The Iron Age 1940-01-25: Vol 45 Iss 4

J. H. VAN DEVENTER President and Editor BAUR Vice-President and General Wanager Managing Bditor News Editor Rditor Emeritus Machinery Editor Art Editor Metallurgical Rditor Associate Editor- OLIVER Washington Editor- Resident District Editors Pittedurgh Chicago Cleveland Editorial Correspondents Lendon, England Cincinnati FRAZAR Boston Hamburg, Germany MBYER CHARLES POST Milwaukee San Francisco CLYDE ENNIs Birmingham SANDERSON Torento, Ontario ALLISON toy EDMONDS Newark, N. J. St Lowis TURNER, Ruffalo A. H. DIX, Manager Reade: Service ADVERTISING STAFF Findley 621 Union Cleveland B. L. Herman, Chilton Bldg., Phila. H. K. Hottenstein. 1012 Otis Bidg., Chicago H. E. Leonard, 239 W. 39th St., New York Peirce Lewis. 7310 Woodward Ave.. Detroit C. H. Ober, 239 W. 89th St., New York D. C. Warren, P. O. Box 81, Hartford, Conn Don F. Harner, 1595 Pacifie Avenue, Lona Beach. Cal. Member, Audit Bureau of Circulations Member, Associated Business Papers Indexed 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. Annual Num ber $1.00. Cable Address, Owned and Published by CHILTON COMPANY (Incorporated) Editorial and Publication Office Executive Offices Chestnut and 56th Sts., 239 West 39th St., Philadelphia, Pa., U.S.A New York, Y., U.S.A OFFICERS AND DIRECTORS Cc. A. MUSSELMAN, President HILDRETH, Vice-President GEORGE H. GRIFFITHS, Vice-President EVERIT TERHUNE, Vice-President J. H. VAN DEVENTER, Vice-President BAUR, Vice-President WILLIAM A. BARBER, Treasure: JOHN BLAIR MOFFETT, Secretary JULIAN CHASE, THOMAS L. KANE HARRY V. DUFFY Contents 1940 Big! Copper Cast Machining Stainless Steel Practical Annealing Alumina and Silica Refractories What's New Presses the Assembly Line Washington News THE NEWS BRIEF Weekly Ingot Operating Rates Rate Activity Capital Goods Plant Expansion and Equipment Buying New Industrial Literature Products Advertised Just Between Two Index Advertisers Copyright 1940 by Chilton Company (Inc.) 102 103 126 aw, na. 4 are rge Ost ust Int the ic- ‘ed in its ire ng ‘ Ir- 10 nt ar n, ie ~ ak : img | DEEP DRAWS present problems Ameri- can Quality Cold Rolled Strip Steel. Here typical example the way this product sim- deep drawing problems. What Material did these Manufacturers use Costs? PARTS THAT ARE LIGHT weight, tive finish and durable can made low cost with American Quality Cold Rolled Strip Steel. American Quality Steel. Note smooth, shining, finish. The products which can fabricated from our Cold Rolk Strip Steel without limit. that American Quality Cold Rolled Steel fabricates more easily and doing outstanding job many places where expensive metals were formerly used. with ease fabrication and reduced costs, this product offers variety that attract the consumer’s eye. amazing number parts can duced from American Quality Strip Steel well. The edges, tempers, finishes and widths this product available makes ideal parts that must light weight, accurate size and attractive appearance. Whether you make complete products parts can assist you planning the economical application Cold Rolled Steel your needs. Why not put your Call the man from the American Steel Company—today. AMERICAN STEEL WIRE COMPANY Cleveland, Chicago and New York Columbia Steel Company, San Francisco, Pacific Coast Distributors United States Steel Export Company, New York ¥ _ Lae 5 : f ... THE IRON AGE ... JANUARY 25, 1940 ESTABLISHED 1855 Vol. 145, No. BIG! LINCOLN had the rare gift combining wit and wisdom. friend, poking fun Lincoln's unusual height, once asked him how long thought man's legs should be. Lincoln replied: enough reach the That was practical answer. Some others, less wise than Lincoln, might have men- tioned definite number inches the proper length, forgetting that Mother Nature intended that some men should have long legs and some short ones. Today some our New Dealers are asking: large should company cor- poration permitted had Abe Lincoln with today, think that his answer would be: enough best serve the interests the Lincoln would not have been likely try put arbitrary limit the size our industrial concerns, expressed either the number men employed the number dollars business done per year. would know that the nature things, some under- takings must done large scale while others can done properly small scale. would realize that the Infinite Wisdom which created the universe saw need for size regimentation either celestial bodies the earth's creatures. Witness the differ- ence physical stature between the whale and the honey bee. Both have their uses. large should company corporation permitted the Ford Motor Co. too large, the United States Steel Corp., American Telephone Tele- graph Co., General Motors? true that you not hear such questions from the people who work for these concerns, from the customers who purchase their products and services. The chap who steps the starter button his V-8 does not say himself: would get much better car for money Ford were limited employing 30,000 men instead When you pick the receiver get long distance call the thought does not occur you that you might get better service less cost your call went through companies instead being handled one. No, the everyday man and woman are not asking that question. How big should industrial concern permitted be? Big enough best serve the public interest. And the definition that size cannot made intelligently legis- lators. best made the public which buys the product. Wire 4 ts _ AS 3, yverer ng a | “tough” draws are easily made and reject losses drop, the result greater profit. This can happen only when the right quality sheets fitted shop equip- ment, fabrication methods and product. Inland experienced metallurgists are able and willing study your problems and recommend the steel best suited your need steel that will take your “tough” draw, reduce rejects the minimum, make finer products and add your profit. your request, Inland metallurgist will call your plant discuss your problems SHEETS STRIP TIN PLATE BARS PLATES FLOOR PLATES STRUCTURALS PILING RAILS TRACK ACCESSORIES REINFORCING BARS St. Louis, Kansas City, | | | | ; Dearborn Street, Chicago Sales Milwaukee, Detroit, St. Paul, irons are undoubtedly be- coming increasing impor- tance both the engineer and the foundryman, although numerable cases unalloyed irons are used successfully. There growing tendency the part the engineer demand either special physical properties soundness increasing- intricate designs, and for both foundrymen have learned depend more and more Unfortunately, cure-all has yet been found, and until that time comes, necessary have least general knowledge the effects the individual elements order use them most economical- ly. After all, economy essential part metallurgy and good foun- dry practice. Alloys combinations alloys are worth while the foun- dry only when they can increase the profit, decrease the loss, otherwise TOM BARLOW Engineer, Copper Iron and Steel Development Association, Cleveland NLY recently has the use copper gray cast iron received much attention print even though its use has progressively grown. The function copper iron mild chill reducer and con- troller, pearlite stabilizer, strengthener and hardener are all described detail herein, this the first section two-part report. show increased economy for the foundryman the engineer. Engineers not and will not write costly specifications unless they are convinced that the increase physical properties engineering properties actually saving them monev. Likewise, the foundryman cannot use alloys un- less offsets their cost either increase the selling price de- crease the other foundry costs. Until recently, the use copper gray cast iron has received very little publicity although copper cast irons have had extensive use for many years. That the use copper the foundry has grown strictly its own merit speaks well for its value the foundryman. Nevertheless, the copper producers, who have been cooperating for the past eight years among other things, the effect cop- per alloy cast iron, have now set service and development office make this information available. From long program research Bat- telle Memorial Institute Columbus, Ohio, sufficient data are now available show what copper does when added small percentages gray cast iron. This research is, course, being con- THE IRON AGE, January 25, = | it. 4 tinued because only research that the metallurgist can keep step with the increasing demands de- signing and mechanical engineers. Mild Chill Reducer Copper cast iron essentially mild graphitizer chill reducer. Its effectiveness this regard estimated from the following relative empirical power Silicon 1.0 Manganese Aluminum 0.5 Molybdenum Nickel 0.3 0.4 Chromium Manganese, chromium, molybdenum, and vanadium have negative graphit- izing values they are carbide sta- bilizers and have effect chill op- posite that copper. Although the relative graphitizing values just given are the best obtain able and are based recent research this country and Europe, they must used with discretion, taking into account the characteristics the individual elements well the basic analysis the cast iron. For example, silicon nearly per cent acts softener graphitizer ordinary cast iron, regardless the original microstructure the iron. (This gra- phitizing effect much nounced than the strengthening effect the silicon the ferrite, but under some circumstances, very low carbon iron, the strength- ening effect the silicon can util- breaks down carbide and reduces chill, but the same time tends break down pearlite give free ferrite, thereby graphitizing all sections the casting with corresponding weak- ening effect the heavier sections together with increased perosity and resistance. Frequently, shrinkage trouble results when silicon added excess the amount re- quired maintain pearlitic structure the section involved. When silicon used graphitize thin sections eliminate chill, the heavier sections the castings are almost invariably soft- ened beyond the point pearlite and frequently show porosity. The chill reducing effect copper utilized many applications, par ticularly light castings ma- chined. For example, small pistons often difficult maintain the de- sired degree machineability the light sections and simultaneously ob- tain the required density the heavy lug sections the same casting. Cop- '“Ford Alloy Castings,” by R. H. Mc- Carroll and Metal Prog- ress, 1936 20—THE IRON AGE, January 25, 1940 4 HIGH carbon, high silicon gas furnace section containing from 0.50 0.75 per cent copper and 0.30 0.50 per cent chromium for the purpose increasing heat resistance and reducing growth under condi- tions involving rapid variations temperature. Photo courtesy Forrest City Foundry Co., Cleveland. per 1.5 per cent has proved very effective such are many similar applications which method eliminating annealing treatment gray iron castings maintain the proper degree machine- ability. When the use copper prevents scrap eliminates the neces for heat treatment, the cost the copper more than compensated heat treating costs. Pearlite Stabilizer Copper has practically effect the breakdown pearlite. Although reduces chill the lighter sections, does not weaken soften the heavy sections the same casting. has evening leveling effect that utilized castings intricate de- sign which desirable main tain uniform properties throughout the castings, regardless the changes the section size. Because copper effective breaking down excess carbide, reducing chilled corners, and eliminating hard spots cast iron, reduces the hardness light sections which would otherwise tend mottled white. the same time, pearlitic matrix cast iron and re- fines the graphite structure When copper added casting having both heavy and light sections, promotes greater uniform- itv both physical properties and structure throughout the therefore referred decreasing the section sensitivity, increasing sec- tion uniformity, the pearlitic structure. sections. quotation from recent paper and the Ford Motor which uses nearly six tons copper per day alloy steel and i } | | “% 7 | castings, illustrates the pearlite structural stabilizing effect admirably. “For cylinder blocks generally recognized that the hardness the bore must maintained high enough resist wear piston rings, and find that copper additions make such more machineable. The graphite also has more finely divided char- acter; copper has what may de- scribed stabilizing effect the graphitization carbon. This evi- find cop- per even more satisfactory than nickel for these effects and less cost.” The structural stabilizing effect copper equally applicable many other castings requiring density, ma- chineability, and uniformity, such pressure castings, pump castings, ma- chine tool castings, fly wheels, cylinder heads, sheaves, pulleys, gears. Another quotation from the paper McCarroll and McCloud’ regard 3.10 per cent carbon, |.60 per cent silicon cast iron pneumatic cylinder containing per cent copper for the purpose increasing tensile and transverse strengths, machineability, density, and decrease section sensi tivity. This casting weighs approximately 2800 and has metal sections varying from in. in. Copper raised the tensile strength from 40,000 45,000 per sq. in. maintaining transverse strength 3800 flection 0.310 in., and Brinell hardness 241. Photo courtesy Bowler Foundry Co., Cleveland. dent the diminishing chilling thinner sections adjacent more massive ones, and general tightening the structure these heavier tions. “As definite example, copper aids making sounder castings around valve ports without too great hardness the bore sections. achieve this lowering the carbon would achieve this, the other hand, in- silicon induce too much wheel castings illustrates the bene fly wheel, the sections are great that some element must introduced ‘close the has already pointed out, copper accomplishes this better than low silicon content since the copper does without sacri ficing any Chill Controller \nother application the graphit izing effect copper developed the Motor Co. also becoming increasing importance the foundry- man. This use copper typified the Ford camshaft. The prime requisite for this casting accurate control the chilling tendency give white cam tip and gray shaft without the use external chills. This done replacing large per- centage silicon copper. quote again from the paper and McCloud, “The use copper lessens any innate tendency for the swing either direction (referring quite common for the foundry oper- ate day after day without additions either the alloys ferrochromium ferrosilicon the ladle.” non-automotive foundry, this characteristic copper significant that provides means iron out and eliminate the variations chill and Brinell hardness due the nor- mal fluctuations the chemical com- position during day’s run the cupola electric furnace. For ex- ample, chilled sprockets, the use copper replace percentage the silicon promotes greater uniformity the chill depth around the circumfer- ence the casting and from one cast- ing the next. The use 1.0 per cent copper this type casting normally accompanied increase strength approximately per cent addition increase the uniformity strength single heat and from one heat the next. There are many other similar applications which the increased uniformity and better control analysis due the use copper can realized with economy. Fortunately, the low price and the ease handling copper make this entirely practical. Strengthener izing alloy such copper not strengthening agent the same extent that molybdenum, vanad ium, chromium are. However, due valuable strengthening agent applications. Copper hardens and strengthens the matrix cast iron chill reducer, does in- crease the strength somewhat. this respect, copper differs silicon, which more potent graphitizer but tends reduce strength rather drastically. this rule the use silicon primarily some and its use low- carbon irons such analysis that the strengthening effect the silicon THE IRON AGE, January 25, : ie ty? “ | the ferrite becomes importance Even these two exceptions, how- ever, silicon has tendency induce porosity the heavier portion casting unequal section. The strengthening effect copper can utilized many ways. the first place, the use copper addition cast iron percentages sufficiently great, for example, 2.5, tensile strength from 10,000 15,000 Ib. per sq. in., particularly low silicon cast iron. Presumably those percentages, the strengthening effect copper the matrix over- balances the weakening effect the additional graphite formed. Foundrymen are using copper in- creasingly combination with other elements for strengthening purposes. The ability copper re- fine the graphite, increase density, and decrease the section sensitivity, com- bined with its beneficial effect ma- chineability and chill, warrants its use formers molybdenum, vanadium, and chromium. these combinations, copper increases the 22—THE IRON AGE, 25, 1940 density, and toughness the cast iron without detracting from the beneficial effects the carbide forming elements the physical properties. The use copper combination with molybden- um, vanadium, and quently responsible for increase strength greater than that due the carbide forming element itself, from the copper alone. fact, com- binations alloying elements quently give different results than might expected from summation the effects the individual ele- ments. For example, when copper added molybdenum vanadium cast iron, apparently becomes very definite strengthening element addi- tion its effect machineability and density. This also true some- what less extent when copper added chromium cast iron, although this case, the copper almost invari- ably added for its softening and chill reducing effect. Hardening Alloy Although copper decreases chill thin sections and reduces hard spots creases the Brinell hardness and wear EAVY duty brake drum made from Grade Meehanite con- taining over per cent copper for the purpose increas- ing Brinell hardness, heat resistance. wear resistance, and This casting was ma- chineable with Brinell hardness approximately 280 anda tensile strength over 000 Photo cour- tesy Meehanite Metal Corp. resistance the heavier sections the same casting. other words, aside from the effect copper the breakdown free carbide chill, hardens the pearitic matrix and there- fore promotes greater uniformity hardness from section section. The refinement the graphite and the in- crease the uniformity the struc- ture usually result increase machineability spite the higher hardness. This taken advantage such applications pump castings, machine tool castings, sheaves, pulleys, etc., where increase the wear resistance and density desirable addition what might termed “free machining.” similar application this same effect found the copper- molybdenum copper-vanadium com- binations which high hardness and excellent wear resistance are combined with good machineability. Castings this type are usually machineable with Brinell hardness over 300. Ed. Note—Next week the author will conclude with detailed data the pro- duction, characteristics and uses ical copper alloy irons and special copper irons. General foundry practice also described. q 1 | | 4 | | | tie ral co ~ ste c ° H ( i VERY timely basic re- search the impor- tant problem machining stainless steels reported herein. Speed-tool life rela- tionships are given for turn- ing operations, very effec- tive chip control feature SUBSTANTIAL each the standard grades stainless steel finds its way into the machine shop for finishing opera- tions turret automatic lathes. Much this steel intended for prod- ucts parts which are produced large quantities—thus, the machining very important part the cost the finished product, and may decisive factor the choice the steel the source supply. examination the literature the machining stainless steel reveals deficiency specific information. Heretofore, each shop faced with production machining operation STEVENS Metallurgist and Research Machinist Respectively, Rustless lron Steel Corp., Baltimore described, grooved drill described has shown life holes against holes for conventional grind, and helpful data are presented for the most efficient thread- ing and reaming the various stainless alloys. has had start with meager precau- suppliers’ handbooks, plus its own broad machining experience, and de- velop trial and error operating technique yielding tolerable production Naturally, this experimental cedure has brought forth much valu- able experience and specific data relat- ing number materials, products and machine operations. However, these scattered data are not generally available, nor are they complete enough reliable guide esti- mating setting new job. Neither are machine operators assured that they are doing better worse than the generally accepted standard, and therefore cannot altogether confident that their costs are line. analysis problems presented the laboratories the Rustless Iron Steel Corp. revealed that questions about machining bulked large, and were diverse and scattered signify widespread need for com- parative information, well funda- mental knowledge general nature. attempting meet this need, broad laboratory investigation the machining stainless steels has been initiated which proposes evaluate the cutting qualities each the common stainless grades one more important machining operations, and discover the important factors tool set-up that control tool life and work finish. the active course the investi- gation advanced, became necessary recognize that the factors control- ling production machining rates are manifold and complex offer little expectation deriving com- plete formula for machining the stain- THE IRON AGE, January 25, 1940—23 gh | 4 ‘ tha! less steels, even after culling the liter- ature and amassing vast amount data laboratory investigation meth- ods and through experience with other steels. This led the decision that the first purpose the investigation would the accumulation specific, quantitative data relative production steels. express differently, the results were inform the machinist how set for the more common lathe cutting operations, and what tool life and production rate expect for each grade stainless steel. The Turning Test attack this complex problem logical fashion and acquire informa- tion sound, practical nature, test- ing the various stainless steels done production basis. new, heavy-duty, ram-type turret lathe has been used. (Fig. 1.) This unit was selected provide flexibility cut- ting tool application and also avoid the rigidity set-up and operating The machine tool Fig. adapted heavy duty turning, threading, drilling and forming operations. Ample power supplied hp. variable speed motor. Special reduction gears are provided for use the feed train permit use fine feeds. Sufficient versatility the machine tool there- assured permit close approxima- tion the diverse set-ups used en- gine, turret and automatic lathe prac- tices followed production shops. The turning operation, the simplest and most obvious, was chosen the starting point for systematic ap- proach understanding the machining problems stainless steels. When this selection was made, was 24—THE IRON AGE, January 25, 1940 ABOVE tur- ret lathe was em- ployed for all the test work. RIGHT IG. Roller- rest, box type tool holder with continuous chip emerging from the chip control groove. recognized that turning did not entire- represent the entire field metal cutting operations. Also, was not accepted that single turning opera- tion would represent the entire field turning conditions. Since the rigidity tool and work support vital importance, the fol- lowing summary points involved the selection tool holding and work supporting apparatus given. box- type tool holder (Fig. 2), equipped with roller-type back-rest was se- lected provide rigid support the work piece. The cutting tool rigid- clamped position heavy cut- ter-block. The cutter-block and the roller-rest are rigidly held inte- grated unit the frame. This unit amply designed withstand heavy stresses and the lim- ited dimensions incorporated provide extra rigidity support. The cutter- block also holds the cutting tool ap- propriate angles distribute cutting loads the top and side gibs which support the ram. This holder stock item. Its selection did not depart from the policy holding closely possible production conditions. Heavy construction and short, rigid design the box-holder allows only limited space behind the cutting tool for chip disposal. This difficulty overcome when deep cuts are made placing chip control groove the top face the cutting tool produce continuous chip, which re- moves all the metal displaced. the course investigation, was discov- ered that the chip control feature was closely tied with the method grinding the cutting tool. Chip con- trol grooves also are used produc- tion practice connection with box- holders. The cutting tools used were made 18-4-1 high speed steel. This material was selected for initial consideration because its widespread use and Data relative this material are sum- marized Table not assumed that carbide and non-ferrous types cutting tools are not worthy consid- eration, but since they are not wide- used high speed steel, investiga- tion their cutting characteristics would need deferred. The mechanical conditions the test procedure were arbitrarily chosen from the wide field turning condi- | H | > rd a ' | TABLE Summary Data High Speed Cutting Tools Analyses: Heat 0.715 0.22 0.720 0.28 0.705 0.26 Heat Treatment: 0.020 Trace 0.31 0.020 Trace 0.28 0.017 Trace 0.26 17.68 4.00 1.02 17.88 3.97 0.97 18.20 4.00 1.03 All the tools were heat treated preheating temperature 1550 deg. F., quenching oil from 2340 deg. 2350 deg. F., and drawing 1050 deg. The tools were held the drawing temperature for hr. Hardness: All tools had Rockwell hardness numbers 67. tions presented. They were selected represent shop practice and estab- lish initial basis comparison for the cutting qualities stainless steels. One-inch round bars were selected for tests since such size large enough for heavy turning and easily obtained. The depth cut was fixed 0.25 in. This heavy cut, but not heavy prevent combining rough- ing and finishing one cut. Feed was set 0.0075 in., fairly coarse feed, requiring considerable power and imposing medium high sures. The length cut adopted was 5/16 in. This length was selected because was found that turning longer pieces considerable quantities heat were, some cases, stored the finished work and might influence the tests degree. viscous commer- cial mineral oil containing about per cent vegetable oil, per cent ani- mal oil and per cent sulphur was Ly 3—Cutting tool with chip con- trol groove. used cutting This oil was cut 1:1 with paraffin oil make the cutting compound. realized that this mix probably does not represent the usual shop conditions, but was selected provide initial basis comparison for studying effects varying cutting oil mixes. Fig. shows the shape and fmish the com- pleted work piece. The basic shape the turning tool was evolved several preliminary runs. tool ground tool grinder that each angle and detail can measured and duplicated. De- spite fairly exhaustive preliminary investigation evolve the optimum tool, may that the precise form chosen not the single best one, and quite possible that considerably modified form will developed later for different conditions feed, speed and depth cut. The important tool angles and dimensions are listed Table and illustrated Fig. point which the cutting tool ceases cut satisfactorily based com- mercial practice and operator’s judg- ment. When the cutting tool placed the tool holder, set 0.010 in. advance the roller-rest. Cutting started and continued until the rolls just begin drag the shoulder the test piece. This setting has been adopted the result operating and testing experience, which has shown that 0.010 in. wear the cutting edge the maximum amount that can expected with maintenance factory cutting conditions. performance tests, tool failure where the periphery the work piece and the front clearance side the tool met. (Fig. 6.) After certain cutting time elapses, minute frag- ment the cutting tool chips off the place mentioned. This chipping may take place two ways. First, the chipping may occur the front clear- ance side the tool land. When this . happens, tool failure follows shortly. Second, chipping may take place the groove side the cutting tool land. this case, the chipping does not materially affect the cutting ability the tool, and cutting continues until the chipped-out portion abraded through the front clearance side the land. When this type failure progress, there possibility that the first type may occur before the second has exerted its full influence. Consequently, all tools were under careful observation and these phenom- ena were closely watched. All figures given herewith are based the first type failure which occurred most rapidly and hence was considered the most severe condition. Observations the mechanism tool failure commercial practice showed identical with that met testing. result consultations with several shop supervisors, operators and principals, the standard tool life hr. per grind was adopted repre- sent commercial opinion. was realized that unless extremely variations speed were used the pos- sibility obtaining absolute 5-hr. tool life was remote. Consequently, runs were made peripheral speeds which produced tool life approximat- ing the 5-hr. figure. each case, the data were carefully preserved and sub- jected analysis ascertain the prop- speed-tool life relation and main- tain check the accuracy and control the tests. Data speed-life relations for given speed 4—Test piece the type used turning tests. THE IRON AGE, January 25, | j 3 | ‘ < ‘ > - kane angle Top View rake angle Back rake clearance Front cleara angle angle Front View Side View cutting tool, showing normal type failure. F's. 5—Cutting tool working angles and chip con- trol groove details. under the cutting conditions already mentioned. These data were analyzed points, the line plotting tool-life minutes ab- ipheral surface ft. per min. ordi- this method number experimentally determined may located and deviations may readily scissae against cutting speed noted. Data accumulated and analyzed are life values given analysis over those obtained for annealed material, with the single exception the type 440 steel—and that the abrasive quali- ties steel are observable indicat- the varying slopes the curves —the steeper slope indicating the more abrasive material regards its effect the cutting tool. These curves also nates log-log paper. Since the life-speed relation expressed will have straight line type curve when expressed logarithmic form. Consequently, with sufficient Table III and shown Fig. These data show that the ma- chining quality given material primarily dependent the analysis, that cold drawing will raise the speed- indicate proper speed-life relations for tool-life other than hr. and they are given cover the range 6-hr. tool-life. They also show the relative machin- ANNEALED MATERIAL BRINELL HARDNESS 180 Cutting speed, surface ft. per min. ft. per min. 150 200 250 300 350400 100 150 200 250 300 350 400 Tool life, minutes Tool life minutes Tool life, hours Tool ABOVE FIG. Relative cutting speeds stainless steel; in. depth cut, 0.0075 in. feed. Chip curler cutter, box tool holder, sulphur-base cutting oil. Type 430F, Rustless free machining grade: 0.12 max.; Cr, 14.00 18.00; Ni, 1.00 max.; and 0.15 min. (2) Type 416, Defirust machining grade: 0.15 max.; Cr, 12.00 14.00; Ni, 0.50 max.; and 0.15 min. (3) Type 410, Defirust grade: 0.15 max.; Cr, 12.00 14.00; Ni, 0.50 max.; and 0.04 max. 26—THE IRON AGE, January 25, 1940 (4) Type 303, Defistain machining grade: 0.20 max.; Cr, 18.00 20.00; Ni, 8.00 10.00; and 0.15 min. (5) Type 302, Defistain grade: 0.12 max.; Cr, 18.00 22.00; Ni, 8.00 12.00; and 0.40 max. (6) Type 420, Rustless 13-HC-35 arade: 0.40 max.; Cr, 12.00 14.00; Ni, 0.50 max.; and 0.40 max. (7) Type 440, Rustless 17-HC-90 grade: 1.10 max.; Cr, 14.00 18.00; Ni, 0.50 and 0.40 max. | | 250 COLD DRAWN MATERIAL BRINELL HARDNESS 180 220 200 | Land Grooves ABOVE 8—Chip control groove applied drills. ° RIGHT 9—Tangent type chaser and die head. ing levels the standard Rustless grades. order cutting speed per given tool life, the Rustless straight chromium stainless irons—type type 416, and type 410—rank highest order given while the Rustless chro- mium-nickel stainless steels—type 303 and type 302—rank next and the Rust- less straight chromium stainless steels —type 420 and type 440—stand last the rankings. applying these data grades made other stainless pro- ducers due allowance should made for variations introduced the differ- ent melting and processing practices involved. Chip Control Feature Since the chip curling type tool removing considerable vol speeds while maintaining long tool life and tolerable finish, explanation this performance was sought order that the use the chip curling feature could extended. was observed, testing that the built-up edge common encountered cutting tools was entirely eliminated. This, believed, due the fact that the use the land, inherent this type grind, promotes dragging action metal being cut, thus producing em- brittlement the metal advance the cutting edge through cold work- ing. This grind also introduces steep rake the immediate region cutting, which tends relieve the ef- fects severely work-hardened and hot chips dragging over the tool face angle promoting maximum fric- tional effects. The groove itself placed the tool force the chip curl into helical coils, and lieved that the contact the chip and the back portion the groove pro- motes lifting effect the chip which tends also relieve tional effects the cutting tool. Drills This chip curling feature was ap- plied drills. Two grooves were ground the flutes drill parallel the cutting edges. (See Fig. 8.) TABLE Summary Cutting Tool Angles and Dimensions Tool size in. Tool holder angles Longitudinal Transverse deg. Working angles Back rake angle deg. Top rake angle deg. negative Front rake angle deg. Side clearance angle. deg. Front clearance angle deg. Chip curler angle ... Chip curler details—tool angles and sions Width land 0.010 in. Chip curler rake angle deg. Chip curler groove Width chip curler groove* 3/16 in. Radius chip curler groove* in. Radius chip curler plane emerg- Trailing edge point maximum emerg- ence chip curling deg. Measured in. back from tool tip. The drill was standard diame ter stock item. Tests were made cold drawn, round, 18-8 free ma- chining stainless steel. The drill was operated surface ft. per min. peripheral speed and 0.0075 in. feed per revolution. The hole drilled was in. deep and the drill was not backed out the course drilling. Sulphur-base cutting oil was applied methods common turret lathes. The grooved drill made holes against for the conventional grind before the drills failed. Concurrently, drilling time was reduced per cent with the grooved drill. These drills were later checked drill-torque machine and the grooved drill showed much lower torque rating than the standard drill. Forming Tools The chip curling feature can also applied forming tools. particu- larly effective the 18-8 types stainless steel. Forming tools, how- ever, are very often governed their shape and certain cases this chip curling grind impracticable. Practical Observations the course routine laboratory work many questions relative form- ing, threading, tapping and reaming have arisen. has not been possible the present engage exten- sive studies these phases the ma- chineability problem. However, these questions have arisen, tests have been devised provide means settlement. Due the lack sys- tematic approach and the broad scope these problems, not possible THE IRON AGE, January 25, a 4 ) ONE 4) discuss these tests detail without in- troducing infinite quantity small details. The findings these tests are summarized and presented here in- dicate the type preliminary work that leads the adoption testing program. Tool Materials general, tools made high car- bon tool steel have been unsatisfactory for cutting stainless steel. High speed steel and cobalt high speed steel have given satisfactory service with stain- less. Carbide and certain types non- ferrous alloys have also given prom- ise, but their adoption should made only after careful consideration the operation involved. Threading threading applications, the tan- gent type chasers (Fig. 9), perform very well, particularly with the larger sizes. These chasers can ground with steep lip angles which aid elim- inating built-up edge. Lip angles deg. have been successfully used all the stainless grades except the type 430F grade. This latter grade requires lip angles deg. Hobbed-type chasers have also proved satisfactory. (Fig. 10.) However, the maximum angle obtainable with safety deg., which will thread all the stainless grades with the exception the type 430F which requires 10-deg. lip angle. Hobbed chasers have also been valuable obtaining smooth threads since the chaser fol- lows the contour the thread. either case the production smooth threads demands low threading speeds and sulphur base cutting oils cut 1:1 5:1 with paraffin oil according the 28—THE IRON AGE, January 25, 1940 IG. type chaser and die head. demands the job. Peripheral speeds from surface ft. per min. for the free machining grades and surface ft. per min. for the other grades have been satisfactorily used connection with sulphur-base cut- ting oil diluted 1:1 with paraffin oil. When tapping applications have been encountered, high steel, ground, and relieved thread taps with 15-deg. hook grind have been found successful. (See Fig. 11.) thread tap, cross- section. The relieved thread tap, however, has tendency cut slightly larger than concentric thread tap. Gun taps are best suited for tapping through holes Since these taps throw the chips ahead the tool, they are not suited tap ping blind holes. Three four flute taps have been found satisfactory for tapping blind holes. Two and three flute taps are suggested for use screw machines sizes in. cases where 15-deg. hook grind the regular tap fails per- form satisfactorily, interrupted thread taps with uneven number flutes have been found help since they require per cent less power than the regular taps. is, general, inadvisable tap more than per cent the full thread. has been found helpful, particularly the straight-chrome and free machining types, use negative grind the heel the tap, prevent taps from tearing the threads when backing out. essential use ample quantity good sulphur-base cutting oil with 1:1 5:1 paraffin oil when tapping. The mixture required depends the job and the thread quality demanded and, course, should determined experiment. Taps should always sharp and alinement with the hole order prevent breakage. Drilling Drills for general use with stainless grades should have heavy web and short spiral with point included angle 118 deg., lip clearance deg. the case the chrome- nickel grades, the grooved drill just described has found successful appli- cation. Occasionally, instances are found, particularly the smaller sizes, where the standard drill will not work satisfactorily. This difficulty has been overcome the use the cotter pin type drill which has smaller helix angle. The use this device increased chip clearance and freedom the drill flutes. has also been found the case drills 3/16 in. and smaller diameter that modification the clearance angle will help. This modification made first grinding the drill the conventional shape and then regrinding the portion adjacent clearance. (Fig. 12.) This device utilizes the principle primary and secondary clearance applied mill- ing cutters obtain strength and last- ing the cutting edges. some cases where severe drilling conditions have been met drilling the chrome-nickel clearance angle Secondary clearance angle clearance angle drill. As ted ae nm : ( e / 7 \ Concentric | | ‘ | 4 ‘4 q q 4 | bearing grades, has been found ad- vantageous increase the point in- cluded angle from 118 deg. 130 deg. The use sulphur base cutting oils necessary drilling operations achieve optimum drill performance. Due the wide variety feed, speed and other conditions general practice, has not been found advisable make general recommen- dations drilling speeds, but at- tempt devise methods solve the specific problem hand. Reaming Reaming speeds are also governed the quality demands the finished product. has been found necessary reaming the chrome-nickel grades leave ample metal removed order permit the reamer continuously and protect against rapid wear and failure. has been found, however, that the free machin- ing grades can reamed speeds ranging from 120 surface ft. per min. while the ordinary grades may reamed speeds ranging from surface ft. per min. Conclusion Results obtained controlled cutting tests have indicated that defi- nite influences are exerted the com- TABLE Relative Cutting Speeds for Stainless Steels Cutting conditions: Depth cut Feed per revolution Cutting tool Cutting tool holder Coolant Type Grade 430F Rustless 416 Defirust machining 410 Defirust 303 Defistain machining 302 Annealed Material position and processing irons and steels with regard the cut- ting-speed tool-life relation. Data ob- tained have been sufficiently encourag- ing justify further extension the work estimate the effects varying the feed, depth cut, method tooling and cutting arrive quantitative information that will di- rectly aid the shop man and the same time aid establishing well- applications where high tensile, high hardness, and deep hardening alloy desired, and where large sections uniformity hardness from the surface the cen- ter sought, the Joseph Son Co. has developed new alloy Ryerson called H.T.M. This steel chrome-nickel-molybdenum alloy, con- taining 0.35 0.45 carbon, 0.50 min. manganese, 2.0 min. nickel, 0.90 min. chromium and 0.40 min. molybdenum. The alloying elements are said steel. balanced permit the develop- in. 0.0075 in. Chip curler type Roller-rest box tool per cent sulphur-base cutting oil cut with paraffin oil. Cutting Speeds for 5-Hr. Tool Life Cold Drawn Material 137 137 116 123 S.F.M. 105 S.F.M. 114 S.F.M. 105 S.F.M. S.F.M. S.F.M. S.F.M. S.F.M. S.F.M. rounded and balanced machineability test. Study the chip control features has yielded information practical value obtaining increased tool life and production rate for certain types tools, particularly drills. Prelimi- nary studies tool materials, thread- ing, tapping, reaming, and drilling tools and methods have also yielded in- formation highly practical and di- rectly applicable nature. Steel ment high hardness with either oil quench air cooling. Ryerson also claims that H.T.M. machineable under ordinary shop conditions after being hardened more Typical physicals round samples are shown the table. Air from 1650 deg. Elongation Draw Tensile Strength Strength in. Reduction Brinell quenched 311,000 159,000 0.5 1.85 578 700 241,000 215,000 37.0 477 900 205,000 184,000 13.5 42.0 415 1100 158,000 137,000 14.0 53.0 Oil quenched from 1550 deg. 700 237,000 207,000 11.5 205,000 194,000 13.0 158,000 142,000 18.0 44.0 461 44.0 415 58.0 321 THE IRON AGE, January 25, 1940—29 ng as @ | ; | 900 | A | \ al this, the second section two-part article, the au- thor tells the annealing ac- cessories now use for the control temperature and the preparation and control atmosphere, and also de- scribes the characteristics direct, radiation and convec- tion furnaces. Last week, data sidered annealing the con- trol temperature. The use temperature control instruments too well known require any elabora- tion, nor the author concerned with their various types and mechanisms. However, controlling the thermal treatment annealing, should directed the suitability application the particular operation being performed. must remembered that the in- strumentation temperature control involves affecting thermocouple bead which necessarily the focus heat waves its immediate vicinity. The temperature indicated therefore that certain restricted area the laboratory the heating chamber—it 30—THE IRON AGE, January 25, 1940 Research Director, Surface Com- bustion Corp., Detroit were given the various an- nealing methods use, en- veloping atmospheres, etc. These data were first pre- sented Dec. the sym- posium the cold working metals sponsored the Metallurgy Department the Carnegie Institute Technology. may have but indifferent relation the temperature which the work itself being subjected. For sake illustration, consider pile several tons sheets being annealed box annealer. thermo- couple placed point the fur- nace between the heating elements and the stack sheets. During the first part the heating cycle, the heating elements will appreciably hotter than the temperature indicated the instrument, the bead the couple affected the low temperature the adjoining work. When the edge the stack finally reaches tempera- ture near but somewhat below that which the controller set for, the couple now more readily affected the higher temperature the heating elements and rises its set temper ature, reducing the supply The heating elements their excess heat the stack, the temperature drops and once more heat turned on. This goes until the edge the sheets has reached the set temperature. The input heat has now been considerably decreased, yet the annealing operation far from completion. While the edges the sheets were coming temperature, there was constant flow heat conduction the center the pile, this flow being direct function the con- ductivity the steel and the differ- ence temperature between edge and center. obvious, therefore, that the wider the sheet the longer heat has travel from the edge order equalize the temperature through- out the mass. therefore, will elapse before such equalization can reached, and nothing can done hasten the operation provided that the heat input and the radiating sur- face the element adequate the requirements the mass being nealed. other words, there can thermal head applied without over- heating the edges the pile. The very opposite this operation - | | | i | ¢ | ° ° | | | | | | : 7 | ° ° ° 2 | 7 7 4, the process continuous sheets are caused progress rapid rate through the furnace means the control the heating elements they are bracketed into zones, with its own instrument. The control temperature now set point high the furnace structure mechanism will reasonably stand with out regard the temperature which the sheets will heated. The control temperature sheets themselves will the speed which they will travel through the several zones and may practice much 200 deg. lower than the set furnace temperature. well remember, therefore, that considering temperature its control, metallurgists should exercise care predetermine both metal tem perature well time cycle, leaving the practical annealer devise the equipment and establish the prac tice which will produce called for without necessary any set temperature the control instruments. The several factors the operation will determine what this set temperature should be. regard With understanding the Two radiant tube controlled atmosphere furnaces for annealing and normalizing cold rolled strip continuously. ous the annealing operation, one purpose of this article should translate these terms equipment necessary for practical attempt will made evaluate the merits various equipment now available. utilization. pointed out, considerable dif ference opinion exists the ready equipment best adapted secure particular would impossible to do justice to the subject the brief span this article. ature available those delve more deeply into it. Yet, this However, there ample liter would incomplete without sketching the paper means which practical annealing applied. Equipment Used Mention was made last week mechanism annealing its simplest form—the application open flame structure. Next, order simplicity, the batch annealing fur nace. might well point out this time that not here intended the means available for heat Solid, respective merits liquid and well electric energy all play part the art practical annealing. application and the economics their utilization have pounded numerous occasions. For sake simplicity and from the fact their wide distribution and use, tention will confined furnaces utilizing the readily available natural and purified coke gas. diagram furnace directly fired fuel gas shown Fig. metal refractory with refractory hearth supported spaced refractory piers, and with burn- ers firing between these piers alter- nately opposite directions and burn- ers similarly disposed the arch and firing tangentially thereto. tory lined closure disposed one end providing entrance for charge work. This method firing pro- vides for rapid circulation the gases which, their sweeping action over all surfaces the refractory lining, tend impart their heat uniformly the lining and the work placed the hearth. thermocouple placed the center the furnace and disposed between burners avoid impingement will in- THE IRON AGE, January 25. | he dicate within practical limits ac- curacy the true temperature the laboratory working space the furnace. When furnace temperature, which meant that the only fuel input required that necessary take care its inherent loss radiation, the door opened, charge work placed the hearth and the door closed. Immediately the furnace tem- perature drops due rapid radiation the refractory lining