air Filter Roto-Clones are utilized for dust collection. One noteworthy section the unit the weighing arrangement. the !RON AGE, March 1940 Permeability number sketch shows, the new sand, old sand and cement bins are located alongside each other. Below these bins, and above the mullers, enclosed area, self-powered lorry having built- scale. One side the lorry tunnel glass enclosed and the entire area under slight negative pressure keep the atmosphere clear preparing mix, the operator guides the lorry, via the rod-like motor controls, visible Fig. from bin bin, and means the bin chute control levels seen the top the photograph, admits weighed amount each component into the lorry. Then the lorry put position over the 5—A compar- ison grain dis- tribution meability typical car new silica sand and batch re- claimed sand. measured This water machine and mulling amount water added. measured meter, visible near the left hand Fig. This set-up represents singular advance over the old shovel method but, course, economically feasible only where quantities handled justify it. The base sand used the Ansonia foundry No. New Jersey silica sand, with about per cent the grains concentrated the 40, and mesh sieves. The sand No. classification. When this sand or- dered specified that more than 0.2 per cent pass through the 200 sieve and little possible below the 150 sieve. comparison the grain distribution typical car new silica sand and batch the reclaimed sand given Fig. Four basic mixes are used cover all steel and iron casting requirements the plant. No. mix consists silica sand and cement and used facing for steel molds. Mix No. made new sand and old sand plus cement, and used for fac- ing iron molds. the two molding machines all old sand, plus cement mix used, while No. mixture, used backing sand, consists all old sand and smaller quantity cement. While the amount new sand used varies with the trend the demand for the various mixes, the average monthly ratio approximately part new sand parts old sand. The ultimate aim, and one which felt within reach, bring the new sand additions down per cent. The amount cement used each mix varies from per cent, de- pending upon the type castings be- ing made. making the cement addi- tions the batches, the cement con- tained the reclaimed sand con- sidered zero. While actually the bulk the cement removed from the old sand the exhausting and sieving process, amount re- mains firmly affixed the grain. This cement coating has some remaining bonding power, investigations have taken having influence the mix. The adjustments the reclaiming system are directed toward giving the reclaimed sand structure similar the base sand, the No. New Jersey silica sand, far fines and grain distribution are concerned. claimed sand does not have the same degree fines are present the new sand and consequently has much higher permeability. Compara- ble tests made the plant indicates that new sand with permeability 125 135, will have permeability reading about 200 after has passed through the system. Roughly per cent the material finds its way into the This sludge made large- cement fines and does possess some bonding qualities, but the quan- tity obtained not sufficient war- rant its commercialization. Cie Randupson, Marseilles, France. World rights are owned Société Exclusive United States rights are held Birdsboro Steel Foundry Machine Co., Birdsboro, Pa. 2See: “Cement Bonded Sand Used by Mold Maker,” Nov. 19, 1936: “Bonding Steel Molds with Ce- The Foundry, December, 1935, January, February and March, 1936; “The New Foundry David Brown Sons, Ltd., with Special Reference the Rand- upson Process,” Foundry Trade Journal (London), Jan. 28, 1938; “The Randupson Process Cement Molding,” Foundry Trade Journal (London), June 28, 1938; “Manganese Bronze Propellers Cast Cement Molds,” Shipbuilder and Marine Engine Builder, October, 1938. 200 = fe —_ = 150 = ° ° ° ‘ = = = 100 = = = — => = = GS S = OW = ° ° ° 200 250 ° RACTURES hardened specimens. Hardening tem- peratures, deg. Top row right) 1450, 1500, 1550 and 1600; bottom row 1650, 1700, and AIR-HARDENING DIE STEEL tool steel, designed develop the char- acteristics desired dies, punches and similar tools, has recently been introduced Bethlehem Steel Co. The following approximate anal- ysis was found give the properties desired: Carbon, 1.00; manganese, 2.00; chromium, 2.00; molybdenum, 1.00 per cent. The characteristics claimed for the steel are: (a) when air quenched, comparable cer- tain liquid quenched die steels; (b) low quenching temperature, 1550 1625 deg. F., 100 200 deg. below that required for certain other air- hardening die steels with equal hard- ness—the furnace operation simplified, the chance overheating the corners machined die les- sened, and distortion and danger cracking are minimized; (c) satisfac- tory machinability annealed condi- tion; (d) high abrasion and wear re- sistance; (e) ease heat treatment; and good hardness penetration. For forging this new steel slow and uniform heating important, which preferably carried out between 1950 and 2000 deg. preheater available advantageous hold the parts 1200 deg. until thor- oughly heated, before they are brought full temperature the forging furnace. Forging temperature must not drop below 1500 deg. F., and necessary the parts should reheated. Due their air-hardening properties, the forged parts should cooled lime, ashes, silocel some other heat retaining medium. The annealing cycle prescribed has two purposes, produce steel with good machinability, and develop structure which will insure effective hardness under 229 small and me- dium sized parts developed heat- ing slowly and uniformly 1600 deg. F., holding that temperature for least hr. per in. average thick- ness, and cooling rate deg. per hr., down about 400 deg. The parts are then reheated 1325 deg. and held this temperature for about hr. per in. thickness. Finally they are removed from the furnace and cooled room tempera- ture. alternate annealing cycle may used provided slightly higher hard- ness not objectionable. This cycle consists heating slowly 1400 deg. and holding that temperature least hr. per in. thickness the average dimensions. Cooling car- ried out rate deg. per hr. 900 deg. cooling room temperature. followed furnace stated that care must exer- cised heating and quenching order keep distortion minimum, and prevent decarburization. The steel should always heated slowly the hardening temperature. Pack hardening advocated for large parts, insure maximum surface hardness. about 1200 deg. F., and soak thorough- that temperature. The recom- mended hardening temperature 1550 1625 deg. F., depending the size the piece. The pieces should held the hardening temperature for hr. per in. average thickness. They are then air cooled. For large dies air blast should directed against the face during hardening. Parts are charged into the temper- ing furnace after cooling about 200 deg. Depending upon size and de- gree hardness desired the tempera- ture then slowly raised between 325 and 375 deg. F., where main- tained for least hr. per in. average thickness. This followed slow cooling room temperature. Tests were carried out with steels the following analysis: 0.95 2.04 Mn, 0.016 0.017 0.23 Si, 1.93 Cr, and 1.04 per cent Mo. Dilatometric tests round specimens, heated and cooled rate 400 deg. per hr. gave the following ranges: Heating: range, 1370 1440 deg. Cooling: range, 1300 580 deg. For hardness tests, specimens 1-in. square and in. long were hardened still air temperatures ranging from 1450 1800 deg. F., 50-deg. intervals. The hardened specimens were fractured and fracture ratings and Rockwell hardness determined. The accompanying photograph shows the fractures. The fracture ratings The Rockwell hardness figures are 57, 62, 63, 63, 63, 63, and 44. THE IRON AGE, March 3 | | MITCHELL* WELFTH Series Articles the Technical and Economic Aspects Metal Cleaning and Finishing often accomplished blasting, tumbling, rolling ing. The method used depends partly upon the type metal being cleaned, the size and form the article, and partly the final finish given the parts. Sand blasting the most common the blasting series due the fact that was the first method used for this type cleaning. the name implies, the sand, which used the abrasive, hurled against the work surface blast air. the great dust bowl the Middle West sand blasting carrted the winds picking the dust particles and car- rving them with some force against objects. Paint removed from build- ings, farm implements and automobiles this action the elements. industry, sand blasting carried more scientific manner than place the abrasive sand is_ selected with great care obtain the hardest grains possible, and, secondly, classified provide uniform size grain. This material then projected toward the surface cleaned the use stream compressed air 100 gage pressure over. this type cleaning apparatus, other abrasives than sand have been discovered which are less harmful human health, produce better surface the work and the work far less time. Such materials *Technical director, Magnus Chemical Garwood, 54—THE IRON AGE, March 1940 metal shot not only amount dust emanating operation but reduce certain ex- tent the silica hazard well the maintenance expense nozzles. Considerable study has been made nozzle wear, effect grain contour nozzle wear and the force required make the abrasive effective. Tung- sten carbide nozzles have been used and show life exceeding that chilled iron four times. Boron carbide also used nozzle construction material saving nozzle expense. These materials are the hardest known, only being ceeded the diamond. saved the prolonged retention nozzle size. Experiments have shown that gran- ular abrasives wear the nozzles much faster than globular grains. Likewise requires longer blasting clean with the globular grain than does with the granular grain. Again, the globular grain can projected with greater speed with less wear nozzle than the granular grain. Con- sidering all data pertaining both kinds abrasive, readily appar- ent that metal shot the preferred material. When using lb. gage compressed air the nozzle, 3¢-in. nozzle will pass 211 cu. ft. free air per minute. This the equivalent 40.5 hp. this nozzle permitted wear to, say, 7/16 in., the air flow increases 286 cu. ft. air per minute and the horse power increases 54.9, in- crease over per cent. ob- vious, therefore, that nozzle wear ETAL CLEANING important and requires due attention with the sand blast method. tries, Inc., for cleaning the surfaces bearing races following heat treat- ing. this operation the heat treating scale removed prior The races, which are in. diameter, are laid the rotating table and carried under the blast nozzles. The operation continuous since cleaned parts are removed and other parts are placed the table the front the machine. The time required for clean- This type equipment relatively high initial cost, ranging from $2500 $3500 depending the size the machine. However, the ma- chines prove economical labor cost well improving working conditions the cleaning room. Almost any desired finish surface the work may obtained the blasting method using the proper abrasive mixture abra- sive. Blasting, however, polish the surface, although the sur- face may given satin finish the use low air pressures. ferrous metals the air straight cleaning should from 100 gage. For non-ferrous metals the pressure should from gage, depending upon the nature the work and the degree cleaning desired. Fig. shown machine known the Roto-Blast built Pangborn Corp. Hagerstown, Md. This equip- ment uses metallic abrasive delivered against the work com- pressed air perform the work cleaning. This type equipment adaptable cleaning practically all kinds work and particularly adaptable cleaning small fragile ° ° | | ‘ | | | SAND BLASTING, TUMBLING, ROLLING AND BURNISHING castings. instance, the Pennsyl- vania Lawn Mower Works the use the equipment shown Fig. solved with mower wheels. The loss due breakage practically elimi- nated whereas prior the installation the Roto-Blast the breakage ex- ceeded per cent. piece equipment use the Fletcher Works, Philadelphia, shown This equipment used clean cast parts prior japanning and produces remarkably clean surface. Another type equipment makes use high speed, special design wheel combining centrifugal, tangen- tial and air dynamic forces form the work cleaning. The cen- trifugal blast machine eliminates the therefore the operation air com pressor, which itself expensive piece equipment. The air compres- sor not only expensive power quirements but lubrication and main- tenance are high, usually, percentage air actually effective work does not exceed per cent that taken into the compressor, because leaks the distribution Tumbling the least expensive all the mechanical cleaning operations. This may justly claimed. However, some other claims are made for tum- verified, for instance, the claim that tumbling actually strength the castings due the peening action given the surface the casting. While possible that this action does relieve some the surface stress most unlikely that this advantage penetrates very far be- neath the surface. The internal stress best relieved some standard ac- ceptable method. Tumbling one the oldest forms used cleaning. White iron stars “jacks”, small chips iron, various sizes other abrasives are used the tum operation, mixed the Rolling very similar tumbling. However, the term usually applied work that placed tilted bar- rel and the barrel turned until the de- sired effect the work obtained. both barrel rolling and tumbling, material actually removed from the surface the work, the amount re- moved depending upon the time the work allowed remain the rotating machine and the amount, size and hardness the abrasive used. Small parts relatively simple con- struction may placed the barrel and rolled without aid abrasive other cleaning and cutting elements. However, work having deep recesses, irregular contour, designed with curves and twists, which cause them entangle nest, require other treat- Tilting barrels are usually used for rolling. altering the tilt the barrel the intensity the rolling ac- tion may changed. The speed For light, fragile castings the lower speed necessary eliminate |—Rotary table blast machine used for cleaning bearing races