The Iron Age 1938-12-08: Vol 142 Iss 23

FRITZ FRANK President VAN DEVENTER Editor Editor News Editor Editor Emeritus Machinery Editor Art Editor Metallurgical Bdibtor Associate Editors JURASCHEK Consulting Washington Editor MOFFETT Resident District Editors Pittsburgh Chicago Cleveland Detroit Editorial Correspondents London, England Cincinnati Boston Hamburg, Germany MEYER CHARLES Post Milwaukee San Francisco SANDERSON Asa ROUNTREE, JR. Toronto, Ontario Birmingham ALLISON Roy EDMONDs Newark, N J St. Louie TURNER, JR. Buffalo Owned and Published Precision Machine Tools Built Welding ............ Publication Office B. L. Herman, Chilton Bldg., Chestnut & 56th Sts., Philadelphia, Pa. Leonard, 239 39th New York Peirce 7310 Woodward Ave., Detroit Ober, 239 39th St., New York W. B. Robinson, 428 Park Bidg., Pittsburgh » i leo Ine. D. C. Warren, P. 0. Box 81, Hartford, Conn. Copgvight 1908 by Cithen Company Chestnut and 56th 239 West 39th Recent Machine Tool Developments Philadelphia, Pa. New York, OFFICERS AND DIRECTORS Selecting Furnace-Brazing Metals and JOSEPH HILDRETH, Statistics Metal-Working Activity GEORGE GRIFFITHS, EVERIT TERHUNE, Vice-President WILLIAM A. BARBER, Treasurer Washington Ne . JOHN BLAIR MOFFETT, Secretary THOMAS KANE, CHARLES BAUR, BAUR, General Advertising Manager DIX, Manager Reader Service Plant Expansion and Equipment Buying ....... 104 Member, Audit Bureau Circulations Member Associated Business Papers Indexed in the Industrial Arts Index. Published every Thursday. Subscrip- tion Price: United States and Pos- ° . 16 sessions, Mexico, Cuba, $6.00; Can- New Industrial Literature Foreign, $12.00 a year. Single copy, cents. Cable Address, STAFP Emerson Findley, 621 Union Bldg., Cleveland Products Advertised 129 . | | - Write For This Valuable Book Are you helpful your department managers? They look you for suggestions and approval. Are they getting it? the case steel—a new, quite remarkable plan has been developed can mean thousands dollars savings increased profits. But are you familiar with it? Have you passed your steel buyer? The book illustrated above explains the com- plete plan how alloys are selected, pre-tested and accurate data given your heat treater for guidance eliminating testing, spoilage, re-treating—saving many hours, dollars and increasing profits. The book gives similar information the carbon steels and shows how all departments are served. Executives—He Your Purchasing Agents This Book Shows How know this book will surprise you and are sure you will want show your production manager, superintendent, metallurgist and purchas- ing agent. Get now you can really help your department heads. The coupon included for your convenience. Joseph Ryerson Son, Inc. Plants at: Chicago, Mil- waukee, St. Louis, Cincinnati, Detroit, Cleveland, Buffalo, Boston. Philadelphia, Jersey City. Joseph Ryerson Son, Inc. Plants at: Chicago, Milwaukee, St. Cincinnati, Detroit, Buffalo, Boston, hiladelphia, Please send me, without obligation, copy the Ryerson Certified Steel Book. Firm | | | | | | THE IRON AGE ... DECEMBER 1938 ESTABLISHED 1855 Vol. 142, No. Beware ACK 1919, undertook the job organizing the Army Ordnance Association. This organization, which includes its membership the civilian experts and Reserve officers who had been engaged World War service well the executives hundreds manufacturing plants which had supplied munitions, became the forerun- ner present-day industrial preparedness plans. From this idea developed the present plan and the whereby American industry will all set the arrival the so-called cite this record show that the remarks which follow are not written pacifist. Beware emergencies, real fancied, and beware, particularly, the oppor- tunities which either kind afford crafty and designing people who know what can done and through them. Orson Welles demonstrated this his recent hair-raising broadcast the the When you can make millions Americans believe that have been attacked Mars, you can surely make them believe that are going at- tacked Japan Germany, even the Swiss Navy. may purely coincidence, but since Mr. enlightening demonstration American credulity took place, there has apparently been four-folding the war scare and headlines emanating from Washington. Latest the vulner- ability the Panama Canal, just discovered after years. need preparedness. should produce armaments which will make vincible—at home. But preparedness essentially long term program. has be, because the plants this country capable producing armament material could not possibly absorb half the amount now being talked about for next expenditure. Japan has its hands full China and will have for some time come. And Germany, with navy less than half the strength ours and with its problems home, not likely soon undertake overseas adventure. The capital goods industries, true, are the chief direct beneficiaries increased armament program. But shall selling our birthright for mess pottage aid and abet the advocates through manufactured and imaginary emergency set aside the verdict the elections and steer new course toward regimentation. | ayer ne | ba the & 4 Hairline Imperfections The Nature the first half this article, last week's issue, page 32, the author defined hairlines, described methods for detec- tion and rating, and discussed various control techniques. The following data pertain non- destructive testing for hairlines, all the experimental cured. examining various non de- structive procedures pointed out that visual examination the surface and end condition steel and steel products unquestionably the oldest method for the determina- tion imperfections. smooth sur- face finishes, this means detecting imperfections still very valuable, and careful inspector may readily observe objectionable surface imper- fections and even hairline discontinui- ties. The suitable magnifica- tion and lighting facilities aids satisfactory visual examination. Examination with the Aid Surface Coatings: old method detecting cracks steel castings has also served limited extent material. The material examined first immersed, soaked washed with kerosene oil, any other thin pene- trating light oil, and then the surface wiped off cleaned. The relatively dried surface then painted coated with thin mixture whiting and water, any other white powder and water, and allowed dry. Any surface defect crack the material will tend disclose itself discoloring the white surface since the penetrating thin oil, soaked the crack, will gradually rise the sur- face and color the powder. This method visual examination may materially assist the detection cracks irregular shaped mate- rials such casting, complicated forgings, etc., but, for finished straight 30—THE IRON AGE, December 1938 there are other methods more efficient the determination surface im- perfections non-magnetic material steels, brasses, bronzes, aluminum and its alloys, has been recently mar- keted the Magnaflux Corp. This method inspection really quite simple and seems excellent way detecting cracks, strains any other surface imperfection which capable causing local stress and strain concentration. The procedure employed coat- ing the surface the material with specially prepared brittle lacquer which adheres very tightly, after dry- ing, the surface the material. The coated specimen then vibrated strained produce local strain concentration. any local strain con- centration exists the material, ruptures the dry brittle lacquer coat- ing and indicates the position and location the strain concentration and thereby the imperfection—a crack the metal claimed produce strain concentration approximately the dry lacquer coating. Consequently, only necessary strain the material normal the crack surface imperfection one tenth value the coating order rupture the lacquer and dicate any crack present the metal. Cracks obtained this method inspection are shown Fig. These photographs reveal crack present aluminum propeller blade after the blade was lightly vibrated. Magnetic Test Methods; Magnaflux Test: This method inspection means new, and, general non-destructive aspects, not surprising see the vast strides which has made recent years. Since Major first application this test for the inspection gages and its subsequent use spection aircraft valve spring wire and springs the Wallace Barnes Co., Bristol, Conn., for the Pratt Whitney Aircraft Mfg. Co., this type testing has received full recogni- tion and wholesale adoption the aircraft industry, the Army and ever increasing number manufacturing plants. This form magnetic testing was originally described Hoke (Patent 1,426,384) and further devel- oped deForest (Patents 1,960,898 and 1,960,899) through the use spe- cially prepared iron oxides defi- nite size and surface covering. The test consists magnetizing the speci- men such manner that discon- tinuities the material will create break polarization the lines flux. After magnetization, the speci- men thoroughly covered with dry powder high magnetic permeability | j | | j | | | ° ° ° io ‘ | | ~ Hairlines and Methods for Their CARL SHAPIRO Consulting Engineer, Syracuse, ° ° ° Detection Semi-Finished and Finished Steel Products preferably immersed suspen- sion magnetic oxide powder either light oil, kerosene, varsol, etc. either these methods (dry wet) the discontinuities, suf- ficient length, width and depth, are indicated local periphery adhesion the magnetic powder the direc- tion the defect. Since this test has practically been widely adopted, some details this means testing and its potentialities are discussed briefly. Apparatus: The magnaflux testing apparatus, being marketed (and its the Magna- flux Corp. America, usually em- rent approximately 4500 amp. Connected the source current are copper contacts rails which the material magnafluxed held clamped during magnetization. The sensitivity the test has been greatly increased the use copper rods, adapters and special operating tech- nique. order create local polarization the point defect the speci- men, necessary magnetize the 1H. Noble, Inspection Methods Airplane Engines,” Metals and Alloys, July, 1936, pp. 167-170. part such manner that the flux lines are right angles the defect. because any discontinuities running parallel the lines flux will obvi- ously not detected. Consequently, the magnetization the specimen un- der test extreme importance, and necessary the case irregular shaped pieces shapes such sphere magnetize the material several directions order insure that all surface and sub-surface im- perfections are made visible. Between subsequent magnetizations, ad- visable that the specimen demag- netized since magnetization two more directions tends oppose each other and reduce the amount residu- magnetism, thereby reducing the sensitivity the test. comparison the dry and wet testing methods subsequent magnetization the specimen has heen very ably presented Noble, whom quote the “The wet method used pref- erence the dry for several rea- sons. more sensitive and more easily discernible machined ground surface. most cases the need for cleaning the work eliminated. Also, the inspect rs ABOVE 7—Imperfections revealed the dry powder magnaflux test method carburized material. The two specimens are shown here natural size, the one the left being annealed and that the right being annealed and carburized. LEFT 6—This aluminum propeller blade was coated with brittle lacquer and lightly vibrated. The crack shown was thus disclosed. have found more agreeable work with the dry powder has the matter sensitivity have found that the wet powder will adhere cracks small that they can seen only under fairly lars are frequently used connection). occasion when had reason suspect the certain location, found one less than 0.010 in. long, which defied detection 100 diameters when the powder had been removed. course, the dry powder would not show anything this case, the particle size too large. the other hand, the wet powder will not pile give indication depth, regardless the size the defect. “In the case large crack with appreciable width, the wet powder will fill the crack and not pile up, and black line will still visible, even after attempts wipe off. the dry powder were used, would pile up, the deeper the crack the greater the amount powder would hold, and the more the powder would resist dislodgment tapping blowing. Thus, with amount experience, inspector can estimate the seriousness defect. rough forgings and welds, only the dry powder can used advantage.” More recently the sensitivity the magnaflux test has been greatly en- hanced magnetizing the specimen while immersed the test solution. obvious that this method, employing (Maximum magnetic lines which can induced the specimen) against the usual (residual lines magnetism remaining after the mag- netizing current will materially intensify the polarization caused imperfection. Being strictly magnetizing test method, any condition (surface sub-surface) capable producing THE IRON AGE, December | t | localized magnetic polarization will shown the adherence some the powder and, consequently, the re- sults this test are subject all the advantages and shortcomings the physical laws magnetism. view the foregoing, the sensitivity this test largely dependent on: com- position and structural condition the material, shape and surface finish, the type magnetization which used B,) and the dimen- sions (width vs. depth) the imper- fections, etc. general, any chemical, structural mechanical condition which influ- ences the magnetic characteristics the material will affect the sensitivity the magnaflux test since and determine the amount polariza- tion under any fixed conditions. Con- sequently, the magnaflux test will not only show actual hairline discontinui- ties, cracks, seams any similar sur- face defect, but will also show any surface sub-surface strain condi- tion, structural segregation, and non- metallics which are located near the surface. other words, this test will reveal means magnaflux lines any conditions which are capable causing local polarization. illustrate the foregoing, con- sider actual experience the plant manufacturer airplane parts from electric furnace steels the SAE 2512 and SAE 3312 types where, spite the most rigid final inspec- tion tests the mill, well close acceptance tests the incoming mate- rial the customer, was common occurrence for stock which had satis- factorily passed the spection the annealed condition rejected the same tests the finished, carburized and heat treated parts. attempt correlate these re- round (SAE 2515) particular lot question, were magnafluxed the annealed condition, and the test show- imperfections whatever. The 6-in. pieces were then cut half; one the halves being hard- ened accordance with tomer’s procedure which consisted carburizing hr. 1700 deg. cooling), reheating lead bath (1550 deg. F.) for min., oil quenching and reheating again an- other lead bath 1425 deg. F., oil quenching and tempering 275 deg this heat treatment, the specimens reinspected magnaflux test. The results, which Fig. after the dry method magnaflux test, showed that some the carburized specimens had were are given 32—THE IRON AGE, December 1938 EXTRA THICKNESS DEFINITELY VISIBLE INCHES 0.30 0.50 THICKNESS STEEL INCHES PER CENT TOTAL THICKNESS DETECTABLE 0.60 070 0.60 090 100 1.10 8—Sensitivity 200,000-volt Coolidge tube the detection irregu- larities steel. thickness detectable per cent. imperfections running the entire length the 3-in. pieces; whereas, the original annealed material was absolutely free from any defects. microscopic examination revealed the annealed material entirely free from any structural segregations imperfections, even the point which the magnaflux lines occurred the carburized sample, while the carburized specimens showed definite sub-surface hairlines determine the cause phenomenon, series annealed speci- mens were subjected microscopi- cal and magnaflux examination after each the above steps. The findings the investigation showed that after the first heat treatment (1550 deg oil) the specimens were still satisfac- tory; whereas, after the additional hardening (1425 deg. F.) which was followed oil quench- ing, many specimens were found contain open discontinuities the eutectoid portion the carburized case. Experiments determine the underlying cause this phenomenon indicated that the rapid rate heat- ing the lead bath was primarily re- sponsible for these failures since sev- eral series samples which received the second heat treatment elec- tric furnace, instead the lead bath, were found entirely satisfactory. Commenting the merits the magnaflux test method, the author would say that date this test really excellent means for the non- Upper curve gives thickness inches and lower curve gives Greatest sensitivity material. products. However, its use semi- finished material, for instance billets, bar stock rough forgings, considered not very satisfactory view the following (a) The surface condition semi- finished contrast finished prod- ucts such that the test much less sensitive. Moreover, the finished prod- ucts are usually hardened; whereas, the semi-finished are not; thus, the sensitivity the magnaflux test further increased. (b) The rough surface the semi- finished products makes interpretation results very difficult. (c) The difference size and di- mensions between raw materials and semi-finished stock and products usually sufficient make impossible intelligently interpret the magnaflux test results the semi- finished stage with respect what may observed the finished part. (d) The additional magnaflux test may indicate every- thing from open surface discon- tinuity light subsurface structural segregation; fact, any condition which will produce local polariza- tion some kind, and inasmuch suitable standard has been devel- oped for satisfactory interpretation certain types magnaflux lines, cause the author consider this test method rather dangerous and ex- pensive tool the hands the inex- perienced. The adage that test better than the interpretation its fact that 7 0.008 | | | | 7 7 a | results” particularly true case. Since the adoption the magnaflux method, numerous modifications have been developed for special re- quirements. The following two have found rather wide application. Instead the direct use high and low voltage magnetizing current, gineering Co., Ltd., London, energizes the test piece, which forms the yoke closed magnetic circuit means specially wound coil. control the sensitivity, slider po- tentiometer high resistance em- ployed, the electrical supply being coupled the two ends the poten- tiometer coil, while the electromagnet coil connected the two sliders. Thus, any desired value current Bevan Swift, “Magnetic Crack De- Heat Treating Forging, Vol. XXIII, No. June, 1937, pp. 279-280. Inspection Equipment,” Ferrous New York—Catalog No. “Sensitivity X-Ray Examination Metal AGE, May 24, 1934, pp. 12-14. q t can passed through the coil either Another method which especially useful castings and forgings the so-called flash magnetization method developed the Woolwich Arsenal (England). Instead the usual sta- tionary magnet, this method employs magnetizing coil which through steel cylinder forming closed magnetic circuit with the ap- plication the current. placing the specimen cylinder, magnetization effected. The subse- quent inspection similar the mag- naflux, that is, either the wet dry method may employed. illustrate the electrical testing methods, the so-called test briefly described. sheets and wire and measures primari- the comparative magnetic permea- bility the material against previ- ously determined standard. The prin- ciple involved simple. Two coil units contain primary and secondary wind- ing. The material tested passes through one coil while the known 9—Cracked bronze bar stock and auto-radiograph cracks. (Kaiser). standard used the core the other coil. Therefore, since the coil windings oppose each other, any varia- tion the physical characteristics the unknown the standard will pro- duce difference the relationship between these windings, which then recorded means oscillograph either straight line sine wave, depending upon the difference the material. Radiography: X-ray and gamma- ray tests depend upon variation the intensity the penetrating beam when reaches the photographic film directly behind the exposed specimen. This variation the penetrating beam results from the different rates ab- sorption the material through which the beam passes and, variation the absorption rate the material exists (inclusion, heterogeneities discontinuities the film uniformly exposed, indicating homogeneity. The sensitivity the X-ray non- destructive test for determining the hairlines, seams, streaks, etc., has been clearly shown the report Abbott and Lippert,, which 200,000-volt, air cooled Coolidge X-ray tube was used. Quoting: “This investigation demonstrated that thickness 0.5 in. steel differences thickness paral- lel the path the X-radiation representing 0.5 per cent the to- tal thickness may detected. For in. steel thickness, the sensitivity the X-ray method the neighborhood 0.8 per cent the thickness, and for in. in. sections defects representing difference per cent thick- ness may readily detected. The upper curve (Fig. shows the minimum thicknesses steel de- tectable for various nesses steel penetrated the rays. “The lower curve (Fig. shows the same data different form. The per cent total steel thick- ness detectable plotted against the total steel thickness. ray photograph casting metal joint has even density, can then estimated that any de- fects that are included but not de- tected are less than the minimum established the data Although X-rays and gamma rays are capable showing defects steel, they cannot classified useful tool for the determination surface imperfection since the pene- trating beam must pass through the entire thickness the material the photographic film fluorescent screen THE IRON AGE, December | | | 4 . 4 4 2 7 | before the defect may observed. Hence, the interpretation these results, the exact location the defect the material cannot readily as- certained without further tests. Con- sequently, for normal routine labora- tory mill inspection for the deter- mination surface imperfections semi-finished and finished steel prod- ucts, X-rays and gamma rays cannot classified commercial test method for detecting surface imper- fections. Radioactive Methods Examina- tion: entirely new method de- fects detection metallics has been the United States Naval Research tion present does not apply the determination surface imperfections but, nevertheless, explained brief- since possesses great merit and promises open new field in- spection the future. The underlying principle involved this test method introduce into the cavity, crack, fissure, etc., radio- active substance which later detected either photographic electrical means. The radioactive material used may any the radioactive elements. However, due their cost and danger handling, the pure elements are never used but only liquid solutions the radioactive salts. Since the most inexpensive and safest the elements thorium, the thorium compounds, ThO, and offer the de- sired properties These salts are prepared various kinds fluid solutions such as, (a) aqueous solutions (many the com- pounds the radio elements are fair- soluble water and the gaseous radio elements dissolve according Henry’s law), (b) non-aqueous solu- tions radioactive compounds gases, and (c), the use viscous fluids which the radioactive mate- rial held mechanical suspen- sion. The advantages these salt solutions are, (1) inexpensiveness, (2) easier handle, and (3), they vield much higher concentration 5H. Kaiser, “Possible Uses Radio- active Substances in the Testing of Metals,” Preprint No. 20, 1938. Metallography and Heat Treat- ment Iron Steel,” Albert Sauveur, 6th Edition 1936, McGraw-Hill Sons, New York. 7 Micro-chemical Surface Examination (Mikrochemische Oberflachen Profung), Neissner, Berg und Huttenmannisches Jahrbuch, Vol. 84, Oct. 27, 1936, 105. Methods (Ueber den von Oxydinschlussen durch Mitsche, Berg and Huttenmannisches Jahrbuch, Vol. 83, Dec. 23, 1935, pp. 127- 133 (Metals Alloys, June, 1936). Metal Progress, March, 1936. 34—THE IRON AGE, December 1938 radioactive atoms than that obtainable the radioactive gases. determine the condition the material, the radioactive solution introduced into the cavity the crack, fissure, gas hole, etc., with without the aid hydraulic pressure. After the surface the defect im- pinged with the radioactive concentra- tion either surface contact with the solutions the gaseous eman- cipation, the material examined photographically electrical meth- ods. When examined photographically, the use sensitive plates films, the film wrapped around the speci- men shown Fig. and exposed for period approximately six days. After the film developed, the blackened lines indicate the position, form and relative size the. defect. The electrical method detecting and measuring small amounts radio- active substances present the metal, after the solution treatment, works upon the principle electrical ioniza- tion measuring the amount the atoms molecules air other gas through which the radiation passes. The ionization the gas allows the passage electric current between electrodes placed the ionized gas. Consequently, the magnitude this ionization current measure the intensity the radiation producing the ionization. Fig. shows port- able machine which amount ionization. Inasmuch this radioactive method for detecting defects metallic alloys has just been advanced and since seems offer another method for de- termining hairline imperfections, should not overlooked the com- ing vears for the detection surface and internal defects metals and alloys. Micro-chemical Examination: This method surface examination de- pends upon the chemical which occurs between surface non- metallics and emulsified (photo- graphic gelatine) paper which saturated impregnated with acid reagent. This method surface ex- amination has been quite universally adopted for the determination sul- phur inclusions and, some extent, for phosphorus. Heyn and Bauer were. the first apply this method sur- face examination, which was further developed Baumann. Although there are numerous modifications, the Baumann method illustrative the principle involved. Baumann Method: Emulsified paper soaked dilute solution su)- sec., depending upon the com- position the material, size defects and type photographic paper. The specimen, which examined, gently pressed against the acid impregnated paper, held for from sec. and fixed sodium hyposulphite re- move the excess bromide, then washed and dried. The dark stains recorded the photographic paper indicate the presence inclusions. more com- plete description this and other Niessner Method: Another method micro-chemical examination has been developed Niessner,’ for the identification iron bearing surface inclusions. (emulsified gelatine) soaked weak solution hydrochloric acid (1.20) for approximately five minutes. The paper dried, remove all free acid drops from the emulsified surface, and the polished surface pressed for short period time upon the emulsified surface the acid saturated paper. The time usually sec., depending upon the type photographic paper, com- position material, type inclusion and developing conditions. The paper then developed either solution ferric ferrocyanide. The cyanide development indicates the presence iron bearing non-metallic inclusions the presence dark blue spots. Since this method has only recently been developed, further details may obtained from article, “Iron Oxide The foregoing described test meth- ods are used throughout the metal- lurgical industry detect imperfec- tions steel, and the manner which they are detected (test method) de- pends mainly upon personal preference and the type material under inspec- tion. This fact has been clearly and markedly illustrated the results the questionnaire and the author wishes add, before closing, that becoming more and more necessary that the various tests become stand- ardized and evaluated before much progress can achieved the elimi- nation surface imperfections. SUMMARY summarizing the foregoing in- formation, which necessity had presented most generalized form, the author would like stress the following points: (1) Hairline discontinuities steel and steel products are minute imper- fections which are caused during the | | j | | % 7 7 ‘ 7 7 7 | liquid state the metal and which must considered heat condition characteristic. (2) Minute imperfections steel are classified and defined follows: hairline may generally de- fined discontinuity, crack rupture hairline dimensions metal. seam hairline proportions (hairseam) defined solid elongated non-metallic discontinuity due the presence non-metal- lics inclusions, etc. Streaks, ghost lines, dendrites, etc., are considered solid hetero- geneities metallic non- metallic nature, both, within the material due segregation tion(s) compound(s) other than non-metallic inclusions seams. (3) means favorable melt- ing procedure and suitable subsequent processing practices, possible limit the number and severity these imperfections some extent. How- ever, date the author knows melt which has ever been found entirely free from these defects. (4) Due their analyses and structural characteristics, certain com- positions are more prone hairline imperfections than others. (5) While acknowledged that any hairline discontinuities are unde- sirable, their actual seriousness points stress concentration and causes for premature service failures highly stressed parts has not been definitely proved. Straightens and Commercial Bars pickled and limed com- mercial bars can ened, sized and finished within 0.002 in. the rate 200 300 ft. per min. new machine just put the market the Sutton Engineering Co., Park Building, Pittsburgh. The ma- chine will also size the same ac- curacy bars that have not been pickled and limed, just they come from the mill. that case, much the scale will removed and all pit marks will rolled in, giving the bar very Geiger-Miiller counter and simplified counting rate meter for detecting and measuring small amounts radioactive material. (Kaiser) (6) The hot acid etch test combined with careful microscopic examina- tion for non-metallics and the taper stepdown hairline test are considered the most useful inspection methods for the determination the hairline con- dition heat steel. (7) finished steel products, the outstanding test for the detection hairline imperfections the magna- flux test method. unfortunate that the results this test are very much subject misinterpretations the actual quality characteristics the material under test and hoped that suitable interpretation standards for this test method will soon de- veloped. (8) The magnaflux test not suit- able for routine preliminary finish acceptance test semi-finished steel products, because the many varia- bles which influence the test results and their interpretation. rolled bars can straightened within small limits this newly de- veloped Sutton high speed straightening machine. ACKNOWLEDGMENT The author wishes express his sincere thanks and appreciation the following men for their coopera- tion and interest our questionnaire and work: Boegehold, Bubb, Jr., Charl- Van Horn, van Wert and White. The author desires express his Schempp, metallurgist the Hal- comb Steel Division the Crucible Steel Co. America for his con- structive criticisms suggestions throughout the course study. smooth finish. can ac- complished bars from in. diameter. The unit will also straight- high tensile oil-quenched round bars from in. diameter. This machine Timken equipped throughout. Except for four grease fitting points, lubrication taken care separate motor driven pump. The rolls the ma- chine are Shore hardness, and the angle all rolls adjustable that uniform results can obtained all sizes bars. Because the speed the operation, the processing done very low cost per ton. THE IRON AGE, December 1938—35 j 7 7 ‘ 7 q Precision Machine Tools ing has progressed very rapidly the last few years. Progres- sive machine tool builders, like those other industries, have investigated the possibilities using this method at ditional work with welded steel struc tures has been predicated early results. Naturally some mistakes were made practically every field that welding has entered, because the initial efforts were not always properly directed nor intelligently supervised. pleasure report that ma- chine performance problems directly attributable weldng are quite rare and seldom indeed get past our off” inspection. Rigidity Machine Tools Let consider the matter gidity. This subject about which machine tool builders are indeed sen- sitive. How many times have heard the remark that steel just where rigidity rather than strength the important consideration using 34-in. wall section cast iron. calculated the corresponding sec- tion steel, assuming that could done. Since modulus the mea- sure rigidity, tried multiply 12,500,000 30,000,000 *W. Dalby, Phil. Trans. Roy. Soc., Ser. 221, 1920. ‘Love Mathe- matical Theory Elasticity, pages 114- 115. getting 0.3, and 36—THE IRON AGE, December 1938 then built machines with wall 5/16 plate. found the structure flimsy. was warped out shape too much welding, and the bare rod weld- metal deposited was quite brittle and Stress relieving was LEFT look- ing into No. centerless grinder bed, showing the in- ternal ribbing. RIGHT 2—Front view completed No. centerless grinder bed, illustrating the smoothness the joints. not understood and was properly done, all. What was wrong with our theories Was not modulus gidity? Was there way produce stable structures? Were all steel struc- tures noisy, subject trouble- some vibrations Let consider -what learned from our problems. When stop and look our present develop- ments welded machine tool struc- tures and consider the weaknesses and errors our first attempts welding, realize that the error was not our The was primarily where put this material, how joined the adjacent pieces, and what steps took re- lieve the stresses after fabrication. What Was Overlooked When first started substitute steel for cast iron overlooked the that castings contained many ribs, generous fillets — most vital condition, that is, one tion blends into another manner that all the surfaces, walls and ribs work together one mass, The common frequency such structure quite low, and addition cast iron does indeed have much lower response frequency structures age relieve stresses even under ordinary use and condition. also known that the stress-strain curve cast iron not linear, namely the proportionality be- “tween the stress and the correspond- ing deformation strain even light stresses, does not follow straight line. Consequently the deformation duced any structure made cast iron partly elastic and part plastic, thus resulting permanent set. This particular behavior cast iron has been investigated Dalby.* the case steel, the stress-strain | - | | a a q a ‘ ° ° fe} 7 Welding—| straight line the true limit beyond which slight increase stress may produce con- siderable increase strain. Now, have welded steel structure, the stresses which are produced due welding may intensity such subject the structure deforma- tions obtaining beyond the limit therefore, ture will distorted, until equilibrium reached between the stress and cor- responding strain. The additional load, which corre- sponds the residual stress, will cause still greater permanent deformation. order avoid this condition, desirable reduce the internal stresses Fic. 3—No. centerless grinder used rough grind pistons. point far below the proportional limit. The stress thus obtained added external stress produced load under use, should not exceed the proportional limit; otherwise, when high loads are applied, will pro- and Use Creep Re- vention. The Rupture Strength Steels Elevated Temperatures, White, Clark Wilson, 1937 Convention. Stress Relief Annealing, Research Supplement The Welding Journal, Nov., 1937, page 38. The Welding Handbook, pages 403-415. MADDOX Chief Engineer and Supervisor Weld- ing, respectively, The Cincinnati Milling Machine Co. Cincinnati Grinders, Inc. what has been done prominent builder milling ma- chines, grinders, and broaching machines making use welded steel con- struction told this article, which from paper Developments the Welding Machine Tools," presented the 19th annual meeting the American Welding Society, held recently Detroit. Welded construction has been thoroughly studied and carefully applied. Knowing both cast iron and steel, the authors state that use welded steel future constructions depends largely upon the suitability the material for particular application and its ability equal get below the cost cast-iron designs. For convenience the article divided into two parts, the first which includes discussion the problem rigidity and some the advantages welded steel, including flexibility design, lighter weight, and possibilities the direc- tion more modern styling. Use the newer process illustrated this part connection with centerless grinders and Hydromatic milling machines. flow and permanent will result. then, some type stress-relieving process, the residual stress may reduced some value less, stable structure will pro- duced. the matter thermal relief, there much experimental evi- dence available’ show that heat welded steel structure through the correct heating and cooling cycle, holding approximately 1200° for reasonable length time usually hour/inch thickness), the residual stress will below 3000 per sq. in. This value definitely below the proportional limit for steel that stable structure insured.. This fundamental and essential dif- ference the plastic flow cast iron RIGHT Looking into the end fixed-height rail hav- ing built-in spindle carrier. Used the special Hydromatic pictured Fig. THE IRON AGE, December 1938—37 ba: | | » d n and steel has most important bear- ing the use welded construction. other words, build good stable, accurate cast-iron machine tool and put foundation that not the best and the foundation settles, the cast-iron machine will take set that definite. Even the trouble corrected, the bed will still out, until remachined forced back into place new stress produced clamping and jacking make take new set. Steel the other hand will, shown above, proper stress relief, permanent un- less forced past the proportional limit. Take large stress-relieved flat steel bed, support three corners for indefinite period, level it, then check and will not have taken set out flat. This indeed valuable characteristic. Valuable Properties Cast would not well for the ma- chine tool builder forget the wonderful properties cast iron. almost ideal material for his pur- pose from many points view. Its strength more than sufficient for most requirements encountered ma- chine tool design. has deadening amazing ability able_metal possesses. has natural internal properties that enable dampen vibration set the vari- ous machining processes. planed milled form “way” guide surface which suitable for almost all applications. You are all familiar with machine tools 10, and years old whose scraped sur- face has not worn the few tenths thousandths depth the scraper mark. Early welded structures used ways are still being used some ap- plications. The rigid and hard re- quirements imposed production ma- chine tools high production shops number cases has led the use hardened way surfaces. Whether this justified for ordinary usage matter much discussed and now being carefully considered. This development having one in- teresting result—it reduces the differ- ence cost between cast iron and steel for certain structures. This means has become economical RIGHT 6—Bottom view light-weight welded steel Hydromat- milling machine bed after welding. Note bracing and ribbing. place certain structures steel which would have been made cast iron because the cost applying sep- arate slide way strips for the steel machine. The Design Problem The designing engineer fabricat- ing machine tool steel has the problem getting all the essential properties into the steel structure that are inherent good casting, the technique for the making which has been many, many years the development. For example, big flat uninterrupted area considered bad foundry practice, while such flat slab more less inherent steel. Nevertheless, such area cast iron definitely more dead, more suit- able for machine tool structure than the flat steel plate corresponding size. The average machine tool designer has worked long with cast iron that LEFT 5—Front view special welded steel Hydromatic milling ma- chine. Only the table cast iron. | | | 38—THE IRON AGE, December 1938 think tra effort. has strive keep thinking terms cast iron and then building the product steel. like foreign language, one does not become really proficient speak- ing foreign language until learns think that language rather than think his own, then translate into the other language. Appearance Just the early automobiles had whip sockets, early efforts the use steel construction were along the lines copying cast-iron struc- tures going extremes box construction. now recognize that just because method design was good when applied cast that fit into the proper use fabri- cated steel structures. Figs. and are excellent examples sibilities along this line. This machine combines castings and welded steel make special purpose machine which, while not conventional, certainly not displeasing the eye. find such machinery this, that the shape, the lines, the massive You Large Centerless Grinder Built Welded Steel full realization the inherent possibilities welded steel fabrica- IG. 7—Completed Hydromatic milling machine, the base which shown Fig. Consists cast iron spindle carrier with intricate ribbing and brackets, steel spacer, steel bed, and steel table. iron, does not follow that steel applicable like manner. True, some manufacturers demand cast-iron shapes for appearance sake and they get them steel, but they pay the price and that price not low. are changing, lines, ap- pearances, styles us. They may seem harsh and strange today, yet some them will the pace setters tomorrow’s styles. With versatile method manu- facture welding available, cer- tainly cannot content build steel machines with lines and styles that looked up-to-date yesterday. feel that the proper thing establish styles and appearances tion, far our company con- cerned, came after designed and built the large Cincinnati No. center- less grinder welded steel. This precision centerless grinding ma- chine finishing pistons, for example, limits 0.0002 in. for size and roundness. The former cast-iron ma- chine the same design weighed over 9600 Ib. for the main alone which consisted two pieces. This grinding machine was made two sections because the lack equipment handle large work. Even that, was not good casting cast machine. The up-to-date steel counterpart weighs 6600 and is, course, one piece. This machine 8—Upside-down view Hydro- Tel milling machine base, showing rib construction prior placing the bottom plate. producing finishes the highest type extremely rapid rate stock removal. One application these grinding machines employs in. diameter wheels, in. wide, driven 100 hp. motor. The performance this machine excellent and there has never been any problem chatter, vibration any the other kindred ills sometimes attributed welded steel machine tools. Figs. 1-3 show how this grinder built up. The careful placing metal exactly where needed should noted, also the pleasing lines obtained cold bending. This structure worked out that extremely rigid, yet its weight moderate, and are able produce with sav- ing weight and cost. Welded Steel Milling Machines What can done with welded steel milling machines, where vibration especially serious and where the aver- THE IRON AGE, December 1938—39 Pe — 4 : > 5 ~ i 2 f 4 age milling cut would tend set chatter? This problem especially serious where intermittent cuts are made using one more large in- serted blade mills. Well remember one our early efforts fabricate steel rail. was used carry standard spindle carriers for used milling ma- chine which rebuilt for customer. The vibration this steel rail was ter- rible, the distortion under the cut was disgrace, yet with all the distor- tion was constant and the machine ran full year. During this time had learned much and when this machine was returned for rebuilding some our problems and errors were better understood and the answers were ready. Even so, when considering the rebuilding this machine cast-iron rail was deemed best. However, the excessive overhang, the insufficiently supported heads, the internal ribbing were modified. other words, the features that were really responsible for most the trouble with the steel rail were properly taken care when the rail casting was made. the future, would make that rail steel (as have numerous others) and know be- fore built that would satis- factory, that would weigh less than the cast-iron rail, and its construction steel would carry all the interlock- ing advantages that come from the fabrication welding this type structure. More recently, built Hydromatic milling machine with four 40—THE IRON AGE, December 1938 ABOVE the Hydro-Tel, consisting welded bed, column and special steel rectangular over- arm, making type cut prone set unusual vibration. BELOW headstock show- ing finished painted structure prior machining. spindles for milling the seven surfaces two-cylinder engine block. Figs. and show this interesting ma- chine tool. Fig. particular interest be- cause shows intricate bracing used for additional rigidity. number shafts and large gears into the com- partment shown. The large steel cast- ing the spindle carrier proper. use this and the other three steel castings also shown, elaborate burn- ing, welding and milling operations are eliminated. Fig. view the complete Hydromatic milling machine. feel that this good looking machine tool and are told that giving ex- cellent results. order know just how rigid welded machine tool can be, three very accurate reading dial indicators were placed the outer corner the fixed height rail carrying the vertical spin- dle carriers. The deflection readings were extremely low, definitely less than could hope for machine with cast-iron rail designed for similar work. The skeptics within our own organization, needless say, felt about welding after this demonstration proved that machine welded steel was indeed very rigid. Further, careful analysis the source the small deflection did find, taught some things which will enable produce similar machine lighter weight and yet more rigid. Hydro-Tel Milling Machine Figs. and illustrate excel- lent example large welded Cincin- nati horizontal machine. This machine which (CONCLUDED PAGE 70) 7 oOo Troy, Y., has just installed their plant complete strip grinding and polishing unit for use with coated abrasive paper cloth belts. This the second unit this company has installed the last months for experimental and demon- stration purposes, and represents many new features well en- tirely new design. has capacity for strip in. wide. The grinding and polishing unit, built specially the Hill Clutch Ma- chine Foundry Co., Cleveland, includes new automatic compressed air control for belt auto- matic pressure control for grinding polishing which permits positive set- ting for fine grinding polishing; air control pressure for rough grinding and maximum stock removal wherein the head may float over regular surfaces; and air actuated head which quickly makes breaks the contact between the belt and the strip. The passage strip through the machine all times electrically under the control the operator, all controls being mounted the machine head within easy reach. combina- tion reels the Broden Construc- tion Co. and special circuit, controls, motors and motor-generator Reli- ance Electric Co. and Clark Controller Co. complete this unit. This set-up provides constant sion nine steps from 200 8000 required, depending the gage and width steel and may regu- lated instantly while the machine operation. Likewise, the speed the strip may regulated anything from seven ft. per min. the first stage 150 ft. per min. the second stage. either range, the change may made while the ma- chine operation. designed that the operator has access to, and clear vision the strip entering the grinding area, permit any necessary lubrication the surface and detect surface im- perfections which may require extra grinding. such cases, the strip may instantly reversed, maintaining tension and speed merely throwing reversing switch, and this may repeated until the imperfections have been removed. The grinding unit may used conjunction with any type reel with friction drag, but the electrical con- trol for strip speed and tension, claimed, more positive and smoother operation. This machine may used for grinding hot cold rolled strip the heavy gages for polish- ing down 0.005 in. Its purpose reclaim stock which because surface imperfections can- not otherwise satisfactorily rolled out; improve cold rolled finishes and produce fine ground surface match standard sheet finishes. The Behr-Manning Corp. inviting all manufacturers of, fabricators using strip steel other metals alloys, see demonstration this new equipment. STAMPED steel riser bracket corner block for bedsprings has been de- veloped the Wrought Washer Mfg. Co., Milwau- kee, replace the malleable iron casting previously used for this application. Said superior strength and rigid- ity the older type, this tricate st