The Iron Age 1938-06-30: Vol 141 Iss 26

FRITZ FRANK President J. H. VAN DEVENTER Editor c. E. WRIGHT J. A. ROWAN A. 1. FINDLEY Managing Editor News Editor Editor Emeritus Machinery Editor Art Editor Metallurgical Editor Associate Editors JURASCHEK Consulting Editor Washington Editor Resident District Editors T. C. CAMPBELL RoBeErtT G. BINGHAM Pittsburgh Chicago Cleveland Detroit Editorial Correspondents London, England Cincinnati FRAZAR Boston Hamburg, Germany Milwaukee San Francisco SANDERSON ASA ROUNTREE, JR. Toronto, Ontario Birmingham LEROY ALLISON Roy Newark, N. J. St. Louis TURNER Buffalo Owned and Published CHILTON COMPANY (Incorporated) Publication Office Editorial and Chestnut and 56th Sts., Executive Offices Philadelphia, Pa. 239 West 39th St. New York, OFFICERS AND DIRECTORS Cc. A. MUSSELMAN, President FRITZ FRANK, Executive Vice-President FREDERIC STEVENS, Vice-President JOSEPH HILDRETH, GEORGE GRIFFITHS, EVERIT TERHUNE, WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JOHN VAN DEVENTER JULIAN CHASE THOMAS KANE CHARLES BAUR CARROLL BUZBY BAUR, General Advertising Manager DIX, Manager Reader Service Member, Audit Bureau of Circulations Member, Associated Business Papers Indexed in the Industrial Arts Index. ( Published every Thursday. Subscrip- tion Price: United States and Pos- sessions, Mexico, Cuba, $6.00; Can- ada, $8.50; Foreign, $12.00 a year. Single copy. 25 cents. Cable Address, “‘TIronage, N. Y."’ ADVERTISING Emerson Findley, 621 Union Bldg., Cleveland B. L. Herman, Chilton Bidg., Chestnut & 56th Sts., Philadelphia, Pa. H. K. Hottenstein, 802 Otis Bidg., Chicago H. E. Leonard, 239 W. 39th St., New York Peirce Lewis, 7310 Woodward Ave., Detroit C. H. Ober, 239 W. 39th St., New York W. B. Robinson, 428 Park Bidg., Pittsburgh D. C. Warren, P. 0. Box 81, Hartford, Conn. RON Cont 1938 Centralizes Making Air Conditioning Equipment Mechanical Properties vs. Service Controlled Atmosphere Electric Furnaces Design Trends Die Casting and Injection Molding Automotive Industry Plant Expansion and Equipment Copyright 1938 Chilton Company (Inc.) 20—THE IRON AGE, June 30, 1938 BETHLEHEM result using Bethlehem carbon bars, made under open- hearth control system. The factors affect- ing response heat treatment are held uniform through heat after heat that, once treating cycle established, accurate results are almost certainty. ESTABLISHED 1855 JUNE 30, 1938 Vol. No. Step the Voltage determined seek the advice expert. sought out distinguished economist who was reported have profound grasp the intricate fac- tors which influence the ups and downs business. business man, faced many have been with declining sales, The business man posed this question: the best course pursue make more The economist replied, best way make more sales end the depression and thus decrease sales resistance normal The business man pursued the matter further. asked: the quickest and best way end the The economist replied, best and the quick- est way end any depression begin making more not know whether not the business man was satisfied with what the econo- mist told him, but was worth every cent that paid for the advice. For that the one and only way end depression reverse downward business trend. ought have learned that fact this time and have paid out cash and promissory notes many billions dollars find out. ought know now that you cannot end depressions passing laws, confiscating property, marking price tags down monkeying with currency standards. You can't end depres- sions generating circulation billions dollars unless there buying and sell- ing back these transactions. It's sale unless the cash register rings. How are going make sales today the face abnormal sales resistance? taking lesson from the electrical engineer. The electrical engineer has found that when resistance goes up, you have step the voltage. There would electrical power transmission worthy the name our country today the electrical engineer let line resistance intimidate into cutting voltage down. And that exactly what many hundreds, not thousands, sales organizations are doing today. there should time reduce your voltage sales effort, during those prosperous periods when your sales power flowing freely because less resistance. Then you might think, perhaps, cutting down the voltage. But not today. Remember, the one way end the depression make more sales and the way make more sales, today, step the voltage selling effort. | | = | : | - SECTION Stock Flow Conveyor baking oven Unload Hand rolls. rolls Stock Flow Mens Stock flow Bench Bench sheet machines G-E Centralizes Manufacture HEN General Electric Co. de- cided centralize the manu- facture all related air con- ditioning apparatus Bloomfield, J., several new departments had created specifically for this work. The air conditioning sheet metal de- partment, the layout which shown article, some the high lights will presented the new boiler weld- ing division where the heart the heating plant made. Although sheet metal work had been carried here for many years for making cases for small and medium size electrical controllers, the new di- vision has been set self-con- tained unit get the most ef- fective arrangement equipment and straight line flow material, con- sistent with economy production. 22—THE IRON AGE, June 30, 1938 result, few pieces existing equipment were put work this department, with the exception group hand operated machines. Most the larger equipment new. Air conditioning still its in- fancy and what with the variety size equipment needed cover range house sizes, production any one piece not large. For ex- ample, there are four sizes G-E oil burner furnaces, and these may steam, hot water hot air. this sheet metal department, the sheathing for the boilers formed, also the units house the heating coils, filter banks and humidifying ap- paratus, besides the cases for room coolers. Sheet metal parts attic ventilating fans are also made here. With production lots varying from 25-500 pieces, the most general-pur- pose type equipment employed. Some the pieces are bulky, but may only necessary notch the corners and fold the edges, that large and heavy equipment quired. The gages are usually light and in. material about the heaviest seen this department. Equipment consists shears, pres- ses, press brakes, spot welders, solvent cleaner, spray booths and baking oven. Material entering through the door the left first goes through the shears, one which new Cincinnati ft. capacity machine. Fig. shows interesting set-up for notch- ing two corners sheet simul- taneously. With few exceptions, the other presses this room are inclin- able-back types medium size, with very simple tooling. Among the new units are five No. and one No. Spray Box shop \ LEFT IG. the new air conditioning sheet me- tal department General Electric's Bloomfield, plant. Nearly all the presses, shears, brakes and spot welding equipment are new. RIGHT 2—A universal set-up for notching the ends job-lot sheets. Two No. Bliss punch presses, with 4-in. square punches, are mounted graduated bed, one being fixed, the other moved screw and crank along the ways. 4 ‘ & Conditioning Equipment Niagara presses. The ordinary set-up uses step gage conjunction with standard shoe, typical the uni- versal type tooling employed. The Strippit dies used the Bliss No. 24-in. throat adjustable-stroke press, Fig. another example. With this so-called Wales die, only necessary provide different tem- plates get the variety multiple punching desired. Such plates can readily laid out and drilled jig borer. Where the holes are line, gang punching dies are used the special set-up the Bliss No. inclinable press, shown There only one straight side press this department, Bliss size No. 5-60 with bed in. and 8-in. stroke. this press, Class dies with stripper plates are used, employ- ing G-E standard shoes and four pil- lar posts. Most presses are equipped with the simplest kind dies, and frequently rubber knockout plugs are used over the punches, rather than the more formal stripper plate. One horning press been converted into brake for mak- ing square bends short pieces, not over in. long. battery four new steel press brakes, ranging from ft. capacity, and seven spot weld- ers, five them just installed. Here notched, blanked and perforated sheets are bent shape and subassemblies are spot welded into larger units, suit- able for knock-down shipment the field. There also has been installed new Pexto power roller ft. in. capacity and Niagara 3-ft. hand f ° ° FRANK OLIVER Associate Editor, The lron Age ° ° roller for rolling the familiar round jackets and for the dome walls for G-E oil burners. New Welders Three the new spot welders are 50-kva. Taylor-Winfield air-operated welding presses. One illustrated Fig. These units have pancake type transformers with water-cooled, cast copper secondaries and primary coils wound for 550 volts. Solid copper horns are used, with the lower horn in. diameter. Pressure the work provided 4-in. diameter, 3-in. stroke double-acting air cylinder which permits pressures 1000 per sq. in. the welding points, with Ib. line pressure. Control the unit two-stage foot switch. six-point voltage changer provides the necessary flexibility for various THE IRON AGE, June 30, 1938—23 q ; ~ ~ ps: | — | | >. 4 ABOVE 3—An example adapta- bility. Multiple punching sheets being done Bliss deep-throat press, using Strippit Corp. Wales dies, which may set any desired arrangement the lower template. gages work, and control valve with gage allows the air pressure adjusted accordingly. One the Taylor-Winfield units provided with Thyratron control for accurate timing the welding cycle. new National 150-kva. projection welder for materials also press type welder, but the pressure this design developed motor driven cam and toggle mechanism that moves the upper electrode and ram as- sembly vertical line. Regulation compression spring. single treadle switch controls the entire cycle. solenoid switch the motor drive starts the ram downward, and when the desired pressure has been built up, the welding circuit automatically closed and remains closed proper length time complete the weld, after which automatically cut off, and the upper turns its normal position. The drive this machine arranged IRON AGE, June 30, 1938 give infinitely variable speed strokes per min, suit each particular The transformer has points heat regulation. new press welder has much the same fea- tures the National unit just de- scribed. Variable strokes the ec- centric driven upper head effected through Reeves variable-speed drive and worm gear reducer from the ac- tuating motor. Strokes can varied from per min. Stroke move- ment variable eccentric, giving the welding pressure this unit air cushioned head with built-in BELOW 4—Adaptability also found the gang punching die shown mounted Bliss No. inclin- able press. Punches fit the dove- tail slot and are held set screws. step gage used with the lower ie. a if A Mn, _ variations gage stock. This Thomson-Gibb unit intended primarily for which accounts for its large capacity. Flat pads for projection welding dies are located directly line with the air cushion cylinder. The adjusting post for the lower horn solid cop- per bar, and provide gidity, there adjustable backup strut just under the die pad. This ma- 5—Two the four new Cincin- nati all-steel press brakes installed the air conditioning de- partment. Most the work performed simple right angle bends. chine also equipped with G-E control. Finishing Equipment Latest Type The rapidly increasing need for ac- curately controlled lacquer finishing metal parts constantly calls equipment and proper relation the new production set-up. G-E Bloomfield plant, this ex- ception, since the space available for such installation was one originally used for another purpose. Practical compactness conserve valuable space expansion program that does not contemplate new buildings additions becomes item essential efficiency the new order production. The minimum floor space was used and the height was restricted allow for the operation existing crane. The sequence finishing operations the various sheet metal parts clearly shown the plan view, Fig. Work room, spray booths and material transfer are enclosed within air conditioned section order assure thorough cleanliness and worker com- fort. The degreaser, however, the shop atmosphere. This work room kept under positive pressure prevent admission any dirt-laden air the entrance and exit points. The which can heated from side air can apportioned be- tween inside and outside air. Steam the air heating means has the ad- vantages indirect heat desirable work this nature. Temperature the work room automatically regulated. Air Filters Installed Velocity the air entering the work room relatively low elimi- nate drafts and harmful air currents, and the capacity the system large gain the full flexibility this re- serve. All air passes through auto- matic self-cleaning filters, installed eliminate manual attention and pre- vent interruptions production cause the necessity cleaning in- the air conditioned work room glass with steel sash partitions give maxi- mum amount daylight and good ap- pearance. Water Curtain Spray Booths Spray booths are the Binks wa- ter curtain type, which make for the greatest possible cleanliness the back the spray booth, since all paint and lacquer fumes must pass through constantly running curtain water. The fire protection features are ob- vious. Although some installations, the overmatter caught the curtain can recovered the form float- ing scum and reused for factory main- tenance painting, present use made this by-product the Bloom- field plant. DeVilbiss tanks and guns are used, and the material sprayed Glyptal lacquer, product the General Elec- tric Co., having synthetic resin base. The material was selected because its high adherence metal and its tough and durable finish. The conveyor oven A-type and has its own conveyor sys- tem. Material lifted off the swivel hooks the monorail conveyor that goes through the degreaser and spray conveyor going through the oven. Bak- ing carried 375 deg. and the cycle time hr. Heaters for the oven are oil fired, indirect type prevent the products combus- THE IRON AGE, June 30, 1938—25 { | =f | ABOVE 6—One the five new spot welders. This direct air-oper- ated type with in. throat and kva. capacity. There are two 150- kva. machines handle material tion from coming into contact with the The design the supply ducts from the heater such assure uniform temperature and air distribu- tion throughout the entire oven, and prevent discoloration the work. Part this distribution effected the recirculation system, which co- ordinated with the exhaust system provide efficient heat seal the en- tering and unloading ends and the same time dispose the volatile mat- ter. There are number dampers the duct system give proper bal- ance. Prior spray painting and baking. all cabinet panels and other product components are cleaned special vapor-spray-vapor Detrex solvent de- greaser. Work, hung the hooks the monorail conveyor just after 26—THE IRON AGE, June 30, 1938 emerges from the transfer point front the baking oven, enters the ft. per min., which speed 6000 Ib. work per hr. can cleaned. Hot solvent vapors (188 deg. F.) condense the cold work and carry off portion the dirt, oil, and grease. Then the work passes through bank nozzles through which warm solvent sprayed. This solvent de- livered the spray nozzles two motor-driven centrifugal pumps. passing through the sprays, the re- maining solids and insolubles are washed off, and the work cooled the lower temperature the liquid solvent. passing through final vapor stage, condensation again takes place, giving final rinse and reheat- ing the work 188 deg. Emerging from the opposite end the machine, (CONTINUED PAGE BELOW 7—The Binks water curtain spray booths are air condi- tioned chamber. The filter banks through which the air drawn may seen this view. Temper- ature the workroom controlled thermostat. 7 designer and manufacturer machinery processing and galvanizing sheet steel, the author naturally has interest the subject sheet gal- vanizing, and developed certain theories and opinions regarding the mechanism the process. the past, the machinery required for sheet galvanizing has been viewed largely conveying means, but appears though sheet galvanizing pot with all its necessary and co- relating equipment should viewed known that the average galvanized oz. per square foot sheet surface, and also known that the coating consists three distinct lay- ers. The alloy directly adjoining the steel base iron and alloy, hav- ing the formula the middle layer and the outer coating pure zinc. The inner alloy, has brittleness and lack ductility, and regardless how elastic the outer surface may be, severe bending opera- tions may cause the zinc flake off. The demands the trade seem increasing for steel coatings that are sufficiently elastic permit heavy forming and deep drawing op- erations; and accomplish this end, steps are being taken develop coat- ings having minimum amount alloy. *Abstract address before the annual meeting American Zinc Institute, Inc., St. Louis, April 25-27. SHEET ° ° WEAN President, Wean Engineering Co., Inc. With this end mind, consider the data determined George Brayton, Newport Rolling Mill Co., which show the percentage iron spelter bath Tuesday, Thursday, and Saturday, and also show the per- ° centage iron the various levels throughout the depth bath. This information shown the chart Note that the iron content the bath varies from 0.030 high 3.200 per cent. One interest- spelter bath for three days near the end the week; also, percentage iron various levels the bath. TUESDAY IRON, THURSDAY IRON, SATURDAY PER CENT PER CENT PER CENT TOP 0.042 0.746 2.250 2.100 2.800 3.200 THE IRON AGE, June 30, 1938—27 | | fi Ly > ' =! ' ° ° ° ' : ' t =! ' ' ' H H 7 ing thing the indication that the content the upper in. the bath grows less the week progresses, the iron content increasingly heavier the lower part the pot, and the part the bath which the iron more highly concentrated about per cent the lower depth the entire bath. The author definitely the opin- ion that there some relation between the percentage zinc-iron layer coated sheet, which generally from per cent per cent, and the per- centage iron the bath, indicated Mr. Brayton, which arises from the realization that the steel sheet passing through the zone the bath carrying the high per- centage iron. Very likely the product were passed through only the upper part the bath having 0.030 0.040 per cent iron, much thinner layer zinc-iron alloy would formed the sheet. However, not practical pass and feed sheets depth only in. to. in. below the surface the metal. the theory correct that there relationship between the iron con- tent the bath and the iron content the coating, then some practical means certainly can devised pass the sheet through that portion the bath having low iron content. The immediately obvious way doing this make pots deeper that the high concentration iron will be- 2—Analysis iron content gal- vanizing pot equipped with single bottom roll. Note the disturb- ance set the dross the rolls. Pa 28—THE IRON AGE, June 30, 1938 ——— 4—P lan and elevation views typical from 100 ft. per min., and spangle low the zone through which the sheet passes. Additional ways accom- plishing the same result can probably devised this theory producing flexible coatings correct. the moment tests are being made, but the justify conclusive statement. recent years, longer pots have come into use several plants. How- ever, seriously question whether these longer pots result the propor- tional gain production oretically can expected. The longer pots require two sets bottom rolls the machine order convey the sheet through the longer bath, sketch showing what, the opinion, takes place such bath having the iron content the various levels shown Fig. Note that one set working rolls the bottom the bath sets certain amount disturbance the dross iron particles which have heavy enough settle the bottom the pot. attempt has been made show this the shading the Lead and lead zinc alloy 0 nodern galvanizing unit. These units formation can closely controlled. = dross spots Fig. and since has been proved that the greater the dis- turbance the bath, the more these particles adhere the sheet and either increase the iron content the sheet cause dross spots the sheet, the more necessary becomes eliminate far possible the agitation disturbance this dross. The dross movement and the tur- bulence created when double-bot- tom roll machine used definitely may objectionable. the author’s opinion the disturbance operate more than twice the disturbance the single-bottom roll machine, largely because the concentrated distur- bance set between the two sets rolls. This shown Fig. While this increased pot length should give greater speeds through the machine, order keep down this distur- bance dross will necessary operate slow speeds which will, course, defeat the purpose intended. This would not true the ma- chines were operated only zine baths, but here again there an- other factor which works against the higher speed, that most sheets call- ing for coating are gage that will not stand too high speed through the bath without cob- bling. install expensive item equip- ment out which cannot get max- imum tonnage production due some other limiting factor than the speed the equipment. The rule reason must followed the instal- lation all equipment, and particu- larly this true galvanizing de- partment. modern galvanizing unit today, especially when using the dual motor drives, has unlimited speed control possibilities within the maxi- mum and minimum speeds for which the equipment designed, and the limiting factor speed not the machinery but the conditions prevail- ing the bath and the speeds which the various gage sheets can passed through the machine and still have satisfactory coating. The method firing and operating the pot and the proper attention and care the bath are all contributing fac- tors. Spangle formation the sheets can very nicely controlled, and va- rious methods are employed. Greater adherence the coating not par- ticularly function the machinery but the manner which the pot operated. The proper and prozres- sive cooling the sheets important factor, and with proper equip- ment largely under the control the oper- ators. Fig. shows typical modern galvanizing unit, equipped with dual mo- tor drives having infinite variable Per cent ities, then magnet roll 0.03 for holding the sheet comes out the bath, controllable cooling con- veyor, washer, squeezer units generally are 100 ft. per for light gage material and, n lead zinc alloy The turbulence created here may definitely objectionable. iron content galvanizing pot using double bottom roll. course, for heavy gage material the speed range lower. Eight these units have been installed since the first the year, are process installation this time. THE IRON AGE, June 30, 1938—29 | \ — Mechanical Properties vs. title this paper suggests attempt correlate the me- chanical properties materials with their liability fail service. Such suggestion could considered most inappropriate; for the results none the most commonly adopted mechanical tests can correlated with usual service failures, and only special circumstances, such when there jam seizure, faulty lubrication, severe shock, that any direct relationship exists. The usual failure traceable faulty design workmanship, carelessness oper- ation, such causes torsional other forms vibration. The title however affords convenient heading for the subject matter which the au- thor proposes discuss. Methods testing, such that are called for purchasing specifications, may excellent far they act check the qual- ity the material, and also enables the purchaser verify whether the ma- terial meets recognized standards. The author fears, however, that standard tests, far they are intended give information that really useful judging the relative suitability different materials for service, are cer- tainly very deficient. For the most part, the methods constitute that has been handed down for sev- eral generations. They were ingrained the average engineer his student days, and there general reluctance depart from them. only re- cent years that engineers have started wake and take notice, and only recently has there been realization how misleading the information given many forms test may be. Much yet remains learned, and meanwhile argument must take place deciding upon the most suitable material for given me- chanical part. was not long ago that the author was advocating that certain test should stipulated for testing some important welded joints, when the purchaser replied that could not understand the function the particular test. However, did de- sire tensile test, which was test 30—THE IRON AGE, June 30, 1938 that could understand. added that served the purpose showing the load the material would withstand before could pulled asunder. Un- fortunately, however, part service not pulled out until fractures, tensile test. Though consequen- tial failure may take place this well known, results from creeping sudden rip from initial crack, either case without measur- able distortion. The value the ten- sile strength the material therefore has direct bearing the usual failure, and, though within limits, may true that the fatigue value material proportional the ten- sile strength, such occurrence can only looked upon fortuitous, and any such happening was into consideration when the remark was made the purchaser the welded material. Naturally, true that con- sequential failure the material may drawn out, and connecting rod bolt may serve example. The usual occurrence when connecting rod bolt fails is, short seizure sim- ilar mishap, for the primary failure take place one bolt only; creep- ing crack formed this one bolt, and the second bolt then becomes over- loaded with eccentric load, and consequently either bent some- times pulled out tension. The use the yield point often recommended basis design largely with the object making use the stiffness alloy steels. The au- thor wishes say, however, that frac- turing service the varied class parts which has examined dur- ing extended period, short other defect the material, has never been due unsatisfactory yield point. Naturally the measurement the yield point affords excellent check ensuring that manufacturer ob- taining the class steel that has ordered that may necessary for certain works process, and knowl- edge the value the yield point importance parts such steam turbines, having fine tolerances small shrinkage fits, other parts liable deform under particularly se- vere conditions load. And, again, the yield point importance the design columns and certain parts liable fail collapse. But, troubles arising from such consideration not constitute fracturing The aim designing part should clearly ensure that the proper- ties the material are suitable for resisting the form failure feared most, and, for the general design machine parts, the use the yield point basis definitely wrong. Should the part work under severe conditions shock, raise the yield point just the opposite what required. Naturally, part has work under special conditions are imposed elevated temperature, the yield point cannot have greater importance, for its value does not fall for temperatures below 400 deg. F., and for higher temperatures there definite yield point. Safety Factors Vary important objection the use the yield point that, for alloy steel, its value may raised much 115 per cent, while the fatigue range raised only per cent. Consequently, with the used basis design, the factor safety must varied for different materials, and generally much larger factor required for alloy steel than for mild steel. point certain parts means necessity disadvantage, but may far readily enables material adjust itself the piling lines eral basis design the use the yield point unsatisfactory, only because the measurement does not rep- resent fundamental property material, and many materials have yield point. heat treated alloy steel does not usually give definite yield point, such given mild steel; and the characteristic mild steel which allows appreciable strain the yield point without increase stress has certainly distinct advan- tage. Again, seeing that occasional SCHUSTER British Engine, Boiler General Insurance Co., Ltd. overload may raise the yield point many materials without lowering the fatigue value tending facilitate failure, the initial yield point has not necessarily specific significance. Fur- ther, may cited that commer- cial testing the accuracy the value the yield point recorded the test sheet often open considerable suspicion. the question the limit pro- portionality, the author does not think necessary add anything the remarks the yield point. known metallurgist commenting the making the tensile test said that none the test figures recorded com- mercially represent fundamental prop- erties material, and the only funda- mental property given the test was the elastic limit, which not usually recorded for acceptance tests. How- ever that may be, when breakdown service under consideration, the au- thor looks upon measurement the limit proportionality even less value than the yield point. bears relation the mechanism fail- ure under fatigue, and any insignifi- cant work hardening the material will cause its value altered Such basis would certainly not benefit with heat-treated alloy steel, the load-extension dia- gram for such material may start tail off with zero load. the other properties materials usually specified, ductility obtained various methods generally consid- ered the most important; yet all these methods miss the mark giving information the real char- acteristics materials that determine their behavior service. con- sideration results, the average engi- neer’s interpretation the elongation measured tensile test perhaps the most erroneous. The measurement undoubtedly affords check ensur- ing that consignment metal the standard for that particular grade material, but comparison the figures does not afford any guide the relative manner which two different grades material will behave service. The author believes can say without fear contradic- tion that, when the word “ductility” referred to, the intention real- ity refer that property which represented the measurement the reduction area tensile test. can seen, the same property ob- tained approximately measuring the elongation infinitely small gage length, and the same property indicated approximately when bend specimen first fails. The point under consideration is, however, the relation between this ductility and the liability mechanical breakdown. can safe- said that there direct rela- tionship. Though perfectly true that good ductility has shown itself proof whatsoever that, one material gives reduction area per cent and another only per cent, the one giving the higher value will give better service. fact the reverse might readily take place. has been pointed out, crack spreads ser- vice part with appreciable plastic deformation the material, and the measured ductility certainly not de- veloped. Naturally, for other test results, the measurement the re- duction area ensures that given material standard quality. Bend Test Useful the question the bend test, can said that when this car- ERE explained why many the standard mechanical tests may fail give completely accurate picture the suitability certain steels for various ap- plications. The author de- fends his criticisms ably, and, addition, advances reasons why less well-known tests with proper interpretation may more satisfactory. The in- formation presented herein abridged from lecture presented before the Mid- land Metallurgical Societies, Birmingham, England. ried out methodical manner the first crack will break out after cer- tain degree deformation, which approximately calculable measurement the reduction area tensile test. The test, made determine ductility material, clearly redundant the ductility has already been obtained other means. It, however, affords cheap and rapid method determining ductility, which can used lieu other methods, occasion when the reduction area not, cannot, measured tensile test, for flat plates ir- regular sections. The test is, however, made for addi- tional reasons, and for material that during the later stages manufac- ture, certainly useful. deter- mining the suitability materials meet the conditions service often great value, affords method which the outside surface part can readily tested for im- perfections, and the surface the part that crack will almost in- evitably set service. Similar- not uncommon for failure non-metallic matter lying near the sur- face the part. There need enlarge upon the serviceability the bend test detecting porosity castings the presence other de- fects. Undoubtedly the method apply- ing the load fatigue test ap- proaches the conditions service more nearly than that any other test, even though not regular works test. Clearly, however, assumed that the fatigue range bears approximate ratio the ultimate strength the material, the test fails THE IRON AGE, June 30, ty | 4% ° ° ° | | | A | 3 | mf 7 give information not given knowledge the value this latter quality, and make the test would serve useful purpose. Moreover, the fatigue strength, commonly de- true criterion the liability fail service, and other properties materials must therefore not dis- regarded. giving basic knowledge the effect fatigue, the usual method test does certainly serve purpose, but experimenters are now more and more realizing that the test- ing machined specimens may quite misleading for assessing the re- sistance against the failure the out- side skin the part represented. The outside layer the mechanical part may very different quality from that the test specimen, both re- ment, segregation, distribution im- purities, work hardening, other surface conditions. Moreover, the usual test does al- together fail ascertain the relative behaviors materials discontinu- ities, such are common. well known, the failure under fatigue many instances starts scratch, fillet, drilled hole, keyway, the root gear tooth, that the infor- mation given the usual test means all that required. More- over, the stress system the part service likely complex and, though much effort being made make good the deficiency, much data are yet required the behavior under fluctuating stress materials sub- jected several variations com- bined stresses. The author inclined the opin- ion that one the most useful prop- erties material for resisting severe service conditions its capacity for yielding without appreciable increase the load; material giving well marked yield point which there appreciable strain, such steel, probably the most suitable for withstanding rigorous service. This rather points the particular impor- tance the fatigue bend test, when made notched specimen, either test being carried out the point first failure, and then discontinued. Such tests are able give informa- tion the capacity materials accommodate themselves stress con- centration discontinuity. What the Izod Test? Before completing these remarks upon mechanical tests, mention should made the Izod test. 32—THE AGE, June 30, 1938 has been the result this test does not essentially show the ca- pacity material for withstanding impact. The velocity any such notched-bar test, usually applied, far too low for such purpose. Though the result depends upon sev- eral factors, which not the purpose this paper enlarge, may said that the final stage the test does afford indication the ease with which crack will spread through metal, after has once been formed. This phase the test re- lated service failures inasmuch as, when incipient crack breaks out machine part, there certainly advantage for the material have high resistance the spread the crack. The more resistance the spread crack, the greater the chance that will discovered be- fore the whole section the part broken, and otherwise severe conse- quential damage may readily take place other important parts the engine machine, and human life may often jeopardized. Those re- sponsible for the safe working boiler plants have guard against the use material which crack will extend dangerous rate. tough material crack may existence for considerable period be- fore final fracture takes place, and this allows discovery during peri- odical inspection before the failure has become dangerous. would seem that, considering the usual failure service, the earlier part the notched bar test decided- the greater importance, that the energy expended during the early stages fracture shows the relative capacity different materials de- form notch without initial crack- ing, and therefore, measure, shows their capacity for standing stress concentration notch. The test, when results are duly considered, certainly shows the capacity the material deform without extension the initial crack into the body the specimen. must agreed however, that the Izod test, which gives integrated value expended during all stages the test, clumsy method obtain- ing this information. The energies can, however, always separated out making load-deflection diagrams from prior knowledge the class material. Useful information also obtained for mild steels ex- amination the surfaces fracture. Though the general fracture may show crystal facets, structural mild steel, offers high resistance failure, will show, just below the notch, darker area, where failure has taken place shear. The greater the resis- tance the spread the initial crack, the deeper will this area. The opinion has frequently been ex- pressed some the most eminent and experienced authorities that study service failures shows that failures are far more common ma- terials that give low Izod value, and that good Izod value un- doubtedly conducive satisfactory be- havior. Such evidence cannot ig- nored. the evidence accepted, would seem that the significance can- not lie the capacity the test for detecting the resistance material the spread crack, which inciden- tally often considered the prime value the The brittle failure material may not take place until after amount energy has been expended, and moreover does not commence formed. Seeing that when material has developed even minute crack, has already mechanically failed, high Izod value due toughness can- not reduce the number Consideration this reasoning there- fore leads the conclusion that the significance the evidence must lie the capacity the test discrimi- nate between materials which offer good and indifferent resistance the inception crack, that is, under conditions concentrated stress. The crack breaks out any machine part, matter how small the crack may matter what may the cause, failure may certainly con- sidered have taken place; for the crack, given time, will undoubtedly spread under the pulsating loads service, and complete fracture the part will inevitable. This should also borne mind considering the relationship between the Izod value and the liability fracture part shock. The value given the notched-bar specimen the overall value, and, therefore equivalent structural part with notch given blow intensity appreciable less than the test value, may not broken entirely, but small crack may readily initiated, which will spread during future service. This point that does not seem fully appre- ciated when test results are being con- sidered. view the unsatisfactory ser- vice that often given running parts with coarse structures, may sometimes considered surprising what satisfactory service is, not in- frequent occasions, given mild steel | \ \ with grossly overheated structure. considering such results, two points come particularly mind. First, the fatigue value mild steel when overheated lower than when the structure normal. The tendency for the value higher, and there- fore, with smooth surfaces, con- centration stress and steady work- ing conditions, there cause for the life lower. Second, though such material may give very low value Izod test, found that, when the other properties the ma- terial are satisfactory, specimens, sim- ilar Izod specimens, when deformed rate, absorb very satisfac- tory amount energy. words, the low Izod value purely speed effect, and part working un- der favorable conditions loading may thus give good service. ‘Though innumerable examples could given the failures parts due their having been repaired fu- sion welding, the author shall refrain from doing so, this form repair, when skilfully carried out, does oc- casion prove invaluable asset the engineer, and there wish give any impression opposition repairs welding. Note, however, that experience shows that great cau- tion required before parts subjected fatigue stress are repaired this manner. Another type stress causing fail- ure corrosion fatigue, but most en- gineers have had experience with this form failure, and nothing new will added the subject this time. Torsional vibrations crankshafts though the primary cause such fail- ures incorrect design operation, the use metals with good damping properties desirable preventing the development high stresses; for this purpose, well known that normalized mild steel superior heat treated alloy steel. Sometimes cases failure this type are en- countered that not give marked evi- dence the cause, and the other hand instances have been experienced sional vibration has been the cause the trouble even when has been pos- sible prove, from examination the fractured surfaces, that the re- verse has been the case. Failure usu- ally takes the form multiple crack- ing, especially fillets, such cracks commonly lying complementary principal planes shear. Space limits will not permit ade- quate consideration transverse fail- ures. best merely emphasize Photo Joseph Ryerson Son, Inc. tensile test serves useful purpose checking material, but service the material generally not pulled out until fractures, although consequential failure may take place this manner. Most frequently service fracture results from creeping crack, usually without measurable distortion. the folly relying the properties material obtained from the usual longitudinal test, the greatest stress service transverse. Thus the transverse properties material used for such parts gear teeth, keyways and crankwebs are clearly all im- portance, and moreover should considered that such parts are sub- jected considerable concentration stress. For such parts certainly necessary ensure that the transverse resistance the initiation crack discontinuity not unduly low. making the test, consideration should always paid whether the grain the material lies perpendicu- lar parallel the notches the Izod specimen, and the position the notch most importance that which propagates crack the direction that would propagate service, this radial tangential. The results from notches lying different planes should not averaged. The last type failure con- sidered here the failure certain mild steels and wrought irons from induced brittleness. The prime cause this failure metallurgical change the metal, which outside the scope this paper. As, however, the mechanical cause the failure induced which the vis- ible metallurgical change looked upon indication, the sub- ject would seem legitimate mention. The author refers form which often leads the presence well marked needles. several oc- casions when certain qualities wrought iron have failed, these needles have been present, and the ductility the material has been every instance the material has worked elevated temperature, and ex- periments show that the needles can produced exposure for six months 410 deg. The needles are unaffected short heat treat- ment 572 deg. F., but are eliminated 752 deg. The trouble has often been found such parts boiler plates, bolts, nuts and studs attached steam fittings. wrought iron, the needles are often confined cer- tain piles, and experiments made the author have shown that certain grades wrought iron are more sus- ceptible than others. This subject itself affords scope for lengthy re- search paper, and may provide fruitful matter for discussion. THE IRON AGE, June 30, 1938—33 e 4 y y tool microscopically. Note the tool top the instrument. the art heat treatment re- fined, there demanded greater economy and precision the various steps making the cycle treatment. One the contributions the art has been the controlled at- mosphere electric furnace and the ad- vantages accruing thereby, both for non-ferrous and ferrous alloys, are now widely recognized the Amer- ican industry. Many furnaces have been described magazines serving the electrical industry, and their oper- ation has been discussed. But, com- paratively little attentton has been paid recently the type work which first showed the marked benefits gained from the use electric heat, namely, the hardening high speed steel. cause used cutting and form- ing operations high production 34—THE IRON AGE, June 30, 1938 rates—rates high, fact, that the tool use reaches temperatures high 900 deg. 1000 deg. This severe service requires steel that will retain its hardness, toughness, and cutting ability these high tem- peratures. Various analyses steel are used, containing carbon, tungsten, chromium, vanadium, and some cases molybdenum cobalt main alloying elements. All these high speed steels are hardened quenching from high temperature, varying according the analysis the steel and type work from 2200 deg 2400 deg. The tools must heated uniformly and thoroughly, and the steel must protected from attack the surrounding atmosphere while being heated. The author has had years’ ex- perience with many types fuel fur- naces, and has been able study the Atmosphere Electric Furnaces ° ELMER HAUSER Metallurgist, Weldon Tool Co., Cleveland advantages and disadvantages each form for supplying heat. When the Weldon Tool Co., manufacturer patented double-end mills, cutters, and special tools, moved into new and en- larged quarters, there was offered opportunity install whatever type equipment was needed produce the best results. For this new installa- tion electric furnaces. were selected, built Hayes, Inc., and equip- ped with “certain curtain” patented at- mosphere control. This decision was based five years’ experience with this same type furnace, and com- parison with furnaces other types. One the furnaces installed used for preheating the high speed steel 1600 deg. before putting into the high temperature furnace. has and connected load kw., 220 volts, single phase, cycle. The tem- a 4 q perature automatically controlled potentiometer indicating controller. furnace equipped with nickel- chromium resistors and suitable for preheating the high speed steel, also used for hardening carbon and alloy steels within range. The second furnace, used for super- heating the high speed steel, has and connected load kw., 220 volts, single phase, cycle. This also automatically controlled potentiometer. Globar brand metallic heating elements, and designed for use 2500 deg. These elements have proved very economical for use elevated temperatures. Their replace- ment cost low, and they may changed when necessary few min- utes without dismantling the furnace. Their life this service has averaged 1200 1500 hr., which equivalent Weldon shop. They are changed when the power input the highest trans- former tap drops below the desired in- put indicated the meter. There sudden failure requiring emer- gency shutdowns when the furnace use; for the operator has several days’ warning before the change re- quired, and there need for dis- turbing the production schedule re- place the elements. The “certain curtain” atmosphere control with which both furnaces are equipped consists essentially the use controllable mixture pre- combusted gases. Natural gas and air are fed controlled amounts burner combustion chamber which separated from the work chamber the furnace except for slot ex- tending the full width the door opening. The products combustion are forced through this slot, forming transparent curtain across the door opening, thereby excluding the outside air and filling the work chamber with The flow gas and air controlled valves and indicated manom- eters. When the furnace door opened, the volume gases auto- increased effectively pre- vent entrance air from the room. The ratio gas air set pro- vide atmosphere which protective the steel being hardened, the temperature being used. Since one atmosphere protective all steels all temperatures, flexibility ad- justment necessary. This provided the “certain atmosphere control. With these furnaces, has been 2—High speed steel heat treating furnaces operating the air condi- tioned heat treating room the Weldon Tool Co. possible tor the Weldon Tool Co. con- sistently produce work that the highest standards. Close control over heat treating conditions main- tained microscopic inspection hardened specimens our modern laboratory. All tools are checked for hardness and dimensions before being shipped. The close control temperature the electric furnaces, and the use the “certain curtain” atmosphere con- trol have practically eliminated rejec- tions after hardening. Soft skin due decarburization has been eliminated. Burning and blistering the surface and edges fine tools prevented, and cost cleaning and grinding the tools has been greatly reduced. The hazards hardening expensive tools older types equipment have been eliminated. All these advantages have been gained without sacrifice economy. The maintenance cost the fur- naces very low, and the operating cost moderate. T