The Iron Age 1941-05-01: Vol 147 Iss 18

Your Production Costs and Plating Problems Are Solved inthe Thomas Research Laboratory..... ELECT vin ° Eng ifle Y | j | ¥ ta The edict clear. America the arsenal that must furnish guns, tanks, planes and shells the democracies. The productivity men and machines will called upon never before. The turret lathe one the key machine tools vital this emergency. Working night and and Swasey cannot build new turret lathes fast enough. alternative is—Get more Production from the Turret Lathes you now have. There are many ways you can this: New turret and cross slide tools that take heavier cuts higher speeds; new parts for revitalizing old machines; new tooling setups; training make better operators. help you these things have increased our number field engineers, field service men, factory engineers, and operator training staff. They offer practical solutions your turning problems. Write Warner Cleveland. You CAN BETTER. FASTER. FOR LESS WITH WARNER SWASEY TOOLS MAY 1941 VOL. 147, NO. VAN DEVENTER President and BAUR Vice-President and General Manager Managing Editor News Editor Technical Editor Machine Associate Editor Editor WINTERS Art Editor Washington Editors MOFFETT JAMES ELLIS Resident District Editors CAMPBELL HERMAN KLEIN Pittsburgh Chicago Cleveland Detroit Editorial Correspondents DEARING ROBERT McINTOSH Buffalo Cincinnati FRAZAR CHARLES POST Boston San Francisco HUGH SHARP JOHN McCUNE Milwaukee Birmingham SANDERSON ROY EDMONDS St. Louis LEROY ALLISON Newark, Editorial Technical Articles Screw Machine Steels How Make Chuck Jaws Inexpensively and Case Hardening Small Polishing with Liquid Cold Glue Measuring Thickness Sheets Flux for More Efficient Tinning .... Report Open Hearth Conference Features Washington News and Market Reports News Industry ........... 108 Summary the Week The Industrial Pace ...... District Market Reports Products Advertised Index Advertisers s > DIX, Manager Reader Service Advertising Staff Emerson Findley Robert Blair 621 Union Bldg., Cleveland Herman, Chilton Philadelphia Hottenstein, 1012 Otis Bldg., Chicago Leonard, 100 East 42nd St., New York Peirce Lewis, 7310 Woodward Ave., Detroit Ober, 100 East 42nd New York Don Harner, 1595 Pacific Avenue, Long Beach, Cal. Member, Audit Bureau Member, Associated Business Papers Indexed the Industrial Arts lished every Thursday. Subscription Price: United States and Possessions, Mexico, $6.00: Canada, $8.50; Foreign, $12.00 year. Single copy, cents. and Steel Prices Warehouse Prices Machine Tool Activity Non-Ferrous Market Scrap Market and Prices Construction Steel Owned and Published CHILTON COMPANY (Incorporated) Publication Editorial and Office Executive Offices Chestnut and Séth 100 East 42nd Philadelphia, Pa. New York, U.S.A. U.S.A. OFFICERS AND DIRECTORS MUSSELMAN, President JOS. HILDRETH, Vice-President GEORGE GRIFFITHS, Vice-President EVERIT Vice-President VAN DEVENTER, Vice-President BAUR, Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JULIAN CHASE, THOMAS KANE. HARRY DUFFY CHARLES HEALE 118 119 122 124 132 é | were selected for All Door = MAHON STEEL ROOF DECK overhead Before the Wabash Railroad erected this loading dock Chicago, Mahon engineers were called and consulted. result, not only were Mahon Rolling Steel Doors selected for all door openings but insure the utmost security, firesafety and permanence, throughout, the building was roofed with Mahon Steel Roof Deck. Thus, almost the entire structure rep- resents Mahon installation. just such recognition this architects, builders and owners that placing Mahon Entire Wall Rolling Doors and Roof Deck more and more installations each year. Mahon engineers will fully explain the many More than 2500 square feet Mahon exclusive and outstanding advantages these two impor- Rolling Doors were fitted the ex- tant Mahon products. terior door openings this loading dock Representatives Principal Cities Manufacturers Rolling Steel Doors and Grilles, Kalamein and Tin Clad Doors, Steel Roof Deck and Cast Iron Roof Sumps 28—THE IRON AGE, May | The Town Full Strangers can conservatively that for every thousand new men going into growing industries, there will ten changes executive positions. The factory manager will need couple more assistants, the production engineer moved upstairs, foremen become department superintendents and the purchasing agent, hired away competitor. replaced another. goes, some moving up, some moving and some moving out. With five million new workers coming into manufacturing industry, this means 50,000 executives new positions. And half that number will our metal working industry. Twenty-five thousand new acquaintances and friends make! equivalent ringing all the doorbells Ann Arbor, Mich., Ithaca, Bill Jones went back visit the home town after three year absence. After three years big city where did not know one person thousand, looked forward spending week where knew every- MAY 1941 body. wanted see his old friend Joe, the station agent, and borrow ESTABLISHED friendly chew his plug tobacco. wanted slap the one man police 1855 force the back and ask about its seven kids. wanted say Mazie, the blond cashier the Eureka House, whom called bygone days. First thing Bill did arriving the home station was look for Joe But Joe the station agent had been drafted and there was new man his place. Even Sam, the amiable driver the ancient taxi. was gone and his place was stranger with shiny six. Driving along Main Street, Bill found that most the stores had changed ownership and carried new and unfamiliar names. And stop- ping off the Eureka House discovered that “Toots” had left town year ago get married and now had twins. father and mother had changed, too, but could still recognize them. And the first thing said them was: “Gosh, the old town full There may moral this story for some the sales and promotion executives who are slumbering the somnolent sunshine Uncle billions. the days come, when you need orders, you want find your towns full strangers. The time make their acquaintance before you have sell them. | V | | | | ! ~ ig if 4 : | | Sound Raw Material Program Leads INLAND QUALITY STEEL One the most important means used Inland produce steel highest quality program which assures continuous flow uniform raw materials. This Inland practice illustrated the great care taken selecting, mixing and blending basic iron ore. assure uniformity and continuity supply, Inland owns large ore reserves known quality. These are mined methods which avoid inclusion impurities. Every car ore, used Inland, sampled leaves the mine. When these cars are dumped into pockets the upper lake docks, the highest and lowest different elements are evened out with infinite pains blending. Further mixing occurs when the ore flows into the steamer. The ore mixed third time during the process un- loading and piling the mill. Again, when loading the skips that feed the Inland blast furnaces, the grabs that dig through the ore accomplish final mixing. Equally important are Inland’s large stocks specialty ores that allow adjustments down manganese, phosphorus, silicon and other elements meet manufac- turers’ special requirements for particular products. Throughout this program, uniformity the watchword the Inland organization. begins with the mining raw materials distant points and follows through every step the Inland process making quality steel. SHEETS STRIP TIN PLATE BARS PLATES FLOOR PLATES STRUCTURALS PILING RAILS TRACK ACCESSORIES REINFORCING BARS | term steels” very general and would cover one interpre- tation all steels cut screw ma- chines. For the purpose this article machine steels” will defined steels specifically pre- pared produce maximum ma- chinability. general, steels chem- ically made produce maximum machinability, obtain machinability the expanse physical strength. The steels fall into carbon classi- fications, medium approximately 0.30 .40 per cent carbon and low approximately 0.10 0.20 per cent carbon. There are four general plans which may followed increase machinability. (1) The addition sulphur and/or phosphorous. (2) The control micro-struc- ture. —An examination the metallurgy, physical properties and performance the commercial steels. All these data are particularly timely today with all energies now directed toward stepping production. ° JAMESON Metallurgist, International Harvester Co., Chicago (3) Cold drawing. (4) The addition lead. discussing the items the order named, must understood that the assumption that they were logically arrived plan- ning. This was, course, not the case. For instance, bessemer steel, which has very good machining properties, was made before mass production demanded fast machin- ing steels, and cold drawing was used for increasing strength and obtaining size control. might well said this point that the first three plans just mentioned reduce the plasticity the metal. machining, loss plasticity leads chip which breaks easily from the parent body (work piece). From Fig. will observed that the chip not cut but forcibly torn from the parent body. chip that breaks easily from the parent body makes for life and less power consumption. machining low and medium car- bon steels, the ferrite the micro- structure the constituent which prevents the formation free breaking chip, and also this ferrite which, when work hardened, wears the tool; its work-hardened state exerts considerable resis- tance the free passage the tool. Sulphur and Phosphorus Consider first the addition sulphur. Sulphur, when added the steel the absence manga- nese, will form iron-sulphide (FeS) which has tendency segregate envelopes the grain boun- daries. doubt this steel might machine well could rolled, but cannot rolled forged. Actually, such steel never met with, sufficient manganese al- ways added form manganese- ably iron manganese sulphide insure hot work- ability. The Fe,Mn.S, present the form inclusion. This in- clusion located the ferrite areas, shown Fig. These inclusions tend break THE IRON AGE, May 3 * i : i | q a H ie | ts | | ° ° ° | | | | ‘ : il | al 2 ; i LEFT Dia- grammatic representation steel. BELOW IG. 2—Photo- micrographs sions ferrite. Nital etched and 100 diameters. Cross section (left) section (right). 3—Photomicrographs inclusion low carbon sulphurized Longitudinal direction. Unetched and diameters. Undesirable (left) and desirable (right). 32—THE IRON AGE, May the continuity the ferrite, and make more brittle, therefore, more machinable. The silicon con- tent the steel held low percentage, for the presence sili- cates phur inclusion, makes the inclusion highly abrasive thus causing ex- cessive tool wear. The presence aluminum the steel also detrimental the tool life forms abrasive oxide inclusion. phur steel the inclusions should the type shown Fig. Now the addition phos- present steel iron phosphide (Fe,P), but unlike the sulphur does not occur inclusion but solution adds the strength the ferrite constituent and makes more brittle, thus improving machinability. duces the solubility carbon iron. The effect this will dis- cussed later. Phosphorus used such great extent this country sulphur for improving machinability. Before giving typical analyses containing sulphur and phosphorus, both, some remarks might made manganese additions excess those required satisfy the sulphur content. Manganese added high sulphur steels im- prove the strength these steels and thus offset the weakening fect sulphur. Bessemer screw stock tains nitrogen, which has some ef- fect producing good machining properties. Table gives the chemical com- position typical screw machine steels. discussing the strength the steels shown Table first con- sider the factors which affect their strength, bearing that screw steels have strength requirement well machinability requirement. The factors which cause increase the tensile strength these steels are: (1) Higher carbon content. (2) Higher manganese content. (3) Higher phosphorus content. (4) Higher silicon. (5) Lower sulphur. (6) Cold working. (7) Smaller grain size. will noted that many | \ | | | instances the analyses shown Table several factors are in- volved the same time, some working increase strength and others working decrease strength. Table shows average tensile properties steels shown Table their cold drawn condition. The loss strength due sul- phur not very noticeable di- rection longitudinal the direc- tion rolling. The greater loss occurs transverse direction. Figs. and give the results longitudinal and transverse tensile and impact tests sulphur steel, compared with those obtained from steel similar carbon content not containing over 0.030 per cent sulphur. The direction tendency evident the longitudinal microstructure screw machine steels, shown contrast the plain carbon steel that marked ferrite banding evident the steels containing sulphur and phosphorus. Experience the application screw machine steels summarized Table the low carbon screw machine steels containing sulphur and phos- phorus are often applied car- burized parts, should interest- ing consider their behavior Phosphorus the amounts pres- ent these steels does not have any appreciable effect retarding the hardenability the case. It, course, does have the same em- brittling effect the carburized case has the original mate- rial which would the core steel. Sulphur, mainly present inclusion does not affect the rate carbon penetration but again its weakening effect evident the carburized case. general, the screw machine steels not have the form carburizing properties plain carbon steels. This not due the presence sulphur phosphorus, but due the melting practice which aims for semi-killed metal. This means high oxygen content, which the element most detrimental form carburizing Fig. shows the average carbon penetration and distribution for few screw machine steel analyses. The addition manganese these IG. 4—Longi- tudinal and transverse tensile tests. steel; 0.20 0.52 Mn, 0.027 0.014 0.21 Si. sulphur-man- 0.20 1.18 Mn, 0.100 0.016 0.21 Si. Heat treatment fol- lows: water quenched from 1450 deg. F.; (2) water quenched from 1600 deg. F.; (3) water quenched from 1650 deg. F.; 1450 deg. Treated 0.5-in. IG. 5—Longi- tudinal and transverse impact tests. car- bon steel; 0.20 0.52 Mn, 0.027 0.014 0.21 Si. sulphur-man- ganese 0.20 1.18 Mn, 0.100 0.016 0.21 Si. Carbu- rized 1700 deg. for case depth 0.040 0.050 in. IG. Longi- structure screw machine steel. Nital etch, and 100 diameters. (Upper left) 0.15 0.51 Mn, 0.033 0.015 0.25 Si; 0.19 0.89 Mn, 0.122 0.014 0.06 Si; (lower left) 0.14 0.86 Mn, 0.204 0.093 0.02 Si; (lower right) 0.19 1.22 Mn, 0.241 0.017, 0.01 Si. 100 TENSILE STRENGTH test bar size. 100 CARBURIZED SPECIMEN COOLED RQ-W- tock | | ‘ ' 100 80 OV f=) | * & | TABLE Chemical Composition Typical Low Carbon Screw Machine Steels Practice Min Max. Min 0.08 0.16 0.60 Bessemer 0.08 0.16 0.60 0.08 0.15 0.70 Open 0.15 0.25 0.60 Hearth 0.10 0.20 1.00 0.10 0.20 1.00 Base Steels 0.10 0.20 0.30 Open 0.15 0.25 0.30 Hearth 0.15 0.25 0.70 steels, besides increasing the ten- sile strength the uncarburized material, improves the hardenabil- ity the carburized metal. Fig. illustrates the effect the man- ganese the hardenability carburized case. Fig. shows the relative hardenability carburized screw machine steels estimated hardenability specimen. The medium carbon steels are im- Chemical Composition Max. Min Max. Min. Max. 0.90 0.10 0.20 0.09 0.13 0.90 0.20 0.30 0.09 0.13 1.00 0.10 0.20 0.06 0.90 0.10 0.20 0.045 1.30 0.10 0.20 0.045 1.30 0.20 0.30 0.045 Silicon Under 0.08 0.60 0.05 0.045 0.60 0.05 0.045 1.00 0.05 0.045 0.30 Per cent addition sulphur. Medium-car- bon bessemer steel which also con- tains high phosphorus content not used widely. The chemical com- position the typical medium car- bon screw machine steels shown Table IV. The medium carbon which sulphur added contain higher manganese content like the lower carbon steels. far ten- sile strength concerned the un-heat treated condition, the addi- TABLE Average Longitudinal Tensile Properties the Screw Machine Steels Shown Table (Cold drawn condition, 114 in. diameter) proved machinability the Average Composition Bessemer 0.12 0.75 0.25 0.11 34—THE IRON AGE, May Tensile Properties Lb. Per Lb. Per Per cent Sq. In. Sq. In. in. Per cent 95,000 15.0 45.0 14.0 44.0 77,000 20.0 55.0 75,000 19.0 54.0 85,000 20.0 56.0 Base Steels 80,000 20.0 62.0 75,000 85,000 19.0 58.0 tion the manganese offsets the effect sulphur, although the transverse properties are still re- duced due the presence man- ganese-sulphide inclusions. The obtaining physical strength heat treatment also manganese additions. Fig. shows average longitudinal erties plain carbon and sulphurized steel after heat treat- ing quenching water 0.50- in. test bar size from 1550 deg. F., and intervals 100 deg. from 600 deg. 1100 deg. Fig. curves obtained from 1-in. round specimens quenched water from 1550 deg. The effect the man- ganese content and the effect austenitic grain size can noted tration. Control Microstructure Controlled structure impor- tant element maintaining good machining properties. When con- trolled structure spoken of, car- bon distribution, micro-grain size and hardness are included. These are controlled rolling tempera- tures and cooling rates although the grain size also function steel making. The structure aimed for coarse grain struc- ture with distribution separating the ferrite micro-con- stituent into the This true both low and medi- carbon steels. Fig. illustrates the effect the finishing tempera- tures the carbon distribution and micro-grain size 0.15 per cent carbon steel. Microstructures similar the one produced air cooling from 2200 deg. pre- ferred low carbon steels. Fig. microstructures 0.40 per cent carbon steel. Cold Drawing Cold drawing improves the ma- chining properties all low and medium carbon steels and prob- ably the greatest single factor improving machinability. also preferred because its closer dimen- sional tolerances make for ease handling the screw machines. The standard draft for cold draw- ing about 1/16 in. This draft improves the machining properties making the ferrite constituent more brittle and, therefore, mak- ing for more easily breaking chip. The effect cold drawing the r e c | ( 0.45 0.03 0.02 Open 0.20 0.45 0.03 0.02 Hearth 0.20 0.85 0.03 0.02 TABLE Recommendations for the Application Screw Machine Steels Shafts Exp. Open Hearth and The letters and the above table represent preferential groups; being the most suitable and the least suitable. physical properties illustrated Table will noted Table that the effect cold drawing the physical properties raise the yield point increasing thereby the ratio the yield point the ten- sile strength and elongation value. These are certain extent measures ma- chinability which can read from the tensile test. late there has been tendency increase the amount cold drawing increasing the draft, giving the steel further drafts, thereby increasing the amount cold work the ferrite constituent and making even more machin- able. the first place, the increase the draft from 1/16 in. in. insures greater uniformity the cold working effect from center outside the cold drawn bar. There may drop hardness from the outside the center the bar about points Rockwell “B” after 1/16-in. draft with consequent drop machining qualities. This illustrated Fig. 14. in- creased draft will minimize this center drop. With reference low carbon steels, the increased draft will also increase the surface hardness about points, from 1/16 in. draft draft. This increase hard- ness, which represents decrease the plastic flow range, brings the yield point closer strength and decreases the elonga- tion value. This makes, stated before, more brittle chip and su- perior machinability. connection with increased cold working, there may certain disadvantages such increased tendency warpage and reduction toughness, in- dicated impact tests, which may require annealing operation remove some part the cold work strain. Fig. shows what hap- pened the tensile strength when cold worked steel strain an- nealed. will noted that tempera- ture about 600 deg. there increase tensile strength. This increase remains until tempera- ture about 900 deg. reached. After this there decrease tensile strength; this decrease due recrystallization the cold worked ferrite. For the prevention excessive warpage and strength bars which have been subjected heavy draft, the an- nealing done 900 1000 deg. The exact annealing tempera- ture will, however, depend the amount cold work and the an- alysis the material. This appears opportune time discuss strain aging after cold work. Steel cold worked standard draft often improved machinability heat treatment, which consists heating 600 900 deg. for the purpose in- troducing strain effects which in- crease the general brittleness the structure. Fig. 15, will noted that there increase tensile strength about 600 deg. This due age harden- ing; age hardening said due the presence oxygen the steel, that the presence oxygen promotes the susceptibility the age hardening. Some state that oxygen precipitated the TABLE Chemical Composition Medium Carbon Screw Machine Steels Chemical Composition S.A.E. 0.30 0.40 1.35 Max. Min. Max. Min. Max. 1.65 0.075 0.15 0.045 1.65 0.20 0.30 0.045 1.65 0.075 0.15 0.045 0.90 0.08 0.11 Silicon 0.08 Max. 0.30 0.40 1.35 S.A.E. 0.35 0.45 1.35 0.30 0.40 0.50 Base Steels 0.35 0.45 0.60 S.A.E. 0.40 0.50 0.60 0.90 0.05 0.90 0.05 0.045 0.045 0.30 Per cent THE IRON AGE, May | 4 = bs | | | | | | | ' ; | TABLE Effect Cold Drawing the Physical Properties Screw Machine Steels Elongation Hardness Chemical Composition Lb. Per Lb. Per Percent Hearth Cold 72,400 74,000 18.5 47.4 0.98 156 Bessemer Cold Drawn 91,600 94,400 14.0 45.0 0.97 174 Hearth 72,000 80,000 19.5 60.7 0.91 228 Hearth 71,800 80,100 17.5 51.9 0.89 166 Hearth 77,400 16.5 62.9 0.93 153 Hearth Cold 97,900 15.0 36.4 0.95 196 Hearth Cold Drawn, 95,400 16.0 42.2 0.88 207 grain boundaries oxygen com- pound, which formulae Machinability Ratings for Screw Machine Steels plained the precipitation car- bon the grain boundaries. Others would include nitrogen and hydro- Machine- gen being factors also involved. ability any case two things are known, Rating, and they are; that steels containing 0.12 0.80 0.25 0.10 125 semi-killed steels) are susceptible working reduces the solubility carbon ferrite, and also the solu- Open Hearth bility other elements present ferrite. 0.08 0.45 0.030 0.625 0.15 0.45 0.030 0.025 The Addition Lead 0.15 0.80 0.030 0.025 cent development, although early S.A.E. X1020 0.20 0.80 0.025 1926 lead was added steel S.A.E. 1120 0.20 0.80 0.15 0.025 control grain size. The resultant S.A.E. 0.15 0.025 product was, however, lead oxide, S.A.E. 0.80 that the lead added remains lead, 0.35 0.025 which doubt greater part does. However, the fact that these steels 0.20 0.50 0.025 0.20 1.80 0.25 indicate that some lead forms S.A.E. 5120 0.20 0.50 0.036 0.625 0.20 0.80 oxide. The addition lead does in- crease considerably the machin- 0.40 0.20 1.00 crease the transverse physical prop- S.A.E. 6135... 0.35 0.75 0.030 0.025 0.20 0.10 erties does phosphorized steel. This 36—THE IRON AGE, May i | WA )\\! SS a BESSEMER STEEL .86 188 BESSEMER STEEL 284 093 COMPOUND AND SLOWLY COOLED 020 040 .060 080 120 160 .180 VALUE UPPER LEFT 7—Carbon penetration and distribution carburized screw machine steels. CENTER LEFT 8—Effect manganese the hardenability IG. carburized case. Low carbon, open hearth, fine grain steel. Less than 0.050 and 0.040 0.14 0.19 Cr, 0.15 0.25 Si. UPPER RIGHT 9—Hardenability carburized screw ma- chine steels. CENTER RIGHT IG. tensile properties plain carbon and sulphur steel after quenching from 1550 deg. and tempering shown. RIGHT curves for medium carbon screw machine steels. =x00n ” DISTANCE FROM END MELTING .79 .132 .065 COARSE OPEN SULPHUR .75 .107 O14 COARSE OPEN SULPHUR-MANGANESE 141 O16 FINE KILLED CARBON STEEL .84 025 COARSE KILLED 600 700 800 900 1000 1100 TEMPERING TEMPERATURE DEG. FAHR. YUMZOD>I fal crmsxnon 6 4 SPECIMEN RADIUS INCHES THE IRON AGE, 080 H 4 | | 4 S 020 3 | 40 02 38 38 “a | | eq | NO AH AZMODMV 100 Per INCHES 14—Cross-sectional hardness. 0.87 Mn, 0.160 0.007 0.03 Si, 0.04 Cr. ° ° IG. tests carburized specimens. cent transverse longitudinal energy ab- sorbed. p N WATER STEEL .20 .48 018 .25 SULPHURIZED STEEL 106 .060 NIL MACHINED FROM BILLET CARBURIZING TEMP. CASE DEPTH 38—THE IRON AGE, May Cold drawn (1/16 in. draft) steel, in. round; 0.19 LEFT IG. crostructure screw machine steels, illustrating the effect fin- ishing ture distribution and micro grain size. Nital etch, and 100 diameters. 126 Brinell. Air cooled from 1600 deg. (upper left), 1800 deg. (upper right), 2000 deg. (lower left), and 2200 deg. (lower right). ° ° ° RIGHT IG. Mi- crostructure desirable and un- desirable struc- tures for medium carbon steels. Nital etch, and 100 diameters. Unde- sirable (top) and desirable (bottom). AVERAGE TENSILE STRENGTH COLD 620 FORMED ABOVE sile strength mens. ° ° ° 'Sd HLONSYLS JTISN3L 700 800 900 trated Fig. 16. The ture obtained after heat treatment also more uniform. This illus- trated Fig. 17. Machinability can be, therefore, plain carbon steel without ap- preciable decrease physical prop- erties, contrast sulphur and phosphorus additions. Machining Tests machining tests, research- ers the machinability steels 96,000 | IG. tudinal core ture. Nital etch, and diam- eters. Leaded steel above; 0.20 0.48 Mn, 0.026 0.018 0.27 Si, 0.25 Pb. Sul- phurized steel be- low; 0.12 1.06 Mn, 0.212 the tool may the cause rough finish; however, rough fin- ACT! e the material, certain mate- LEFT rials tend build gather BESSEMER 150 steels for the purpose determin- ing the relative machinability. 24USF THREAD The surface finish can scien- PIPE TAP tifically recorded and classified The development scientific ma- chining its infancy, and mean time general shop experi- ence. Table one which has IG. 19—Profil- been developed shop experience ographs cover all the steels generally turned machined the cold drawn condi- have preferred rate machinabil- ity the basis tool life. doubt this the most productive scientific data. general shop practice, the method base ma- chinability pieces per hour with desired surface finish. Surface finish would include mean dimen- sional accuracy; long the tool life not excessively short, the shop satisfied. this discussion must borne mind that finish may actually dependent tool life. other words, the dulling Top bottom; rough, medium and smooth. ft ‘he tion, including low and medium carbon steels, and low and medium alloy steels. ¥ THE IRON AGE. May 1941—39 é : f | How Make Chuck Jaws Inexpensively and Quickly ITH the present shortage demands for fixtures and other tools required munition and related production, anything which facilitates such tooling and saves machine work merits careful attention. this class are the sim- fixture and related parts herein illustrated and described. Although they not relate directly arma- ment and munitions items, the same principles involved are equfally ap- plicable such items, anyone familiar with tooling will readily see. Examples here given should suggest uncounted applications which may well help many plants, now .tooling preparing for the production war and re- lated items, swing more quickly into actual production. Although the type fixtures here described and the method making them especially for small forgings, die castings and molded plastic parts which, made, are held within fairly close HERBERT CHASE dimensional limits, can ap- plied many other types prod- uct which close fitting parts are required for location and/or hold- ing purposes. necessary, how- ever, have part from which work model the part (or the critical portions it) made actual size, the process requires the casting around the piece the model alloy bismuth, called Cerromatfix, made Cerro Pasco Copper Corp. this alloy has melting tem- perature 248 deg. and starts soften about 212 deg. F., can employed only where will not attain temperature above 212 deg. service. The low melting point, however, ad- vantage handling the metal and can cast contact with wood plastic without injuring these materials. Although only Brinell, adequate for such applications are here de- scribed and the metal said not peen out under heavy service. great advantage employing casting method that the matrix formed makes close fit with the IG. partly assembled, with the die casting (which the part held for machining later) supported wooden spacers. ° ° ° | | A | | surface the piece model against which the metal cast that very little machining re- quired and what needed very simple and demands little skill. the material has the property ex- panding upon cooling contracting, most metals do), and the total change dimen- sion only 0.002 in. per in., the matrix makes close fit with the piece. some cases, possible make few hours jig which the usual machine methods would require several days pro- duce. tions herein will give excellent idea the basic method mak- ing one type fixture. The piece which desired grip securely die casting this instance) shown the center Fig. provide gripping members two mat- rix blocks are cast inside the two box-like brass castings which have square outer surfaces. the mat- rix blocks are not fit the entire outer profile the piece, they are made the required thickness nailing two thin strips wood thicker piece between. The thin strips have sawed slots spaced fit corresponding ribs the piece and channel left between the strips filled with babbitting clay. When the blocks pressed against the piece, the clay makes tight joint and the blocks support IG. blocks they appear when holding the die casting which machined. The blocks can used the jaws chuck the supporting parts fixture. the die casting and locate de- sired, shown Fig. Clamps are next used hold the box-like brass castings against the wooden blocks, Fig. Molten metal 300 350 deg. well stirred and then poured into the free space between the box portions 3—Parts mold clamped together and ready for matrix metal poured in. and the piece. When the metal has solidified, the clamps are removed and the cast matrix blocks, shown Fig. are completed. They, course, make close fit with the piece they are hold and are separated, when tight against the piece, thickness equal that the wooden block used making the mold. These openings provide plenty space for chip clearance. still simpler way accomplish- ing the same result, equivalent one, would cut length pipe, equal that the brass blocks, center the die casting this and pour the molten metal be- tween the two. When the metal solidifies, the assembly thus made could cut apart sawing. This would destroy single die casting, and would give pair matrix THE IRON AGE, Fic. 4—Matrix blocks, right and left, they appear after casting. | 2 afl blocks with cylindrical rather than square The space single saw cut or, preferred, two cuts would remove any desired thickness. Blocks made either method can attached actuating parts arranged open and close them any convenient way can used chuck with the blocks acting chuck jaws. The matrix metal, being soft, would not mar the castings and would hold them, without distortion, against shifting any direction. Blocks such those Fig. are made entirely the matrix alloy cast around brass forging and are used hold the latter while undergoes milling operation. Such blocks can cast very simple box-like mold with the forg- ing desired relative posi- tion while the cast made. separate the blocks, piece sheet metal cut with contour fit the forging used the mold the could cast one piece and later cut apart saw- ing the parting line. Blocks this type have ample compressive strength for clamping, but should bending. Jaws could even cast box retain the metal while solidifies, and then would require machining external surfaces. Such holder can also made very simply such way that blocks cast from the matrix metal for sev- eral different shapes parts can inserted required. 42—THE IRON AGE, May pieces machined are uni- form size, matrix blocks such those described have been shown stand for long use, even when employed for parts much harder than the matrix metal. Chips may embed themselves the metal, re- sulting still harder surface, but need not, general, affect the utility the fixture. very pre- cise location the piece neces- sary, however, possible insert the matrix block, when being cast, even afterward, hardened steel pins other locat- ing pieces which are highly resis- tant wear. these are put critical points, should possible locate accurately with jigs made entirely steel, but with less time spent machining. Parts which may distorted machining because they are thin section, brittle parts, such those molded from rather brittle plastics (which are easily broken not given proper support over adequate areas) can ABOVE IG. Blocks matrix metal for holding the brass forging (shown below them) while mill- ing operation performed the latter. LEFT IG. netic chuck made casting matrix metal around and between the and the wheel netic portion. readily fixtures which the bearing clamping portions both are cast fit the piece close- ly. such cases, the matrix meta] cast against the piece which does the clamping supporting, and thus sure make goot fit. well, however, provide stiff backing for the matrix metal, espe- cially considerable pressure applied. Another type jig uses matrix metal for the clamping portion which holds molded plas- tic ear-phone part steel jig while the molded piece being drilled. this case, the central portion the clamping part cast, but backed and strength- ened steel bar which provides the hinge and contacts with the clamping screw. Another type holding device made advantageously the use the same matrix metal above men- tioned the magnetic chuck Fig. this case, the metal cast around the magnetic parts and insures tight joint with them without peening, because the metal expands cooling. the bismuth alloy diamagnetic,. also serves well position the magnetic parts and does not affect their hardness. the melting temperature low. this, other cases, however, use should confined applications which temperature are maintained below point water, condition readily fulfilled when (as most magnetic chuck work) the work and chuck are flooded with coolant. Alnico and other permanent magnet materials which are too hard machined for conventional fastening are readily cast the shape needed and are held securely the chuck casting Cerromatrix around them. Chucks consisting cylindrical fla i B q 4 | a | | | I | cup that has tapered shank are readily adapted for holding square, flat, hex, fluted other pieces non-circular contour the use matrix metal. necessary only provide fixture, such that shown Fig. hold the chuck and the piece desired relative position and then fill the cup with the molten metal. When the metal expands cooling, the hole might expected enlarge, but, the walls the cup prevent radial ex- pansion, the hole cannot enlarge and the only expansion parallel the axis the chuck. Chucks made this way frequently have clamping screws and are not designed for rotation but for hold- ing the piece fixed position. However, chucks for rotation could made the same means. large chuck recently made for use rotating spindle and threaded fit the spindle instead designed hold square part which fits the recess formed matrix metal cast around such piece. Although matrix metal espe- cially well suited for forming mat- rices fit various parts, also readily employed effect as- sembly parts forming jib RIGHT Simple fixture used for holding chucks while matrix metal poured into the cyl- indrical recess and around rod which forms hole the required sectional shape. LEFT 9—Drill jig which the bushings are held larger holes matrix metal which poured into the annular space around the bushings. fixture even the parts die. such cases (as the magnetic chucks, already referred to) one several parts made some other way are locked the desired posi- tion relative themselves and/or some other member. Suppose, for example, desired make drill jig, especially one which the holes are spaced somewhat ir- regularly. convenient and inex- pensive way making such jig provide ring chase and set this plate along with drill bushings already machined and hardened. Once these bushings are set and fastened temporarily correct relative position, the matrix metal cast fill the space re- maining inside the ring. When the metal solidifies, the bushings will supported required and held securely the matrix metal. The outer ring prevents the matrix metal from expanding (except axially), hence center distances will remain desired and originally set. Another way accomplishing similar result cast plate frame, Fig. with holes cored later drilled for bushings. The latter are then set and held the holes (which are made with suitable clearance) after which the annulus around each hole filled with molten metal. When the lat- ter cools, the bushings are held where required. results could secured, course, using wrought steel plate and drilling clearance holes for bushings with- out special precautions locate them precise centers, and after- ward casting the bushing place before. Bushings should not much away from the center the hole, however, then there may some tendency for them shift slightly through the differential expansion between the thinner and thicker wall cast metal around the bush- ings. not contended, course, that the uses matrix metal the manner indicated, similar applications which the foregoing may suggest, will result necessarily the best possible fixtures jigs which can built. The process has its limitations, but also has its good points, and not the least these the saving machine work and the rapidity and convenience with which tooling can made. THE IRON AGE, May 1941—43 _ | al i é Case Hardening Small Parts IGHT case hardening wide variety small steel parts used Buick automobiles for 1941 being carried out new boasting number constructional and operating innovations. The following tabulation shows parts processed the furnace, the steel from which they are made and details the heat treatment: Clutch release yokes: S.A.E. 1010 with 1112 pins; 0.007 in. min. case. Selector shafts: S.A.E. 1112; 0.007 in. min. case. Shifter rails: X1315; 0.007 in. min. case. Shifter control levers: S.A.E. 1010; tile hard case. Pushrod lower ends: S.A.E. 1112; 0.607 in. min. case. Pushrod upper ends: 1112; 0.007 in. min. case. Valve adjusting ball studs: S.A.E. 1112: 0.007 in. min. case. Brake pedal pins: file hard case. Propeller shaft couplings: X1345; harden-no case. Flywheel ring gears: S.A.E. 1045; Rockwell teeth. Oil pump shafts: S.A.E. X1015; 0.010 in. min. Knuckle spindle nuts: S.A.E. 1112; file hard case. Clutch release lever pins: S.A.E. 1112; file hard case. Steering knuckle support nuts: S.A.E. 1112; file hard case. Oil pump idler car- burized with 0.020 0.030 case: file hard case. tockwell C40 min. case. Parts are pushed through the furnace trays, two rows which ride side side alloy steel rails resting structural cross members. Each row includes are moved pusher mechanism the charging end which exerts pressure the two trays being charged and thus moves the entire row trays and discharges pair onto the quenching fixture the discharge end. conveyor chains dogs are required inside the fur- nace. The furnace case sealed tight. fired through return bend U-tubes heated through low-pres- 44—THE IRON AGE, Moy sure gas burners. Seven burners fire each side over the charge; three fire below one side and two below the opposite side, these the front charging end the furnace; one burner fires below the charge near the discharge end. Temperatures are controlled three zones the furnace, oper- ating temperature being range 1500 1525 deg. Radiant tubes are in. diam- eter and exhaust into short vertical stacks outside the furnace either side. Trays are special design, made either hold loose charge small parts, racked charge parts, the latter supported alloy grid placed over the top the tray. Bottoms are open mesh, and sides are perforated permit ready passage the carburizing gas. The trays are kept lined inside the furnace means lips the two outside rails which they travel. Center rail has double web and flat top. Each tray carries average load about lb. Furnace capacity 1500 per hr., allowing hr. the furnace 1500 deg. Hardening gas mixture prepared gas, city gas, propane and ammonia, the following typical proportions, the hourly consumption: Prepared gas 700 cu. ft.; city gas 200 cu. ft.; propane cu. ft.; ammonia 180 cu. ft. Gas prepared patented type generator which city gas and air proportions 1.7 parts air gas are partially cracked inside alloy bottle heated externally. After cracking the the mixture passed through dehydrator and then through char- coal which builds the ratio. Gas admitted the fur- nace through three sealed inlets the side, just above the level the tops the trays. Circulation provided three power-driven fans set circular openings the refractory bottom the furnace, about in. below the tors for the fans are outside the furnace and driveshafts are sealed with bushings prevent gas leaks. the generator indicate flow rates the various gases. Ammonia tanks are manifolded, six bank, with three use one time. was found necessary use three tanks because with only one supplying gas, would tend freeze because too ‘apid flow. Gas passes through pressure regulator, with flow gaged from manometer. Pressure the carburizing gas regulated from 0.15 0.30 in. water, the pressure recording outlet pipe being located about the center the furnace, half way the sidewall. vestibule provided the charging end prevent loss gas inside the furnace. outer door opened and two trays are placed position the rails the vestibule (see Fig. 1). The door closed and inner door opened, following which the pusher mechanism starts its cycle and moves the line trays ahead one position. screw type pusher used, controlled through timeclock. Pushing cycle may varied from min., depending upon the type case desired the parts. Where specifications call for file hard case, the cycle usually set min.; where heavier such .010 in., required, the cycle lengthened min. Thus, the only variable the push- ing cycle, temperature and carbur- izing gas mixture being held fairly constant. Double doors also are provided the discharge end. two trays emerge into the discharge vestibule, set arms pulls them out onto elevator which lowers them into the oil quench tank (see Fig. 2). The cycle this elevator also controlled electric timeclock, the same basis the pusher. the oil the trays rest inclined ‘a | | H I continuous gas furnace conveyor which moves them and out the oil permit operator unload. parts are unloaded from the trays, the latter are placed inclined roller con- veyor which returns them the charging end the furnace for the 6 47. ANN next load. unusual feature the quench tank that not set the customary pit the floor, but instead above floor level, easily accessible for maintenance and inspection. This possible because the rails which the trays ride inside the furnace are in. above floor level (see Fig. 3). Other dimen- sions the furnace are: Overall height, ft. in.; inside width, ft. in.; inside length, ft. in.; available height inside, ft. in.; width outside buckstays ft. in.; sidewall thickness, in.; distance between centers top and bottom radiant tubes, ft. in. Design furnace and generator was developed Hol- croft Co., Detroit. RIGHT IG. Dis- charge end the furnace, showing the quench tank and trays coming out the oil. BELOW IG. 3—Cross- sectional di- mensions the nace. The case and vestibule are welded gas tight. top BELOW ing end fur- nace from the generator side, showing two trays entering the ves- tibule. always possible vary op- eration the furnace for special purpose. For example, propeller shaft couplings require case, merely clean hardening, the ammonia shut off when these parts are being processed and they are given heating 1525 deg. and oil quench. Polishing With Liquid term “liquid cold glue” defined meaning any glue that does not require cooking before use. This includes the ce- ments which are mainly silicate soda products built the addi- tion other materials give the final product those properties which are necessary the polish- ing room. Silicate soda has been used for many years certain classes work with good results, but general adhesive the absence certain qualities prohibits its use polishing wheel. First these flexibility. When the moisture driven off, pure silicate soda be- comes too hard for use flexible wheel. Second, silicate soda does not dry fast enough. Speed drying essential when setting wheels; therefore, this basic lack discourages the use pure silicate soda polishing wheels. However, now the manufacturers liquid cold glue using silicate soda base vary the final result obtain flexibility and fast dry- ing; thus, the main objections straight silicate soda are elim- inated, but its good adhesive prop- erty retained. Most cold glues are ready use received. preparation re- quired. The cooking glue has occasion caused difficulty, and per- fection the finished product can only obtained uniform tem- perature. The bacteria animal glue multiplies rapidly, certain temperatures, giving glue odor that not pleasant. Also, the final results sometimes vary due the fact that some plants the pro- portions glue and water used are not standardized. There are, course, cold glues the market that require the addition thinner order use them for certain sizes grain, but, gen- erally, cold glues can bought that are ready use. Silicate soda and animal glue 46—THE IRON AGE, May not mix chemically without dis- astrous results the adhesive qual- ities both; therefore, clean wheel must always used. There have been, the past, cases where wheels glued together with animal glue have split when headed with cold glue. However, the past three years, the writer has not en- countered such condition. now well established that wheels put together with cold glue have long life and are not subject splitting when used where polish- ing creates lot heat. Heat does not destroy the adhesive qualities cold glue, therefore the wheels cannot split. Sizing clean wheel when using cold glue. All the old glue and grease must raked out. For most work, cold glues with Baume deg. may used for sizing; but for hard wheels, this viscosity lowered order obtain penetra- tion. Water may used thinner. Five per cent gen- erally used with good results, al- though the use much per cent not harmful. The thinner the cold glue used for sizing, the harder the wheel be- comes; therefore, the amount water used should vary with the flexibility wanted. The thinner the sizing coat, the more penetration and the harder the head. This, course, applies only muslin, can- vas and felt wheels and canvas belts. Leather wheels need special care. Direction Travel might well mention here the first rule good polishing— run the wheel the same direction all times. All wheels should have some marking them that the operator knows which direction the wheel must run. the sizing brushed the wheel that the nap the cloth laid down, the wheel set with grain the same manner and then run the right direction, that wheel will pro- duce many times more work than wheel that run against the nap. well known that the hand rubbed against the nap felt hat piece velvet, feels rougher than when the hand run with the nap. This also holds true polishing wheel. the wheel runs against the nap, the wheel will not last long, due leverage created under the grain that tears the grain loose from the adhesive. This practice also applies the finish produced piece work. the work travels the same direction the wheel running, i.e., down, the finish smoother than the work travels against the direction rotation, up. When against the direction rotation, the groups grain are set edge and sharp grains dig into the work. When the work travels down, with the direction rotation, these groups grain are laid down with the nap and better finish ob- tained. This first principle polishing but often overlooked careless operator. true that faster cut created when polish- ing against the nap, ques- tion which the more impor- tant, speed polishing better finish and longer life the wheel. Grain Not much can said about set- ting the grain wheel. The amount cold glue applied the wheel depends the work and the viscosity the material used well the size grain. Best prac- tice, however, put well brushed down coat since coat, well applied, will last longer than heavy uneven coat. im- portant that the wheels warmer than room temperature. they are too warm, the cold glue will set quickly and not enough grain will picked up. Here again, cold glues have the advantage over ef’ of i i | | Glue hot glue. cold weather, wheels and grain must using hot glue that the glue does not become warm grain can used with cold glue hasten the and this way reduce the drying time the wheel. Drying When using more than one head grain the drying time between heads important. Subsequent heads should applied soon possible after the preceding heads that the two knit together one. the second head applied when the first just dry the touch, this second head moistens the first enough knit them to- gether. too long period passes before brushing the second coat cold glue, the chances are that there will moist layer nearest the wheel that will sealed and consequently take longer dry. Therefore, either put the second head soon possible wait until the first head thoroughly dry. Cold glue set-up wheels can dried temperatures 200 deg. with excellent results. word caution, however, about th