The Iron Age 1944-06-01: Vol 153 Iss 23

President and Editorial Director Editorial and Advertising Offices East 42nd New York 17, Editorial ° ° ° Business Managers Technical Articles Owned and Published CHILTON COMPANY (incorporated) | Features 7 estnur an $s. A bl Li 66 ssembly Line Philadelphia 39, Pa., U.S.A. OFFICERS AND DIRECTORS West WILLIAM BARBER, Treasurer JOHN BLAIR Secretary JULIAN CHASE THOMAS KANE News and Markets Member, Audit Circulations Ammunition Container Program Export Excess Steel Pricing Iron and Steel Institute Meets Excess Tool Scrapping Flayed Member, Associated Business Steel Casting Output Machine Tool News 140 Non-Ferrous Metals News and Developments 142 Non-Ferrous Metals Prices; Scrap Prices 143 Iron and Steel Scrap News and Prices 144 Comparison Prices Year 146 ond U.S Steel Pipe and Tubing Prices re. Wire Product Prices 151 Pig Iron and Coke Prices Railroad Material and Stainless Steel Prices 153 ° | ° ° Index Advertisers 223 | - | Positive All Ryerson oys Confirms Quality ..... Prevents Shop Errors Each bar alloy steel Ryerson stock painted the receive. This gives you reliable information for heat end indicate the type alloy and then stamped treatment that will produce the desired result. the side near the end with the number the heat This unique and valuable Ryerson alloy service one from which the bar was rolled. Smaller size bars are many reasons why will pay you concentrate your bundled and tagged with similar identification. steel purchases with us. This important you, because offers unmistak- Joseph Ryerson Son, Inc., Plants at: Chicago, able means verifying the alloy steel you receive from Milwaukee, St. Louis, Cincinnati, Detroit, Cleveland, Ryerson. Also, both heat number and color marking are Buffalo, Boston, Philadelphia, Jersey City. recorded the Ryerson Alloy Steel Report that furnished with each alloy shipment. The Report Sheet contains accurate data the analysis, working temper- atures and the heat treatment response for quenched and drawn and inch rounds the steel you June 1944 VAN DEVENTER President Editorial BAUR and General DIX Monoger, Reader Editorial Associate Editors WINTERS LLOYD BARMASEL Assistants SCHIEN WILLIAMS ROGERS News and Technical CAMPBELL Pittsburgh 428 Park Bidg. POST Chicago 4134 Otis Bidg. MOFFETT DONALD BROWNE EUGENE HARDY Washington Press MacDONALD Cleveland 1016 Guardian BRAMS Detroit 7310 Woodward Ave. OSGOOD MURDOCK Francisco 1355 Market St. Editorial Correspondents ROBERT Cincinnati PENLEY Buffalo FRAZAR Boston HUGH SHARP Milwaukee SANDERSON Toronto, Ont. RAYMOND KAY Los Angeles JOHN McCUNE Birmingham ROY EDMONDS St. JAMES DOUGLAS Seattle Compulsory Maintenance Customers HEN men and women look the compulsion law obtain for them economic ends that can only won hard work and merit, they are barking the wrong tree. Nearly every one, for example, would like have larger income. There are some exceptions this this era confiscatory taxation but they are few But passing law double every- one’s income would futile spitting against hurricane. Customers must won merit and kept merit. And customers determine the incomes those who serve them, whether they doc- tors, lawyers, employers factory workers. this basic truth, and fundamental and unfortunately disregarded are often the Ten Commandments, lies the fallacy the idea the guaranteed annual wage. not know any employer who would not delighted able tell his employees: “Your jobs and your wage rates will stand for the next twelve months.” some few instances and lines where day and day out demand has been traditionally constant, has been pos- sible this. But it, the employer has able see year ahead and know several things with considerable assurance. has know that will have many customers for much sales volume next year this, that productive efficiency will least remain constant and that unlooked for administrative regulations will not introduced hamper his operations. The man who can see year ahead under today’s conditions would indeed seer without peer. would several degrees ahead the celebrated mythical people who “see things under beds that are not there.” The employer looks under his bed and finds something. Some which him are bad finding Huns. Undecided Govern- ment policies with regard contract terminations and undecided pol- icies with regard the disposal the huge prospective surplus Government bought and owned capital and consumer goods. Undecided policies taxation the immediate postwar years and undecided prospects whether he, the National Labor Relations Board, the War Labor Board the unions are going run his business. So, faced with the demand that guarantee employment for present forces present wages, comes back the meat the coconut. “Who going guarantee buyers for product? done law?” Then merit and service and the asset superior products out the window. And with them the urge and the in- centive initiative and advancement. If, instead selling products their merits and thus cultivating and holding customers are henceforth going Government fiat and subsidy financed mounting debt, the honest thing would put the electorate. Ask the people this country the coming election: “Do you want guaranteed employment? there only one employer who can give you and that only long the money lasts. And when you accept that you have accept also State Socialism, Fascism Communism which are three different labels for the same poison.” Don’t afraid offending your employer you choose the af- firmative. Most employers are fed administration blunderism that they would glad hand their business over and fishing. ees Pap Technical | | | | j This only one the many remarkable war records being made Inland Ledloy. the case history Ledloy used for the manufacture mm. shell Canadian munition plant. Experiences like this led rapid in- crease demand for Ledloy before the war. Today, all the Ledloy that Inland makes going into millions shell and Sales Offices: Kansas City 25% Less Scrap 22% More Production 50% Longer Tool Life Inland lead-bearing, faster machining, low unit-cost steel. INLAND STEE Dearborn St., Chicago Ill. Canadian and British manufacturers use Inland Ledloy speed war production. many parts for war equipment ing faster production, lower unit cost, and great savings critical cutting tools. When peace comes Inland Ledloy will again available for general manufac- turing use—helping produce finer products lower cost—products that can priced attract the most buyers. “Foreign LIMITED, Cannon Street, LONDON. Sheets Strip Tin Plate Bars Plates Floor Plate Structurals Piling Rails Track Accessories Reinforcing Bars COMPANY Milwaukee New York St. Louis St. Paul gi News June Much the success the jet airplane and the newer gas turbines due the improvements the field special alloys for withstanding dynamic stressing high temperatures. data composition and performance are still hush but new types high temperature testing like were developed find the high temperature load carrying ability the alloy. refuting the USWA claim that the steel industry can plan its operations per cent its production can based anticipated sales, Kemp Fuller pointed out that were this possible, would entail additional capital investment billion dollars for warehouses. addition steel companies would run the risk product obsolescence through competitive, commercial and technological developments, well changes manufacturing processes and equipment. The new steel ammunition container production program will take 125,000 tons steel during its first three months. Although not yet standardized the Ordnance Department, orders have already been placed for its production. Since fiber linings will used, great savings paper will effected. Down for the duration which undoubtedly means forever, Ironton's No. blast furnace which was moved DPC from Joliet, Ill. This stack has proved impractical, obsolete and virtually impossible operate continuously. West Coast shipyards are expected try two 10-hr. shifts, which aircraft plants have successfully practised for some time now. Marine machinists and riggers Oregon Ship, Portland, have slashed the time for setting place Victory ship propulsion machinery from three days six hours. The NLRB has climbed thorny fence ruling that while management for- bidden interfere with the organization foremen, under compulsion bargain with any such group once organized. Robert Keys, president the Foremen's Association America, known have talked with many other unions about possible affiliation and support. far the CIO wants part the organization, but once recognition comes FAA, the CIO might move try gobble the youngster organization. However, giving the foremen passive help. Foreseeing postwar demand for about million tons steel year, Walter Tower suggests using excess capacity produce steel for export, mantling such uneconomical marginal units have been kept operation solely swell wartime tonnages and treating standby plants those government financed units which private interests not want acquire. Certain natural graphites added iron powder gived medium carbon steels, according Prof. Kuzmick Stevens Institute Powder Metallurgy Samples are readily obtainable with 0.75 per cent combined carbon, tensile strength 150,000 lb. per sq. in., and hardness Rockwell Powder steels with physical properties this order should find wide applica- tion after the war for parts where machining costs are high. the other hand, powder metallurgists are looking for increased competition from the cold chamber die casting process and from centrifugal (and precision) castings the iron and steel class. Patent litigation decisions involving metal powders have since 1936 shown decided trend favor the defensive side. appears, therefore, that the value patents very great for defense and less important for offense. the first weeks operation the new payment" law, Army has paid $635,000 3345 honorably discharged personnel their survivors. Newspaper reports from Italy frequently mention the use smoke screens. one action there, Chemical Warfare troops, firing 4.2-in. chemical mortars, maintained for hr. smoke screen miles long and 1000 ft. high. far total men armed forces have suffered total blindness. The Army furnishes complete care, takes care re-education and training, and Supplies "Seeing Eye" dogs desired. } q wee.” \ ise discoveries and improve- ments the field special alloys for withstanding dy- namic stressing high tempera- tures will emerge some day from the secret files one the most fascinating and dramatic metallurgi- cal stories World War II. “Turbo- superchargers,” “jet propulsion units” and “gas turbines” have become magic words. There has been feverish search for the alloys which have made these developments possible. Like most worthwhile studies these days, the results are composite the sustained efforts viduals, companies agencies. Furthermore, the work progressing larger scale than ever before, and will never considered complete any more than the development improved materials for tem- perature service ever believed closed book. the purpose this article describe some the metallurgical and engineering factors which enter into the study superior heat resisting alloys for dynamic stressing. These descriptions must general 38—THE IRON AGE, June 1944 nature, since specific composition test information cannot quoted this time. The precise data are only available war contractors and under certain conditions. lieved, however, that the following comments will some measure in- dicate how the problem must ap- proached, and this provide check list for engineers and metal- lurgists who may now the future working structures involving these new materials. should pointed out that the field “dynamic” loading, with com- bined radial and transverse forces, quite different from sphere application heat resistant materials, about which great deal known and which involves the se- lection oxidation and/or corrosion resistant alloys stand under fairly simple stress systems (furnace parts, oil refinery Although dynamically loaded high temperature equipment has been successful service for many years (blowers, steam turbines, has been possible keep both tempera- tures and stresses within the capa- bilities materials which are rela- tively weak high temperatures. contrast, the newer equipment listed below will not perform its function ° ° ° Metallurgical Engineer, Universal- Cyclops Steel Corp., Titusville, Pa. successfully unless can operate much higher stresses and/or tempera- tures than heretofore believed prac- ticable: which permit Allied bombers and fighters fly the rarefied at- mosphere 35,000 ft. (sub-strato- sphere) with the same performance sea level. (2) Diesel engine exhaust super- chargers weighing only small fraction the engine itself and occupying critical space but which increase the power per cent. (3) Jet propelled aircraft with higher speeds and quicker take-off than ever before achieved, plus other military and aerodynamic ad- which are just beginning explored. (4) Gas turbines which possible the production enormous quantities 100-octane gasoline special catalytic process. (5) Gas turbines for main power drives which, within certain horse- power limits, seem certain com- Diesel and steam power, and which eventually may far exceed the potentialities these established prime movers. “The first really new kind power plant half the advent the steam turbine. addition the above, many kindred projects are the minds engineers everywhere. Also worthy mention are the many improve- ments which should now feasible older designs and processes which were formerly limited because metallurgical considerations. The development the improved alloys seems likely make many | Factors the Development and Selection ° ° ° 4 ( Cr the-e “dreams” possible, but every instance there must understanding both the engineering countered. The following points sum- marize many these Testing Fig. illustrates the TEMPERA- TURE STRESS STRAIN TIME square embodying the today the evaluation high strength high temperature alloys. and others, are also listed the table below: portant tests used (a) Stress-to-rupture (b) Creep (c) Creep-relaxation (d) Oxidation and/or corrosion (e) Effect temperature tions (f) Effect stress fluctuations Fatigue (h) Damping capacity (i) Effect stress concentrations (j) Change ductility with time, temperature, stress and rate strain (k) Change shock (impact) sistance with time, tempera- ture and stress. (1) Thermal expansion (m) Thermal conductivity (n) Density (o) Changes microstructure (p) Changes hardness (q) Hot hardness Short-time tensile, impact and modulus elasticity. should noted from Fig. that the four STRESS-STRAIN-TIME considered simultaneously form the complete pattern. Also, note the in- clusion “Unknown Factors” the the many considerations which thus far have defied quantitative tures. There are many modifications and combinations the above tests. Often they must performed given alloy many different forms pro- cessing and heat treatment. When The jet airplane and the newer gas turbines are built the metals the turbosupercharger. What are these metals and how are they being developed, and what are the problems involved heavily loaded alloys service for long periods time very high temperature. These are some the questions answered herein, insofar security regulations permit. summed up, they describe the “high temperature load-carrying ability’ the alloy. The more tests include stress-to-rupture, creep, oxidation and/or corrosion. the other hand, the short time tensile test and hot hardness test have been proven almost worthless evaluating the service capabilities high temperature alloys, except for very specialized ap- plications, and are not included Fig. Some the above terms designate relatively new types high tempera- ture testing, and these are described briefly below: Stress-to-Rupture typical plot shown Fig. breaking loads decreasing size are applied set specimens until stress against time for rupture. These loads which will produce fracture more than 2000 hr. Ordinarily, three four points 1000 hr. are suffi- cient. Changes ductility and impact with time can measured the ruptured specimens. Usually periodic strain measurements are made the specimens stretching under the lower loads, that accelerated creep data are obtained. When the stress-rupture time rela- ordinate paper, straight line ob- tained which has changes slope only some structural surface in- stability the alloy Such in- stability may may not serious but the detection these points one the most useful features the test. Creep-Relaxation typical plot shown Fig. This test yields data directly appli- cable high temperature bolts. plot strain against time constructed Temperature Oxidation and/or corrosian tests are seldom extended beyond the develop- ment and selection high temperature alloys for dynamic loading. Effect fluctuations Thermal expansion conductivity Effect fluctuations Stress-to- rupture Creep Creep -relaxation Unknown factors Time service life) Effect concentrations Fatique Damping capacity Stress THE IRON AGE, June Allows for Dynamic Loading Ss e which single specimen the alloy given temperature receives series loads which are decreased every time predetermined constant strain reached. This strain corre- sponds the initial bolting stress which the stud will “pulled up” room temperature. may seen that series secondary creep rates are obtained which can plotted against stress log-log coordinate paper. straight line with definite slope produced and mathematical formula derived Electric Co., Schenectady, permits the the residual relax- ation stress which will remain the bolt temperature after any time period. successful high temperature bolt- ing steel requires unusual balance creep resistance and ductility. The test yields great deal valuable information concern- ing the load-carrying characteristics alloy. Creep Fig. illustrates typical creep curve. This test has been universally used high temperature work for many years but should discussed here for completeness. contrast creep-relaxation testing, the stresses used for creep tests are quite low and most creep tests not stretch the specimen beyond the second stage continuous flow. When the stresses are increased produce the third stage creep, and hence fracture, short time periods (2000 hr. less) the test comes within the category stress-to-rupture testing. Creep test units are constructed that strain measurements taken taken very accurately. Damping Capacity This appears inherent each material, and sometimes described the “logarith- mie plain language, Stress, lb. Time for 40—THE IRON AGE, June the ability alloy cease vibrating through internal molecular friction. Since alternate pulsations, particu- larly associated with partial admis- sion turbines, can build very high vibrating stresses, the ability material “damp out” quickly wotld seem considerable im- portance. There are several ways measur- ing this property, the most popular utilizing simple fork. (2) Selection Sometimes all the above tests (and more) must performed alloy qualify for given applica- tion. other instances, few tests may sufficient. all times essential that the TEMPERATURE- STRESS-STRAIN-TIME approach the expected ser- vice conditions closely possible. When sufficient creep stress- to-rupture data exist, may pos- ible construct series design curves plot the type illustrated Fig. This scheme gives the de- signing engineer quantitative working information, and was first demon- strated the writer Mochel Westinghouse Electric Mfg. Co., Essington, Pa. The “transition point curve” plotted from the stresses and corresponding times where the creep rates increase per cent above the secondary rate (indicating the beginning the third stage creep). many structures, conditions may complicated that the only re- course select material ma- terials qualitatively from standard tests, build test “mock-up” unit and run under service conditions. This test should run soon choice materials. the only way which the “Unknown Factors” Fig. can determined, short actual service experience. single alloy has been found which has all the ideal characteristics all the temperatures which may ex- RIGHT creep plot. LEFT plot. ist most units. Even the more out- standing compositions can only con- sidered superior other alloys over temperature range. given temperature, one com- position may superior for high stresses service and totally different alloy outstanding for service where the stresses can kept low. Likewise, the time element ex- treme importance. Materials suitable for 1000-hr. service life may to- tally unsuitable for 100,000-hr. ser- vice life. (3) Availability Suppose that after thorough test- ing and consideration the various selection factors there found material which appears “fill the bill” for given part the proposed structure. Can that material ob- tained commercially the form and quantities which desired? Can commercially? Wherever possible these questions should answered before the testing actually begun and certainly be- fore any actual units are constructed. Many difficulties may ericoun- tered producing these high strength high temperature materials into the desired forms. These can under- stood when realized that work- ing these materials normal hot working ranges nearly equivalent working low-alloy steels absolutely cold. However, under the spur im- portant war developments, many in- genious processes have been devised, and the writer’s knowledge project being held the pres- ent time for lack the “raw mate- although sometimes has not been practicable obtain either the exact shapes the maximum working the alloys desired. De- tailed problems fabrication cannot come within the scope this discus- sion, but can stated that here again American industrial genius has triumphed over many obstacles, and the continual introduction new Temperature Stress Stress Stress Strain, inches per inch proc not allo; all. ing, frec per: wro pro 194 for abil tior atic tha son con bee des alli the thi po: ing Temperature Third stage. Second stage Strain, inches per inch First stage Time, hr. processes, particularly the field welding, indicates that there are major problems sight which will not eventually solved. Also, many the outstanding alloys need never hot worked all. Where small parts such blad- ing, are involved, these metals can frequently cast into the desired shapes. Especially for very high tem- perature service, these castings have superior properties best wrought materials. The “lost wax” “dental investment” precision casting process (THE IRON AGE, Feb. 10, 1944) appears very successful for this work. Under this heading also must mentioned alloying ability, since many these composi- tions contain large percentages strategic constituents. This consider- ation has emphasized the testing steels containing relatively low total alloy contents, and has been found that over certain temperature ranges some these grades are actually superior much more highly alloyed compositions. (4) Effect Size and Processing Variables This subject should possibly have been discussed under “Testing” but deserves special emphasis. Since most these high strength heat resisting alloys will not respond heat treat- ment the ordinary sense, the man- ner and section which they are worked has profound influence the resulting properties. All the fac- tors cannot discussed here, but this subject the utmost im- portance and receiving increas- ing amount study. The following points are rather obvious, but are nevertheless signifi- cant: Alloys which show relatively high strengths small sections will show relatively high strengths large sec- tions. The weaker properties the Fracture RIGHT design curves. w LEFT Typical creep plot. large sections are most evident for short time periods and very high stresses. The preliminary long-time data large sections, properly man- ufactured, are quite encouraging. When the above factors are considered, not surprising that progress the field high strength heat resisting alloys for dynamically loaded structures has not been rapid. fact, many the more promising alloys which exist today were actually developed prior the war, and only recently that their full capa- bilities have been recognized and ap- plied. Unquestionably, the war, per se, has been tremendous spur these developments. Various government agencies are sponsoring comprehen- sive research programs which have constant Jotal strain (e)=4% hr. had far-reaching influence co- ordinating and assembling data addition accomplishing substantial share the complicated and costly testing which required. These pro- grams have had the wholehearted support and cooperation private in- dustry. There good reason believe that there will increasing num- ber successful new basic power. developments involving high strength high temperature alloys. Obviously, the metal maker’s part this work will large, but the foregoing intended show that here again suc- cess cannot attend unless both the designing engineer and metallurgical engineer work very closely together considering the many complex fac- tors their proper proportions. Spatter Proof Liquid Serves Dual Purpose the fabrication welded steel bases which are designed with numerous ribs, the cleaning weld spatter the Republic Structural Iron Works, Cleveland, was consid- erable item labor costs. This prob- lem was solved using spatter proof liquid called No-Spat. first was brushed the steel, covering about in. each side the arc weld. attempt speed this operation, Alex Dawson, welding foreman, developed homemade spray device accidentally stumbled idea that saved per cent cleaning time after stress relief heat treatment 1200 deg. Obviously when the steel base was sprayed, larger surface was covered the No-Spat liquid. Dawson noticed that surfaces covered this spatter proof compound left the mill scale much looser the steel and the oxide film was much easier re- move. result, all steel structures are sprayed completely with No-Spat before and after welding. Even though they may remain open yard for several days waiting their turn into the furnace, the sur- face protected from rusting. In- stead the usual hr. cleaning time per base after heat treatment, the time has been reduced hr. Fur- smoother surface left receive the priming coat paint. The spraying device was made cutting in. pipe part way with hack saw and bending deg. One end attached piece rub- ber hose connected the shop air line and the other end pushed through cork the mouth bottle con- taining No-Spat liquid. This forms simple type aspirator. The atomized liquid sprayed through the break the pipe. THE IRON AGE, June re X- 0- k- Grinding Lead Screws HREE principles linear measure- ment are commonly used ma- chine shops and toolrooms: The graduated scale The size block end measure The precision lead screw mi- crometer screw. All three methods have their ad- vantages and their disadvantages. All three have been used machine tools. The scale has the advantage not being subject wear. However working extremely fine lines must used, requiring optical provision for reading. the average shop, this not only slow but im- practical because the exacting strain placed the operator. The end-measure method will pro- duce accurate results provided all con- ditions are right, but these conditions are many: Blocks alone are insufficient. micrometer screw must used “tenths” and dial pressure indi- cator keep constant pressure the end measures. End measures are subject ex- pansion contraction from temperature variations and there- fore must maintained con- stant temperature. Contact between blocks must perfect, inasmuch the smallest particle dirt will alter the setting. This condition dif- ficult achieve because dust and abrasive particles avoided when drilling, boring grinding. The end-measure method more complicated and requires more skill than either the other two methods. the slowest because the many motions required for single setting. Lead screws the other hand, are fast set, accurate and simple 42—THE IRON AGE, June 1944 Accurate 0.0002 In. In. Not everyone talking about accuracy actually achieves it. This article describes the elaborate techniques worked out the author's company over period years achieve the ultimate accuracy the manufacture micrometer screws for small jig borer. Highlight the method the use electronic thermostat maintain the temperature the coolant and hence the work constant differential with respect the master lead screw the thread grinder. the second and concluding part the article, unusual methods checking the product are illustrated. MOORE Secretary, Moore Special Tool Co., Inc., Bridgeport, Conn. read eliminate human errors and the need great skill. Enclosed the body the machine, they are not subject temperature fluctua- tions affecting exposed scales. However, obtain good re- sults with lead screws, the screws and their mating nuts must made the highest possible standards re- finement. Neither milled threads threads chased lathe will produce sufficiently accurate leads good enough surface finishes for high pre- cision measuring. Besides, soft lead screws would wear too fast. This leaves one alternative—use har- dened, thread-ground screws. this country, the Moore Company ground lead screw measuring de- vice machine tool about years ago, Fig. Any question the soundness the principle measur- ing with lead screws was soon dissi- pated. Table settings are made rapidly and accurately. The wear problem overcome hardening. Tests made lead screws Moore machines constant use for five ten years show that the wear negligible. Having established these facts, the Moore Company undertook the job producing the most accurate lead screws possible. the result thorough study the problem and the development new techniques solve it, today lead screws ground the Moore plant accurate 0.0002 in. in. Effect Temperature One the major phases that temperature control. The importance this readily recognized when realized how much effect slight de- viation temperature will cause. piece steel in. long expands ap- proximately 0.00006 in. for each degree Fahrenheit temperature barely perceptible the feel the fingers, cause dimensional changes far greater than the tolerances allowed the finished work. -This temperature deviation effect appears many places—on the work- piece during processing, the ma- chine which the grinding done, the finished workpiece and the checking devices. These effects are | C | ° ° ° the interrelated that none can con- sidered independently. the.schematic view thread grinder, Fig. will seen that the work spindle and the master lead screw are geared together, causing the workpiece advance and rotate the same time. The idea simi- lar the gearing lathe; the chief grinder, the workpiece advances, while lathe, the carriage advances. readily seen that the pitch lead the master screw definitely con- trols the pitch the workpiece being ground. Any pitch errors the master lead screw are immediately re- flected the workpiece. There are two general types error the master lead screw thread grinder—errors created during the making the screw and those subsequently introduced its temperature. The first type, the error created its manufacture, some impor- tance, and course, must com- pensated for. This will dealt with later the article. The second type, that subsequent temperature changes, far greater importance, and the type error which has apparently been neglected all previous attempts precision lead screw grinding. Previously, has been thought that, the work ground constant-temperature ° ° curate lead screws exemplified the Moore jig borer which uses dials for reading table settings. With pre- cisely made lead screws this method claimed the fastest, most accurate and simplest system now available for making accurate table settings small machines. room, with coolant supplied ap- proximately room temperature, con- ditions would satisfactory. some cases observed the writer, the coolant was merely “cooled,” with- out regard for accuracy control. other words, previous attempts ac- curate lead screw grinding have neglected the one cause error which, although the least obvious, the most troublesome. The frictional heat developed driving motors and gearboxes, and the friction between the lead screw and its nut conspire raise the tempera- ture the screw. The writer has observed cases where this tempera- ture has risen much deg. above room temperature, expanding lead screw with in. thread length 0.0025 amount when dealing tenths. This error transferred the workpiece proportionally its length. work- 2—Basic elements thread grinder, showing master screw geared work spindle and controlling longitudinal movement head- stock. Pitch master screw directly controls lead workpiece being ground. Errors master screw are reflected lead errors workpiece. mes Lamson Machine Co.) nic ice the WRK + | eg. | piece with in. thread length, ground temperature, will have overall pitch error approx- imately +0.002 in. Compensating Temperature Changes now evident that any attempt solve the problem merely work- ing constant-temperature room maintaining the coolant arbi- trary constant temperature would fruitless, since the major source error would not taken into account. There are various means com- pensating for changes temperature the master lead screw the thread grinder: Using gearing change the ef- fective lead the master screw bo Making the master lead screw shorter the first place Warming the coolant. Although either the first two methods can compensate for known, fixed error, neither takes care temperature fluctuations. The third method worth investi- gating, since the temperature the coolant can varied take care the fluctuations. way example, suppose are operating under con- ditions where the master lead screw deg. above room temperature. The pitch error the workpiece will then plus 0.002 in. approximately. However, during the grinding the workpiece medium 3—This electronic thermostat correlates the response two resistance thermom- eters, holding the coolant any predetermined temperature differential with respect that the master screw the thread grinder. Electric timer right holds down running time compressor prevent too low temperature. workpiece held the same temper- ature that the master screw, will shrink when subsequently cooled. Furthermore, will shrink the cor- rect amount, provided the coefficients expansion the master lead screw and the workpiece are alike. Therefore devised means matching the coolant temperature that the master screw. could then flood the workpiece with the as- surance that would shrink proper 4—Resistance thermometer attached base thread grinder measures temperatures the master lead screw with sufficient accuracy this point, since the screw entirely enclosed the base the machine. The visual thermometer for the convenience the operator and not part the automatic control. This view also shows arrangement for compensating aperiodic errors master screws. Rotation master nut achieved linkage and lever against serrated cam plate above resistance thermometer. size when cooled room temperature. This method not entirely success- ful, however, since impossible keep flooded. Inspection for finish, thread form and pitch diameter necessitate stopping the flow coolant and sometimes removing the workpiece from the machine. During these periods out the influence the warm coolant, and the air the room immediately drops its tempera- ture. The warm coolant and the cool air the room constantly oppose each other. result, the work- piece not held constant temper- ature, and the lead the finished workpiece not uniform. therefore, keeping the coolant temperature near possible that the room. order this, can either use master lead screw about 0.0025 in. short, can shorten its effective lead small in- crements manipulation the change gears. Since impossible purchase standard thread grinder with short-pitch master screw, the logical solution change the gears. Pitch Change Gearing Since the principle achieving small increments pitch change gearing not well known, would example. The thread grinder used in. machine, with 8-pitch lead screw. There are four change gears the ratio, arbitrarily called C,and These letters are also used represent the number teeth each € I | ( . gear. The formula for the lead ground the workpiece is: Lead 2/5 change gear ratio Lead 2/5 A/B C/D suitable gear ratio grind thr. per in. the workpiece might be: lead 2/5 40/80 60/96 in. 0.125000 in. suggested gear combination shorten this lead might be: lead 2/5 63/50 31/125 0.12499200 in. Multiplying thr. per in. makes the effective pitch the master screw in. per in. Suggested gear ratios for shortening the effective lead still more are these: 26/63 53/70, which will produce effective lead 0.999909270 in. per in. 30/97 98/97, which will produce effective lead 0.99989371 in. per in. can seen from the above that change gears, change the effective pitch the master lead screw small increments. warmed sufficiently cause expand ap- proximately 0.0001 in. per in., its effective pitch can brought nearly standard either the above two ratios. Since its effective pitch now nearly standard, the workpiece ground room temperature, without the necessity subsequent cooling reduce its lead. The coolant kept approximately room temperature. This would satisfactory can ° ° ° 5—With the two pres- sure filters the right, all the coolant supplied the lead screw grinder filtered eliminate the danger scratching the workpiece with dirt particles. Arrow points approximate location resis- tance thermometer coolant line end heat exchanger. constantly measures the temperature the cooled liquid. assumed that operating are always uniform. Unfortunately, they are not. Stopping and restart- ing the machine when setting up, in- specting the work and making adjust- ments cause fluctuations, which must also accounted for. neces- sary, therefore, have automatic means changing the temperature the coolant accord with changes temperature the master lead screw. (Since the coolant contributes the major part the control over the below air temperature without fear any serious conflict between them.) 6—Dynamic balancing thread grinding wheels accomplished with the setup shown, using Davey Vibroscope. The stroboscope (right), flashed synchronously with rotation, indicates the direction and amount correction required. Balancing weights are shown the wheel holding flange. order make the test sensitive enough register readable amount, the spindle housing floats springs during this operation. the temperature the master screw rises, the coolant temperature must also raised, and vice versa. Electronic Thermostat ingenious electronic thermostat was found accomplish this, Fig. Two resistance-type temperature mea- suring devices are used. One at- tached the base the thread grinder, Fig. close proximity the master lead screw. Since the temperature the master screw fol- lows that the base very closely, readings taken this point are suf- ficiently accurate for the purpose. The other resistance unit the coolant supply line, point where the coolant leaves the heat exchanger, Fig. Each element contains low voltage resistance wire, the resistivity which varies with changes tem- perature. The electronic thermostat correlates the two temperatures measured, and through relay starts stops the refrigerating system required. The thermostat adjust- able the control knobs shown the photo. has range adjust- ment about deg. each way. Considerable experimentation re- quired ascertain the proper tem- adjusted meet varying conditions. For example, for fine finishing and with the proper gearing place, usually found that the coolant tem- perature should run somewhere be- tween and deg. below that the master screw. the correct value found be, say, deg., the controls are set that the ther- mometers register Now, the base thermometer reads THE IRON AGE, June 1944—45 deg., the coolant thermometer should read deg. the base ther- mometer drops deg., the thermo- stat will automatically drop the cool- ant deg., which can immediately read the coolant thermometer. may noted that refrigeration used the coolant, but that reference made heater. All the coolant supplied must filtered, and the friction the oil through the pumps and the pressure filter supplies more heat than required. through diatomaceous earth de- posited upon wire screens. The only control, therefore, the refriger- ant. Filtering Another phase the temperature control problem consideration factors affecting the temperature the workpiece itself. Grinding Generates Heat Rough grinding, due the high rate stock removed, generates more heat than finish grinding where only few “tenths” are removed per pass. This heat must absorbed the coolant, and is, therefore, necessary supply the coolant considerably lower temperature order that the resultant temperature the work- piece correct. Considerable experi- ence and skill are required judge just what temperature should used here. Often the coolant run deg. below the master screw during the roughing stage; with this differ- ential, the coolant absorbs just about enough heat keep the workpiece its proper temperature. During finish grinding, every pre- caution must taken keep the workpiece within deg. the proper temperature differential. The dead center the tailstock end must generously flooded all times; otherwise the friction the rotation this point sometimes warms in. the dead center end the piece, causing serious trouble. The wheel dressing diamond must kept sharp assure clean-cutting grinding action. When they become dull, the wheels glaze and fill quickly, heating the work. This additional heat results short and non-uniform leads. When the diamonds are worn flat about 0.005 0.006 in. 46—THE IRON AGE, June 1944 across, they should discarded resharpened. This matter entail- ing considerable expense, since the diamonds remain sharp for only about hr. Grinding wheels and all rotating parts the machine must dy- namically balanced and free from vi- bration. the grinding wheel does not balance, all the work load ried small portion the wheel. This portion soon becomes dull and glazed, resulting production short, non-uniform leads. Static balancing the grinding wheel not sufficiently accurate. balanced dry, the balance changes when the coolant added, since dif- ferent parts the wheel absorb greater lesser amounts coolant, resulting imbalance. new wheels are balanced before the diamonds being dressed, different amounts material from different parts the periphery, resulting imbalance. Dynamic Balancing The only satisfactory way bal- ance the grinding wheel balance dynamically, after dressing, the same spindle which will used, and with the coolant actually flowing it. arrangement for doing this shown Fig. vibrometer with stroboscopic phasing device used. The vibrometer held between the work centers the machine, its con- tact point touching arm attached the spindle housing. During the balancing operation the spindle hous- ing isolated from the main wheel slide springs, allowing “float” and vibrate from the effect the im- balance. The heavy side the wheel indicated the stroboscope. The balancing weights are adjusted until the displacement less than 0.0002 in. The cap screws holding the wheel spindle the wheel slide are then tightened. The resulting vibration now found too small show any reading the vibrometer! The springs which the spindle floats are left permanently place, but ex- cept when performing the balancing operation, they are out action. Dur- ing grinding, the cap screws are tightened, holding the wheel spindle firmly the machine. minimize any pulsations the vertical belt pull, the vibroscope placed measure only the horizontal component the imbal- ance. Correcting Aperiodic Errors far, only the errors caused thermal expansion have been dis- cussed. the master screw could always made perfectly uniform pitch, this would the only type error necessary compensate. There another type, however, mentioned earlier, but not discussed. The mas- ter lead screw long, heavy piece, and the problem grinding that small piece multiplied many fold. The master lead screw, therefore, almost certain have some error, non-uniformity pitch. Although may accurate from one end the other, will probably have places where the pitch too long, and other places where too short. This type error called aperiodic, and compensated the following manner: The standard thread equipped with adjustment for roughed, partly ground, because the grinding wheel must follow ex- actly the same path the original thread the workpiece. this, the workpiece shifted axially while rotating. the Jones Lamson thread grinder, this accomplished rotating the nut which the mas- ter screw runs. worm geared shaft, equipped with handle and dial, pro- truding from the front the base the machine, provided for this pur- pose. compensator our own making was devised work conjunction with this (see Fig. 4). cam plate cut with the proper serrations fastened the table the machine. Form serration determined plotting average errors large number workpieces. lever and linkage follow the serrations, trans- mitting rotation the nut, forward backward, the case may be, compensating the errors the screw. [In the second and part the article, the author will describe and illu- strate methods and equipment especially devised for checking highly accurate lead are mact forg ing ing, and Divi Tole sive blar sad pres rect low w DOIN Carbine Sight Made From Brazed front sight for the cal. 0.30 carbine now being made from rolled and stamped pieces that are brazed together instead being machined from solid forging. Cost compared with 85c. for the forging. Only press dies and form- ing equipment are needed for the re- designed sight. shown the draw- ing, the assembly consists three pieces—the blade, the saddle base and the guard. manufactured the Prestole Division the Detroit Harvester Co., Toledo, the blade made progres- sive die from strip stock. blanked, coined fit the slot the saddle, shaved and ejected. One blade completed each stroke the press. The saddle made from wire section which fed through set rolls and has shal- low V-shaped groove formed one RIGHT tube mounted Transite asbestos flanges used form hydrogen chamber for brazing six sights time Ecco high frequency induc- tion unit. The structure supporting the work also made Transite. Work pushed through the furnace cooling tube the rear and thence water seal tank. View partially formed guard show true dimensions stamp Break sharp Section A-A and after edge Stampings face. After being cut length press die, the individual saddle pieces are fed into press which coins the keyway slot the bottom the the middle the groove semi- circular depression formed pro- vide clearance for cross drill ma- chining the assembly. give press fit for the blade the saddle, slot milled the bottom the keyway and the blade assembled means air operated fixture. Four progressive press operations 3 Blade Guard Base are required complete the guard. This includes blanking and piercing, embossing and forming, the latter two strokes. Saddle with blade at- tached then assembled the guard jig which establishes the correct relationship between parts. There enough spring the guard hold the saddle place preparatory spot welding fixture which ac- curately establishes the final critical dimensions. Copper wire looped through the guard form the braze which obtained controlled at- mosphere induction furnace un- (CONTINUED PAGE 134) usual design. the induction hydrogen furnace, LEFT are brazed together form the carbine sight— the blade the saddle base and the stampings THE IRON AGE, June 1944—47 at r Control Moisture Electrode ANDERSON Formerly engineer charge the Coatings Absorption moisture electrodes seriously affects the quality arc welds and real problem shipyards where the relative humidity coastal areas seldom less than per cent. After carrying out some laboratory experiments electrode dry- ing, this shipyard has developed system for storing electrodes under controlled conditions until the time they are actually used. electrodes used shipyard welding should approved the American Bureau Ship- ping for the work involved, but there are many things that can enter into the weldability results the elec- trode that may not contemplated the approval. Through accident, the electrode manufacturer may leave out one the ingredients that enters the electrode coating may forced circumstances beyond his control substitute ingredients ob- tained from other sources. The elec- trode coating may eccentric, and the electrode has been improperly stored, the moisture the coating may have built point where the are characterized excessive spatter and blow and the presence pin holes the deposited metal. round figures may said that electrodes cost approximately 6c. per lb. converting these electrodes, es- pecially small diameters, into de- posited weld metal the labor’ cost may between 25c. and 30c. per lb. the electrode results are poor, be- comes necessary chip out the weld metal which means expense an- ° ° ° IG. elec- trode coating ec- centricity gage reads directly thousandths. 48—THE IRON AGE, June 1944 General Testing Laboratory, California Shipbuilding Corp., Wilmington, other 10c. 20c. per and re- deposit the metal costs additional 30c. is, therefore, poor economy use electrodes doubtful quality which will produce poor re- sults due eccentricity excess moisture. protection the production departments California Shipbuild- ing Corp., procedure has been set for identifying all electrodes arrival and for the complete testing electrodes before they are released the production departments. rigid system control disbursement electrodes from he