The Iron Age 1939-03-16: Vol 143 Iss 11

FRITZ FRANK President VAN DEVENTER Editor ROWAN E. WRIGHT Managing Editor News Editor Editor Emeritus A. 1. FINDLEY Machinery Rditor Art Raditor Metallurgical Editor Associate Editors Washington Editor Resident District Editors Pittsburgh Chicago Cleveland Detroit Editorial Correspondents London, England Cincinnati FRAZAR Boston Hamburg, Germany Milwaukee San Francisco Toronto, Ontario Birmingham Newark, N. J. St. Louis TURNER, Ji: Buffalo Owned and Published by CHILTON COMPANY (Incorporated) Editori Publication Office Chestnut and 56th Sts., 239 West 39th St., Philadelphia, Pa. New York, OFFICERS AND DIRECTORS MUSSELMAN, President FRITZ FRANK, Executive Vice-President FREDERIC Vice-President JOSEPH HILDRETH, Vice-President GEORGE GRIFFITHS, Vice-President EVERIT Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JOHN VAN DEVENTER, JULIAN CHASE, THOMAS KANE, CHARLES BAUR, CARROLL BUZBY, FAHRENDORE BAUR, General Advertising Manager DIX, Manager Reader Service Member, Audit Bureau 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, “Tronage, ADVERTISING Emerson Findley, 621 Union Bldg., Cleveland B. L. Herman, Chilton Bldg., Phila. H. K. Hottenstein, 802 Otis Bidg., Chicago H. E. Leonard, 239 W. 39th St., New York Peirce Lewis, 7310 Woodward Ave., Detroit nson W. J. Fitzgerald 428 Park Bldg., Pitts. D. C. Warren, P. O. Box 81, Hartford, Conan. RICCIARDI RON Contents MARCH 16, 1939 War—Overproduction—Unemployment What About Grain Size Notes the Early Manufacture Stainless Steel Selection Furnace-Brazing Equipment Machine Tool Design Changes Being Accelerated Convention International Acetylene Association FTC for Absolute Mill Basing the Assembly Line Washington News THE NEWS BRIEF Statistics Metal Working Activity Rate Activity Capital Goods Weekly Ingot Operating Rate Plant Expansion and Equipment Buying Just Between Two Products Advertised Index Advertisers Copyright 1939 Chilton Company (Inc.) 100 106 109 134 fy > O- his the nch and art- kee, and hal- Now you can sure... You can depend better results less time when your heat treater guided the Ryerson alloy data charts. These charts show him the exact properties the steel with which working and show him how get the desired results. does not have test. takes chances. Spoilage eliminated and sound dependable job high accuracy and uni- formity assured. addition saving production costs, the Ryerson Certified Alloy Plan benefits the Purchasing Department, they can keep detailed record the exact analysis every alloy purchased. Thus possible duplicate particularly desirable close range specifications repeat orders. The Metallurgical Department benefitted for they can call for any reasonable physical requirement and sure the Heat Treater can produce the required properties. Ryerson Certified Steels also include carbon, tool and stainless steels that meet definite quality stand- ards. They offer many advantages steel users. Let send you booklet which tells the complete story. Joseph Ryerson Son, Inc. Plants at: Chicago, Milwaukee, St. Louis, Cincinnati, Detroit, Cleveland, Buffalo, Boston, Philadelphia, Jersey City. RYERSON CERTIFIED STEELS HEAT ANALYSIS AND CARBURIZING DATA SHEET jate chant rete Stee! from the partcular heer Be sure the heat mbol leve On thy theet ere the a the letter: on the alloy nee! delweredsto yo S. AE. Type 4615-20 La the hee jer, only to “ee the letters OF the emer ay The date sheot are the Heat Symbol ALYSIS Ve 5. a. & Tyee 3156-40 = 1.38 Ce ol owt strength tensile Yield Point Special Ryerson Data Sheets While two heats alloy steel may almost identical chemical analysis, one may much more responsive heat treatment. For this reason ,Ryerson data sheets show results. Two types data sheets are used, one for the carburizing steels which gives complete analysis and the results carburizing tests. The other, which for the higher carbon steels, shows actual quenching and drawing results. Both charts are accurate guides that help the heat treater save time securing desired properties. 22—THE IRON AGE, March 1939 —_ | | | | | en? = | | | 2) = | = j 3 | = ESTABLISHED 1855 ... THE IRON AGE ... MARCH 16, 1939 Vol. 143, No. War Overproduction Unemployment that invention and improvement are not blame for present unemployment, let's along the lines thought expressed last week this page, namely think about what war—and the preparation for war—does nation's industry. First, develops unnatural and abnormal expansion productive capacity. Those you who are old enough remember what went 1917 and 1918 may remember the mushroom growth plants, financed Uncle Sam, that occurred during this period. What happened these plants after the War? What happened the new machinery with which they were equipped? Were the plants burned down and the chinery thrown the scrap pile? No, indeed! Uncle Sam, with characteristic liberality, sold these buildings and their equipment private industry. And private industry, longer facing market and demand for war material, turned these plants over the production peace-time products. There was plenty labor then man these plants. man and woman them. you may also remember how, make for the boys who went abroad fight for democracy, combed the nation for able-bodied housewives who were willing swap aprons for overalls return for day. And what happened? Just this. Whereas, under normal conditions, industrial plant capacity and the number people engaged industry increase accordance with the normal increase consuming power the nation, the abnormal demands war and armament production induced sudden and unwarranted jump both that normally might have been justified years later. And again, what happened? Spurred the false impetus huge Government spending, entered the golden years too big for our breeches. The golden era when half the servant girls America had credit balance some stock- broker's office. The silk shirt, crap shooting era with two cars every garage and two chickens every pot. Then came the deluge. And now hear people say that invention and improve- ment are blame for it! When man climbs the top 20-story building and then jumps off, you can hardly blame the architect the builder. any product—can used constructively destructively. Should condemn the chemical industry, which produces many remedies save and lengthen life, for the relatively few cases accidental intentional poisoning which take place? with the machine and mechanization. view what these have done for this country, should condemn them because mistaken judgment their use? the average many hundreds shop experiences holds true, you can make important savings machining costs substituting Inland Ledloy similar analysis for the steel you are now using. The economy worthy test. probable that you can save from $10 more than $50 per ton every ton steel machined. Others are doing it. You can increase machining speeds 30% 100%. You'll get 100% 300% longer tool life. you can use steel higher chemistry without increased machining cost. special equipment change any process required, for, aside from its superior machinability, Inland Ledloy has the same properties ordinary steel. This saving machining time was reported automotive parts manufacturer, who also adds: “The finish with this increased machining speed was excellent.” 918 1,330 PARTS PER HOUR appliance manufacturer obtained this increased production substituting Inland Ledloy 1115 for Inland Ledloy can ordered any standard analysis and any rolled form through your nearest Inland office, cold finished form from your cold finisher. For complete information call the nearest Inland office, write for the new Inland Ledloy Bulletin No. 11. SHEETS STRIP BARS PLATES STRUCTURALS PILING RAILS TRACK ACCESSORIES REINFORCING BARS * ‘ — South Dearborn Street, CHICAGO District Offices: DETROIT KANSAS CITY MILWAUKEE ST. WHAT ABOUT GRAIN SIZE? ART Which deals with various methods which austenitic grain size de- termined. Part Il, which de- scribes the factors influenc- ing the austenitic grain size, and Part Ill, setting forth the effect the austenitic grain size upon the mechan- ical and physical properties steel, will appear fol- lowing issues. NASMUCH time does not per- mit most executives, metallurgists, treaters devote many hours per day reading foreign and domestic publica- tions dealing with controlled grain size or, technically speaking, the aus- tenitic grain size steel, the writer attempts present within the scope this paper concise version grain size control. accomplish this the briefest manner, necessary divide the paper proper into three sections, which describe turn (a) the various methods which the austenitic grain size determined, (b) the factors which influence the austenitic grain size, and (c) the ef- Davenport and Bain, Trans- actions M., Vol. 1934, 879. ° ° CARL SHAPIRO Consulting Engineer, New York fect the austenitic grain size upon the mechanical and physical properties steel. Before describing the various meth- ods which the austenitic grain size may determined, seems ap- propriate this time state that mention whatever made the “in- herent grain size” steel paper. “Inherent grain size” mistaken idea. There are “inherent and “inherent characteristics” steel but “inherent grain size” since grain size can refined coarsened proper thermal me- chanical treatments. Hence, sug- gested that the term “inherent grain omitted from our vocabulary has already been done most the leading metallurgists. The various test procedures used today determine the austenitic grain size steel may classified under one the following methods: (1) Etching room temperature reveal the austenitic grain size that existed prior cooling. Etching elevated tempera- tures and observing condition that existed this tempera- ture microscopic examination room Fracture examination room temperature. The outstanding tests these three methods, which are used determine the austenitic grain size steel, are described briefly McQuaid-Ehn Carbur- Test: This test consists pack carburizing for definite period time standard temperature fol- lowed cooling slowly. The dura- tion time usually hr. and the temperature 1700 deg. The aus- tenitic grain size denoted cementitic network around the pearl- itic grain which indicates the parent austenitic grain whence originated. Further interpretation and evaluation this test are defined the Standards (Designation 19- 33T). Optimum Rate Cooling: The principle employed this test pro- cedure delineate the austenitic grain size precipitating constitu- ent during cooling the austenitic grain boundaries. This easily ac- complished hyper-eutectoid steels containing more than 0.90 per cent carbon simply air cooling from any desired temperature above the thermal critical range. This normalizing treat- ment (air cooling) rejects the excess cementite from the austenitic grains into the grain boundaries, thereby de- lineating the original parental grain. However, steel eutectoid com- position, which contains neither excess ferrite nor cementite, Davenport and Bain’ recommend an- other treatment. specimens ap- proximately one inch thickness, which cannot harden all the way through, they advocate that the specimen brine quenched, and THE IRON AGE, March 16, | | examined microscopically for grain size. The austenitic grain size re- vealed between the hardened case and core (troostite) the troostitic boundaries around the martensitic grains. the eutectoid steel not sufficient thickness yield case and core effect upon quenching, Davenport and Bain ad- vise gradient-quenching treatment which consists heating the specimen the desired austenitizing tempera- ture and quenching one end the specimen brine while the other end air cooled. this method, con- tinuous series cooling rates ob- tained and the structural conditions range from the pearlite the air cooled extreme. The austenitic grain size observed near the martensitic portion the gradient bar the troostitic boundaries around the martensitic grains. hypo-eutectoid steels, Vilella and showed that the austenitic grain size may best determined the gradient quenching treatment since the grain size may checked two methods: (1) the ferrite network, and (2) the fine pearlite (nodular troostite) around the martensite grains. Examples this new method are shown Figs. and Quenching and Etching: Another test ascertain the austenite grain size etching hardened (marten- sitic) steel reveal the parent aus- tenitic grain. This procedure involves careful polishing and etching tech- nique develop the required contrast between the grain The etchant used Vilella and Bain disclose the austenitic hypo-eutectoid, eutectoid alloy steels composed one gram alcohol. Their etching procedure immerse the specimen from sec. the above acid, repolish slight- two more times and re-etch develop maximum contrast microstructure. Although this test bringing out the austenitic grain fully hardened tempered steels, seems work best when the specimens are slightly tem- pered 400 deg. 600 deg. (200 deg. 300 deg. C.) for short time (15 min.). Another etchant which 2J. Vilella and Bain, Metal Progress, Sept., 1936, 39. Tobin and Kenyon, Transac- tions M., Vol. XXVI, 1938, Schempp and Shapiro, Trans- actions A.I.M.E., 1937. Gruzdoz and Fedorchenka, Kach- estvennaya, Stal. No. 1937, 40. Vol. 1934, 979. 26—THE IRON AGE, March 16, 1939 carbon steel. (Vilella and Bain) work very satisfactorily was sug- gested Tobin and This etchant per cent alcoholic hy- drochloric acid solution. The time etching ranges from min., de- pending upon the heat treatment the specimen examined. hardened hyper-eutectoid steels, Schempp and developed the parent austenitic grain size etching solution one per picric and nitric acid alcohol for min., washing and drying. Another etchant which worked very successfully hardened and tempered hyper-eutectoid steel was per cent solution nital (15 cc. HNO, per 100 cc. ethyl alcohol). high alloy steels such stainless and high speed steels, they found that aquaregia solution HNOs) methe- nol (absolutely pure alcohol) the proportions 1:3 gave excellent results regardless whether the material was the hardened, tempered annealed condition. Temperatures: This method de- termining the austenitic grain size in- volves the etching, chemical attack, polished specimens some cor- rosive medium such gas, liquid 0.50 carbon steel. 100 diameters. (Vi ella and ~ molten salt elevated temperature. The austenitic grain size revealed room temperature after careful polish and microscopic examination. Molten Salt Method: This test de- veloped Schempp and Shapiro‘, consists immersing polished speci- men, attached fine wire, molten chloride compound (cadmium chloride) any desired temperature for min., quenching water, washing alcohol and examining for grain size after slight repolish. The above method has recently been successfully modified various Rus- sian investigators with excellent re- sults. Instead molten salt bath, ° ° ° 1G. Jernkon- toret and Shepherd scales fracture grain size, showing them equiva- lent within the limits the black band. The circles shown here correlate these fracture grain sizes and the austenitic grain size indi- vidual samples determined the new microscopic methods. the polished specimen etched chloride gas atmosphere the desired temperature. This modification not only improves the etching technique but removes the hazards involved the handling molten chloride salts. Oxidizing Method: Another method etching elevated temperatures reveal the austenitic grain size con- sists etching polished specimens oxidizing atmosphere. This test was suggested Gruzdoz and Fedor- ished specimens placed pre- heated muffle furnace for period time, quenched, polished slightly, etched picral nital and examined microscopically for grain size. This test particularly suited for low carbon steels and may im- proved leaving moist surface upon the polished specimen, prior heating, order facilitate the oxi- dizing attack and intensify the contrast between the grain and boundaries. Method: Inasmuch the ordinary methods determin- ing the austenitic grain size cannot applied readily very high carbon steels and those which are heated above 1900 deg. F., the grain size effectively ascertained decarburiz- ing specimens any desired tempera- ture. The procedure employed very simple since consists heating the polished specimen oxidizing at- mosphere until decarburization occurs, quenching water oil, cross-sec- tioning, polishing and examining mi- croscopically after etching. The aus- Fracture Grain Size tenitic grain size read between the columnar decarburized grains and the original undecarburized matrix. The only precaution necessary read the grain size the polished cross- section decarburized specimen and not the longitudinal surface the decarburized piece. III. Fracture Examination Hardened Specimens: The last method which the austenitic grain size may determined the frac- ture examination hardened speci- mens. This test was used practically smiths and, then later, heat treaters, fractured hardened specimens order examine “the body” the speci- men. This test fractured grain size was first standardized the Swedish Iron Masters’ Association Sweden and later Shepherd America. The former employed ten fractured standards whereas Shepherd graded the fracture grain size only eight numbers. These two standards are correlated Vilella and Fig. Fracture (P-F) Test: Although this test recent origin’, has become too well known describe fully herein. How- ever, consists essentially heating definite size standards in. long in. diameter) 1450 deg, 1500 deg., 1550 deg. and 1600 deg. for min. respectively, and quenching specially designed vertical jig flushed with per cent brine solu- tion. The hardened specimens are dried, notched midway, fractured and examined for grain size comparing the fractured surface with the set standards. The fractured grain size read whole and quarter numbers, such 8%, and 6%, for the various hardening temperatures (1450 deg., 1500 deg., 1550 deg. and 1600 deg. F.). summarize the foregoing, the use the following tests recom- mended for determining the austenitic grain size various types steel, al- though individual occasions require special etching technique and modifi- cations each and every test. Low Carbon Hypo-Eutectoid Steel: The McQuaid-Ehn carburizing test recommended since denotes the grain size, the normality the steel and the coarsening temperature. Moderately and Eutectoid The gradient quench- ing treatment advocated since the most accurate and simplest. Hyper-Eutectoid Steel: general idea grain size desired, air cool- ing from above the critical sufficient. However, accurate grain size count necessary, the Shepherd P-F test recommended. Alloy Steels: high carbon alloy steels, the austenitic grain size should determined either the decarburiz- ing method hardening and etch- ing. the steel austenitic char- acter, the aqua-regia etchant ap- propriate; ferritic, Vilella’s and Bain’s etchant more suitable. The shortcomings the various methods are that they may require too long time (McQuaid-Ehn Test), fine polishing and etching technique (quench and etch method), special facilities. Ed. Note: The second part this three-part article, that dealing with the facts influenc- ing the austenitic grain size, will appear within two weeks. THE IRON AGE, March e | | : = pages from the note book Frank Garratt showing data the manufacture the country's first cutlery stainless and stainless iron May and June 1914. Although corrosion tests showed excellent results, the World War interfered with fur- ther commercial development this important series alloys. 28—THE IRON AGE, March 16, 1939 Some Notes the Early Manufacture tainless Steel the United States IRON AGE 22, 1938, carried account interesting dinner held Pitts- burgh celebrate the twenty-fifth an- niversary stainless steel. The occa- sion brought the writer’s mind his first experiences with this interesting metal, and thought that the cir- cumstances attending the melting the first small heats, and the results obtained, may interest others this particular time. During the early part 1914, the writer, who was that time charge chemical and metallurgical work for the Firth-Sterling Steel Co., Keesport, was called upoa make some non-corrosive steel being developed Harry Brearley, Thos. Firth Sons, Sheffield, England. Mr. Gerald Firth, who now president the Firth-Sterling Steel Co., was that time connected with the Firth in- terests Sheffield. had brought McKeesport 1914 some interest- ing accounts the work being done Sheffield, and requested that similar material made further investi- gate the new type steel. The metallurgical laboratory Mc- Keesport was equipped with small electric melting furnace the carbon plate resistor type that accommodated crucible about capacity, and was planned make some the new steel this small furnace. The crucible was the plumbago type, commonly used for steel melting purposes, and had clay lining pre- vent carbon contamination from the graphite the crucible. the time making the material, the optimum carbon content was some- what uncertain, and was Mr. Firth’s thought that should aim for car- bon content about 0.15 per cent the first heat. The “mix” was accord- ingly proportioned yield such fig- ure, but the clay lining the crucible cracked during the melting operation, and the metal absorbed sufficient car- bon from the crucible finish 0.34 per cent, with the chromium conteat showing 13.94 per cent. The writer has always considered curious fact that this first heat, FRANK GARRATT Vice-President and Technical Director, Universal-Cyclops Steel Corp. accident rather than design, yielded steel which today considered ideal carbon content for cutlery purposes The result could hardly improved, although the chromium slightly higher than desirable for carbon content 0.34 per cent max- lieved that this was the first stainless steel, intended for cutlery purposes, made this country. the first trial was interesting, the second was equally so. One week later, after having obtained the chem- ical analysis the first melt, another ingot was made, and order com- “pick-up” case another accident with the clay lining the crucible, was made carbon-free Swedish iron. The clay haved beautifully this case, how- ever, and the resulting ingot was found contain 0.08 per cent and 15.42 per cent chromium. The carbon content will recognized ideal for present day stainless iron, thus repeating the previous perform- ance obtaining ideal composition accident rather than design. also believed that this was the first stainless iron, intended for general corrosion resistance, that was made. Preliminary corrosion tests made annealed material from heats E546 and E550 soon emphasized the impor- tance low carbon material resisting general corrosion such en- countered domestic use and weathering, but series circum- stances interfered with the commer- cial development the stainless iron type material. The outbreak the European War late July, 1914, im- mediately resulted pressure work the McKeesport plant, and discouraged any further efforts development nature. Two pages from one the writer’s old note books showing data covering the melting heats E546 and E550 are reproduced herein. The data re- produced represent the first stainiess steel and stainless iron materials pro- duced this country. New Turbine Alloys Tested for Creep engineer the General Electric Co., recently described the creep tests which his company subjects steel used power plant turbines order determine the amount expansion and relaxation that will take place the metal during the life the units. these tests, sample rods vari- ous steels are sentenced terms long years’ solitary confinement electric furnace where con- stant temperatures high 1200 deg. are maintained. According Mr. Robinson, probable that the length the terms the rods will have serve the future will short- ened five-year maximum because the more rapid developments steel that have come with increased edge the metal make longer tests impractical. Instruments used take the regu- lar measurements changes occur- ring the metal the creep tests disclose expansions small mil- lionth inch per inch length. Steel turbine must restricted millionth per hour, changes occur from time time otherwise the turbine shell may leak, its fast-whirling rotor may get out line. Mr. Robinson states that one part molybdenum two parts tungsten will help slow down the distortion rate steel, and provided the metal given proper heat will able withstand 200 hotter temperatures result. Generous portions nickel and chromium also are desirable ingredients steel that above 1000 deg. THE IRON AGE, March 16, q 4 | | > 3 | Factors Affecting Selection equipment consists elec- cooling chamber, along with the neces- sary power and temperature control and auxiliary device for supplying protective atmosphere the furnace. The most common types brazing furnaces are the box-type, the mesh- belt-conveyor type, and hearth conveyor type. Choice the type furnace used depends upon number factors, important among which are the rate produc- tion, the weight, shape, and size the assemblies, the price the equip- ment, and the cost operation and maintenance. Just how these factors affect the choice brought out the discussions the individual types be- low. The Box-Type Furnace box-type furnace shown Fig. 82. has heating chamber inter- ° 82—G-E box- type brazing furnace used for brazing all tem- peratures 2100 deg. Work loaded trays baskets. While one tray load being brazed the heat- ing chamber, three tray loads are being cooled protective atmosphere cooling chamber. 30—THE IRON AGE, March 16, 1939 WEBBER Industrial Department, General Electric Co., Schenectady, connected with water jacketed cool- ing chamber, and refractory door the two keep the heat in. Controlled atmosphere maintained within both the heating and cooling chambers, supplied from source. End doors are provided for charging and discharging the work which moved through intermittently trays baskets. The trays rest cast-alloy rails within the heating chamber and the bottom plate the liner the cooling chamber. The cooling chambers the box-type and other brazing furnaces are generally made sufficiently long pro- vide about three times the heating period for cooling, this having been found essential for average work order cool the parts sufficiently bring them out bright. This means that the box-type furnace the heat- ing chamber holds one tray and the cooling chamber three. Flexibility Feature The box-type furnace has ad- vantage that suitable for braz- ing assemblies almost any weight— light, medium, heavy. best for low rates production, develop- mental work, because its relatively small size, but some cases multiple units have been installed increase the output. The furnaces are, course, available different capacities, typical which are ratings 50, 150, and 250 Ib. gross per hour including work and travs. These ratings are for urnace-Brazing Equipment copper brazing 2100 deg. and depend upon the ability the assem- blies absorb heat. For low-temper- ature brazing these furnaces have ca- pacity heat more work, but the slower rate heat absorption the work lower temperatures should taken into account. The box-type furnace relatively low first cost and maintenance be- cause there conveyor mech- anism involved. Another feature its flexibility. can used not only for furnace brazing, but also for bright annealing normalizing, scale-free hardening, pack carburizing. Parts brazed, bright-annealed, nor- malized are first heated, then pushed from the heating chamber the cool- ing chamber trays baskets, where they are allowed cool normal rate the protective atmosphere. For scale-free hardening, hinged-bottom trays are employed and quench chute provided the bottom the cooling Rod for pushing tray Tray being pushed from heating chamber quench-chute opening 1G. 83—The box- type furnace can used for scale- free hardening quenching parts from hinged-bottom trays through quench chute the bottom the cool- ing chamber. work into oil Tray bein Hinged pan dumps removed from discharge end cooling chamber HY, where and how use elec- tric-furnace brazing has been covered Mr. Webber previous articles this highly informative series. this article, the describes the various types fur- naces and discusses the influence production rate, size assemblies, cost operation and maintenance and other factors meeting indi- vidual requirements. chamber shown Fig. 83. When the parts the trays are thoroughly heated, the trays are pushed out the heating chamber one time over the quench-chute opening, where the hinged bottoms drop and allow the parts fall into the quenching me- dium, then the travs are pulled out Hook for pulling tray — the discharge end the cooling cham- ber. Being the protective atmos- phere the entire time, the parts have clean surfaces free from oxides and scale. Because the uniform heat- ing provided the electric heat, and the quick transfer the quench, the parts are uniformly hard and can held close specifications. The interior typical box-type brazing furnace under construction shown Fig. 84. The view look- ing down into the furnace before the hearth rails are installed and before the flat roof tile and insulating blocks are laid place. Heavy side-wall nickel-chromium ribbon resistors are shown hanging refractory hooks built into the light-weight refractory lining, and floor units the end bays are also evidence. The latter pro- vide compensation for the heat losses the ends the furnace and thus working length. Ther- mal insulation, the form large blocks slabs, backs the refrac- tory lining and enclosed sheet- steel casing welded gas tight. This brazing furnace, with the others described below, built give long life copper-brazing service about 2100 deg. but equally suitable for use with lower-melting brazing metals reduced furnace tempera- tures. typical charging cycle starts with pulling the end tray out the cooling chamber, then pulling the other two trays toward the end that empty space left next the heating cham- ber. The operator then goes the charging end the furnace, pushes the hot tray brazed assemblies into the cooling chamber, and pushes new tray unbrazed assemblies heating chamber, where remains until the parts heat and braze, the end which time the foregoing cycle repeated. Various Styles Trays Employed Trays for brazing are available number styles for different types service. For example, wire-mesh trays woven with heat-resisting alloy THE IRON AGE, March 16, ; Quench d Pan Supporting > y he furnaces. This one made such that shown Fig. are ap- plicable. still heavier loading, the ribbon-mesh trays reinforced around the rim, the bottom, both. For exceptionally heavy load- cast trays are sometimes used, the design which generally patterned best support the assemblies with which they are used. Special rods and hooks are required for pushing the trays into the heating chambers and for pulling the trays out the cooling chamber. 84—Looking into the top box-type copper-brazing furnace under construc- mesh-belt conveyor-type braz- tion. Heavy ribbon-type heating elements are hung the side walls and supported ing furnace, shown Fig. 86, built the floor end bays means refractory insulators. similarly the box type, that has heating chamber and cooling cham- ber attached, but addition wire such Ni-20 about small light-weight assemblies such equipped with conveyor with drive in. mesh and with turned-up edges those for business machines. and take-up mechanisms. Assemblies are sometimes employed for brazing heavier loading, ribbon-mesh furnace brazed are generally loaded ° ° ° 86—The mesh- belt conveyor-type brazing furnace eminently suited for tion. can used either for furnace brazing bright an- nealing, and fea- tures uniformity time, temperature, and atmosphere. | IRON AGE, March 16, 1939 fot assemblies through box-type brazing ade heat-resisting alloy ribbon. directly upon the belt which sup- ported cast heat-resisting alloy rails, grids, hearth plates the heating chamber, and the bottom plate the liner the cooling chamber. The belt usually made heat-resisting- alloy wire such Ni-20 Cr, the same alloy the ribbon resistors. The drive mechanism constructed that the belt speed can adjusted over range order braze assemblies widely different heating characteristics. The mesh-belt furnace best suited quantities greater than those practical handling intermittently the box- 87—Roller-hearth conveyor-type furnace the Kelvinator plant Detroit, copper type furnace. available num- brazing refrigerator sub-assemblies such steel-fin condensers and shells for hermetic her sizes, but heating-chamber units. Charging end. length limited the pull the load behind the hottest weakest portion the belt. Accord- expressed net pounds per square mum loadings used vary from ingly, the longer the furnace the lower foot uniformly distributed, for given net per sq. ft., decreasing the permissible loading the helt-life expectancy. Typical maxi- the heating-chamber length increases. ° ° ° 88—Discharge end Kelvinator nace. Trayloads work automatically emerge from the cooling chamber and return the charging end roller conveyor, where the trays are ferred the charg- ing table, loaded and pushed near the door shown Fig. 87. Charging automatic and self- timed. THE IRON AGE, March 16, 89—Flexible trays such this are employed for carrying assemblies through the roller-hearth. They are made channels formed from sheet alloy. Mesh belts commonly employed, using these loadings copper-brazing ser- vice, weigh about per sq. ft. For lower-temperature brazing the belt loadings increase considerably, and lighter belts are sometimes used. Typ- ical ratings mesh-belt furnaces for copper brazing are 150, 250, 500 and 700 gross per hour including the work and the conveyor. The mesh-belt furnace can con- sidered production line machine, its continuous feature providing con- trol the uniformity time during which the assemblies are the heat- ing and cooling chambers. Accessories provide control the uniformity temperature and phere. Uniformly high-quality work thereby assured. Roller-Hearth Type Furnace The roller-hearth-type furnace, such the one the plant the Kelvina- tor Division, Nash-Kelvinator Corp., Detroit, shown Figs. and has the same arrangement heating and cooling chambers the box and mesh- belt types, but differs the types conveyor and carriers. The conveyor consists series driven rolls throughout the furnace which extend through the furnace walls self-alin- ing ball bearings mounted the out- side the casing. The rolls have in- dividual sprockets driven endless chains which run alongside the heat- ing and cooling chambers gas-tight boxes. The assemblies brazed are loaded directly the roll table they are long enough, loaded cast-alloy rails, fabricated trays, made cast rails sheet-alloy chan- nels tied together such shown Figs. and 88. Fig. shows typ- ical tray made sheet-alloy chan- nels. the assemblies are small, the trays are covered with grids such shown Fig. 90. Typical ratings 34—THE IRON AGE, March 16, 1939 furnaces have been built are 500, 900, 1500, 1900, and 2200 Ib. hour including the work and carriers. The roller-hearth furnace permits great flexibility its design because there are practically limitations its length, which renders highly suit- able for large-scale production. From heating standpoint, economical operate for brazing assemblies light, medium, heavy weight. Main- tenance cost low, because the rolls last several years result the fact that they continuously turn and re-distribute their stresses, carriers have reasonably long life since they are free from any pulling pushing stresses. Its operating cost can quite low incorporating auto- matic charging and discharging mech- anisms, such used the furnace shown Figs. and 88, which makes the furnace practically self-operating. New possibilities for the use elec- tric-furnace brazing have been opened the roller hearth furnace, par- ticularly the automotive and refrig- eration industries where high rates production are encountered. Gases Used for Atmospheres Hydrogen makes excellent at- mosphere for brazing furnaces, does also dissociated ammonia, which per cent hydrogen and per cent nitrogen. The most commonly used gas for furnace atmospheres, how- ever, inexpensive mixture formed the partial combustion natural gas, coke-oven gas, butane, furnace-atmosphere controller supplies brazing furnace gases con- sisting inexpensive mixture hydrogen, carbon monoxide, carbon dioxide and nitrogen. re-forms coke oven, natural, butane propane gas partial combustion. ? Cc 0 r | . it. ¥ ’ q —— 4 i Pp e Cc e propane. This mixture contains about per cent hydrogen, per cent car- bon monoxide (both which give reducing effect 2100 deg. F.), per cent carbon dioxide, and per cent nitrogen. This gas costs only 10c. 50c. per 1000 cu. ft., and produces very satisfactory results. The machine illustrated Fig. 91, which the gas processed, called combustion-type, furnace-atmosphere controller. The ingoing gas and air pass through visual flowmeters where the ratio and the rate flow can observed glance. The gas and air then enter motor-operated mixer which positively controls the input ratio and pressure, and holds them constant regardless the load. The gas-air mixture then burned over catalyst bed combustion cham- ber, from which the products com- bustion pass through surface cooler. Fic. 90—Grid placed tray support small assemblies. Here some the moisture con- densed out before the gas goes the furnace. the heating and cooling chambers the furnace the gas forms protective atmosphere which pre- vents oxidation the work, and en- courages the brazing metals wet and the parts. Accessories are available for treating the gases they leave the furnace-atmosphere con- troller, should special requirements dictate that moisture further completely removed, the gases otherwise purified, before they enter the furnace. (TO Elasticity Cast Determined optical method for measuring the deflection cast iron trans- verse test bars the breaking strength has been developed Krynitsky and Saeger, Jr., the Department Commerce. De- flection determined measuring the distance between reference point and rubber band mounted the test bar, the deflection readings being in- dependent any movement parts the testing machine. Using the above method, three types cast irons have been investigated. The irons were heated maximum temperatures 2552 deg., 2732 2912 deg., and 3092 deg. Test bars 1.2 in. diameter were cast vertically, bottom poured green sand molds 180 deg., 270 deg., 360 deg., and 450 deg. above the liquidus tempera- ture. Transverse properties the test bars were determined interrupted loading and direct loading breaking load. From the data obtained the total, plastic, and elastic deflections, modulus rupture, relative modulus elas- ticity, total, plastic, and elastic resili- ence were determined for all test bars investigated. The load-elastic deflection curves are not straight lines for their entire lengths. The relative modulus elasticity was, therefore, determined the portion the curves, and also the breaking load. general, the lowest and highest elastic properties were observed for the maximum heating temperatures 2552 deg. and 3092 deg. F., respec- tively. These properties showed ten- dency decrease with increase pouring temperature. The microstructure the test bars was examined. Comparatively graphite particles were discovered, which are associated with higher transverse properties. pearlite-like structure observed some unetched specimens and the pres- ence large graphite particles sub- divided into hexagonal-like grains are particular interest. Sticking Weld Splatter with Coating eliminate the necessity grinding chipping weld spat- ter from the metal surrounding weld the object two new metal coatings, known and Spatter-Ex, sold Wayne Chemical Products Co., Detroit. Both these compounds are soluble water, and their application prevents the adhesion spatter either the part, dies the welding holder jaws. After the welding operations have been com- pleted, any spatter which might still resting surrounding flat sur- faces merely brushed off. The Spatter-Ex compound trans- parent and light jell consistency. and effective either arc, flash butt welding. The com- pound, which white and pigmented, largely used with resistance welding prevent the dies and welding holder jaws from becoming jammed with spatter, and with non-ferrous metals having greater heat conductivity than steel. Both compounds are said have been thoroughly tested production use and are now being used regularly axle plants, steel mills, steel drum manufacturers, auto body plants and many other the country’s major industries. THE IRON AGE, March 16, | Machine Tool ATEST addition the Heald line the No. Bore-Matic, heavy duty, precision boring machine designed for multiple opera- tions comparatively large, heavy work. There are two hydraulically ac- tuated table movements, angles each other. The front table, which slides ways parallel the front the machine, provides space for mounting either tool blocks stationary work fixtures. The rear table accommodates the boring heads and their driving motors. These heads may equipped with chucks for re- volving the work, using the front tool blocks for generated facing opera- tions for boring. Movement the front table also provides for indexing between stations. Forward movement the rear table provides the stroke for boring, turn- ing, plunge grooving and plunge fac- ing operations. Multiple operations can performed several different parts, progressive operations 36—THE IRON AGE, March 16, 1939 several similar parts. Both tables are actuated cylinders controlled single throttle but with independent control feeds, infinitely adjustable. Both tables travel rapid rate and from the work and for indexing. Two-Spindle Automatic Bar Machine NUMBER design changes have been made spindle Di-Matic automatic bar stock machine the Billings Spencer Co., Hartford, since this company took over the manufacture from the Windsor (Vt.) Automatic Co. The most important change the addi- tion independent cut-off slide, placed over the non-indexing spindles and operated the same manner the forming slide. The arrangement permits removal blades for regrinding, without the rest the tooling set-up. the model unit, with maximum capacity in. round stock, the LOSE-UP view the forming slide and newly added upper, cut-off slide the improved Billings two-spindle Di-Matic bar stock automatic, now furnished two styles, with indexing and non-indexing tool head. esign Changes NCREASES size, range and adaptability have been made nearly all classes machine tools according recent announcements the manufacturers, the largest as- semblage such digested items pub- lished date these monthly re- views. Wider universality featured several machines, including pre- cylindrical turret has two tool sta- tions. removing the indexing tur- ret and substituting simple tool slide carrying two identical tool positions, one opposite each spindle, production unit has two sizes, for and in. round stock. Forming slides are tooled, and chucking and feed catus are arranged feed through both sic sho on pumP erations gene 4 of 42 Bore Me cations os, the gacind rook we \unge an. 2 4 ABOVE new draw-in master collets and pads are designed accommodate stock the full capacity all Acme-Gridley automatics employing such ABOVE types collets. Note the changed position the holding screws. OLLET pads can com- pletely changed min. the perfected new Britain- Gridley master collets for bar stock automatics, now avail- able all sizes. RIGHT PECIAL triple broach guide set-up designed for machining the slots for the synchronizer arms Buick gear shift clutches. Broaches are pushed from the top and are guided both top and bottom, just above the machine platen. The lower holder shown counterbalanced receiver, which lowered manually the end the stroke for the broach clear the part and then raised re-engage the push-pull head. The tooling Colonial Broach Co., Detroit. cision boring unit that does many other operations besides and tool room grinder that capable any conceivable movement effect the grinding intricate tool shapes one chucking. Speed changeover exemplified new quick change collet pads for automatic bar turning machines. stop. the model machine, the collet opens and the stock fed through alternately, one spindle time, during dwell the mid-point the 180-deg. index. Quick Change Collet Pads facilitate the quick change collet pads the new master col- lets for use Acme-Gridley multiple spindle automatics, the National Acme Co., Cleveland, has located the hold- ing screw the face each pad. These screws may loosened with small hex socket wrench without hav- ing hold the tube the rear end without removing the collet. the inner end prevents complete withdrawal screws from the front, although they may removed from the back side the pads. dovetailed shoulder the pad tongue insures positive setting each pad and main- tains bearing along the full radius its collet RONT end location the pad screws also used the new precision master collets offered the New Britain-Gridley sion the New Britain Machine Ce. The two screws are designed slide the hardened and ground pad firmly into its seat against shoulder. Collet made special spring steel give the proper spring tension required releasing. patented feature the use round ° ° ° FRANK OLIVER Associate Editor, The Age ° ° felt plug each split the collet prevent coolant and chips from wash- ing back the collet seat. Further protection against chip entrance also given oil-resisting neoprene pants placed around the main body the collet. Surface Grinder ALL tracks hardened tool steel are employed control the table, saddle and spindle column travel surface grinder being marketed for the first time the Taft-Peirce Co., Woonsocket, Original- the machine was built for use the company’s own tool and gage di- visions. The special way construction said assure uniform parallel and rectilinear motions, eliminating inac- curacies that may arise from varia- tions temperature, oil film and wear the table and saddle ways. Ball bearings are also used for all rotating shafts. The machine compact size, but THE IRON AGE, March 16, 1939—37 | | | | ~ ad S, rt) built heavy proportions. The spindle column exceptionally heavy and mounted that the wheel may adjusted for depth cut with great precision. unique mounting the wheel spindle permits swivel vertical plane about the center BELOW RACTICALLY frictionless table and spindle column travel found the Taft-Peirce surface grinder, now offered the general trade. Capac- ity in.; height under wheel, 38—THE IRON AGE, March 16, 1939 LEFT HIEF innovation the improved rack-type gear finisher made the Michigan Tool Co., Detroit, hydraulic mechanism for continuous os- cillation the gear-carrying arbor across the face the rack while the rack itself moving back and forth endwise, thus distributing the wear more evenly. This auxiliary hydraulic mech- anism interlocked with the machine controls. Length stroke adjustable well the speed oscillation. heavier and hence more rigid head con- struction also incorporated, and the method supporting head slides and work arbor has been changed for bet- ter balance over the center the BELOW FOUR-SPEED precision, sensitive drilling machine, with low speed 750 r.p.m., has been added the line two and three-speed machines made the High Speed Hammer drill sizes from No. in. and the low speed enables tough alloy steels, like stainless, drilled. Top speed 6000 r.p.m. for very small drills. the wheel, thus simplifying set-up and adjustment and making possible finish surfaces with the angular face the wheel well the periphery. Plain Grinder DENTICAL features the Nos. and sizes THE Ace March 10, 1938, 36, but larger capacity the No. elec- trically controlled plain grinding ma- chine, announced the Brown Sharpe Mfg. Co., Providence. has capacity in. between centers compared with and in. respec- tively the smaller sizes. All three swing work in. diameter. Thread Grinder IKE the 48-in. thread grinders now wide use, the new 30-in. universal grinding machine offered the Jones Lamson Machine Co., Springfield, Vt., designed around the automatic wheel truing device. Accuracy thread angle guaranteed within min. the half angle, lead 0.0002 in. per in., with cumulative error not exceed 0.001 in. in. production work the machine will grind threads automatically pitch diameter tolerance 0.0005 in. The grinding wheel spindle and its driving motor are mounted cradle permit tilting the wheel corre- spond with the helix angle the thread. The wheelhead unit operates roller bearings which ride between hardened and ground rails. Speed changes for the work spindle are made through sliding gears. Positive for- ward and reverse speeds are provided for two-way grinding threads, and four independent rapid traverse speeds are provided for returning the grind- ing wheel the starting position when grinding one direction only. The adjustable tailstock includes tungsten-carbide-tipped center. Ad- justment provided for grinding slight tapers means graduated screw. Tapers combinations thereof more than few thousandths are obtained inserting hardened and ground formers, which directly con- trol the action the wheel slide and make unnecessary compensate for either lead form the grinding wheel. also possible apply formers for automatically feeding the wheel and out cuts. The m