The Iron Age 1928-10-04: Vol 122 Iss 14

THE IRON New York, October 1928 ESTABLISHED 1855 Obtaining Satisfactory Zinc Coating Some Factors Affecting the Quality Zinc for Hot and Lead Not WALLACE IMHOFF the best ways obtain high-quality zinc the galvanizing pot. special interest know coating through the use good, reliable brand about all the metals that are the zinc, know how they zine for galvanizing purposes. This immediately got there and know what effect these metals have upon brings the question “what factors affect the quality the quality the zine coating and the physical properties zine for zincing?” the Metals may practical value because their chem- Metals found hot zinc galvanizing baths are lead, ical composition because their physical properties. iron, cadmium, aluminum, tin and, occasionally, antimony. The American Society for Testing Materials has set Only two these, lead and iron, are mentioned the standard for the chemical composition “Prime Western standards for prime Western slab zinc. seen that Slab Zinc,” which that such zine shall not contain over some cases has been thought not undesirable put 1.60 per cent lead and 0.08 per cent iron. Prime West- other metals in, and other cases has been found im- ern slab zine the standard used for galvanizing. possible keep other metals out. Some the metals are the time the zinc has reached the coating stage, that present large quantities; others are present very low is, hot, molten metal the galvanizing pot, contains percentages. The important thing know what metals other metals besides those set the standards for such zinc. are present and what quantities. Some these are put into the purposely; others find Since present the largest quantity, only their way into the metal during the regular daily operation natural ask “Is possible galvanize with pure zinc?” IMHOFF, formerly metallurgist the electrical materials department Hubbard Co., Pittsburgh, consulting metallurgical engineer pickling and galvanizing Pittsburgh. His practical experience the galvanizing field covers years, beginning the galvanizing depart- ment the American Steel Wire Co., Rankin, Pa. His technical training was the Carnegie Institute Technology, Pittsburgh. later studied the University Wisconsin, Harvard University and the University Pitts- burgh. the years following became actively engaged the practical operat- ing end the blast furnace, the basic open-hearth furnace and the electric furnace. After months lieutenant the Air Service, Mr. Imhoff again resumed his work the steel business assistant the general superinten- dent Eastern steel plant. 1920 became research engineer for the Sheet Metal Ware Associa- tion New York and Buffalo, investigating the field hot galvanizing for large steel companies. This work was carried for five years Mellon Institute Industrial Research, University Pittsburgh. The investigations included all the troubles that the practical galvanizer likely encounter, well improved methods galvanizing. number patents were taken out, including one the field electric galvanizing. VOL. 122, No. One the best practical galvanizers the country once remarked that the zinc use was too pure for galvaniz- ing purposes. There least still some doubt whether spangles can obtained when pure zinc used. interest perhaps mention briefly some the qualities very pure zinc, the purest sheet available. This zinc contains considerably less than 0.1 per cent impurities. The cost such metal is, course, high that would impractical use for commercial gal- vanizing purposes, even small way. sheet this metal was found soft and ductile. could easily bent back and forth without showing any signs splitting cracking the bend. was very difficult dissolve this metal acid compared with dis- solving ordinary samples from slab suitable for gal- vanizing. Our photomicrograph this pure rolled sheet zine shows that the grains are very fine, having been mashed and broken the rolling process. other metals im- purities can seen, even under the microscope. discover what would happen from galvanizing with pure zinc, experiments were made with one the very best quality commercial slab shown the analyses two samples below: Sample Sample Per Cent Per Cent Zin 99.25 99.46 Lead 0.80 0.52 Iron 0.02 0.02 This was very pure zinc, although contained consid- erable lead. Before any metallic additions were made, large number sheets were galvanized and very good spangles were produced them. This shows that spangles can obtained without the addition aluminum mak- ing other metallic additions the bath. additions were made the bath for three days, and sheets were galvan- ized discover what would happen under these conditions. the photomicrograph this slab zinc the large size the zinc crystals shows that the metal was cast and not rolled. impurities can seen the metal, although much higher magnification they would perhaps become visible. After three four days’ operation the zinc began show evidences contamination with iron. was no- ticed that scum zinc oxide was formed much more over the surface the bath. During the first day’s operation the bath surface stayed bright and mirror-like, and when the sheets were drawn through they were bright and had good spangle them. Surface Oxidation Causes Trouble couple days, however, the surface became dusty looking, dull, and was longer possible skim bright mirror-like surface. fast the skimmer was drawn over the top the surface closed behind it, leaving dusty, yellow surface through which draw the sheet. Thus seen that, when metallic additions are made the bath, the surface quickly oxidizes after few days operation. also clear that spangles can obtained simply using zinc with metallic additions, but for only short period time. Hannah and Rhead* state that “pure zinc alone in- capable producing spangle.” The zinc used here con- tained small amounts lead and iron and may possibly have had large enough quantity develop spangle. All metals have skin and show surface tension, much the same the skin the surface water. Pure zinc exception. The mechanism the formation the spangle seems that this skin breaks into pieces the sur- face the galvanized iron, leaving some places bright and others dull. Thus pure should give what ordinarily known spangle. But, from practical standpoint, pure zinc will not give *“Crystallization Effects Galvanized Dickson Hannah and Rhead. Journal the Institute Vol. XXX (1923), page 93. 812—October 1928, The Iron Age spangle, for pure zinc quickly becomes contaminated with small amounts iron. Also, the surface the metal oxi- dizes quickly, producing dull, powdered luster, which pre- vents the formation the spangle. What really happens that the metallic skin which produces the spangle gone, and its place are the very fine particles non-metallic oxide. Therefore spangle can form, because the materia] form longer there. may perhaps physically possible obtain spangle with pure zinc, but not possible from practical standpoint, because the zinc can- not long kept pure under practical conditions. Why Lead Rarely Gives Trouble Lead does not seem harmful zinc, for two rea- sons: First, alloys with zine only very small second, any excess lead over the amount that will alloy with the settles the bottom the pot, and en- tirely harmless from galvanizing standpoint unless be- comes too deep. lead were lighter than zinc, and thus came the surface the bath, would quickly oxidize zincing temperatures, and perhaps harmful. Surface Slab Commercial Slab Zine High Iron Content. This kind metal apt brittle and decrease the resistance the coating against corrosion Hannah and Rhead added considerable quantity lead (sufficient saturate the zinc and leave excess) molten pure zinc. They state: “It was found that span- gled coating could produced readily, and that there was optimum temperature for the production spangle grains maximum size. This temperature was found lie about deg. above the melting point zinc. cannot absolutely fixed definite value for articles varying mass, owing the impossibility deciding upon the average size the spangle grains sheet, with suf- ficient definiteness.” They state that the addition lead bismuth facili- tates the production the spangle, but the discussion > | | 7 their paper John Welding said that had never found necessary add lead the galvanizing bath. was also interesting note what Garland. Cos- sipore, India, had say regard lead the zinc bath. was interested note the conclusion that the presence lead was necessary the production the spangle. found that pails dipped temperature 890 deg. Very Pure Com- mercial Slab Zine Used for Galvanizing Purposes. This not pure metal that shown the other view this page, but thoroughly satisfactory use and finan- cially practicable Fahr. the spangle most pronounced, and had come the conclusion that the dipping temperature was the chief factor for its production. But since reading the authors’ paper, had looked the analyses reports the zine used his work, and found that contained 1.9 per cent lead. Discussions other authorities galvanizing have shown that, from the practical standpoint, lead has not been found harmful zinc. The objections large quan- tities lead from practical angle have been due price, and the fact that settles the bottom the kettle. This raises the dross into level which the articles galvanized must pass through it, thereby keeping the dross stirred and producing very inferior, low-quality coat- ing. not uncommon practice have dip out ex- cess lead when this happens. Difficulties Caused Iron Iron, the third impurity found zinc for hot zincing purposes, far the most important. The limit set for iron the American Society for Testing Materials 0.08 per cent. Most the practical galvanizer’s troubles come from iron the zinc. Hence some explanation neces- sary account for the difference between this very low per- centage the metal, bought, and the high percentages iron found both the molten zinc bath and the gal- vanized coatings. Iron, although specified low the standards, times may high slab zinc. This was found true most galvanizers during the war period, and for few years after the war. present, however, most the slab zinc the market meets the requirements the standard set for metal for this purpose. But only matter good business policy check all the slab zine when re- ceived. Physical appearance and chemical analyses will quickly show the quality the metal. These facts are best illus- trated example large shipment slab zinc that did not meet the standard. This metal was prime Western zinc, and not remelt zinc. not inferred, however, that most the slab zine the market today low quality, because exactly the opposite true; most well within the limits set standard. Deleterious Metal Easily Detected The purpose this illustration show how high iron content affects both the physical and chemical qualities slab zinc, and how may detected. All slab zine should analyzed according the method given the American Society for Testing Materials standard for sampling and analyzing slab zinc. After doing this and finding the zinc not standard, was check the results some additional sam- ples and analyses. Our third illustration shows the. top surface one the slabs metal. The metal was not all like this, and the strange part was that other slabs, without this crystallization, were even higher iron con- tent. That the iron had segregated the middle this slab shown the analyses two samples from this crystallized area. Per Cent Iron Sample 1... 0.238 Sample 2...... 0.255 the slab, which appeared composed purer metal. Samples from these areas showed the following results: Per Cent Iron Sample 0.0952 Sample 2.. 0.0535 Sample 3.. 0.0714 Average 0.0654 Thus can stated definitely that the chemical com- position the does affect its physical appearance and fracture, for the average the two samples drilled HOTOMICROGRAPH Pure Rolled Sheet Zinc Containing Less Than 0.1 Per Cent All Other Metals. This material too expensive used for commercial galvanizing the poor-looking area was 0.246 per cent iron content, compared with 0.0654 per cent content for the clear crystalline area. This difference the appearance the fracture the slab through these two areas was easily de- tected, also. Iron zine has the tendency give the metal brass-yellow color and give the grain fine, sandy ap- The Age, October Attention was then turned the better looking area | 7 pearance. Pure metal has bluish luster and large, bright Zinc high iron very brittle; pure metal somewhat ductile. Other slabs were drilled and the average all showed high iron content. was found after going over many slabs that, first, the physical appearance affected the chemical composition the second, the most highly contaminated part the metal found toward the center the slab; third, iron gives the zinc fine, sandy fracture and light brass-yellow discoloration; fourth, pure metal highly crystalline and has bluish luster, and the surface the slab smooth and clean. With good, high-quality prime Western zinc, takes from two three weeks saturate the metal with iron that dross will settle out. the kettle overheated this will occur, course, much sooner. Iron tends make the coating brittle and decrease its resistance corro- sion. Cadmium found some zincs and has not found favor, especially from the sheet galvanizers. tends produce very fine, small spangles, which themselves are not attractive. Aluminum has been put the zine bath for some time and very desirable when the bath open—that is, not entirely covered with molten sal-ammoniac flux. tends give the coating bright appearance, and keeps down ex- cessive oxidation the very desirable ob- taining good spangle. Tin, also, has been used for some time the sheet gal- vanizing industry, and the tin that develops the large spangle sheets. Antimony often finds its way into the bath, due the charging scrap metal into the galvanizing pots. tends make the coating brittle and will cause considerable trouble giving yellow discoloration the sheet, put too large amounts. Cooperative Investigations Die Castings High Melting Brasses, Aluminum-Base Alloys, and Low Melting Zinc-Base Castings Studied England die casting industry (according speakers before the Institute Metals, Liverpool, Sept. suffered serious setback the result bad work generation ago, and buyers are still skeptical about its ability furnish castings uniformly high quality. view the resulting stagnant condition, leading firms or- ganized research into certain phases the technical sit- uation, and some the results attained during the past four years were presented before the mentioned. Representatives the industry present the meeting freely acknowledged that considerable improvement practice had resulted from these investigations. High-Speed Steel Dies Favored Although the question metals for dies was not inten- sively studied, much discussion centered this matter. Suitability various steels for molds and cores when cast- ing copper-rich alloys were investigated agitating sam- ples the melted alloy for one three hours. Marked differences attack were noted. steel and heat-resisting steels were little corroded, but soft and mild steel were rapidly attacked. Chromium plated steel resisted attack excellently, but the plating tended flake off result alternate heating and cooling. com- parative figures were given for cast iron, from which per- manent molds are frequently made England. Some heat-resisting irons have been investigated the Cast Iron Research Association and had successfully been used for severe service. From the discussion appeared that high-speed steel favored for dies for the industry, al- though was noted that one steel from one source might act very differently from similar steel from another manufacturer. Another speaker emphasized the important part played the die designer and tool maker; the com- mercial success more than one firm depended upon the development staff such highly-skilled specialists. more extensive investigation was made into the prop- erties aluminum-base castings, made permanent molds without pressure. Castings studied were per cent copper per cent copper per cent silicon per cent copper, per cent silicon “Y alioy” (Cu: Ni: Mg 4:2:1%) (Cu: 3:13) 1928, The Iron Age Satisfactory results were obtained both test bars and tubular flanged forms except for the first two mentioned. Hot shortness was thought responsible. supple- mentary investigation the impact strength these alloys was found unimpaired temperatures within degrees commencement melting. Shrinkage cavities some castings were controlled close regulation the mold temperature, although was admitted that change mold design might have had similar effect. One the speakers asserted that tensile strengths reported for the 12-per cent silicon alloy were least 2000 below what would regard good works practice. Dr. Rosenhain said this occurred rarely; nearly always the complaint that the laboratory can get better results with refined control. Sixteen zinc-base alloys, having copper and tin, cop- per and aluminum (plus further additions nickel, cad- mium, lead magnesium), were studied the form test pieces made pressure machines operated hand. was found that porosity depends almost entirely the kind pull given the lever, although this effect minimized with wide gates. sound test pieces the tensile strength little affected reasonable changes casting conditions. Such castings were tested after accelerated aging (ex- posure hot moist air steam). was found that chem- ical variations the compositions studied had effect rate growth compared with the form and mechanical condition the casting itself. From prac- tical standpoint, manufacturer these low melting al- loys declared that the casting temperature, temperature mold, size gate and vent, and type pull, were all im- portant variables, but they depended the size and char- acter the casting. axiomatic that the metal should and that the mold should cool enough promote ready solidification, yet warm enough allow the whole the metal get before began solidify. view the complicated form die castings, standardized gate could adopted. The type pull the lever operating the plunger doubtless important, and varies with the skill the workman. being found that the more viscous alloys zinc-aluminum-copper could cast the same conditions the pressure die castings aluminum and alumirum alloys most successfully. > ear Blanks with Minimum Waste New Method Places Toughest Part Bar Where Teeth Will Cut, Thus Promote Strength MCGRODER NIFORMITY grain structure where most needed and minimized waste material are the outstanding improvements effected new method manufacturing bevel ring gear blanks, developed and perfected the forge department Dodge Brothers Cor- poration, Detroit. Using chrome-vanadium steel bar stock, this new process, through novel heading operation, turns the outside surface the bar out and away from its center, until lies right angles the original bar. This places the best the metal, that portion which has been most refined the rolling process, the face Into This Heading Ma- chine (Above) with 6-In. Capacity Are Fed Bars Long. The dies are two positions, the first which presses far into the heart, forcing the outside surface “skin” the bar lie back cir- cular flange, approaching the shape and dimensions the rough blank “doughnut.” The next position brings the shap- ing the “doughnut” nearer completion and shears from the bar, leaving the new bar end with deep impression its center, which the beginning the next “doughnut” the ring blank, where the teeth will cut. also leaves the grain the steel running the general direction which the teeth will cut, straight out from the center the ring, thus rendering the gear-cutting operation easier. Earlier methods failed produce uniformity grain direction and structure and wasted much higher per- centage the material scrap. Most commonly used short section round bar stock, after has been flattened out the required thickness and diameter. This leaves the Under the Gravity Drop mer, Board Hammer, Right, Below, the Rough Ring “Doughnut” Produced the Horizontal Heading Machine Re- ceives Several Blows Which Shape into the Ring Gear Blank, with Slight Flashings Both Inside and Outside. The crank-action trimming press its left removes the flashings, after which the blank receives another blow two under the drop hammer insure accuracy dimensions al The Iron Age, October Right Top the End 12-Ft. Bar After the Heading Machine Has Completed Its First Operation, Pushing into the Center the Bar This shows the side the ring blank which will composed largely and Forcing the Outside Surface Form One Side the Circular Flange. metal from the center the bar. The metal from the bar surface forms the other side the ring, where the gear eventually cut. the center the remainder the bar after the partly formed blank has been sheared off the heading second operation, leaving depression the center the bar which the hole the next “doughnut.” machine. left the end bar worked down too short for the jaws the heading These rough ends are just large enough flattened out have the center punched out and made into two ring blanks the process formerly employed Four Stages the Production the Ring Blank After Leaves the Horizontal Heading Machine. partly formed gear blank turned out the heading machine. the left the rough Next the same after has received several blows from the drop hammer and still bears which are removed the trimming hammer. The two irregular circles are the flashings removed the trimming press. The ring right the completed blank, ready for better surface metal the outside the ring. conse- quence the teeth are tougher near the outside diameter than they are their narrower ends. the inside diameter. Another widely used method bend piece flat bar stock, which has been rolled approximately the re- quired shape, into circle and then weld the ends together. Two this method are that the grain the metal the completed ring blank lies almost right angles the teeth that will cut it, and the characteristics the metal (both chemical and structural) the welding point differ widely from those prevailing elsewhere the blank. Both these conditions render more difficult the gear-cutting operation. third method split “but- tonhole” lengthwise piece round bar stock and then enlarge the opening until approximates circle. But this leaves, opposite sides the ring, two sections where the grain irregular. the present method 12-ft. bars round chrome-vanadium steel are used, containing 0.17 0.20 per cent carbon, 0.15 0.20 per cent vanadium and per cent chromium. These are heated oil-fired furnace and fed into National heading machine, which driven 75-hp., three-phase motor. Tests have shown that the unusually large flywheel with which this heading machine equipped enables deliver momentarily over 300 hp. when the maximum pressure developed the upsetting operation. Two operations are provided for the dies the head- ing machine—the first, upsetting; the second, shearing. The upsetting die punches into the center the bar and mush- rooms the stock out into tulip-shaped, circular flange, with the more highly refined metal from the surface the bar its inside face, where the teeth the gear will air lift raises the bar from the first position and the second operation shears the rough ring from the bar, leaving deep depression the center the bar, which become the hole the next gear blank. 816—October 1928, The Iron Age Etched Sections Showing Just the End Bar Going Through the Heading Machine. left the bar after the first blow from the heading die, which has punched into the center the bar, forcing the surface metal out into circular flange approaching the shape and size the completed gear blank. This places the more highly refined metal from the bar surface the face the blank, where the teeth will cut. right the same bar has received the second blow from the heading machine, which helps shape the ring blank and shears from the bar ™ | ( \ - fog ~ Etched Sections Completed Ring Gears. The illustration left shows the chief advantage the new method. Here the grain the metal lies the best possible direction, straight out from the center the ring, with the more highly refined metal from the surface the bar the teeth the gear, where strain and wear are greatest. the right the more highly refined metal from the surface the bar can clearly seen the side away from the teeth. The “doughnut” used this piece was intention- ally placed face downward the drop hammer, for experimental purposes After being reheated another oil-fired furnace the “doughnut” receives several blows under 3000-lb. gravity drop hammer, board hammer, which shapes into the required dimensions the ring gear blank, leaving only slight flashings the inside and outside peripheries the ring. While still hot the blank placed crank-action trimming press, which removes the flashings. The trimmed blank returned the drop hammer, where receives another blow two under the forming dies insure accu- racy shape and dimensions. accurate are the dies the heading machine, the drop hammer and the trimming press that the flashings removed the press from single blank weigh only oz. This practically all the metal wasted scrap this new method, remarkably small proportion. Operators the heading machine, which produces average 200 rough blanks hour, find possible feed about ft. the 12-ft. bar into the machine while the regular gripping dies are operation. The remaining short ends are allowed accumulate until there large enough quantity hand make worth while fit the machine with special dies adapted gripping these short pieces. But even with these special dies the heading machine incapable using the bar the end. short length left over, containing about enough metal for two more blanks. This sawed into two pieces, which are flattened out under drop hammer until they are about the thickness and diameter the “doughnut” produced the heading machine. hole punched the center each piece, which then put under the drop hammer and trimming press, where receives the same treatment given the “doughnuts” produced the heading machine. The two small pieces punched from the center these blanks add slightly the amount material wasted scrap from each bar, but the waste for each ring gear produced still much lower than that from any method production pre- viously used. Aluminum Productive Capacity Rapidly Expanding UCH data are available seem convince writer “Mineral Industry, 1927,” that world production aluminum steadily increasing, and now excess 200,000 metric tons annually. The writer goes specu- late just how far this increase go, and what the re- sults will be. Fifteen years ago France and the United States produced almost all the world’s supply bauxite, but since that time extensive deposits high-grade bauxite have been developed half dozen different countries, and the production now trebled, with the new producing areas furnishing over half the output. There has also been corresponding increase smelting capacity; the enormous rew Canadian plant the Aluminum America Arvida, Quebec, went into production 1926, and exports from Canada the United States increased 23,170 net tons 1927 from 11,240 the year previous. The most recent move the world’s market was the organization during 1926 the Aluminum Cartel, which includes the principal European producers, thus dividing the field between the two forces, the cartel the one hand, and the Aluminum Co. America the other hand, each controlling about one-half the world’s producing capacity metal. These three factors—plentiful supply bauxite, exten- sion smelting capacity and organized competition—may result marked increase production and correspond- ing lowering prices. the other hand, many users, particularly the automobile industry, have been substi- tuting steels high strength and low corrodibility for alu- minum lower cost and with little increase weight. Figuring back from the value new aluminum pro- duced the United States (Bureau Mines figure $39,- 266,000) and the average price 25.4c. per “Mineral Industry” says that 1927 production amounted some- thing over 150,000,000 The plant Massena, Y., contributed about half the production, the remainder com- ing from Niagara Falls, Y., Alcoa, Tenn., and Badin, Imports totaled 68,389,641 while 16,051,477 ingot, plate and tube were exported. The five aluminum plants operating Norway have rated capacity about 26,000 metric tons an- nually; the production 1926 was 24,429 tons. addition, two other plants, each 10,000 tons capacity, are under construction, and the 7000-ton plant the Norsk Alumi- num Co. (controlled the Aluminum Co. America) enlarged 11,000 tons; this will bring the ca- pacity Norway about 50,000 tons annually. Experiments with high-pressure steam locomotives have been hampered the necessity for using turbines gen- erate the power with expensive intermediate gearing be- tween turbine and driving axles. Nevertheless there has been operation Europe for over year “Schmidt- Henschel” locomotive generating steam 1400 per sq. in. tubular boiler, and delivering 900 the prime mover. The tubes are nickel steel; distilled water used for make up, and the engine has run about 30,000 miles without tube troubles. Another high-pressure locomo- tive different design also running the Swiss roads. The Iron Age, October 1928—817 | ~~ | | Electric Normalizing and Annealing Eight Furnaces Handle Alloy Steels Various Heating Cycles—Large Pit Furnaces Feature—Air Blast for Cooling result efforts the Timken Roller Bearing Co., Canton, Ohio, settle annealing questions raised its production alloy steels has been the installation bank electric annealing furnaces that, individually and collectively, present several features. The problem utilizing electric heat this particular case was complicated number factors. these one the most outstanding was the volume production de- manded. Another was that several different types steel were made, each which required special annealing cycle and subsequent course treatment. fact, some the factors involved threatened make the general use electric heat impractical, spite manifest advantages. The difficulties were overcome, however, and group eight furnaces has been installed; they form total con- nected load 3600 kw. Two more are projected for in- stallation the near future that will increase the total 5450 kw. the furnaces have all been specially designed for their particular work, individual description the different types may interest. Pit Furnaces for Slow Cooling Probably the most remarkable the group, point size and novelty design, are the two 850-kw. pit anneal- ing furnaces. These furnaces were specially built for an- nealing high-carbon chrome steel, any other steel where the annealing cycle calls for slow cooling. The long Two 850-Kw. Pit Type Furnaces (Right) Used for Long-Time Annealing High-Carbon Chrome Steel. Interior the furnace and method protecting heating units are shown above 818—October 1928, The Iron Age cycles required have, hitherto, been decided obstacle the use electric heat for annealing such steels any- thing approaching quantity basis. well-insulated fur- nace the cooling time was usually long that production was seriously delayed. the case these particular fur- naces, this difficulty has been overcome the introduction novel feature the furnace construction. Each furnace ft. wide and ft. long inside, with loading depth ft., and accommodates charges bar tube stock weights tons. The covers are separately framed structures, weighing about tons each, fitting sand seals around the top the pit. They are handled off and the furnaces special electric trav- eling gantry crane running tracks the floor level each side the furnaces. The heating elements are the T-grid type, and are mounted the side walls and bottom the pit. They are divided electrically inte two circuits, one including the side wall elements and the other those the bottom. Each circuit provided with individual control which gives two sets connections, one 440-volt, three-phase for high starting input, and the other, 440-volt single-phase series for soaking heat. The first has power demand 425 kw. for each circuit, 850 kw. total, and the latter 142 kw. for each, 284 kw. total. The charge stacked cradles, and loaded shown one the illustrations, which also shows the method mounting the resistors and the method protecting them from damage during charging dis- charging means heavy heat-resisting alloy guides. Air Blast Accelerates Cooling The operation the furnace briefly follows: The material brought annealing temperature (1450 deg. Fahr.) rapidly possible, which point the circuit — — cut over from the connection series, and the tem- perature held long enough insure uniform heating. The charge then slowly cooled through its critical range, the process being carefully regulated insure the exact metal- lurgical results desired. After the critical range passed, cooling accelerated means air blast system, which consists series pipes built into the furnace through which cooling air forced means two 20-hp. motor-driven high-pressure centrifugal blowers. this forced cooling system that has rendered long time annealing practical commercial basis these furnaces. has eliminated the possibility exposing the charge the air before has cooled suf- ficiently, and, the same time, removes the objectionable feature too long cooling period. The total annealing time from charge charge just about cut half the use forced cooling. third 850-kw. pit furnace the same general construction and operating principle, will installed shortly. Chrome Steel Normalized Special Furnace All high-carbon chrome is, before annealing the pit furnaces, normalized 700-kw. pusher type nor- Side Pusher Mech- anism the Nor- Furnace That Shoves the Charge from the Charging the De- livery Side. The con- veyor which carries the shoes under the furnace for re-inser- tion can seen the right center ii The 700-Kw. Pusher Type Normalizing Furnace with Tubes Being Pushed Upon the Run-Out Table malizing furnace. This also used normalize certain low-carbon steels, and for processing steels that have meet cold shear tests. ft. wide and ft. long inside, and capable handling bars in. square. and ft. long, tubes corresponding dimensions. equipped with three pusher mechanisms, two being lo- cated the charging end and one the side. The latter was developed push the charge across the width the furnace interior from the charge the discharge side. consists five rails crossing the furnace interior equal intervals, and terminating the discharge side large trough which delivers flight conveyor for returning the carrier shoes the transverse pusher. The actual pushing done number shoes, baulks, each trough, which are pushed across the rods the pusher mechanism proper. The charge rests these shoes, and carried across the furnace the movement the shoes the trough. When the shoes come the dis- charge side they are delivered the conveyor and returned the loading side for use. The pusher mechanism designed that the motor circuit tripped the pletion one revolution the cams, that the dis- tance movement limited. The other pushers are The Iron Age, October | 3 4 f | ’ the rod type, and serve push the charge and out the furnace, respectively. The T-grid heating elements are mounted partly the furnace roof, and partly transverse wells located be- tween the piers which support the cross pusher shoe troughs. Electrically, the heating elements are divided into four separate circuits, each with individual control. The operation the furnace quite simple. The stock virtue the electric connections that have been adopted, subjected high initial heat entering, the degree which lowered moves across the furnace. Arrived the finishing, delivery side, the work pushed out the furnace onto run-out table which equipped with manipulators, which deliver motor-driven cooling bed. From the bed delivered directly the cradles which loaded into the pit annealing furnaces. The controls for all the motor-driven operations, includ- ing the side pusher, are located the charging side that the furnace can operated one man. Some idea aa the method control can obtained from one the illustrations. The capacity the furnace about 150,000 lb. stock per day, with power consumption about 200 kwhr. per ton. additional furnace for normalizing work will installed later the year. will rated 1000 kw. Normalizing Small Lots Heat treatment bar tube stock various alloy steels accomplished 300-kw. hearth type furnace. This furnace also used for the normalizing small lots steel which impractical, for one reason another, handle the large unit. The furnace the double end type, being about ft. inside. The stock pusher and, after has been uniformly heated, pushed out the other onto receiving table. This table tilted another motor-driven mechanism, and the stock dumped into oil-filled quenching tank. removed from the tank motor-driven conveyor. order compensate for any local cooling that may take place the ends near the doors, the heating elements 1928, The Iron Age have been grouped into three zones, two door zones, and central main zone. the mounting, part the grids are mounted the roof and part underneath the hearth. the furnace interior, with consequent even heating charge. Two small circular pit furnaces have been installed treating rod coils. They are rated 100 kw. each and are separately supplied from 440/125 volt, single-phase trans- formers. They can seen accompanying picture just the right the hearth type furnace just described. Two Car Type Furnaces for Bar Stock Miscellaneous bar stock, especially that which does not require annealing cycles over 24-hr. duration, which can discharged into the open air high temperatures, annealed two car type furnaces. One them, 315-kw. furnace, was built William Swindell Brothers, Pitts- burgh. The inside dimensions are ft. long, ft. in. wide and ft. high. The car dimensions are ft. long, ft. Normalizing Fur- nace from the Charging Side, Showing the Charging and Discharging Pusher Rods, and Their Control wide and about ft. high. The normal rating the furnace 20,000 per charge, but the car will carry load twice that, necessary. The heating elements are mounted the roof and side walls the furnace proper, and the car bottom. The latter divided into wells, firebrick piers built from the car bed. The elements are mounted these wells, and the whole covered with interlocked alloy sheets that form the hearth. The elements are directly connected the 440- volt, 3-phase supply circuit, two connections being available, 3-phase delta for high initial heat, and 3-phase for hold- ing soaking heat. Automatic temperature control ob- tained means Leeds Northrup potentiometer type single point controller recorder. The average economy 355 kwhr. per ton. The car moved and out the furnace motor- driven rack and pinion mechanism. Connection for the ele- ments the car body made bushing and coupling located one side the door. very elaborate system sand seals has been adopted prevent uneven temperatures the furnace interior due the leakage air from the - ed: . = ‘ s The 300-Kw. Hearth Type Fur- nace Used for Heat Treating Bar Tube 4 Stock. The two 100-kw. circular pit coil furnaces can seen the right background outside. The door provided with seal both top and bottom, and there seal each side the car, which engages with knife edge the furnace wall. The furnace also equipped with vertical cooling ports the side wall, which the rate cooling can accelerated desired. The second car type furnace, furnished the General Electric Co., differs considerably its design and construc- tion. The inside working dimensions are ft. long, ft. wide and ft. high, the overall sizes being ft. The car proper ft. long, ft. wide and has overall height ft. equipped with cradle which raises the charge above the lower level the heating ele- ments the side wall. The heating elements are all mounted the side walls, there being none the roof the car. They are di- vided into two zones, each with separate control. The design the elements proper such that extra heat provided near the door compensate for door losses. Their location 315-Kw. Car Type Furnace (Right) Used for the Annealing Stock Requiring Short Anneal- ing Cycles 460-Kw. Car Tyne Annealing Furnace (Below) | the walls brings the lower ends below the level the charge the car, that heat may radiated through the charge. The furnace supplied with power 220 volts, each zone forming separate circuit. Two connections are available for each circuit delta for high heat and for soak- ing heat. The power consumption the first 230 kw. per zone, 460 kw. total, and that the other 153 kw. per zone, total 306 kw. The furnace has normal ca- pacity tons but, like the other car type furnace, has 100 per cent overload capacity. maximum heating cycle hr., the power consumption averages about the same that the other furnace. High temperature insulation the subject 20-page treatise prepared for distribution Celite Products Co., Los Angeles, containing information whereby the loss heat through various kinds walls may computed, and upon which economical insulated design may based. The Iron Age, October ges ’ m4 as 7 — Discuss Machine Tool User Problems Lubrication, Hardness Metals Cut, Tooling Service, Fabricated. Frames and Productive Capacity and meeting problems which confront the user machine tools were discussed the second annual meeting the Machine Shop Practice Division the American Society Mechanical Engineers, the Hotel Sinton, Cincinnati, Sept. 27. the symposiums aeronautic machine shop problems, lubrication and the use and application machine tools modern manu- facturing methods were contributed seven papers men AYS and means bettering machine shop practice Theory and Practice ROM the standpoint arousing controversial comment the paper Forrest Cardullo, chief engineer Gray Co., Cincinnati, presenting Theory the Lubri- cation Cylindrical Bearings,” was outstanding. After building his theory, Mr.. Cardullo deduced from cer- tain general considerations regarding the design and opera- tion bearings. Assuming, seems reasonable, that the minimum film thickness the most important the fac- tors which determine whether not bearing will operate successfully, arrived the conclusions embodied the following general rules: The load-carrying capacity bearing proportional its diameter. The load-carrying capacity proportional the operating viscosity the lubricant, that is, the viscosity the lubricant the temperature which the lubricating film attains operation. The load-carrying capacity propor- tional the speed rotation revolutions per minute. The load-carrying capacity proportional the surface speed the journal, since this proportional the product the diameter and the speed revolutions per minute. The load-carrying capacity bearing function its length: For very short bearings, such eccentric straps, proportional the cube the length. For very long bearings, proportional the length. For bearings the usual proportions, the load-carrying capacity proportional some power the length greater than the first and less than the third. The power loss bearing proportional the square the diameter. The power loss proportional the length. The power loss proportional the square the speed revolutions per minute. The power loss proportional the square the surface speed the 10. The power loss inversely proportional the operating clearance. 11. The power loss proportional the operating viscosity the lubricant. These rules, said Mr. Cardullo, lead directly the fol- lowing conclusions regarding the ultimate rise tempera- ture bearing operating continuously: The rise temperature bearing independent its length; proportional its diameter; proportional the operat- ing viscosity the lubricant; proportional the square the number revolutions per minute; and inversely proportional the running clearance. Mr. Cardullo pointed out that these rules assume certain conditiors which never are realized practice—that the How Railroads Use ARGE sums money are spent annually railroads making changes machine tools and shop surround- ings, keep with the increased areas and weights parts machined and maintained, said North, shop superintendent Illinois Central Railroad, Chicago, paper dealing with “Machine Tools—Their Use and Application the Railroad Industry.” declared that the number parts the locomotive, well weights, are increasing 822—October 1928, The Iron Age selected eminently qualified speak these subjects. delightful trip the Ohio River steamer Cincinnati Ashland, Ky., inspect the continuous sheet mill the American Rolling Mill Co., constituted novel departure from the routine procedure most conventions. Three the technical sessions were held board the Cincinnati and one the Hotel Sinton. About 275 members and guests registered the meeting, and this number 225 made the journey Ashland. Bearing Lubrication box and the journal are both truly round and perfectly smooth, that they are rigid and maintain their shape, and that their axes are parallel and are not affected tions produced the load. fact, the rules formulated are indicative merely the general trend the behavior bearings. Lubrication Grooves Bearings relitz, research engineer Westinghouse Electric Mfg. East Pittsburgh, said that large number machine bear- ing troubles would eliminated and wear would decreased were more attention paid the fundamentals lubrication during the design machines. Viscosity alone cannot relied upon test for good lubricant. Its oiliness just important, this property greatly decreases fric- tion between the surfaces contact. Furthermore, the oili- ness apparently determines the ability the lubricant the rubbing surfaces, which essential for main- taining efficient load-carrying oil film. The mechanical design bearing must developed with the importance fluid lubrieation kept always mind, Mr. Karelitz declared. The lubricant must fed into the bearing point where the pressure the oil low even preferably where vacuum expected, the “up-side” sleeve bearing. important leave uninterrupted the bearing zone, where the load-carrying oil film formed. Indiscriminate cutting grooves bearing may harmful. The function grooves primarily distribute oil from the source supply over the complete length the bearing. Wherever possible, they must confined the unloaded portion the bearing; the loaded part should left free from interruptions. appears that angle about deg. deg. must had between the line oil admission and the load line allow building efficient load-carrying oil film. While essential feature fluid lubrication con- tinuous rotation of-the journal the bearing compara- tively high speed, unfortunately many instances this condition not fulfilled, said Mr. Karelitz. Their Machine Tools constantly. This fact makes necessary establish new methods and higher production maintain costs satis- factory level. this direction many shop kinks have been developed officers and shopmen, while machine tool builders also have made valuable suggestions. Mr. North emphasized that the “man factor” important considera- tion. the workman can induced realize the neces- sity for proposed changes, and become interested 4 | future betterments, his efforts will enter largely into the further advancement this undertaking. Explaining the attitude the railroad toward introduc- tion new tools and rew methods, Mr. North observed that the “field for external and internal grinding has been de- veloped some extent. Many parts formerly turned, planed slotted are row finished far shorter time grind- ing. Metal saved, which itself adds the life the part beirg machined.” Piston rods, air reverse cylinders, air fire-door opener cylinders, grate-shaker cylinders, stoker engines, crank pins and driving axles are among the parts which are being ground, instead being machined some other less efficient and less satisfactory method. Mr. North pointed out that “some thought has been given tire grinding, also some experimental work has been done reducing flat spots car wheels. Unless very small amount metal were removed, tire grinding would not interest railroad management, grinding the flange would slow this operation compared with machine turn- ing and would destroy any saving that otherwise would effected.” Grinding locomotive cylinders and piston- valve bushings would furnish smoother surface than the present method. Increasingly, grirding will used for future operations, machines are designed for that pur- pose. Milling machines are taking prominent part railroad shop practice, according Mr. North. Further develop- millers can brought about and production can increased and cheapened closer study machine-work needs, the tool builder keeping mind the introduction harder and tougher metals employed locomotive construc- tion. regard drilling operations, there slight use for the full radial. Such angle drilling necessary can done either the semi-radial drill vertical drill presses with tilting tables. When multiple-spindle drills are utilized, they should fitted with simple and suitable chuck for rapidly clamping and securing parts ma- chined. Special chucking features and forming tools used con- junction with high-speed tools and specially designed heavy- duty machines have reduced machining time, have enabled railroad shops keep pace with the increased areas and parts machined, and have relieved the fatigue the operator and added his personal comfort. turning bar stock from which cap screws, hex-head machine bolts, studs and other parts are made, Mr. North said that close study required, avoid spending money for waste material, which otherwise would saved labor this operation were used. The time reduction means special chucking feature has been substantial this one class wo