The Iron Age 1921-02-17: Vol 107 Iss 7

E | New York, February 17, 1921 ESTABLISHED 1855 VOL. 107: No 7 Hand-Labor Minimized at Modern Foundry Mold Carrying, Lifting and Pouring De- vices of Cincinnati Company Increase Production 50 Per Cent BY J. E. N increased production of 50 per cent, with a A corresponding decrease in the number of men required to accomplish it, and at the same time doing away with the arduous work of handling the finished molds by hand, has been secured by a number of ingenious installations in the squeezer department of the Modern Foundry Co. in the Oakley colony of Cincinnati. The installations consist of mold carrying, lifting and pouring devices, and are models of simplicity in that there are no intricate parts that need atten- tion or that can be affected in any way by operating conditions customarily met with in foundries. The mold-carrying device is built somewhat on the conveyor principle, consisting of an inclined track along which the finished molds are carried. The squeezer machine is located directly at one end of the track, and the molder stands immediately behind it, facing the front of the floor. Sand and boards are’ placed conveniently alongside of the ma- i Carrying Track, with Squeezer Machine at the End, and Operating Mechanism (in White). olling an air cylinder actuates a cross slide which moves the tilting dogs back and forth Simple in Design MCDONALD chine. The mold is made in the ordinary manner and, when completed, the molder pulls a lever which actuates a three-way valve to an air cylinder located between the rails of the track immediately in front of the machine. The release of the valve operates a cross slide connected with counterweighted tilt- ing dogs located at the upper end. Upon the opera- tion of the cylinder the dogs slide under and beyond the bottom board of the completed mold, and the counterweights cause it to assume an upright posi- tion. The lever controlling the valve is’ then re- versed, and the dogs engage the bottom board of the mold, which is gently pulled down the inclined tracks. As the mold leaves the machine a centering device engages the battens of the bottom board, thereby insuring the alignment of the molds. This operation is repeated with each mold, the last one coming from the machine gently pushing the pre- ceding ones along the track until they are picked up with the lifting device and placed on the floor A three-way These dogs engage boards of the molds and gently pull them down the track. The centering device is shown by the two parallel white lines between the rails 429 2 ee 436 THE IRON AGE The Mold Lifting Device in Operation to be poured. The average weight of each mold is 160 lb., and the track, constructed of 12-lb. rails, holds 30 molds. The track is 36 ft. long, and the rails are placed 10 in. between centers. The incline is 2 ft. in 30 ft., and a section 6 ft. is laid flat on the floor. This mold-carrying device can be applied to practically any molding machine now on the market. When the track is full of molds, or at any time desired, the molds are picked up by a laborer with February 17, 19°21 a special lifting device. This is a balanced car) pivoted on a cross bar, and is suspended fr chain hoist by means of an eye bolt attache the controlling lever at a point 10 in. back from pivot support. The carrying arms upon which molds rest can be lifted vertically a distanc: 12 in. The chain hoist is attached to a speci designed overhead traveling crane, and in orde: make the movement of the crane as easy as poss the greatest care was taken in the construction the runways to assure perfect alignment. A]! machining on the crane parts was done on ac ately made jigs and Hyatt roller bearings are uy throughout. Simple and efficient accurately describe the pour ing device. It consists of a steel bail, boxed in with Transite board, and a crank handle which hooks to the trunnions for tipping the ladle. The device is attached by a chain hoist to an overhead crane, and “an be very easily moved to any point desired. With this device, the heavy work of carrying the ladles by hand, with the accompanying slopping of iron, is entirely eliminated, and one man is able to handle three times as much metal as could be done with a hand ladle. In its construction special attention was paid to the protection of the operator, and its use has very materially reduced the number of severe burns usually associated with hand-pouring. Better pouring, with very little fatigue to the operator, has also resulted. The ladles used in pouring-off have a capacity of 400 lb. each, and are provided with special bails and trunnions fastened permanently to them. The ladles are filled at the cupola and are transported, three at a time, by an electric lift truck, to the department where the molds are to be poured. By pouring direct from the ladles, the loss of heat resulting from transferring the iron to a hand ladle, is done away with. The ladles are provided with skimmers to prevent slag and oxides from entering the molds. At present seven mold-carrying tracks are in ee he odie’. Sats eS bs ea The Ladles Are Transported to the Squeezer Molding Department by a Lift Truck. The illustration shows —— being delivered under the crane runway, with the pouring device about to pick them up for pouring into the molds February 17, 1921 THE operation, one of which handles molds up to 30 in. in length. Four overhead cranes, and four lifting and pouring devices, each serving two molders, have been installed. The present installation lends itself admirably to further development wherein molding, pouring and shaking out can be made continuous and automatic. A. N. Kelley, superintendent, conceived the idea for the installation, and has protected the funda- mental features of the same. Pneumatic Hammer for Breaking Iron Pigs The Sloss-Sheffield Steel & Iron Co., Birmingham, is manufacturing a pneumatic hammer for breaking pigs and sows apart. It is in operation on several furnaces in different plants at present and is being nstalled on others. It will break pig iron at an average rate of one ton per minute into pieces of proper size. \t the plant of the Sloss-Sheffield Steel & Iron Co. the tool is in use at three furnaces, and the company s expecting to install it at two more. It is also being istalled by the Central Coal & Iron Co. at Holt, Ala. The company sells these hammers only in pairs, for reason that the nature of this work is such that e equipment should be carried in duplicate. Although breakage has been very light, a furnace would irally not have on hand men to handle the iron case of a breakdown of the tool. It is, therefore, iired to carry the equipment in duplicate. rhe superintendent of furnaces for the Sloss-Shef- i company, J. P. Dovel, has supplied the following ition in regard to the details of the pneumatic The cylinder is 8 in. in diameter with a Stroke of 14 in. "he air pressure required is 60 Ib., and the average nsumption per minute amounts to 60 to 75 cu. ft. vice averages 15 strokes per minute and the f the machine is 2500 lb. High Heat Conducting Refractory Material refractory material has been produced at the \mboy, N. J., plant of the Carborundum Co., nas a high heat conductivity. It appears that _Mmetal porcelain enameling furnace in the the Cribben & Sexton Co., Chicago, it took to bring the muffle interior up to 1800 deg result is that the furnace is now shut down ends because of the relatively small amount ecessary to bring it up again to temperature. made of savings in fuel consumption and in furnace production. as compared with the uffle, but exact figures are not available IRON AGE Filling 400-lb. Ladles at the Cupola for Delivery to the Squeezer Molding Department yet. The material has been given the name Carbofrax. It is understood the material is also in use for the roof of open-hearth furnace, but here, of course, for its durable refractory property and probably not for heat conducting capacity. The New York Central Lines in a recent advertise- ment tell of having placed orders for 1921 for 184,275 tons of heavy open-hearth rails, “enough to lay a new single track from St. Louis to New York.” In the same connection it is stated that “in the New York Central research laboratories, out of the experi- ence of never-ending road tests has developed the highest type of rail used in this country.” A comprehensive list of rules relating to industrial sanitation has been proposed for adoption by the Department of Labor and Industry of Pennsylvania. The tentative draft has been printed in pamphlet form and a copy can probably be had by addressing the secretary of the industrial board, Fred J. Hartman, Keystone Building, Third Street, Harrisburg, Pa. The Pouring Device in Operation. The Ladle is Controlled by the Crank Handle. The advantages of this device over the laborious and dangerous method of hand pouring are clearly evident EE aad eet ee a Pe ed 5 a 4352 DESIGN OF FOUNDRIES Important Consideration If Plant Is to Be Operated Economically Important considerations in the design of modern foundries were pointed out by J. H. Hopp, Charles C. Kawin Co., Chicago, in a paper read before the Ameri- can Foundrymen’s Association at its convention in Columbus, Ohio, last October. Mr. Hopp emphasized the necessity of designing buildings with a view of co-ordinating the structure with the demands of opera- tion and protecting the foundry against the elements. First, he said, the building must afford all of the light possible so that molding operations can be carried out without artificial light. He said that there are no manufacturing buildings which require such _ perfect ventilation as foundries because of the gases, steam and dirt ever prevalent. As to location, the modern foundry must be close to railroad facilities and the site should permit of future growth and be correctly situated with reference to the remainder of the plant. Another item, he said, which cannot be disregarded is the disposal of waste products. If the property is suitable for filling in at certain portions it is more desirable than entirely level ground. Because some foundries, poorly equipped or over- equipped, and some without system, have made money is no reason in the opinion of Mr. Hopp why the foun- dryman who is about to design a new plant should pro- ceed along doubtful lines. He made a point of the necessity for scientific planning and scientific operation. Apparently as negligible a thing as sand, he pointed out, can so greatly reduce a given day’s profits, despite its comparatively low cost, as to more than make worth while the separate storage of each car purchased. Sand should be protected against the weather even if it has to be entirely enclosed. The building or buildings in which sand is stored should be heated. “If those to whom this method does not appeal would record the amount of scrap produced by frozen or too wet sand,” he said, “they would agree that heated buildings for sand storage are a profitable investment.” He gave attention to the proper crane service in the storage yard; the area of the charging floor, which he said is frequently too small; keeping machinery free from dirt; keeping elevator shafts entirely closed and other matters of general plant efficiency. Labor-saving Equipment As to labor-saving equipment and other foundry matters he said in part: The limit in labor-saving equipment in the foundry has by no means been reached but considerable prog- ress will be made when a readjustment of selling prices becomes necessary. The cutting of the sand heap by mechanical means, conserving for the molder that energy so necessary to production, has been a big step in assisting the molder. To accomplish this end the arrangement of the floors and the floor construction need to be taken into con- sideration if this work is to be done at a minimum cost. To the writer’s mind the core room presents in the majority of plants, an equivalent to the rest of the in- dustry, comparable with the drafting room or engi neering department of a manufacturing plant. Let there be the slightest opportunity for misconstruction of a figure, an arrow head or a line, and the machine shop, pattern shop and the foundry are ever ready with the timeworn alibi, “Well, it’s up to the engineering department,” or, “it’s up to the core room.” Often this charge is just. In modern production the core room is a much more vital factor than ever before. Not many years ago a foundryman would look at the patterns of a prospec- tive customer, view with dismay the cores as indicated by the prints, and say, “We don’t want the job; we’re running a foundry, not a core room.” To-day we are of one opinion generally, and that is that the difficult parts of the mold can best be made with cores. For this reason, coupled with the fact that skilled men or THE IRON AGE February 17, 19 molders are becoming less plentiful each year, necessary that the core room be given considers thought, not only as to size but the equipment and tine of the work as it progresses through the var stages until the assembled core is ready to be pla in the mold. With the cores becoming a large factor in prod tion as compared with the quantity of sand used, it | been found advisable and economical to reclaim sand, not alone for its sand value but for such po: of the bonding elements as may remain. Many f drymen are still satisfied if they are able to secu bake of cores over night from a given oven. It is « mon practice to see ovens occupying no greater amoun of floor area producing several bakes a day, depending upon the nature of the cores. Generally speaking, a suitable shakeout area has 1 been considered necessary and it is common to find foundries to-day, heaps of core sand, broken cor rods, anchors, etc., piled mountain high under the eran in an area valuable as molding space, with little or , arrangement whatsoever for the convenient remova of this refuse. The problem of arranging for this not a difficult one, but a neglected one. Sand Blast Equipment Has Improved Not many years have elapsed since purchasers wer content to receive castings which had been wire-brushed and chipped. To-day there is a growing demand, at least in certain classes of castings, that they be sand blasted. The crude methods of doing this work a few years ago under conditions that were anything but liv- able have been discarded. Now the operator is almost entirely free from the dust. The location of such equipment must be determined in advance, as suitable pits and foundations are re- quired and the equipment cannot be moved conveni- ently at will. Frequently the sand blast table, room or barrel, as the case may be, is located in some far away corner without thought as to what must be done with the castings after they are brought from the sand blast room. There can be no question that all castings do not require to be sand blasted; therefore, the mill equip- ment of a cleaning room needs consideration. The progress of the castings from the foundry to shakeout in the larger work and thence to the cleaning room and to the various pieces of equipment therein can be readily predetermined, and the equipment for handling the castings so arranged as to assist in the loading and the unloading of the mills for the heavier work. Every foundry should have suitable pattern storage facilities as well as patternmaking and flask repairing departments. As the patterns in any foundry are valuable assets they should be protected from the pos- sibility of destruction by fire. It is obvious that a building used for this purpose should be made as nearly fireproof as possible and should be separated from other buildings. It seems unnecessary to state that patterns should be filed in a systematic manner with suitable records kept covering each one. All shelves must be flexible to permit the reception of patterns of various sizes. Th method so commonly in use of having some one man around the plant who knows every pattern and when asked, “Can you locate it?” casts longing glances toward the heavens and answers, “I’ll look for it,” '5 surely not a satisfactory method for this day and ag Pattern shops or patternmaking departments usua need the same sort of thought with reference to layout, general placing of equipment, storage of lum- ber, etc., as would be incidental to the machine shop contemplating certain manufacturing processes. Thi proper arrangement of the equipment with referenc' to sequence of operations and arrangement of shafting, shaving ducts, etc., is essential. The newly organized Eastern Ohio Mfg. Co. %* purchased the Warren, Ohio, foundry of the MeMyler- Interstate Co., with a monthly capacity of 600 tons Under the new management, production wil! cons!’ of heavy gray iron castings. Castings of Light Aluminum Alloys’ Value of Macroscopic Examination in Foundry Practice—Its Correlation with Microstructure —Methods Used alloys for the determination of defects or failure in service, as well as in development work, a study the macrostructure is as necessary as a study of the rostructure. It has been pointed out by Humphrey in the case of steel that the two are complementary, and ; the opinion of the writer that either one is worth- without the other. For several years the fact information of value may be derived from macro- | N the metallographic examination of light aluminum and Typical - BY ROBERT J Structures ANDERSON t visable to make macroscopic examination of numerous specimens. While the observations have been reported elsewhere in instances, while in others they are incomplete, the subject as a whole has not yet been described, and it appears to be sufficiently interesting to warrant this presentation. The correlation of macrostructure and microstruc- ture in the instance of aluminum alloys is important and interesting from the purely scientific standpoint, made some and aphs of steel has been apparent to a number of and the macroscopic examination of aluminum alloy etallographers, and recently some interesting papers ~ sections is useful in aluminum foundry practice. The Humphrey, Foley, Rawdon, Monypenny, and others object of this short paper is to describe briefly some of (see bibliography at end of this article) have appeared the methods used for the macroscopic examination of Kig. 1—-92:8 Al-Cu Alloy Poured in Sand at Various Temperatures: C, at 630 deg. C A, at 850 deg. C.; B, at 650 deg. C., and Etched with NaOH; Oblique Llumination ; 7 light aluminum alloys, the etching reagents employed and the method of photography. iling with the macrostructure and macrography of For metals and alloys in general, low-power ex- ination, say up to 10 diameters, is of especial value hen the structure is very coarse or when the variation structure over a large area is marked. So far as is known, the macrostructure of cast light In the tine metallographic examination of aluminum alloys in other investigations in the metallurgy of alu- im at the Bureau of Mines, it has been found ad- Examination of Macrosections In the routine metallographic examination of alumi- num alloy specimens in this laboratory, macroscopic examination is ‘invariably made and, as a rule, when micrographs are taken they are accompanied by the corresponding macrographs. When interpreting micro- graphs, particularly in the case of alloys with com- paratively low melting points like the light aluminum ‘Published by permission of the director United States alloys, the macrostructure should be compared, since of Mines. otherwise erroneous conclusions may be drawn. Un- cha a ee ee a ee fortunately, work on the interpretation of the macro- Fig. 2 (Left) Dendritic Struc- ture in 92:8 Al- Cu Alloy ; Etched with NaOH Oblique Illumin- ation; xX 7 Fig. 3 (Right)— Dendritic Struc- ture within Large Grains in 92:8 Al-Cu Al- loy ; Etched with NaOH; Oblique Illumination ; x 4 433 oes ¥s ee ee ee 434 THE IRON AGE ' February 17, 192] a @ ‘ -@ ae 7 Fig. 4 (Left) — Section from Unsound Crank Case : os 92:8 Al-Cu; Unetched : Vertical Illumination ; e s 4 a . xX 7 . Fig. 5 (Right) — 92:8 ; t ee Al-Cu Alloy; Sand Cast 3 Bar ; Etched Lightly with j a. NaOH: \V ‘ertical Illumina- * w f wanes ‘ £ tion; X 6 structure of cast aluminum alloys, comparable to the work of Howe and Belaiew on cast steel, has not been done, and this aspect of the subject is full of develop- ment possibilities, As has been pointed out above, the examination of macrosections is very useful in aluminum foundry prac- routine specimens in connection with microscopy; (2) to the study of especial defects, such as cracks, draw blowholes, porosity, and unsoundness; (3) to the study of the effect of molding methods upon the structure of castings; and (4) to the examination of fusion welds and soldered joints; and to other purposes. Preparation of Macrosections Ordinarily, it is not necessary to observe the same scrupulous care in the preparation of aluminum alloy sections for macroscopic examination as is required for microscopy, but the same general methods may be employed. Where a fairly large surface is to be ex- amined (e.g., a porous specimen, the juncture of a gate and a casting, fusion welds, or soldered joints), a flat surface is first prepared by sawing and filing. The surface is then ground on coarse emery paper, fol- lowed by grinding on a duck-covered wheel with fine carborundum powder, then on a tripoli wheel, and finally polished on broadcloth with metal polish. This procedure leaves the section relatively free from scratches other than microscopic scratches. In case Fig. 6—92:8 Al-Cu Alloy; from a Commercial Cast- . ing ; Etched with NaOH; Vertical Illumination; x 7 tice, and in the case of foundries not equipped with metallographic laboratories, the sections may be read- ily prepared and examined in the foundry—but little apparatus being required. While ordinarily the writer does not recommend this practice because the best re- sults cannot be obtained except by a metallographer, still it is felt that the study of etched sections will be found instructive by foundrymen since it throws light on foundry practice, especially molding methods, and serves as a simple method of check and control. Unfortunately, the study has been so little practiced that it is difficult to see what its possible applications Fig. 7—Blowholes in a Crank Case Casting os are, but some of these will be indicated briefly here. Al-Cu Alloy ; SS eee Os we Macrosections may be examined either etched or un- etched, and it is normally advisable to examine them in both ways. The macroscopic examination of alu- minum alloys may be applied to advantage (1) to all the same section is to be photographed for both micro- structure and macrostructure, then the procedure for preparation described by Hanson and Archbutt* or by the writer} may be followed. After microscopic ex- amination, the section may be etched more deeply for macrography, Etching for Macrostructure Experiments have been carried out with a number of chemical etching reagents for use in developing the macrostructure of aluminum and its light alloys. Al- though this subject has not been studied as fully as de- sired, it may be said in general that aqueous solutions of hydrofluoric acid and of sodium hydroxide are ge erally satisfactory for aluminum and most of its com mercial alloys. The high zine binary aluminum-zine alloys (e.g., 67:33 Al-Zn) tarnish very badly 0” etch- *Hanson, D., and Archbutt, S.-L., The Micrography °° Aluminum and Its Alloys, Jour. Inst. of Metals, vol. ~}+ ° 1, 1919, pp. 291-304. ; : +Anderson, R. J., Metallography of Aluminum: sae Fig. 8—Inclusions of Bits of Crucible in a Commercial tion and Etching of Microsections, Met. and Chem. #"9» Casting; Etched with NaOH; Oblique Illumination; X 7 18, 1918, pp. 172-178. Prepara- vol. February 17, Cast Gate; B, 90:10 Al-Zn, Chill Cast; C, 92:8 Al-Cu, Die Cast; All Etched with NaO8H; Oblique Tilumina- tion; xX 1.5 Fig. 9.— Macro- graphs of Actual Sections Cut from Light Aluminum Alloy Castings; A, 95:5 Al-Mg, Sand- B A 10 per cent solution of sodium hydroxide or surface with the naked eye, under a lower-power hand per cent solution of hydrofluoric acid is satisfac- lens, or, and more conveniently, under a binocular ' The speed of etching may be increased, of Microscope. For the photography of aluminum and irse, by employing more concentrated solutions. The @luminum alloy macrosections, the method employed in e period of immersion in sodium hydroxide may be this laboratory is that one devised and described by n 3 to 10 min, depending upon the depth of etch Foley* for the photography of steel sections. Other apparatus may be used. Vertical and oblique illumi- nation is employed in photographing at low powers. The former is suitable in many cases, and the macro- graphs then correspond directly with the micrographs taken on the usual metallographic bench. “ Obilque il- ' lumination serves to bring out the etching effects in a striking manner. ' Typical Structures The accompanying macrographs will serve to give an idea of the macrostructures found in cast light alu- minum alloys, and they also serve to indicate the use- fulness of macroscopic records. Typical macrostruc- tures of cast substantially pure aluminum have been published} previously. One of the useful purposes to Same as Fig. 10, B, but x 4 which macroscopic examination of aluminum alloys Fig. 12 > tah ty ae tees - «sip Sa “ desired, while in hydrofluoric acid the etching period may be from 1 to 3 min. However, the depth of etch is best regulated by removing the specimen from the solution from time to time to examine its progress. The dark surface film which forms on attack by either of the reagents may be removed and the surface bright- ened by momentary immersion in concentrated nitric acid. Hydrofluoric acid appears to give more con- trasty effects than does sodium hydroxide; hydrofluoric acid may be regarded as more suitable for substan- tially pure aluminum, and sodium hydroxide is better for most of the light alloys. Method of Photography in the routine examination of specimens for macro- ture, it is often sufficient to examine the etched Fig. 11—Same as Fig. 9. B, but X 4.5 may be put in foundry practice is in the detection of i ey, F. B., The Photographing of Etched Sections of : — : zings at Low Magnifications, Chem. and Met. Eng., +Anderson, R. J., Metallography of Aluminum Ingot, Chem. 9, pp. 140-141. and Met. Eng., vol. 21, 1919, pp. 229-234 B Cc lacrographs of Actual Sections Cut from Light Aluminum Alloy Castings; A, 83:7:7 Al-Cu-Sn Alloy, Sand ving Turn in a Gate; B, 92:8 Al-Cu, from a Crank Case: C, 92:§ Al-Cu, from a Crank Case; All Etched with NaOH; Oblique Illumination; x 1.5 m3 : . : ee 434 THE IRON AGE : February 17, 1921 -~g rd ad Fig. 4 (Left) — Section from Unsound Crank Case ; e 7 92:8 Al-Cu; Unetched: » e Vertical Illumination ; ¢ ’ 4 * x 7 : 4 Fig. 5 (Right) — 92:8 - t oi] Al-Cu Alloy; Sand Cast 2 Bar ; Etched Lightly with “»., NaOH; Vertical Illumina- ” a ° we f tion; x 6 structure of cast aluminum alloys, comparable to the work of Howe and Belaiew on cast steel, has not been done, and this aspect of the subject is full of develop- ment possibilities, As has been pointed out above, the examination of macrosections is very useful in aluminum foundry prac- t routine specimens in connection with microscopy; (2) to the study of especial defects, such as cracks, draws. blowholes, porosity, and unsoundness; (3) to the study of the effect of molding methods upon the structure of castings; and (4) to the examination of fusion welds and soldered joints; and to other purposes. Preparation of Macrosections Ordinarily, it is not necessary to observe the same scrupulous care in the preparation of aluminum alloy sections for macroscopic examination as is required for microscopy, but the same general methods may be employed. Where a fairly large surface is to be ex- amined (e.g., a porous specimen, the juncture of a gate and a casting, fusion welds, or soldered joints), a flat surface is first prepared by sawing and filing. The surface is then ground on coarse emery paper, fol- lowed by grinding on a duck-covered wheel with fine carborundum powder, then on a tripoli wheel, and finally polished on broadcloth with metal polish. This procedure leaves the section relatively free from scratches other than microscopic scratches. In case Fig. 6—92:8 Al-Cu Alloy; from a Commercial Cast- ing; Etched with NaOH; Vertical Illumination; X 7 tice, and in the case of foundries not equipped with metallographic laboratories, the sections may be read- ily prepared and examined in the foundry—but little apparatus being required. While ordinarily the writer does not recommend this practice because the best re- sults cannot be obtained except by a metallographer, still it is felt that the study of etched sections will be found instructive by foundrymen since it throws light on foundry practice, especially molding methods, and serves as a simple method of check and control. Unfortunately, the study has been so little practiced that it is difficult to see what its possible applications Fig. 7—Blowholes in a Crank Case Casting of 92:8 * ° * . Al-C / , ig , oy > i Ve Oblique are, but some of these will be indicated briefly here. Al-Cu Alloy; Lightly Etched with NaOH; Obiia ; ‘. . Illumination; X 6.5 Macrosections may be examined either etched or un- etched, and it is normally advisable to examine them in both ways. The macroscopic examination of alu- minum alloys may be applied to advantage (1) to all the same section is to be photographed for both micro- structure and macrostructure, then the procedure for preparation described by Hanson and Archbutt* or by the writer} may be followed. After microscopic &X- amination, the section may be etched more deeply for macrography, Etching for Macrostructure Experiments have been carried out with a number of chemical etching reagents for use in developing the macrostructure of aluminum and its light alloys. Al though this subject has not been studied as fully as de- sired, it may be said in general that aqueous solutions of hydrofluoric acid and of sodium hydroxide are erally satisfactory for aluminum and most of its com mercial alloys. The high zine binary aluminum-zine alloys (e.g., 67:33 Al-Zn) tarnish very badly on etch- *Hanson, D., and Archbutt, S.-L., The Micrography Aluminum and Its Alloys, Jour. Inst. of Metals, vol. -'+ 1, 1919, pp. 291-304. oe . ¢Anderson, R. J., Metallography of Aluminum: De aL Fig. 8—Inclusions of Bits of Crucible in a Commercial tion and Etching of Microsections, Met. and Chem. Eng., Casting; Etched with NaOH; Oblique Illumination; XK 7 18, 1918, pp. 172-178. february 17, 1921 Fig. 9.— Macro- graphs of Actual Sections Cut from Light Aluminum Alloy Castings; A, 95:5 Al-Mg, Sand- A B A 10 per cent solution of sodium hydroxide or per cent solution of hydrofluoric acid is satisfac- The speed of etching may be increased, of rse, by employing more concentrated solutions. The me period of immersion in sodium hydroxide may be from 3 to 10 min, depending upon the depth of etch Fig. 12 Same as Fig. 10, B, but x 4 desired, while in hydrofluoric acid the etching period may be from 1 to 3 min. However, the depth of etch is best regulated by removing the specimen from the solution from time to time to examine its progress. The dark surface film which forms on attack by either of the reagents may be removed and the surface bright- ened by momentary immersion in concentrated nitric acid. Hydrofluoric acid appears to give more con- trasty effects than does sodium hydroxide; hydrofluoric may be regarded as more suitable for substan- ially pure aluminum, and sodium hydroxide is better most of the light alloys. - £& Method of Photography in the routine examination of specimens for macro- ructure, it is often sufficient to examine the etched ‘Foley, F. B., The Photographing of Etched Sections of = torgings at Low Magnifications, Chem. and Met. Eng., 19, pp. 140-141. THE IRON AGE Cast Gate; B, 90:10 Al-Zn, Chill Cast; C, 92:8 Al-Cu, Die Cast; All Etched with NaOH8H; Oblique Iilumina- tions X 1.5 Cc surface with the naked eye, under a lower-power hand lens, or, and more conveniently, under a binocular microscope. For the photography of aluminum and aluminum alloy macrosections, the method employed in this laboratory is that one devised and deséribed by Foley* for the photography of steel sections. Other apparatus may be used. Vertical and oblique illumi- nation is employed in photographing at low powers. The former is suitable in many cases, and the macro- graphs then correspond directly with the micrographs taken on the usual metallographic bench. ‘ Obilque il- lumination serves to bring out the etching effects in a striking manner. Typical Structures The accompanying macrographs will serve to give an idea of the macrostructures found in cast light alu- minum alloys, and they also serve to indicate the use- fulness of macroscopic records. Typical macrostruc- tures of cast substantially pure aluminum have been published} previously. One of the useful purposes to which macroscopic examination of aluminum alloys Fig. 11—Same as Fig. 9, B, but X 4.5 may be put in foundry practice is in the detection of +Anderson, R. J., Metallography of Aluminum Ingot, Chem. and Met. Eng., vol. 21, 1919, pp. 229-234 Cc ‘lacrographs of Actual Sections Cut from Light Aluminum Alloy Castings; A, 83:7:7 Al-Cu-Sn Alloy, Sand ving Turn in a Gate; B, 92:8 Al-Cu, from a Crank Case: C, 92:8 Al-Cu, from a Crank Case; All Etched with NaOH; Oblique Illumination; x 1.5 436 THE IRON AGE February 17, 19. the pouring temperatures of sand castings. The mac- crystals standing vertically may be noted. C, Fj, rostructure of the light aluminum copper alloys, e.g., . is a section cut from a blowholey die casting in 92:8 Al-Cu, is extremely susceptible to pouring tem- Al-Cu alloy. A, Fig. 10, is a section cut at the . ture of a pouring gate and lead-off runner in 8: Al-Cu-Sn alloy. B and C, Fig. 10, are sections from a crankcase in 92:8 Al-Cu alloy; these sect were cut from a boss which had heen chilled on smaller surface. The columnar crystals in B, Fig abruptly change to the normal large grain struct Figs. 11, 12 and 13 show some of the foregoing st) tures at high magnification. Fig. 11 is the same a Fig. 9, but at 4.5 dia. Fig. 12 shows the line of marcation between the columnar crystals and the la) grains; this is the same as B, Fig. 10, but at 4 Fig. 13 shows a portion of the section shown i: Fig. 10, but at 5 dia. Cracked aluminum alloy castings are alway source of interest from the investigational standpoint and the occurrence of cracks, whether they be crac} due to shrinkage or chilling on pouring, or strai: cracks opened on machining, is a question of muc! importance to foundrymen. The macroscopic examina tion of cracked castings is useful in throwing light o1 the occurrence of cracks, but this method has not been applied to any extent for this purpose. Fig. 14 shows a crack in a sand casting made in 92:8 Al-Cu alloy, perature —the higher the pouring temperature, the larger the gross grain size. A, B,and C in Fig. 1 show the macrostructure of 92:8 Al-Cu alloy, sand cast in the form of 1-in. square bars, poured at different tem- a Fig. 13—Same as Fig. 10, C, but peratures. It is necessary to direct attention to the fact that the Al-CuAl, eutectic will be found scat- tered through each of the large grains, shown in Fig. 1, on microscopic examination, Fig. 2 shows the den- dritic structure obtained in sand-cast 92:8 Al-Cu alloy when poured at high temperature 900 deg. C. Fig. 3 shows the appearance of the same alloy where the dendritic structure is confined within large grain areas rather than being interlocking as in Fig. 2. The ex- amination of etched macrosections cut from gates or actual castings is useful in determining the pouring temperature used; it thus serves as a method of con- trol. t is frequently necessary to examine specimens for unsoundness, blowholes, and inclusions; macroscopic examination is useful in determining the amount and extent of these defects. Fig. 4 shows the appearance of a section cut from an area in a crankcase that leaked Fig. 14—Crack in ed piace Sand Casting; in th in the open-gasoline test. Fig. 5 shows unsoundness of os a consistent character in sand-cast 92:8 Al-Cu alloy, while Fig. 6 shows the same defect in another speci- men. Blowholes in a casting are shown in Fig. 7, while Fig. 8 shows the macroscopic appearance of a sample containing included particles of graphite.* Summary It is often desirable to photegraph an etched sec- while Fig. 15 shows the same crack after polishing and etching. The crack follows the boundaries of the larg: grains, i.e., it is intergranular. The necessity for presenting this article briefly pre vents any discussion of the interpretation of the macro structure of cast aluminum alloys, but generally speak ing this will be found more simple than for steels. |" is evident, however, from the remarks made above that exceedingly useful results may be obtained by the mac- roscopic examination of aluminum alloy sections. It is likely that this method may be applied with advan- tage to wrought products, and it may be found of pal ticular value in investigational work in connecti with the development of light alloy forgings. Th study of the macrostructure of cast aluminum alloys, both sand castings and die castings, offers exception opportunities to the metallurgist and foundryman, and ; 2 it is hoped that this presentation of the subject W! Fig. 15—Same as Fig. 14, but After Polishing and stimulate interest. Etching with NaOH; Oblique Illumination; x 6 Selected Bibliography tion at very low magnification, say one or two diam- Humphrey, J. C. W., Macro-etching and Macro-printins, , 973-286 ters, so that the entire surface will be reproduced. Pho- Iron and Steel Inst., vol. 99, No, 1, 1919, pp. #ie-e" 0. ; - a Foley, F. B., The Photographing of Etched Sections ‘ Er tographs of a number of sections taken at 1.5 dia. are Forgings at Low Magnifications, Chem. and M: : m i ‘7 9 g ‘5 is 20. vol. 21, 1919, pp. 140-141. : ce Je shown in Figs. 9 and 10. A, Fig. 9, is the CrOSS S€C- , nderson, R. J. Metallography of Aluminum Ingot, ‘ tion of a gate cut from a sand casting in 95:5 Al-Mg and Met. Eng.. vol. 31,1919. eo the Macrostru alloy; the unsound character of the sample is shown — A oon 5 ee. tee, ne., vel. 23, 192 ? smz ‘ig. 8, shows a section p. 383-389. ame at LOW by the small black areas, B, Fig. 8, Monypenny, J, H. G., Photographing Etched Sections at 10° cut from chill-cast 90:10 Al-Zn alloy; the columnar Magnifications, Chem. and Met. Eng., vol. 22, 19° — 882-883. teel 7 and S *Anderson, R. J., and Capps, J. H., Investigate Hard Spots Rawdon. H. S., Revealing Macrostructure - Iron an in Aluminum, The Foundry, vol. 48, 1920, pp. 337-342. The Tron‘ Age, vol. 106, 1920, pp. 965-968. Electric Melting of Electric Furnaces in the Iron Foundry’ Costs and Advantages of Duplexing or Cold Scrap—Control of Sulphur, Manganese and Phosphorus NE of the gravest problems of the iron foundry () to-day is the accumulation of sulphur in com- mercial serap and its effect on the castings made vith. The ordinary jobbing castings to-day show ohur content of 0.18 per cent, and occasionally as 1s 0.22 per cent. The product of the foundry dur- . war is undoubtedly to blame for this rapid in- « and conditions will become worse as the millions : of gray-iron castings of the war period return foundry in the form of commercial scrap. in the ordinary cupola remelting of pig and scrap, ist 0.02 per cent sulphur is taken up; often double t amount. The high cost and difficulty of obtaining » iron during the war period compelled the use of nsiderable scrap in the mixtures; frequently charges taining 90 per cent of bought scrap were melted. Naturally the sulphur content of the castings increased. Until the advent of the basic-hearth electric fur- ice, the only method of holding the sulphur within reasonable limits was to use high percentages of pig the foundry mixtures. Pig iron seldom contains wer 0.05 per cent sulphur, if well made. With pig iron forming 60 per cent of the charge and the gates, runners, rejections and bought scrap the other 40 per ‘ent, the sulphur content of the castings can easily be held down to 0.10 per cent. Pig iron, however, costs more than scrap even when melting loss differences are considered, hence as small a percentage as possible will ve used. The recent advance in knowledge of rational melt- ing and the consequent reduction in losses directly due to oxidation of the metal and cold iron, has permitted the acceptance of castings with a much higher sulphur mtent than formerly. The steel industry also is seek- ng to determine how high sulphur may go with safety. in the iron foundry, however, there is the danger of low cupola bed or an unduly retarded air-furnace eat, with the consequent raising of the freezing point f the metal and segregation effects resulting from high sulphur with insufficient manganese. The iron foundry- must, therefore, have a ‘means of correcting his iten metal. The electric furnace, with a basic hearth, fers this opportunity. Before the iron foundryman, particularly the pro- iver of gray and malleable iron castings, can pour ‘is molds safely, the molten metal must have a high egree of superheat, be thoroughly deoxidized and rea- ‘onably low in sulphur. A foundryman will get these aracteristies if he uses good materials and melts erly. The electric furnace will give a highly super- ed metal that is thoroughly deoxidized, and a fine egree of desulphurization if the hearth is basic. If, ' greater economy and to fit existing equipment con- ms, the “duplexing” system—cupola metal refined ‘he electric furnace—is used, the best results for laity are obtainable conjointly with a reasonable The foundryman may melt cold metal directly in * acid or basie-hearth electric furnace, or he may re- moiten cupola or furnace metal in either hearth furnace. In duplexing, however, it is doubtful ‘n-hearth metal will be transferred to the elec- ‘urnace; in fact, it is doubtful if even air-furnace will be used that way, as in the foundry the air ace gives 10 to 40 tons of metal at one time, ‘eas the same tonnage from the cupola is either cuted over 2 to 4 hr., or spread over the entire substantially in full, presented at the February the American Institute of Mining and Metal- neers in New York, Feb. 15, and copyrighted —— BY DR. RICHARD MOLDEN KE — working day. The problem of the electric furnace in the foundry, therefore, resolves itself into either add- ing the necessary electric equipment for duplexing, or installing electric furnaces for direct melting and re- fining of cold stock. Of the two hearth systems the basic is to be preferred for its specific value in de- sulphurization. Cost of Electric Melting of Cold Scrap When cold metal is charged into an electric furnace, unless carefully handled, there will be considerable fluctuations in the current until the pigs or pieces of scrap around the electrodes are melted. As the rest of the charge melts in the bath that forms, the fluctua- tions become less marked and when the bath is entirely molten the internal resistance is sufficient to reduce the current demand, in some furnaces, one-half. Melt- ing cold iron ordinarily requires a big current reserve and a higher current cost. Data from steel melting show that melting cold stock consumes up to four-fifths of the total current used; the refining period takes the other fifth. Since, however, refining is going on while melting progresses, the contrast in reality is not so great. Duplexing is not only cheaper, but it is also faster, for melting a cold charge and refining it in the electric furnace might take 2 hr., whereas the refining period after melting would not reach % hr. The advantage of the melting-from-cold-metal sys- tem over duplexing lies in the ability to melt when- ever desirable, whereas duplexing is dependent on the running time of the cupola. The higher cost of cast- ings by either method, unless the lower grade materials used make up this difference, means that the electric furnace will only be used where quality work is pro- duced. Thus, if the total cost of work is, say, 3c. a lb., it is not likely that the foundryman will add an- other %e. to %c.; but for work that costs 15c. a Ib., this addition matters little. The maker of grate bars will undoubtedly stick to the cupola, whereas the pro- ducer of piston rings is already beginning to use the electric furnace. i Influence of Electric Furnace on Methods A foundry melting metal all day is the exception. The general custom is to keep the men molding until blast is put on and melting begins, which is usually so timed that the heat will be completed as near quitting time as possible. When the first iron comes over the spout, the men stop work and prepare to pour off their molds. In the malleable industry, particularly with fur- nace iron or where the nature of the castings lends it- self to the purpose, melting goes on all day, as in a large cast-iron carwheel shop, and molders mold con- tinuously while a special gang pours. This is the ideal way of conducting operations. Electric furnaces of large tonnage are expensive; a 3-ton outfit, which ordinarily would be considered quite large, costs about $35,000 at this writing. For a moderate degree of refining—that is, superheating, deoxidation and desulphurization—the metal, as taken from the cupola, should remain in the electric furnace at least % hr. With rapid repairs after tapping out, fully % hr. will be required for each batch of molten metal. For an average foundry, melting say 20 tons daily in a 50-in. cupola, the heat will last 2 hr., which permits the treatment of only half of it by the duplex method. Unless the product of the establishment can be divided into high-grade and ordinary work, the duplex process will be difficult to install with the pres- ent daily routine. Foundries can do this in most cases, 437 SE et ee a eae ae Ra winhenee et ie ao S wae A an 438 THE IRON AGE hence an electric furnace equipment added to the ordi- nary foundry will work out very nicely. Where it is necessary that one casting will be as good as the next, the entire heat must be melted from cold stock or duplexed. As by using high sulphur pig irons, large percentages of low-grade scrap, briquettes of borings, punchings, shot, etc., it is possible to get from the electric furnace, when melting cold stock, as cheap a molten metal, fully refined, as from the cupola, duplexing will not be required, and electric furnace heats may be taken off all day long if desired. But unless a shop is run on the all-day pouring plan, the owners will hardly care to make the necessary changes in methods such a radical operating departure produces, unless accompanied by a complete shut-down during the transition arrangements. Advantages of the Basic-Hearth The selection of the basic-hearth electric furnace involves several considerations. In the acid-hearth fur- nace the slag situation is easier; deoxidation is readily accomplished by providing a slag cover with additional periodic charging of fine coke on this to hold the fur- nace atmosphere neutral. The intense heat of the bath, with its high carbon percentage, takes care of all oxygen that may be in the metal in some combination. The disadvantages of the acid-hearth furnace are that, whether melting cold metal or duplexing, it is neces- sary to start with comparatively good material, as the sulphur question remains. Further, there is a marked addition of silicon in the bath by reduction from the silica hearth and slag, if refining is carried on for any length of time. The advantages of the acid-hearth are the cheaper refractories required, the furnace body lasting as long as an open-hearth furnace and in much easier slagging conditions. Where, therefore, the ques- tion of extremely low costs is not so serious an item, there is no reason why an acid-hearth electric furnace should not be used for melting from cold metal, for the sulphur can be held down by using high percent- ages of good low-sulphur pig iron—the melting proc- ess gives no additional sulphur, as is the case in cu- pola melting. In view, however, of the sulphur conditions in pur- chased scrap and the desirability of holding down the sulphur maximum, the basic-hearth electric furnace should be used in every new installation, whether for cold melting or duplexing. Nothing prevents running an all-scrap heat through the cupola for ultimate re- fining in the basic-hearth electric furnace. The car- bon conditions can be regulated in the cupola suffi- ciently, or if necessary in the electric furnace by steel scrap additions, if time can be given for this purpose. The silicon can be increased, if desired, by adding ferrosilicon and such elements as nickel, chromium, titanium, etc., provided by direct or ferroalloy addi- tion, or preferably and far cheaper in the pig iron originally used. Phosphorus and manganese require further comment. Control of Phosphorus and Manganese As the electric furnace for the foundry is intended to improve the molten metal only in regard to initial heat, freedom from oxygen in some combination, and elimination of sulphur to the desired minimum, the question of a possible phosphorus reduction does not come up. In fact, unless the steel stage is passed through this is out of the question anyhow. The iron foundry deals with three ranges in phosphorus. In the malleable casting the phosphorus must range from practically nothing to a maximum of 0.200 per cent. For gray iron the low range is anything under 0.300 per cent; actually it will be around 0.175 per cent and results from using Bessemer p