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Cornell University Library 
 TS 565.B7 
 
 ' Seven centuries of brass making; a brief 
 
 3 1924 003 601 634 
 
The original of this book is in 
 the Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924003601634 
 
A- lBriefIMsfojyofiQhLeAiacieiii.lt 
 @^ cLL ii£g eaurly (qimI evsMTecemt^) 
 
 with, f lua1t of iGhie JEIects^cI^vucm&ce 
 aclhieiveiinLem.'i of 
 
 i_ 
 
 1920 
 
COPYRIGHT 1920 
 
 BRIDGEPORT BRASS COMPANY 
 
 BRIDGEPORT, CONN., U. S. A. 
 
ro/ TUDIES of the most ancient and primitive 
 iQ) ruins indicate that the metallurgy of cop- 
 per, tin and iron was practiced in its crudest 
 form in the earliest periods of man's develop- 
 ment. Of these three metals, copper, on ac- 
 count of the ease with which it is smelted, 
 refined, and worked, was probably the first to 
 be used. There is no definite proof of this 
 except that as far as historic times are con- 
 cerned, although iron was known, copper and 
 bronze were in common use long before iron. 
 
 Neither the name of the man who discovered the reduction 
 of copper by smelting nor the method he employed will ever be 
 known because he lived long before men began to make records 
 of their discoveries and doings. We have, however, some 
 evidence of pre- historic metallurgy in the many "founders' 
 hoards" or "smelters' hoards" of the Bronze Age which have 
 been found in Western Europe. These hoards indicate that 
 in those days charcoal and ore were burned in a simple shallow 
 pit in the ground and the fire continued until the copper was 
 melted, then it was allowed to cool in the bottom of the pit 
 forming a rough round cake of from 8 to 10 inches in diameter. 
 Another indication of pre-historic metallurgy is the fact that copper 
 from this period analyzed by Prof. Gowland and others shows a small 
 percentage of sulphur, signifying that the copper was derived from smelt- 
 ing oxidized ores. 
 
 Copper objects appear in the pre-historic remains of Egypt. In 
 fact, they were common throughout the first three Dynasties, and bronze 
 articles have been found that date from the fourth Dynasty (from 3800 
 to 4700 B. C. according to the authority adopted). In Egyptian 
 
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hieroglyphics the crucible is the emblem of copper, which would indicate 
 that crucibles were used for refining. The earliest source of Egyptian 
 copper was probably the Sinai Peninsula, where crucibles have been found 
 in ruins. There, too, are found reliefs dating as far back as the time of 
 Senefern (about 3700 B. C.) indicating that he worked the copper mines. 
 
 Our knowledge of Egyptian copper metallurgy is limited to deduc- 
 tions from metal objects found, and to a few pictures of crude furnaces 
 and bellows, which, however, indicate a considerable advance over the 
 crude hearth method. 
 
 ' The remains of the Mycenaean, Phoenician, Babylonian, and 
 Asyrian civilizations stretching over a period, from 1 500 to 500 B. C. have 
 yielded endless copper and bronze objects, the former of considerable 
 purity and the latter of fairly constant proportion of from 10 to 14 per- 
 cent tin. 
 
 Apparently the first copper used by the ancient people came first (Uniittpr 
 from Sinai and then later from Cypress. Research in Cypress shows 
 that it produced copper from 3000 B. C, and largely because of its copper 
 it passed successively under the domination of the Egyptians, Asyrians, 
 Phoenicians, Greeks, Persians and Romans. Our word "copper" was 
 derived by the Romans, shortening aes cyprium (Cyperian copper) to 
 cuprum. 
 
 As to the tin used in the bronzes, there is some difference of opinion q^\xi 
 as to its origin. Prof. Gowland, for instance, believes that the early 
 bronzes were the result of direct smelting of stanniferous copper ores. 
 However, there is considerable evidence to the effect that this was not 
 true of the Egyptian and other ancient bronzes. As to the source from 
 which the tin was obtained, Spain and Great Britain were used by 
 the ancients. In fact, the name Britanic Isles is derived from the two 
 Phoenician words, breta-nac, meaning land of tin. 
 
 The early history of brass itself is much beclouded on account of the ^i-^qq 
 fact that brass is often confused with bronze and other copper alloys. 
 There are a great many references to brass in the Bible which are un- 
 doubtedly due to faulty translation, either bronze or copper being meant. 
 For instance. Rev. John Hodgson, in a paper published by the Society 
 of Antiquaries, Newcastle-upon-Tyne, in 1822, and entitled "An Enquiry 
 into Aera when Brass was used in Purposes to which Iron is Now Applied", 
 said: "In tracing the connection between ancient implements of bVass 
 discovered in Britain and the mercantile people along the shores of the 
 Mediterranean Sea, it will be necessary to direct our attention to the 
 information which the ancients have left us concerning their knowledge 
 of Tin, which is by far the most common of all the alloys which they 
 used with copper in making brass." This would indicate that even in 
 his time there was confusion in the designation of brass as we understand 
 it today. 
 
ss foundry. Illustration taken from Ecker's "Untererdische Hofhaltung," page 261 , 
 The literal translation of the reference letters is as follows: 
 
 Figure 2. Br 
 published in 1672. 
 
 A. Interior \'iew of a brass furnace showing the D. 
 
 arrangement of the crucibles and how they E. 
 
 are set in place. F. 
 
 B. Furnace in action. G. 
 
 C. Crucible. H. 
 
 Shovel for the calamine. 
 
 Pair of tongs for handling the crucibles. 
 
 Draft opening of the furnace. 
 
 Mold made of British stone. 
 
 Represents the master caster. 
 
 According to description given by the author, calamine and fine coal were mixed together, with water 
 and salt. The crucibles were heated and 46 pounds of the calamine mixture were divided among eight 
 crucibles, then 8 pounds of copper were placed in each crucible. After nine hours in the fire the mixture 
 was well stirred, allowed to stand for an hour and then poured. The process here described is substan- 
 tially the same as revealed by Theophilus four centuries previously. 
 
The earliest accounts of brass making describe the use of calamine 
 (a zinc ore) with copper and it is not until the eighteenth century that 
 the practice of making brass with metallic zinc came into use. 
 
 Zinc as a metal was known in the Far East long before the Europeans 
 had succeeded in separating it from its ores, and it was imported from the 
 East in considerable quantities as early as the sixteenth and seventeenth 
 centuries. Spiauter, from which our term "spelter" was derived, is one of 
 the names under which Easterners marketed zinc. 
 
 Although brass objects dating back to pre-historic times have been 
 found, and many references are made to brass in the earliest literature, 
 the confusion of terms makes it impossible to be certain that brass is 
 meant. The first unmistakable reference to brass in literature is made 
 by Dioscorides in the first century; and the first accurate technical de- 
 scription of brass making does not appear until the thirteenth century, 
 when Theophilus described the calcining of calamine and its mixture with 
 finely divided copper in glowing crucibles. This process was described 
 many times subsequently, and was in general use, substantially as de- 
 scribed by him, down to the eighteenth century. 
 
 The earliest picture of brass making equipment that we have been 
 able to locate is reproduced in Figure 2 from Ecker's "Untererdische 
 Hofhaltung", page 261, published in 1672. According to the author's 
 description, which is very meagre, calamine and fine coal were mixed 
 together, with water and salt added. After heating the pots, 46 pounds 
 of calamine were divided among 8 pots, and then 8 pounds of copper 
 were put in each pot. The heat was applied for nine hours, when the 
 mixture was well stirred, and then allowed to stand for an hour, when it 
 was poured into the mold G, made of Britain stone, so called because it 
 was imported from Great Britain. Though this book was printed in 
 1672, the process it describes is the same as revealed by Theophilus four 
 centuries before. 
 
 A very much better illustration of a brass foundry of this type is 
 contained in an article by Galon, printed in 1764 in Volume V of the 
 Proceedings of the Academic Royale des Sciences. In this article Galon 
 described the art of brass making as practiced at that time. This was 
 followed by two other contributions in the same volume, one by Sweden- 
 borg which covered briefly the practices of the various countries of Europe, 
 and another by M. Duhamel du Monceau who described in detail the 
 equipment and operation of a works in Ville-Vieu. These three articles, 
 together with beautiful illustrations, give a very complete technical 
 description of brass founding work as carried on during the seventeenth 
 and eighteenth centuries. 
 
 According to Galon, foundries were built in units of three furnaces 
 each, and usually not less than two such units were involved in any 
 
 Zittr 
 
 ICttfraturp 
 
 Sra00 Making 
 in tl|f 
 
Figure 3. Tools used in the foundry. 
 Rovale des Sciences, 17b4. 
 
 Illustration from paper by Galon before the Academie 
 
 A. Crucibles for melting the charge. 
 
 B. Tongs used to arrange the crucibles in the furnace and to place pieces of charcoal on the edges 
 
 of the crucibles. 
 
 C. Elbow tongs used to withdraw broken crucibles from the furnace and for pouring from one 
 
 crucible to another. It is also used for holding the crucible while being charged. 
 
 D. Elbow tongs used to withdraw crucibles from the furnace and for pouring from one crucible 
 
 to another. 
 
 £. Tongs for removing the brass bar from the mold, 
 
 F. Rod with a wooden handle for stirring the calamine in the crucible. 
 
 C. Hook for various purposes. 
 
 H. Skimming iron with a wooden handle which is used for cleaning the surface of the fused 
 material before pouring. 
 
 /. Horse for holding the handles of the tongs D when in use for holding the crucibles while charg- 
 ing. 
 
 K. Iron paddle for mixing material in the crucible. 
 
 L. Double tongs for carrying a crucible or ladle when pouring. 
 
 A/. Iron instrument with a wooden handle which is used to form the clay bed for the bars of 
 the furnace. 
 
 A'. Shears for cutting the brass bar. 
 
 0. Tongs for breaking the brass taken from the skimming pits. 
 
 P. Q and R. Potter's wheel for making clay crucibles. 
 
 T. Hammer used for breaking up copper before charging. 
 
 V. Charcoal container. 
 
 A'. Calamine container. 
 
 Y. Measuring box for mixture sufficient for one slab. 
 
 Z. Wheelbarrow for charcoal and cinders. 
 
 10 
 
single installation. Referring to Figure 1 the furnaces are fired from the 
 pit, E, F, each furnace containing eight or nine crucibles arranged as 
 shown in Figure 4. Pulverized charcoal and calamine are mixed in the 
 tub, V, and inserted in the crucibles from the small tub, R, by means of 
 the paddle, T, which was used for mixing and handling the calamine. 
 Copper was used in the form of small cubes or in small balls or shot as 
 in this way a more intimate mixture could be made with the calamine. 
 Having melted the charge, the crucible is removed from the furnace 
 and skimmed in one of the- pits, G and H. The man at 3 is skimming 
 one of the crucibles while the man at 2 is pouring the contents' of the 
 crucible into a larger crucible which was used as a ladle. After the con- 
 tents of the various melting crucibles had been skimmed and poured into 
 the ladle, two men with special tongs, such as shown in Figure 3, carried 
 the ladle as shown at 4 and 5 in Figure 1 and poured its contents into the 
 mold while the latter was in the position shown at I. As soon as the 
 pouring was completed, the mold was hoisted to a horizontal position, the 
 fastenings undone, and the upper part hoisted as shown at K. The 
 workman, 8, is seen removing the slab of brass from the mold. 
 
 J melting furnace construction. Illustration from paper by Galon before the 
 Academic Royale des Sciences, 1764. 
 
 The principal difference between these furnaces and the modern pit furnace is the method of taking 
 care of the gases of combustion. Here they were allowed to pass on through the top of the furnace into 
 the casting shop, where they were caught under a large apron which led them into a common flue; while 
 in the modern furnace the gases are led through the side of the furnace directly into the flue.' The 
 stirring of crucibles in furnaces such as these must have been an extremely disagreeable task. 
 
 11 
 
'^tt iFuniart. 
 
 i! a inr 
 
 (£ Jl1^ittuns 
 
 in * IP 
 
 Those familiar with present practice in brass making will be struck 
 by the remarkable resemblance of methods employed by these early 
 brass makers to the ones in use today. Our modern pit furnaces are 
 constructed for more efficient combustion, but in principle they are 
 similar to the ones shown in Figure 4. Attention is also called to the 
 similarity between the \-arious tongs used today and those shown in 
 Figure 3. In order to compare these old practices with present day 
 practice, photographs have been made showing the stirring, skimming, 
 and pouring of brass melted in a modern pit furnace, see Figures 14, 15 
 and 16. Although no smoke or fumes such as seen in these pictures are 
 shown in the old illustrations, the fact that they were there is attested 
 to by the following quotation from Galon: "The doors and windows of 
 the foundry are kept tightly closed while pouring. The workmen hold 
 the end of their neckties between their teeth when they skim or when 
 they carry or pour metal. By this precaution they diminish the effects 
 of the fire and facilitate respiration." 
 
 Incidentally, the labor conditions existing at this time are extremely 
 interesting. Referring to Figure I it is stated that there were three 
 couches similar to the one in X in each foundry for the use of the work- 
 men, as they spent the whole twenty-four hours of five days each week 
 in the foundry, having Saturday and Sunday off. Quoting from Galon, 
 "the ordinary hours of work are: 
 
 "Pouring the slabs between 2 and 3 o'clock in the afternoon. The 
 crucibles are put into condition and the fires started at 5 o'clock in the 
 afternoon. At 10 o'clock in the evening the fires are replenished and the 
 second pouring is made at 2 or 3 o'clock in the morning. In other words, 
 a complete operation requires 12 hours." 
 
 Figure 5. The ancients worked brass mostly under the hammer. The above illustration shows a 
 forging plant operated bv water power. The details of the equipment are shown in Figure 6. The 
 practice here shown according to Galon was instituted about 1695. 
 
According to Galon there were three workmen in each foundry — 
 a master founder and two assistants — and the work was so laid out that 
 when operations were to be performed which required more than three 
 men, help could be obtained from one of the other foundry units. As far 
 as the pay was concerned the assistants received about 1 2 cents for a day 
 of 24 hours" work. They were also supplied with beer which was con- 
 sidered to be a necessity for all foundry men, and coal for heating their 
 dwellings was furnished to them. 
 
 Evidently master founders were paid on the production basis because 
 Galon says: "It is estimated in 1748 and during the war that the master 
 founders earned, after expenses were covered, 4 florins for each slab of 
 85 pounds." With regard to the skill necessary, Galon says: "Work in 
 a foundry demands continual care in order to feed the fires and maintain 
 
 ' it X 
 
 Fia. 4 . 
 
 P! X 
 
 V i ./„ rim: 
 
 Figure 6. Details of a brass forging plant as shown in Figure 5. Each water wheel operates a gang 
 of three hammers. The cast bars and other shapes are worked into final form under the hammer. The 
 descriptions which accompany these illustrations in the original manuscripts, tell how the metal is heated 
 and annealed between the successive reductions under the hammer. 
 
 13 
 
Figure 7. This illustration made in 1764, shows 
 two views of a machine for finishing brass kettles 
 and other vessels. The process is interesting, in 
 that it resembles the modem process of spinning 
 brass. The work-head is driven by belt K through 
 the pulley I; the vessel is mounted in the work- 
 head M by clamping between M and a movable 
 center P which is engaged by the fixed center 
 Q. Z is the tool used by the workman in forming 
 the interior of the vessel. 
 
 Figure 8. After the brass is hammered into 
 long wide strips, it is cut into narrow strips pre- 
 liminary to subjecting it to a drawing operation. 
 The shears are operated by pressure from the knee 
 of the workman, and the width of the strip is 
 determined by a limit guide D carried on one of 
 the blades of the shear, as shown in the sketch at 
 the right. The illustration is taken from Galon, 
 1764. 
 
 Figure 9. Although practi- 
 cally all copper and brass was 
 worked under the hammer, we 
 find in Swedenborg's "Regnum 
 Subterraneum Sive Minerale 
 de Cupro et Orichalco" 1734, a 
 description of a set of rolls for 
 rolling copper and brass sheet. 
 An illustration taken from this 
 book is shown here. 
 
 14 
 
the necessary degree of heat for casting." He also mentions the 
 various duties in connection with the care of the molds and disposition 
 of the product, all of which fell upon the master founder. 
 
 Duhamel du Monceau previously mentioned refers to the skill re- 
 quired as follows: "The founders learn by long practice to care for the 
 fires of the furnaces and to know when the material is in proper fusion and 
 ready for casting." * * * ''The skillfulness of founders consists in 
 knowing the mixture and above all knowing the degree of heat which it 
 is necessary to give. In order to be more certain they take with a small 
 ladle a portion of molten metal and throw it on a stone and when this 
 thin layer is cold then hammer it. If it breaks they continue the fusion 
 or add a little Flanders scrap. If they use too much heat, the metallic 
 part of the calamine which is zinc will be dissipated and there will remain 
 only brittle metal which will break before it will stretch." 
 
 In attempting to explain how to judge when the metal is ready to 
 pour, Duhamel du Monceau says: "The color of the flame indicates if 
 the material is in fusion. At first it is red as in ordinary forges. It be- 
 comes blue when the scrap is in fusion, then after a short time it becomes 
 clear in which state it is ready to pour. One also determines the state of 
 fusion by plunging into the metal a stirring rod. When the metal runs to 
 the end of the iron, the material is in condition to be poured." 
 
 From the illustrations and the meagre descriptions of technique that 
 are available it is evident that the practice of making brass several hun- 
 dred years ago was little different from that of the present day, except as 
 regards the constituents of the mixture. If we omit that part of the 
 practice which refers to the preparation of calamine and substitute 
 spelter, there has been very little improvement except in minor details. 
 
 Apparently the first attempt to cast brass in the North American 
 colonies was made in 1644 by John Winthrop, Jr., in his iron foundry at 
 Lynn, Mass. It is also known that brass cannon were cast in Philadel- 
 phia before the Revolution. Beginning in 1725 and for 50 years there- 
 after, Casper Wistar, his associates and successors, in Philadelphia, ham- 
 mered out stills and kettles from brass and copper and cast some brass.* 
 
 In 1802, the Grilleys, (Henry, Silas and Samuel), who had established 
 a brass button business at Waterbury, Conn., in 1790, were joined by 
 Abel and Levi Porter from Southington and began making buttons from 
 sheet brass. This was the first known instance in America of brass mak- 
 ing, by direct fusion of copper and zinc according to the process invented 
 by Adams Emerson in England in 1781. This undertaking also involved 
 the first rolling of brass in this country. 
 
 The American brass industry was imported from England in labor, 
 processes, and machinery. Up to 1820 the American brass makers 
 
 *Bishop's History of American Manufacturers, 
 
 iEarlg Sraaa 
 
 15 
 
struggled along engaged principally in making buttons which were sold 
 by travelling peddlers. Competition with the English product was im- 
 possible until James Croft, an English brass maker, came to Waterbury, 
 and hired out to the Scovill Manufacturing Company, where he intro- 
 duced English machinery and processes.* 
 
 In 1830 Waterbury rolled brass became a factor on the American 
 market and from then on the industry grew rapidly. Next came brazed 
 tubing which was used for gas in New York City in 1836.- Seamless 
 tubing was the last important process to come from England where it 
 was invented in 1838. This process was imported by a group of Boston 
 men in 1848 who organized the American Tube Works in 1850. 
 
 The first really basic improvement in brass working contributed by 
 America was the invention of the spinning process in 1851 by Hayden. 
 From this time on American brass makers forged ahead rapidly and soon 
 took the lead over their English competitors. 
 ®ttp N.ait^aturk The brass industry perhaps more than any other requires extra- 
 
 UallPtt ordinary skill that can only be obtained by long experience. Therefore, 
 
 whenever a brass works started it was necessary to obtain one or more 
 men skilled in the art, by taking them away from some works already in 
 existence. 
 
 The brass industry in America started in Waterbury, Conn., in the 
 Naugatuck Valley. The reason for this is probably due to the fact that 
 the people of Waterbury were largely engaged in the making of pewter 
 buttons which was an important home industry and when brass buttons 
 came into vogue these people were threatened with disaster. They were 
 forced to take up the making of brass buttons in order to save themselves. 
 Fortunately the natural conditions at Waterbury, such as water power 
 for driving the machinery, water supply for washing the metal, and wood 
 for annealing purposes, were favorable to brass manufacture, and there- 
 fore having started there, it continued to grow. 
 
 The fact remains that the industry did begin in the Naugatuck 
 Valley and that this valley became famous as the home of the American 
 brass makers. These men evidently liked the place where they were 
 bom as no one has ever succeeded in inducing any considerable number 
 of them to go to another part of the country and this is undoubtedly the 
 real reason why Connecticut has so long remained the greatest producer 
 of brass in the United States. 
 
 *Lathrop's "The Brass Industry in Connecticut". 
 
 16 
 
iWa^^iii„-«KK.-s»««e*; 
 
 "dl 
 
 J 
 
 X/;; 
 
 
 Figure 10. The strips of sheet brgss referred to in Figure 8 were drawn into wire in draw-benches 
 similar to the one shown in the above illustration. The pulling power was derived from a rotating shaft, 
 S, the return stroke being aoxsmplished by the retraction of a spring pole 10. 46 shows a die plate with 
 the different size holes located in the one plate. The clamping mechanism, u, is shown in detail in 
 Figure 11. 
 
 17 
 
-a:~^i~. 
 
 ^ri 
 
 _-£J^._^_p-, _ 
 
 JL 
 
 Figure 11. This illustration which is part of an article by Galon printed in 17d4, shows another 
 form of drawbench and is specially interesting on account of the details. The gripping tongs 3 1 are 
 specially interesting when compared with Figure 12, which is a photograph of an installation in use in a 
 modem plant. 
 
Figure 12. The above illustration is interesting, on account of the fact that the drawing mechanism 
 is practically the same as illustrated by Galon in 1764. The lever which comes up through the floor and 
 carries the tong-grip, travels back and forth along the bench giving a short-stroke draw. In a modern 
 plant it is used to draw the first few feet of wire through the die, so as to get enough wire to permit 
 fastening it to the drum, then the tongs are laid aside and the drum does the drawing. Comparison 
 between this illustration and Figures 10 and 11, shows remarkable similarity between the method here 
 used to start the drawing operation and the method used by the ancients for all wire drawing. 
 
 19 
 
BRASS MAKING 
 
 ilpUing Iraaa 
 
 far 
 
 KoUtng iitUa 
 
 ^mnmts 
 
 THE melting and casting of the metal in a brass mill is the most 
 important step in the whole process of making brass materials, be- 
 cause any failure here cannot be rectified by later manipulation. How- 
 ever, in spite of the vital character of this stage of the process it is the 
 one in which the least advancement has been made. 
 
 Practically all mills that produce brass for rolling into sheets or rods, 
 or drawing into wire or tubes, employ the crucible in the coal-fired pit 
 furnace, which is, basically, the same method as used in the middle ages. 
 
 Referring to Figure 2, which is reproduced from a drawing made in 
 1672, it is seen that the three main elements of the ancient casting shop 
 (furnace, crucible, and mold) bear a truly remarkable resemblance to the 
 corresponding elements in the casting shop of some of the largest brass 
 mills of today. 
 
 During the same period wonderful advances have been made by 
 brass makers in the mechanical working of brass, so that it cannot be said 
 that the practice of casting has remained stationary because brass makers 
 have not tried to improve it. They have tried, and up to very recently 
 it seemed as though it simply could not be done. The process was in the 
 hands of skilled workmen, and each master caster guarded his secrets well. 
 
 Figure 13. Cross section of a typical pit furnace. 
 
 In order to prove the statements just made with regard to the similar- 
 ity of the ancient methods of brass casting and the modern ones, the 
 operation of a modern pit furnace plant will now be briefly described. 
 
 The casting plant of the modern brass sheet, rod, wire and tube mill 
 consists of the following main elements : 
 
 1 — Furnaces 2 — Crucibles 3 — Molds 
 
 The furnaces are almost without exception of the square, natural- 
 draft pit type and usually employ anthracite coal for fuel. Figure 13 
 shows a typical cross-section of such a furnace. 
 
 It should be noted that the principal difference between this furnace 
 and the furnaces used in the middle ages is that the gases of combustion 
 
 20 
 
are carried off at the side, and lead to a cfiimney while in the ancient 
 furnaces they were allowed to pass up through the top and into the 
 casting room. Then, too, the old furnaces were made large enough to 
 hold a number of crucibles, usually eight (see Figure 4), while nowadays 
 there is one furnace for each crucible. The modern practice is to use 
 anthracite coal in most instances although coke is also used quite exten- 
 sively. In ancient times charcoal or wood was the fuel. 
 
 The crucibles which are ordinarily made of clay, and graphite, 
 usually have a capacity of from 160 to 300 pounds of metal. They require 
 great care in handling in order to obtain a satisfactory life, and for this 
 reason and others they constitute one of the weakest elements in the 
 casting shop. Ordinarily the life of a crucible is from 25 to 35 heats, 
 depending upon the manner in which it is handled, and some casters by 
 virtue of special practices get even longer life out of their crucibles. Com- 
 paring modern crucibles with those used in the middle ages, it is difficult 
 to see any appreciable difference except the introduction of graphite, 
 which has greatly increased their durability. 
 
 Cr«nblp0 
 
 Figure 14. A line of pit furnaces in a modern casting shop. The men here shown are stirring the 
 metal, anthracite coal used for laying the fires is stored in bunkers located directly over the furnace 
 openings. Empty crucibles and half crucibles may be seen at various points along the tops of the fur- 
 naces. In the upper right hand side is seen a portion of the hoist used for raising the crucibles and 
 manipulating them during the process of skimming and pouring. 
 
 21 
 
iKnliia The modern mold is made of soft, gray iron, hand finished. Metal 
 
 intended for sheet brass is cast in flat bars of varying widths, while metal 
 for rods and wire is cast in cylindrical billets. Metal for tubes is cast 
 either in solid or hollow cylindrical billets, depending upon the process 
 employed. In ancient times stone was used for molds. 
 
 (I^pin'attnu Casting in this type of plant is entirely up to the caster. He, 
 
 with his one or more assistants, controls the fires, charges the crucibles, 
 stirs and skims the metal, prepares and pours the molds. The whole 
 process from start to finish is up to him, and he is usually paid on the 
 basis of the output of good metal he attains. 
 
 The eight to twelve fires under the charge of one boss are all started 
 at one time. The crucibles are warmed carefully before charging with 
 scrap and copper ingot. If the crucibles are not carefully dried out and 
 gradually brought up to heat, they will flake off and crack and their life 
 will be materially shortened. 
 
 Figure 15. Skimming a crucible. The tongs with which the crucible has been lifted from the 
 furnace are used by the caster to manipulate it during the entire operation of skimming and pouring. 
 To keep the rope from too close contact with the heat and gases from the crucible, a link rod connects 
 the block to the tongs. These tongs should be compared with those shown in Figure 2, as there is prac- 
 tically no difference in the construction. The white smoke arising from the crucible is mostly zinc 
 oxide, which at the present moment is practically enveloping the head of the caster. This is one of 
 the working conditions which makes the crucible process difficult. 
 
 22 
 
AJifttng i'ppltfr 
 
 The charging of the crucible must also be made with care. For (Ehargtttg 
 instance, if the crucible doesn't set firmly or evenly on the bottom, it will 
 be subjected to undue strain and is even liable to tip over. Then, too, 
 the charge itself must be so placed in the crucible that it will not become 
 wedged and cause excessive strain against the sides when it expands 
 before melting. All these points and many more require the constant and 
 keen attention of the caster and his assistants. 
 
 As the copper begins to melt, a handful of salt is added and stirred 
 in to remove the copper oxide, and then the surface of the metal is covered 
 with a layer of charcoal to protect it from the action of the furnace gases 
 or the air. 
 
 After the charge is completely melted and the temperature raised to 
 the proper point, the zinc, or spelter is added. This temperature may be 
 gaged by the expert caster by tlie color of the flame. 
 
 The spelter, being lighter than the copper, will float to the top and 
 finally oxidize and waste away unless it is thoroughly stirred in and the 
 surface protected with a layer of charcoal or some suitable flux. In Figure 1 4 
 is a view of a modern casting shop showing a line of pit furnaces. The casters 
 are stirring in the spelter. In the upper right-hand side of the photograph 
 may be seen the hoisting apparatus that is used for lifting the crucible 
 out of the furnace and manipulating it as will hereafter be described. 
 
 After the introduction of the spelter the crucible must remain in the 
 fire long enough to overcome the chilling effect produced by the introduc- 
 tion of the spelter before pouring. If the crucible remains too long in the 
 fire the metal will be overheated and an undue loss of zinc produced, 
 while if it is poured too soon before the temperature has attfained its 
 proper value, the casting will not be good. 
 
 The caster often judges the pouring temperature through the medium of 
 his stirring rod. His sense of touch is so trained that he can perceive the vi- 
 bration, due to the boiling of the zinc which signifies that it is time to pour. 
 
 Since all the fires are started at the same time, it naturally follows 
 that all the various operations occur at approximately the same time. 
 Consequently it requires extraordinary skill on the part of the caster 
 to manipulate the fires in such a way that each crucible will be poured as 
 nearly as possible at the time it is ready. 
 
 The metal being considered ready for pouring, the coal is poked away Skimming 
 from the crucible with an iron bar and the tongs with which the crucible fllritriblp 
 is manipulated inserted and clamped. With a block and tackle fastened 
 to a light jib crane shown in Figure 14 the helper hoists the crucible out 
 of the furnace and swings it to a position on the cast iron floor as shown 
 in Figure 15, where the caster with a skimming iron removes the 
 dross. This photograph is an excellent illustration of the volatilization 
 of the zinc which is going off in a white cloud because of the removal of 
 the charcoal covering. Incidentally, this picture shows why casters often 
 
 S^mppraturr 
 
 23 
 
pouring 
 (£rurthU 
 
 suffer from "Spelter Shakes" which is a mild form of poisoning supposed 
 to be caused by the inhalation of zinc oxide fumes. 
 
 The helper who manipulates the crane does so with the aid of a rope 
 and a rod. The rope serves to hoist the crucible, while the rod, in addi- 
 tion to offsetting the side pull of the rope, enables the operator to push 
 and pull the trolley and jib to any desired position, thus giving him com- 
 plete control o\-er the manipulation of the crucible. The caster has 
 simply to tilt the crucible. This method of hoisting has been used for 
 more than fifty years without appreciable change, although various un- 
 successful attempts to replace it have been made. Its advantage is quick 
 action. 
 
 As soon as the crucible is skimmed it is hoisted and swung into 
 position for pouring as show-n in Figures 16 and 17. The pouring itself 
 requires great skill as the perfection of the casting depends to a very 
 large extent upon the manner of pouring. As is seen in the illustrations, 
 the caster rests the edge of the crucible on the mouth of the mold, and 
 
 Figure lo. Pouring the first mold in the crucible process. The caster is manipulating the 
 stream and holding back the dross with his skimmer iron, while he pours with the tongs. .Attention is 
 called to the great similarity between the molds here sho'ATi and the one sho'ATi in Figure 1. It will be 
 seen, that the method of clamping the parts together is practically the same in both cases. 
 
 24 
 
as he tips the crucible he holds back any dross or charcoal with a skimmer 
 iron, and at the same time he often uses the skimmer iron to divide the 
 stream into two parts, in this way greatly improving the chances for a 
 perfect casting, especially where wide bars are concerned. 
 
 Previous to using, the molds are coated with a high-grade lard oil 
 which serves a two-fold purpose, namely: it prevents the metal from 
 acting upon the iron, and in burning at the mouth of the mold it envelops 
 the stream in a reducing atmosphere which decreases the possibility of 
 oxidation. 
 
 The molds are slightly inclined so as to make it easier for the caster 
 to pour the metal, thus preventing it from striking against the sides of 
 the mold. If the metal strikes continuously in one spot the casting will 
 be porous on that side. 
 
 No attempt has been made here to cover the almost infinite number 
 of fine points involved in the art of brass casting as practiced by the best 
 men in the industry. In fact, the subject has never been reduced to an 
 exact science and for the purposes of this booklet a more detailed descrip- 
 tion would be of little service. 
 
 Prrpartttg 
 Malhs 
 
 Figure 17. Pouring the second mold from a crucible. This illustration shows plainly the rod and 
 rope by means of which the assistant manipulates the jib crane for hoisting and maneuvering the 
 crucible during the skimming and pouring operations. 
 
 25 
 

 ffllorking 
 (Ennbittntts 
 
 (Emnpnaitian 
 SiarrrprnrtPB 
 
 DIFFICULTIES IN BRASS MAKING 
 
 THE foregoing brief description of the routine operations in melting 
 and casting brass, makes it perfectly plain that the human element 
 enters into every step and detail of the process. 
 
 To keep ten fires right and take care of ten crucibles, putting in the 
 spelter at the right moment, stirring and pouring at the right moment, 
 is a full size job for the caster. There is a tendency among brass 
 casters to use time as a guide in the execution of the various operations. 
 However, this procedure cannot be relied upon for satisfactory results 
 because of variations in the fuel, in the draft, in the weather, in the con- 
 dition of the flue and in many other factors that may act to render any 
 timing scheme for the various operations entirely unreliable. 
 
 In the last analysis it must be admitted that there is no positive way 
 of determining just the right moment for carrying out the various im- 
 portant operations in the melting and casting of brass. It is simply a 
 matter of experience, and even with experience as a guide if the man 
 hasn't the will and the power he may not even do as well as he knows how. 
 In other words, the character, disposition and moods of the men as well 
 as their experience, enter into the making of brass by the crucible process. 
 
 The second undesirable feature of the crucible process is due to the 
 extremely disagreeable working conditions imposed upon the men. Even 
 with the best ventilation they are subjected to noxious fumes and extreme 
 heat, and the more conscientiously they execute their tasks, the worse 
 the conditions they must endure. In Figure 15 is shown a caster 
 skimming a crucible with his head entirely enveloped in fumes. If he 
 attempted to dodge the fumes, he would not be able to skim the metal 
 as quickly and perhaps not as well, the result of which would be an in- 
 ferior casting. To stand over the fires and stir the metal is an extremely 
 hot and disagreeable job and yet the quality of the metal is dependent 
 upon the thoroughness with which it is stirred. These are only instances 
 which illustrate that the caster in the execution of his work must practi- 
 cally disregard the conditions under which it is done. 
 
 The crucible itself is often the cause of discrepancies in the quality 
 of the metal, due to the fact that a slight leak has permitted a portion of 
 the mixture to disappear into the furnace so that when spelter is added 
 the ingredients of the brass will not be in the proportions expected. The 
 proportions are also modified by various conditions which affect the 
 volatilization of the zinc, so that, in spite of the most expert attention, 
 the composition of brass made by the crucible process will vary and does 
 vary more than most brass makers are willing to admit. 
 
 The composition is also affected by the furnace gases to which 
 molten brass in a crucible is always exposed to a greater or less degree. 
 In general, the action of these combustion gases is to change the chemical 
 
 26 
 
composition of the metal by oxidizing its ingredients and thus introducing 
 impurities, as well as by removing a certain portion of the metal. The 
 extent of the damage done by flue gases depends upon such factors as the 
 temperature of the metal, the temperature of the gases, the composition 
 of the gases, the velocity of the gases, the pressure of the air, and the 
 perfection of the coating on the surface of the metal. Evidently, the 
 combined result of these various factors is beyond human power to 
 determine, except under test conditions such as may be obtained in a 
 -well-equipped laboratory. 
 
 To sum up the crucible process of brass melting, it is sufficient to say 
 that it is not susceptible to scientific control and therefore cannot be 
 admitted as a satisfactory manufacturing process for the production of a 
 uniform, high-grade product. Its possibilities are dependent entirely 
 upon the individuals that operate it and the product can be controlled 
 only by thorough inspection and conscientious scrapping of all metal that 
 is below the standard. 
 
 POSSIBILITIES OF THE ELECTRIC 
 FURNACE 
 
 FOR a number of years brass makers have realized that the electric 
 furnace offered many important possibilities for brass melting, but 
 actual experiments were discouraging in that they revealed difficulties 
 that for a number of years seemed insurmountable, or at least of 
 sufficient importance to prevent the commercial utilization of electric 
 furnaces for brass melting. 
 
 Before taking up the description of any particular type of electric 
 furnace it may be well to consider the possibilities resulting from the 
 mere substitution of electric heating for fuel heating. By looking at the 
 problem in this way it will be evident that the electric furnace offers a 
 solution of the brass melting problem only in the event that the proper 
 type is chosen, and the mechanical design carried out in the light of 
 experience in the melting of brass. 
 
 All electric furnaces eliminate the possibility of contamination of the ($n8tB 
 metal from furnace gases since there is no fuel used and therefore no 
 gases generated. 
 
 All electric furnaces possess the possibility of heat control, but not ij^mt (Entttrnl 
 all possess even the possibility of temperature control when the matter 
 of temperature distribution is considered. In brass making, temperature 
 distribution is of first importance and a furnace that does not rapidly 
 transfer the heat input to all parts of the metal without superheating any 
 local portion, cannot be successfully employed. 
 
 On account of the fact that spelter floats on copper, it is necessary ^tilTtttJJ 
 that provision be made for stirring the metal, and not all types of electric 
 
 27 
 
JnHulattnn 
 
 ^pFltFr Unas 
 
 furnaces possess even the possibility of providing in a practicable way for 
 this essential operation. 
 
 All types of electric furnaces may be so well insulated as to remove 
 the disagreeable high-temperature conditions under which the men must 
 work. Also any type of electric furnace may be mounted mechanically 
 so as to facilitate the charging and pouring of the metal thus reducing to 
 a minimum the skill and labor required. 
 
 All types of electric furnaces offer the possibility of enclosed opera- 
 tion, although the commercial realization of this possibility is not always 
 possible. Spelter loss depends not only upon enclosing the space above 
 the surface of the molten metal, but also upon the temperature, the 
 temperature distribution, the pressure, and the length of time that the 
 metal stands in a molten condition. Consequently the effect of the 
 electric furnace on spelter loss depends entirely upon the type and design 
 of the furnace. Some electric furnaces would produce a spelter loss 
 much greater than does the crucible process. 
 
 In short, the electric furnace offers the possibility of applying scien- 
 tific principles in a commercial way; that is, an electric furnace designed 
 to utilize all the possibilities presented should practically eliminate the 
 personal element of the operator and render the process susceptible of 
 accurate control in accordance with carefully worked out plans. 
 
 JFurnarp 
 Claaaifirattntt 
 
 #pparatp 
 Spatatnr Sgpr 
 
 ELECTRIC BRASS FURNACES ' 
 
 THE Bridgeport Brass Company for the last sixteen years has been 
 conducting a series of investigations in its private laboratories for the 
 purpose of reducing the process of brass making to scientific principles 
 that could be effectively applied in the casting shop. 
 
 In the judgment of the Bridgeport Brass Company's investigators, 
 the electric furnace offered the only possible solution of their problem. 
 Accordingly experiments were begun with electric furnaces and these 
 experiments indicated that even the best furnace designs on the market 
 did not meet all the conditions which they considered necessary to the 
 satisfactory solution of the brass melting problem. 
 
 Electric furnaces may be classified in various ways, depending upon 
 the point of view. From a metallurgical standpoint the method of heat 
 production may be classified as follows ; 
 
 1 — ^Heat produced exterior to the metal to be melted. 
 
 2 — ^Heat produced on the surface of the metal to be melted. 
 
 3 — ^Heat produced within the metal to be melted. 
 
 The first method includes the separate resistor-unit type in which 
 the heat is generated in a special resistor and conducted to the metal to 
 be melted through the walls of the hearth and by reflection from the arch 
 or dome of the furnace. One disadvantage of this method is that special 
 
 28 
 
provision must be made for stirring. Then, too, the heat transfer from 
 the surface toward the interior does not give favorable conditions for 
 uniform temperature distribution throughout the mass of the metal. 
 
 Another type of exterior heat generation is the indirect arc. The 
 disadvantages of this type are the same as in the resistor type except 
 that the source of heat being more concentrated, the tendency to local 
 overheating of the metal is correspondingly greater. In one type of furnace 
 this tendency is combatted by constructing the furnace in the form of a 
 cylinder swung on its long axis and rolling it continually first in one 
 direction and then in the other. In this way the metal is mixed, the heat 
 absorbed by the walls is equalized by contact with the metal, and the 
 surface of the metal nearest the arc is continually changed. 
 
 Another type of indirect arc furnace which is successful in over- 
 coming the tendency toipcal overheating is of the same general form as 
 the furnace described in' the preceding paragraph, except that it rotates 
 continuously in one direction and pours from an opening in the end, while 
 the oscillating furnace pours from an opening in its cylindrical surface. 
 
 Other than these disadvantages this type of furnace when properly 
 designed may possess all the advantages listed under the "Possibilities of 
 the Electric Furnace." It also may be added that this method of heat 
 generation is not the most efficient from the standpoint of energy economy 
 and the size of the furnace is larger than necessary with either of the 
 other two types. 
 
 The second type, in which the heat is generated at the surface, is 
 represented by a direct arc sprung between the surface of the metal to be 
 melted and one or more suitable electrodes. This type of furnace on 
 account of the excessive concentration of heat production is not con- 
 sidered suitable for brass melting and therefore will not be considered here. 
 
 In the third type, the metal itself is utilized as a resistor and the 
 flow of electricity through the metal may be established by induction 
 from a primary winding, or the electricity may be introduced through 
 electrodes. The disadvantage of this type of furnace is that a molten 
 charge is neces^gry to start it. When properly constructed to utilize 
 pinch effect, motor action, and heat circulation, this type of furnace can 
 be built so that it will automatically circulate the metal and produce 
 violent stirring with a resultant high degree of uniformity in temperature 
 distribution. 
 
 For the high-zinc brasses the Bridgeport Brass Company adopted 
 the third type of furnace, using as heating element the induction unit 
 invented by J. R. Wyatt and controlled by the Ajax Metal Company. 
 
 The Wyatt heating element consists of an arrangement of circuits as 
 shown in Figure 18. The primary is connected to the alternating current 
 source and may be wound for any commercial voltage. The secondary 
 
 
 
 iRfaiator ®gpf 
 
 Jniurttnn ®^pe 
 
 29 
 
of 
 
 consists of a V shaped mass of metal confined to narrow passages on two 
 sides and open on the upper side. In the narrow passages three forces 
 opefate, namely; pinch effect, motor effect, and gravity effect. The head 
 of molten metal above the V in the chamber of the furnace prevents the 
 pinch effect from actually rupturing the circuit, although it does cause 
 contraction which results in motion of the column in the direction of least 
 resistance. Contraction also results in the generation of extra heat which 
 further accentuates the motion. 
 
 At any instant the electric current in the two converging channels 
 is in opposite directions. Therefore, a repulsion, called motor effect, is 
 produced between the two which tends to throw the liquid out of the 
 passages. Observation has shown that the liquid rises along the outside 
 surfaces of the passages and descends along the inside surfaces. 
 
 The application of heat at the bottom of Ae mass of metal causes 
 circulation which draws the colder metal continually to the bottom and 
 in this way effectively distributes the heat throughout the mass. 
 
 The combined effect of these three actions is to cause a violent pro- 
 pulsion of metal out of both legs of the triangle which thoroughly mixes 
 the charge and carries the heat to all parts of the bath. 
 
 For other copper alloys such as 
 bronze and Phono-Electric, the 
 Bridgeport Brass Company uses 
 the indirect arc furnace of the 
 Gillett type. This furnace is built 
 in the form of a cylinder and is 
 mounted in a cradle so arranged 
 that the furnace is rotated auto- 
 matically first in one direction and 
 then in the other. The electrodes 
 enter in the center of the two ends 
 and coincide with the axis of 
 rotation. 
 
 With these furnaces the Bridge- 
 port Brass Company is able to 
 realize all the possibilities of the 
 electric furnace as listed in the pre- 
 vious chapter ; and since the casting 
 shop is operated on the 24-hour 
 basis, and the grades of metal are 
 thoroughly standardized, it has 
 been possible to build furnaces that 
 are exactly suited to the work they 
 
 Figure 18. Elementarydiagram of Wyatt heating ^^C tO perform. 
 
 30 
 
THE ELECTRIC CASTING SHOP 
 
 OVER three years ago the Bridgeport Brass Company began to use 
 electric furnaces on a commercial scale, and after developing types of 
 construction suitable to the particular needs of the various alloys, steadily 
 increased the electric equipment until it finally displaced the pit furnace 
 entirely. Accordingly the pit furnace casting shops have been com- 
 pletely dismantled and the chimneys torn down. At the present time 
 construction work is under way to more than double the productive 
 capacity of the present electric casting shop. 
 
 With these furnaces, the Bridgeport Brass Company has been able 
 to solve the problem of applying scientific principles to the making of 
 brass for use in its sheet, rod, wire and tube mills and manufacturing de- 
 partments. The process as developed possesses the following advantages : 
 
 1 — ^The human element as far as the actual operation of melting and 
 pouring is concerned is practically eliminated, because all of the factors 
 which enter into the production of brass of a uniform and definite quality 
 are susceptible of exact determination and control. 
 
 2 — ^The heat input is generated within the body of the metal so that 
 the temperature distribution is uniform. 
 
 3 — ^The design of the furnace is such that stirring and mixing is 
 thoroughly accomplished; in fact, the most conscientious brass caster 
 could not stir a crucible as perfectly as the metal is stirred in these elec- 
 tric furnaces. 
 
 4 — ^The temperature of the metal at various stages in the process is 
 indicated electrically, eliminating entirely any question of skill on the 
 part of the operator in the estimation of temperature. 
 
 5 — The heat input and therewith the temperature of the metal is 
 always under perfect control and can be adjusted to give any desire;d 
 heating characteristic. Best of all, the same heating characteristic can be 
 repeated indefinitely. 
 
 6 — ^The purity of the metal is guarded by the exclusion of the at- 
 mosphere, the furnace chamber being entirely closed except when charg- 
 ing or skimming. A further precaution is the use of a layer of charcoal 
 on top of the molten metal, which maintains a reducing atmosphere in 
 the closed space above the surface of the metal. 
 
 7 — ^The heat insulation is so perfect that the operator can lay his 
 bare hand on the outside of the furnace at any time, which indicates the 
 vast improvement in working conditions in the electric casting shop as 
 compared with the pit-fire shop. 
 
 8 — By pouring only part of a charge and then re-charging, any 
 slight errors in weighing of the ingredients are equalized by the blending 
 of several charges in the same furnace. 
 
 iEIrrtrtr iJraHH 
 
 31 
 
Figure 19. Tliese views show the dismantling 
 of the Bridgeport pit furnace casting shops and the 
 destruction of two of the chimneys. The circular 
 chimney was only two years old. when it was decided 
 that the best interest of the Bridgeport product 
 demanded its demolition to make way for electric 
 furnace brass. 
 
 32 
 
9 — Mechanism is provided which gives the operator perfect control 
 of the pouring. He can vary the rate as slowly and accurately as he may 
 wish with the result that any ordinary operator can pour a billet as well 
 as the most expert caster is able to do with the crucible by hand. 
 
 The combined result of these various factors is the production of a 
 brass, uniform and homogeneous in quality and of a higher grade than is 
 commercially possible with the crucible process. Due to the accurate 
 control of the heating, the completeness of the protection from the atmos- 
 phere, and the entire absence of furnace gases, the composition of the 
 metal is maintained to a remarkable degree of accuracy. In fact, practice 
 has shown that the loss in spelter so difficult to control with the pit-fire 
 process is less than one-half per cent. 
 
 At this point it may be interesting to describe briefly the operation 
 of the electric casting shop in the Union Branch Plant of the Bridgeport 
 Brass Company. At one end of the shop are situated the metal bins in 
 which the raw materials, used in the making of brass, bronze and other 
 copper alloys, are stored. These materials are carefully classified by 
 
 Figure 20. A line of weighing machines handling the ingredients of one of the standard Bridgeport 
 alloys. Each man has charge of only one ingredient and has to remember only one weight. In the back- 
 ground are seen bins which contain raw materials classified by careful analyses. It is scientific organiza- 
 tion of this end of the casting shop that insures an extraordinarily high degree of uniformity in the com- 
 position of Bridgeport brasses and bronzes. 
 
 3.3 
 
Figure 2 I . The charging aisle of one batcery of Bridgeport electric furnaces. In the right foreground 
 are shown the charging cansVhich are made of such size that loss of any part of the charge by spilling 
 is practicallv impossible. The can^ are brought from the raw material stores department, by means of 
 an o\erhead traNelling crane. The furnaces are charged through the doors near the top. 
 
 Figure 22. Skimming Bridgeport electric fur- 
 nace preparatory to pouring. In order to protect 
 the surface of the metal from the atmosphere, and 
 to maintain a reducing atmosphere within the fur- 
 nace, a layer of charcoal is kept on top of the 
 metal v.-hich forms a smoke whene\er the door is 
 opened. 
 
 Figure 2 3. Pouring brass bars for the rolling 
 mill. The caster has perfect control of the pour- 
 ing through positive mechanism. With perfect 
 ease he can vary the rate of pouring to suit the 
 exact needs of the work in hand 
 
 34 
 
Figure 24. The pouring aisle of a battery of Bridgeport brass furnaces. These furnaces are used 
 for pouring billets that go to the tube mills and the extrusion machine. 
 
 Figure 25. A line of induction furnaces used for pouring billets. Bridgeport Brass Company 
 employs several kinds of electric furnaces, each furnace handling the same alloy under the same condi- 
 tions day in and day out. 
 
 35 
 

 (£t|argtng 
 
 systematic analyses so as to assure the maintenance of a high degree 
 of accuracy in the composition of the brasses. 
 
 In order to simplify the operation of weighing the ingredients and 
 reduce to a minimum the possibility of errors, each ingredient is handled 
 by a separate workman. In this way the process is worked out so that 
 the weigher has only one weight and one ingredient to look after. The 
 equipment for weighing is so designed that the material after being 
 weighed is dumped directly into the charging can in such a manner as to 
 eliminate the possibility of loss due to careless handling. All these pre- 
 cautions effectively safeguard the uniformity of the product. One line 
 of weighing equipment is shown in Figure 20. 
 
 In order to obtain a positive check on every charge, the complete 
 charge is weighed before it is sent to the casting shop, and if the total 
 weight does not check exactly with the sum of the component parts, the 
 charge is re-assembled. 
 
 The charging cans are made of such size that the charge fills them to 
 less than half of their capacity. This procedure avoids the possibility of 
 spilling any part of the charge before it is used. In Figure 21 is shown 
 the charging aisle of one of the lines of furnaces. The ch&rging cans may 
 be seen at the right. The materials are introduced into the furnace 
 through the charging doors plainly shown in the picture. Before pouring 
 
 Figure 2d. Pouring a billet from an oscillating indirect arc furnace. The raw material is charged 
 from a platform above the furnace. The pouring is manipulated by means of an electric controller. 
 
 ?.(i 
 
the furnace man skims the dross from the top through the charging door 
 as shown in Figure 22. 
 
 When the metal is ready to pour, the molds mounted on a rotating 
 stand are put in place and the pouring accomplished by manipulation of 
 a hand wheel. This wheel is positively geared to the tilting niechanism 
 so that the caster has perfect control of the rate of pouring. At this 
 point it is interesting to note that of each melt a sample is taken, and the 
 results of the analysis of this sample are available before the billets or 
 bars as the case may be reaches the mill to be worked into the finished 
 product. A portion of one side of the pouring aisle is shown in Figure 24. 
 
 Contrasting the actual operation of the electric casting shop with 
 that of the pit furnace casting shop as described on pages 20 to 25, it will 
 be noted that every one of the most difficult steps of the process is accom- 
 
 Inurtng 
 
 ?rtPttttfir 
 
 Figure 27. Pouring a billet. The grease in the mold forms a black smoke which not only protects 
 the mold from burning, but protects the stream of metal from the atmosphere, and absorbs any oxide 
 that tends to form. 
 
plished automatically and practically independently of the skill of the 
 operator. The heating, the judging of the temperature, the stirring, 
 and the pouring, all of \\'hich formerly required the skill of a master 
 caster are now accomplished by the furnace itself. 
 
 The accompanying illustrations will give some idea of the equipment 
 employed and indicate how it is manipulated in service. With this 
 equipment, the Bridgeport Brass Company has been able to produce 
 brasses and bronzes of a degree of uniformity and homogeneity previously 
 unknown on a commercial basis. 
 
 The entire output of the electric casting shop of the Bridgeport 
 Brass Company is made up into \'arious products marketed by the com- 
 pany, such as tube, sheet, rod, \\-ire and manufactured products. A fairly 
 complete set of pictures has been made illustrating the most important 
 steps in the various processes of manufacture. Beginning with the raw 
 material furnished by the casting shop each one of these processes will 
 be briefly described in the following chapters. 
 
 FiSLirc 28. Takins cut off bronze billet of special turbine blading metal 
 
 LrLmywW'^v^^'4Xf^T^''W'P^viT' 
 
 fiA>'.AAA/Wi^A'Wi\V/if///i^/-w* 
 
 Figure 29. Chips remo\-ed from the surface of the billet shown in Figure 28. When it is considered 
 that these chips are taken from the surface of a cast billet, it is evident that the casting itself closely ap- 
 proaches physical perfection. 
 
 38 
 
PHONO^ELECTRIC WIRE 
 
 SOME twenty odd years ago, Phono-Electric trolley wire was developed pro^JprttPH 
 and placed on the market by the Bridgeport Brass Company in response 
 to a demand for a contact wire that would withstand the conditions of 
 severe service better than hard-drawn copper. The greatest advantages 
 of Phono-Electric wire from the railway man's point of view are : Tough- 
 ness, high tensile strength, favorable arcing characteristics, and best of 
 all, these various characteristics are permanent — the wire does not alter 
 its properties under service conditions, which is one of the most serious 
 disadvantages of hard-drawn copper. 
 
 These properties of Phono-Electric wire are due first to the com- ISnUing 
 position of the wire; second, to the uniformity and homogeneity of this 
 composition; third, to the carefully controlled process of manufacture. 
 Phono-Electric billets are delivered from the electric casting shop to the 
 rolling mill where they are introduced into a heating furnace, the entrance 
 to one of which is shown in Figure 30. After having reached the desired 
 temperature, the billet is withdrawn from the furnace by sliding onto a 
 two- wheel car as shown in Figure 31. It is then wheeled to one of the 
 rolling mills and passed back and forth until it is sufficiently reduced in 
 diameter, when it is coiled up and delivered to the wire mill. Figures 32 
 and 33 show the billet at two stages of the rolling process. 
 
 The coiled rod before going to the draw benches is joined into long ilnxiltH 
 lengths by soldering. The joint is prepared by sawing the ends at an 
 acute angle, cleaning the adjacent surfaces with acid and inserting between 
 them a sheet of silver solder. They are next bound together with wire 
 and a brazing furnace swung into position to enclose the joint. After 
 heating to the proper temperature the operator applies more silver to the 
 joint and works it in thoroughly. Having completed the operation, the 
 furnace is dropped down, the wires removed and the joint smoothed up 
 with a file. In Figure 34 is shown the soldering equipment for two men. 
 The joint in the foreground had just been completed, while the other one 
 is being heated in the furnace. 
 
 The drawing of Phono-Electric takes place in the usual way except Srauitttn 
 that extraordinary care is exercised to maintain accurate dimensions. 
 The die itself is special. It is so designed and manipulated that strains 
 are equalized and any unbalanced wear prevented. Figure 35 shows the 
 soldered rod undergoing the first draw. It passes from the rod reel 
 through the die to the drum of the drawing machine and after making 
 several turns around the drum it is wound up on a reel ready for the next 
 operation. 
 
 Phono-Electric wire is described, and its physical and electrical 
 properties given in separate bulletins which may be had upon request. 
 
 39 
 
Figure 30. Phono-Eleccric billets entering the heating furnace. 
 
 Figure 31. Removing a Phono-Electric billet from the heating furnace preparatory to inserting 
 It in the rolls. Although the picture does not show it, the billet is nearly white hot. 
 
 40 
 
Figure 32. The same billet as shown in Figure 31 after the third pass through the rolls. 
 
 Figure 33. The same billet as shown in Figure 31 just before the last pass through the rolls, after 
 which it is coiled up and sent to the wire mill. 
 
 41 
 
Figure 34- Phono-Electric rods are soldered into long lengths with siUer. A completed joint is 
 shown in the foreground — the brazing furnace being swung out of the way. On the other side of 
 the bench the brazing furnace is in position and the tire going. These joints ha\e gi%'en perfect satisfac- 
 tion, both as to strength and conductivity. 
 
 Figure 35. Phono-Electric 
 rod passing through the die 
 for the first draw. Great 
 care is taken in every detail 
 of the drawing of Phono- 
 Electric wire, so as to obtain 
 the ma-ximum advantage from 
 mechanical working of the 
 w ire and maintain the correct 
 .t;age. 
 
 4-J 
 
BRASS AND COPPER TUBES 
 
 THE Bridgeport Brass Company has been making seamless brass and 
 copper tubing for over thirty years, being one of the pioneers in the 
 making of this product. The processes employed in making seamless 
 tubing impose extremely severe conditions on the brass maker if success 
 is to be attained. To begin with, it is all-important that the quality of the 
 metal be definitely known and uniformly maintained for any given result. 
 Years of study in the research laboratories and even more years of prac- 
 tice in the mill have taught the Bridgeport Brass Company what condi- 
 tions are necessary to the making of seamless brass and copper tubes for 
 any given purpose, and equipment has been provided to realize these con- 
 ditions on a manufacturing basis. 
 
 Although there are several different methods of making seamless 
 tubing, practically all tubing made by the Bridgeport Brass Company 
 falls under three processes, namely; the piercing process; the cast shell 
 process and the cupping process. The choice of these three is determined 
 by the character of the tube to be produced. Taking up the 
 piercing process first, cast billets slightly cupped at the end and of 
 suitable diameter are delivered to the piercing mill from the electric 
 casting shop. 
 
 Billets used in this process are turned so as to remove surface im- 
 purities and mechanical imperfections, and in this way insure greater 
 perfection in the surface of the tube. Figure 28 shows the turning of a 
 billet. 
 
 In Figure 36 we see these billets on their way into a heating furnace. 
 In this furnace they are brought to the proper temperature and dis- 
 charged at the proper moment into the intake end of the piercing machine 
 as shown in Figure 37. The operator of the piercing mill by means of a 
 motor controller causes the billet to be inserted into the machine by 
 rotating the rollers upon which it rides. 
 
 Once in the machine, it is subjected to a cross rolling action, the 
 result of which is to cause the billet to travel through the rolls. Just as 
 it leaves the rolls it encounters a projectile-like steel point carried on a 
 long rod over which it is forced, rotating the meanwhile between the 
 rolls just ahead of the point. The working parts of this very interesting 
 machine consist of two power driven rolls, mounted at an angle to one 
 another and having their cylindrical surfaces made up of the frustums of 
 two cones. Just below and between these two driven rolls, is a small 
 idler. The billet passes between the three and is drawn in by the spiral 
 travel of the three rolls, the angles being such that the point of contact 
 travels on the same spiral on all three rolls, giving the billet a powerful 
 forward motion. 
 
 
 Ptprring 
 
 43 
 
Figure 36. Billets entering the heating furnace preliminary to entering the piercing machine 
 
 Figure 37. A hot billet has iust left the heating furnace shown in Figure 3b and is ahiouC to enter 
 the piercing machine, where it will be subjected to the cross-rolling action of three rolls placed at an angle 
 Co the axis of the billet and in such a way that the point of contact describes a spiral drawing the billet 
 forward. Just as the billet leaves the rolls it encounters the hardened point over which it is forced 
 to travel, the function of which is to open up the billet and form it into a tube. 
 
 44 
 
Figure 38. The pierced tube is seen emerging from the rolls and passing over the rod which carries 
 the piercing point. One of the points which has been removed for repair is shown lying on a bench in 
 the left foreground. Finished tubes ready to go to the tube drawbenches are shown in the right foreground. 
 
 Figure 39. Pointing tubing preliminary to drawing. The openings into one of which the tube is 
 about to be inserted are split and opened and closed continually under the action of the driving mechan- 
 ism. The holes just below the pointing dies serve as gages into which the pointed tube must fit. 
 
 45 
 
Figure 40. 
 
 Vertical pointing machine for large size tubes. The operators are just removing a tube 
 from the machine. 
 
 Figure 41. Drawing tubing. At the right a tube is seen partially through the die. The inside 
 dimensions and the shape of the tube are maintained by a tapered plug held in the mouth of the die by 
 the rod seen e.xtending from the end of the tube. It is supported near the end of the tube by a bushing 
 The power for drawing is supplied by a long piston working in a cylinder. As soon as a batch of tubes 
 has been passed through the draw bench, it is picked up by a crane and deposited in the annealing de- 
 partment. 
 
 4ti 
 
F"igure 38 shows a tube issuing from the machine. The rod with 
 the piercing point is inside. The points have to be changed from time to 
 time in order to maintain the proper contour. A point that has just 
 been removed from the machine is shown resting on a block in the left 
 foreground. 
 
 When the billet has been forced entirely through the machine the 
 rod is withdrawn by a travelling work-head which may be seen at the 
 right of Figure 38, although the end of the machine is well beyond the 
 limits of the picture. Tubes produced by this process are shown in the 
 foreground of Figure 38. 
 
 From the piercing mill the tubes go to the draw benches, where they 
 are pointed and drawn. The pointing operation is shown in Figures 39 
 and 40. It consists simply of smashing down the end of the tube suffi- 
 ciently to allow its insertion through the die and into the grip. 
 
 Figure 42 is a general view of the main tube plant. Practically all 
 the equipment in this plant is special. One type of tube draw-bench 
 alone contains 93 elements that are covered by patent claims. Before 
 this mill was built, an experimental mill was set up and every detail of 
 the process worked out experimentally and theoretically before the final 
 decision as to design to be used in the plant was made. 
 
 Figure 41 shows a group of tube draw benches. At the right is seen 
 a tube partially through the die. The rod here shown carries the plug or 
 triblet, which is held inside of the tube at the point where it passes through 
 the die and maintains the internal diameter as well as preventing deforma- 
 tion of the circle. In the outer end of the tube is seen a bushing, which 
 serves as a bearing and guide for the rod. The tube itself is drawn by 
 the action of an hydraulic plunger, located on the other side of the die. 
 These machines are so long that photographing is extremely difficult. 
 
 After each draw the tubes are delivered to continuous annealing 
 furnaces which are maintained at constant temperature, the tubes travel- 
 ling at a definite speed through the furnaces. In Figure 43 is seen a set 
 of tubes on the conveyor which have just emerged from the furnace and 
 are ready to dump into the pickle. Figure 44 shows a bunch of tubes 
 being lifted from the pickle to be carried back to the draw benches for 
 the next operation. This operation of annealing is of the greatest im- 
 portance since it has a marked effect on the distribution of stresses in the 
 walls of the tube and acts to prevent what is known as "season cracking." 
 
 The importance of proper annealing cannot be over emphasized. 
 The Bridgeport Brass Company has studied the annealing operation with 
 respect to temperature, rate of heating and cooling, and as a result of 
 these studies has formulated exact specifications covering both these 
 factors for every quality of metal turned out by the mills. In Figure 83 
 the results of experiments on a certain alloy are shown graphically. 
 
 Painting 
 
 iram S^nrtf? a 
 
 Annealing 
 
 an{i 
 
 prkltng 
 
 Annealing 
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 47 
 
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Figure 43, A batch of tubes issuing from a continuous annealing furnace. The method by which 
 the conveying rolls are driven is plainly shown in the machine just back of the one in the foreground. 
 The tubes here shown are just about to be dumped into the pickle which is accomplished by the 
 operator in the background. The temperature of the furnaces and the speed of travel through them is 
 so chosen, that the mechanical strains from the drawing operation are equalized without detriment to 
 the physical properties of the tube. 
 
 Figure 44. A batch of tubes being removed from the pickle to be returned to the drawbenches 
 
 for the next draw. 
 
 49 
 
^tratglitmng 
 
 ©PBting 
 
 
 BtCtlOttB 
 
 From this diagram it is seen that the annealing temperatures affect 
 vitally all the physical properties of the metal, and when properly under- 
 stood can be used to obtain certain desired properties. 
 
 The temperature of the annealing furnaces is measured with electric 
 pyrometers. The indicating instruments being used by the operators for 
 making heat adjustments, and the recording instruments used for informa- 
 tion of the engineers as well as for the operators, so that the exact history 
 of any given batch of metal can be recorded. In Figure 61 is shown one 
 of the recording instruments. 
 
 When the tubes have been drawn to the proper diameter and gage, 
 they are straightened by passing them through a set of rollers. The large 
 diameter tubes are passed through rollers which travel in a spiral around 
 the tube as shown in Figure 46, while the small tubes such as those used 
 for condensers are straightened by passing through a series of rolls in 
 two different planes as shown in Figure 47. Both of these straightening 
 machines spring the tube in such a way as to tend to equalize any un- 
 balanced mechanical strains that exist and thereby improve the service 
 qualities of the tubing. 
 
 In order to control the quality of the product, samples are subjected 
 to whatever tests are necessary to establish the properties of the tube 
 required for the particular service they are to perform. In Figure 49 is 
 shown an inspector marking samples to be delivered to the laboratories. 
 
 After straightening, the tubes are sawed to standard lengths and 
 each one is subjected to an hydraulic pressure test. These various opera- 
 tions are shown in Figures 48 and 50. 
 
 In addition to pressure tests, each tube is examined by an expert 
 and checked for dimensions and general quality before it is delivered to 
 the shipping department for packing and shipment. 
 
 The cupping process although used only to a small extent is preferred 
 for certain kinds of tubing. In this process, the metal is pushed through 
 a die by a round nosed punch. An operation of this kind is shown in 
 Figure 45. In the liquid bath under the machine may be seen several 
 tubes ready for the drawing operation. The operator at the right is 
 holding a similar tube after the drawing operation. This tube is now 
 ready for an annealing and pickling, after which it will be returned for 
 the next draw and so on until the finished size is attained. 
 
 Although the bulk of the tubes are circular in section, other sections 
 are also drawn. Figure 51 shows a number of special sections and serves 
 simply to indicate the possibilities of the processes. 
 
 50 
 
Figure 45. Drawing tubes by the cupping process. Two of the blanks from which the tubes are 
 drawn may be seen in the liquid under the machine, and in front of the operator. 
 
 Figure 46. A tube passing through the spiral rolls of a straightening machine. The crooked 
 tubes may be seen in the right background; while a portion of the straight tubes is visible in the right 
 foreground. These straightening rolls operate on the machine in such a way, as to spring it and equalize 
 mechanical strains, as well as to straighten it. 
 
 51 
 
Figure 47. Straightening condenser tubes. These rolls spring the tube as well as straighten it, 
 and therefore equalize mechanical strains left from the last drawing operation. 
 
 Figure 48 Cutting straightened condenser tubes to standard length. 
 
 52 
 
Figure 4*5. Sampling condenser tubes for inspection tests. A certain percentage of all tubes manu- 
 factured are thus sampled for analyses and tests in the laboratory. 
 
 Figure 50. Hydraulic test of condenser tubes. 
 53 
 
Figure 51. The Bridgeport Brass Company makes a specialty of drawing bras"= 
 as well as opened sections. These sections find use in building construction wher 
 
 all l-,V„Hc r^( <,r^a^:„\ rU^^oo „f,l„„„^ 
 
 54 
 
either brass or copper is desirable. The principal applications are in connection with the construction of store fronts, 
 skylights, fireproof metai trim, window sash, etc. 
 
 55 
 
SHEET BRASS 
 
 ^tratgt|tpntng 
 
 Anttpaltnj5 
 
 CUtttting off TN the manufacture of sheet brass, bars are delivered from the electric 
 t\^t <&UU ^ casting shop to the rolling mills where the gate is cut off in an alligator 
 
 shear as shown in Figure 52. An expert examines the piece cut off to 
 determine whether the cut is deep enough to eliminate the pipe. He is 
 also able to judge the quality of the casting by examining the metal dis- 
 closed by the cut. 
 
 Having trimmed the bars, they are inserted into a breaking-down 
 roll after which they are straightened by passing through a series of rolls 
 as shown in Figure 53. After being straightened, the surfaces of the cast- 
 ing are removed in a milling machine as shown in Figure 54. The bars 
 are now ready for another pass through the breaking-down rolls as shown 
 in Figure 55. 
 
 Since mechanical working of brass or copper hardens the metal, it is 
 necessary to anneal it at various stages in the rolling process. In Figure 
 56 is shown a group of annealing furnaces from one of which an annealed 
 charge has just been withdrawn. These furnaces are so arranged that 
 the hard brass is drawn in at one end by the same operation that the 
 annealed brass is drawn out of the other. The temperature in these 
 furnaces is accurately controlled by electric pyrometers, facilities being 
 provided for reading the temperature at both ends and in the middle of 
 the furnace. One of the indicating instruments is shown in Figure 57. 
 A recorder is shown in Figure 61. 
 
 Some years ago the Bridgeport Brass Company originated the prac- 
 tice of using tandem rolls in the production of sheet brass, and protected 
 the process by a series of patents. Figure 60 shows a set of these rolls in 
 operation. 
 
 ISoUtnn Rolling brass is an art that up to the present time has never been 
 
 successfully divorced from the human element of the operator. The 
 process as a whole can be planned and controlled according to a definite 
 program but the rollers themselves must be men who have had thorough 
 training and long practical experience. The Bridgeport Brass Company 
 has been in the business since 1865 and has produced rollers who are 
 second to none in the country. Several of these men have been with the 
 company for more than 30 years and one man has been with them for 
 47 years. 
 
 Sheet brass is marketed in various forms, depending upon the thick- 
 ness of the metal and also upon the purpose for which it is to be used. It 
 may be in straight flat bars, in wide coiled strips, or in narrow coiled 
 strips. 
 
 56 
 
Figure 52. Biting off the gate of a brass bar. The removed portion of every bar is examined by 
 an expert to determine if the pipe has been entirely removed, and also to pass upon the quality of the 
 metal. 
 
 Figure 53. Straightening bars after they have been passed through the breaking-down rolls pre- 
 liminary to removing the exterior surface. 
 
 57 
 
Figure 54. Milling the surface of straightened bars so as to remo\'e mechanical flaws and surface 
 impurities from the bar before rolling it to smaller sizes. 
 
 Figure 55. Milled 
 bars passing through the 
 breaking-down rolls. 
 
 58 
 
Figure 56. Between the various stages of the rolling process, the bars are annealed so as to relieve 
 rolling strains and soften the material. The charges are assembled on flat sheets of iron and coupled 
 up in such a way that when a charge is withdrawn from the furnace, it drags in from the opposite end 
 a fresh charge. The fresh charge may be easily identified by the glossy surfaces of the bars. 
 
 Figure 57. The tem- 
 perature of the annealing 
 furnaces is of the greatest 
 importance, and therefore 
 to facilitate its accurate 
 control, recording and in- 
 dicating pyrometers are 
 provided. The operator 
 here shown is reading the 
 temperature of a group 
 of furnaces, so as to check 
 the adjustment of the 
 heat. From the one point, 
 he can read the tempera- 
 ture at the front, in the 
 middle and at the rear of 
 each furnace 
 
 59 
 
Figure 5S. Rolling cold-rolled copper sheet 
 
 Figure 5'- 
 
 Rolling 
 
 brass. The art of rol- 
 ling brass is one that 
 has not yet yielded to 
 perfect scientific organ- 
 ization. The skill of 
 the operator is still a 
 factor of the greatest 
 importance. The 
 Bridgeport Brass Com- 
 pany is fortunate in 
 having a large nvimber 
 of brass rollers that 
 ha\'e been in its employ 
 a great many years, 
 and therefore are 
 trained by experience 
 to produce the results 
 desired by the manage- 
 ment. The roller 
 shoviTi in this picture 
 has been in the emplo\- 
 of the company 47 
 years. 
 
 
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 60 
 
Figure 60. A set of tandem running-down rolls patented by the Bridgeport Brass Company and 
 operated by a roller who has been in the employ of the company 38 years. 
 
 Figure 61. A recording pyrometer 
 which automatically records the tem- 
 perature of a group of annealing furnaces. 
 By means of this instrument, an accurate 
 record is kept of each batch of metal 
 so that the control laboratory can always 
 trace the history of samples taken for the 
 purpose of controlling the mill operations. 
 
 61 
 
•ExtruHtBtt 
 
 RODS AND WIRES 
 
 THE Bridgeport Brass Company uses the extrusion process for the manu- 
 facture of brass rods, while bronre, copper, and Phono-Electric rods 
 are made by the rolling process as described under "Phono-Electric Wire. ' 
 
 The brass billets from the electric casting shop are delivered to the 
 saws, one of which is shown in Figure 02, From here they go to the 
 heating furnace as shown in Figure 63 where they are brought to such 
 temperature as will render the metal plastic. 
 
 The plastic billet is then inserted into the cylinder of the extrusion 
 machine and pressure applied to one end of it by means of an hydraulically 
 operated plunger. The metal being forced out through holes in a die at 
 the other end of the cylinder emerges from the machine as rods. In 
 Figure 54 the rods are seen coming from the machine and lying in the 
 trough extending from its mouth. The muffle \\"hich feeds this machine 
 is seen in the background at the right. 
 
 These rods are drawn to size and straightened for shipment, or 
 wound on reels and delivered to the wire mills where they are drawn to 
 size in the draw blocks. 
 
 Figure d2. Sawing off the gate of brass billets. 
 62 
 
Figure 63. Brass billets on their way into the heating furnace of the extrusion machine. 
 
 Figure 64. The extrusion machine in operation. Billets in a plastic condition are taken from the 
 heating furnace and inserted in a cylinder in the front end of the machine. The operator at the left then 
 applies pressure against the end of the billet and forces it through a die, the rods issuing from the front 
 of the machine as shown. The cylindrical cakes in the center foreground are the ends of the billets re- 
 moved from the machine after the main portion has been extruded. 
 
 53 
 
Figure 65. Drawing rods from the extrusion machine. This drawbench operates on the endless 
 
 chain principle with reversing motors. 
 
 Figure bo. Straightening rods by passing them through three sets of spirally mounted rolls, which 
 manipulate the rod in such a ^ay as to relie\'e mechanical strains left by the drawing process. The 
 cover of the machine is thrown up so as to show the method of mounting the rolls. In operation, the 
 frame containing the roll sets rotates around the rod. 
 
 I.U 
 

 HIHHHII^^^LL 
 
 
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 Figure b7. Springing machine lor removing strains from bars and rods. The matter of mechanical 
 strains in drawn bars is of the greatest importance, since their elimination largely determines the service 
 characteristics of the material. This detail of tube and rod manufacture has been scientifically studied 
 by the Bridgeport Brass Company, and the manufacturing technique so worked out as to eliminate 
 practically all unbalanced strains. This result is obtained by properly choosing the various factors that 
 enter into the annealing, pickling, lubricating, drawing and straightening processes, all of which have a 
 bearing on the strains in the metal. 
 
 Figure 68. Straightening rod of small diameter 
 65 
 
LABORATORY AND RESEARCH 
 DEPARTMENT 
 
 '"T'HE first step in placing the processes of the Bridgeport Brass Com- 
 -L pany on a scientific basis was the organization of a research labora- 
 tory. To begin with it \\-as necessary to make a research man out 
 of e\-ery foreman in the plant, many of whom were technically edu- 
 cated men, thoroughly trained in research methods. Having organized 
 the force, the processes were carefully developed and scheduled, and then 
 it was necessary to provide an inspection laboratory to insure the 
 standards that had been set up. Therefore, the laboratory work of 
 the department may be divided into two parts, the research work and 
 the control routine work. The research work divides itself in two general 
 classes, namely: research work on products of the company and re- 
 search work on materials and equipment employed by the company in the 
 manufacture of its products. The control laboratory systematically 
 samples the product at the \-arious stages of manufacture and performs 
 chemical analyses and certain physical tests, depending upon the nature 
 of the product and the particular step in the process from which the 
 
 Figure b^. Electrolytic cells for determining the copper and lead content of brasses and bronzes 
 as applied in the control testing of the chemical laboratory. The glass beakers are closed at the top 
 with semi-circular pieces of glass, as may be plainly seen at the left. The girl in the center is washing 
 off these plates so as to prevent any possibility of error, due to part of the solution clinging to the cover 
 plates. The girl in the background is setting up a cell. The cells are operated from a special low voltage 
 motor-generator set. 
 
 66 
 
sample was taken. In this way, it is possible to control closely the 
 properties of the products passing through the plant. 
 
 The control laboratory is specially valuable in protecting the various 
 alloys from any impurities there may be in the scrap used in their com- 
 position, and in this way serve as an accurate guide in the determination 
 of the proportions of various kinds of scrap to be used in any given mix- 
 ture. 
 
 The research department develops new alloys, studies details of the 
 manufacturing processes with a view to eliminating wastes, and im- 
 proving the quality of the product. It examines the fuel, lubricating 
 oils and greases, the steel used for the dies and tools, and in many other 
 ways develops and guards the manufacturing process in all its details. 
 
 The activities of this end of the business are far too numerous to be 
 described in this publication, but some idea may be obtained of the 
 extent and character of the equipment from the illustrations shown 
 herewith. 
 
 Figure 70. A view in the Balance Room where an important part of the control work is carried on. 
 
 67 
 
Figure 71. In the 
 control laboratory 
 every possible pre- 
 caution is taken to 
 avoid errors. The 
 measuring devices 
 here shown are so 
 constructed, that an 
 accurate quantity 
 of liquid is meas- 
 ured automatically. 
 All the operator 
 does is to pump 
 until the measuring 
 column is full to the 
 cop. An internal 
 tube extending e.x- 
 actly to the upper 
 graduation of the 
 tube draws off the 
 liquid automatic- 
 ally, leaving in the 
 measuring tube the 
 exact quantity re- 
 quired. 
 
 Figure 72. Spe- 
 cial electric furnaces 
 for burning out 
 filter papers. This 
 is another improve- 
 ment calculated to 
 eliminate possible 
 errors. It supplants 
 the old method of 
 open flame burner 
 with the ever pres- 
 ent possibilities of 
 loss, due to drafts 
 or accidental up- 
 setting 
 
 ti8 
 
Figure 73. One of three micro-photographic machines. These machines are used both in con- 
 trol testing and investigation work. By means of systematic crystal count, the standard of Bridgeport 
 Brass is maintained at every stage of the rolling and drawing processes. 
 
 Figure 74. A group of testing machines used in routine work for controlling the hardness and 
 
 strength of tubes, rod and sheet metal. 
 
 69 
 
Figure 75. Conductivity bridge for routine testing of Phono-Electric wire. 
 
 ■-^•^-'Ji 
 
 Figure 76. Machine for tensile and compression tests. 
 70 
 
Figure 71 . Miniature melting and annealing furnaces for brasses and bronzes. A bar mold and 
 various tools required for casting are shown in the center of the picture. The research laboratory also 
 uses a miniature electric furnace for investigation purposes. 
 
 Figure 78. One of the most important elements in the successful manufacture of rolled and drawn 
 brass is the lubrication of the working parts. The Bridgeport Brass Company has found it necessary 
 to compound its own oils and greases for these purposes. The equipment here shown, is part of the oil 
 laboratory in which formulas for compounding are evolved. 
 
 71 
 
Figure 7^. Fuel testing equipment used for the inspection of fuels used in the power plant, and the 
 various furnaces, which are purchased to specification and carefully checked. 
 
 Figure 80. Electrical apparatus for the determination of carbon content in steel. This apparatus 
 is part of the equipment employed by the laboratory, which controls the metals used for the various dies 
 and tools in the mills. 
 
CHARACTERISTICS OF BRASS 
 
 THE useful alloys of copper and zinc cover a series from about 55 per- 
 cent of copper and 45 percent of zinc up to pure copper, and exhibit 
 a wide range of normal properties and characteristics according to the 
 proportions of the two constituents present. Their physical characteris- 
 tics when cold rolled and annealed vary with the proportion of the two 
 ingredients as shown in Figure 81. These curves were produced by 
 plotting the results of tests on samples of sheet of various mixtures which 
 had been rolled to 0. 1 inch thick and carefully annealed at about 650 
 degrees C. 
 
 Mixtures high in zinc are relatively unimportant because of their 
 comparative lack of toughness which prevents their being readily worked 
 cold. When containing less than 63 percent of copper, however, they 
 are readily rolled forged or extruded when hot. Within this range they 
 are usually alloyed with other constituents for particular purposes. In 
 the intermediate and lower ranges from 57 to 60 percent copper, iron and 
 tin are added, either singly or in combination, to the extent of about 
 1 percent each, to increase strength, forming the manganese bronzes and 
 naval brasses. The range from 60 to 63 percent combined with about 
 3 percent of lead covers the mixtures usually employed for making "leaded" 
 or "free cutting" brass rod for screw machine use. From 63 to 70 percent 
 are the high brasses. ordinarily employed in making sheet and strip and 
 which constitute by far the greater part of all the sheet produced. Mix- 
 tures containing the higher percentages of copper are necessarily more 
 expensive and are required when color or certain qualities of toughness 
 are important. 
 
 
 80,000 
 . (6624) 
 
 ; 70,000 
 \ (4912) 
 
 '. 60,000 
 ; H2t8> 
 
 : 50,000 
 
 I (56161 
 
 ' 40,000 
 
 ; (23121 
 
 ! 30,000 
 
 I (2108) 
 
 [ 20,000 
 ; (1406) 
 
 • 10,000 
 
 (703) 
 
 y 
 
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 Sl'O/V 
 
 
 
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 \ 
 
 \\ 
 
 
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 \ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 100 
 
 80 70 
 
 PER CENT COPPER 
 
 50 
 96-886 
 
 20 30 40 50 60 70 
 
 PERCENT REDUCTION BY ROLLING 
 
 Figure 81. Relation between percentage of 
 copper and zinc an(J the physical properties of 
 brass. 
 
 Figure 82. Diagram showing effect of reduc- 
 tion of area upon physical properties for brass of a 
 given composition. 
 
 73 
 
of 
 
 The properties of any individual mixture may be varied over a wide 
 range by varying the amount of cold working from the annealed state 
 and by varying the annealing temperatures from the cold worked state. 
 The relative effect which a given amount of cold working or degree of 
 annealing produces varies with the proportions of copper and zinc present. 
 
 The effect produced by a given amourit of cold working is dependent 
 solely upon the extent thereof irrespective of whether it is effected by a 
 series of reductions or by one of the same total magnitude. 
 
 360 
 
 460° 660° 
 
 TEMPERATURE 
 
 Figure 83. Diagram showing effect of annealing 
 temperature upon physical properties for brass 
 of a given composition. 
 
 EffrrtH 
 
 nf 
 
 Ami^altufl 
 
 Figure 82 shows the effect of cold rolling on brass containing 67 per- 
 cent of copper. The percentage of reduction is the expression of the 
 initial thickness minus the final thickness divided by the initial thickness 
 and multiplied by 100. 
 
 Figure 83 shows the effects of annealing a brass containing 67 per- 
 cent of copper and 33 percent of zinc at varying temperatures. These 
 values may be influenced somewhat by the degree of cold rolling to which 
 the material has been subjected prior to annealing. 
 
 It is a usage of the trade to express the temper of cold rolled brass 
 in terms designating the amount of reduction given in the final rolling 
 after the last anneal. "1 number hard" or "quarter hard" corresponding 
 to 10 percent, "2 numbers hard" or "half hard" to 20 percent and "4 
 numbers hard" or "hard" to 40 percent. Similarly the degree of anneal- 
 ing is somewhat roughly designated as light annealed, soft and dead 
 soft, corresponding to about 500 deg. C, 600 deg. C, and 700 deg. C. 
 respectively. 
 
 74 
 
ADDITIONS AND IMPURITIES 
 
 THE quality of copper ordinarily employed in brass is exceedingly 
 high, containing ordinarily 99.9 percent or more of copper, the bal- 
 ance being largely oxygen, the presence of which is required mainly to 
 enable the metal to be cast in suitable form. 
 
 Zinc is, however, obtainable in various qualities, the chief variable 
 impurity in which is lead, which is found in various percentages, from 
 a few one hundredths up to as high as 2 percent. 
 
 The quality of brass is affected to a considerable degree by the BjraJi 
 amount of lead carried by the zinc of which it is produced. The effect 
 of this ingredient is to lower its toughness, ductility and ability to with- 
 stand cold working processes, involving stretching and distortion. The 
 presence of lead also has a very marked effect upon the ease with which 
 brass can be cut with a tool, and where this property is of importance, 
 lead is purposely added up to 3 percent or slightly over. 
 
 Next to lead the most important impurity carried by brass is iron, Jron 
 which is introduced partly with the zinc in which metal it exists in vary- 
 ing quantities according to the grade of the latter, and also from accidental 
 contamination when in the molten state. The effect of iron is to reduce 
 ductility and increase hardness and its influence in these Fespects is 
 markedly detrimental when present in quantities over 0. 1 percent. 
 
 Other metallic impurities are seldom present in amounts sufificient 
 to be detrimental, altho antimony and bismuth, which are particularly 
 objectionable, are usually carried in minute amounts by copper. 
 
 Arsenic is sometimes present when grades of copper carrying that 
 element are employed, but its effect, however, is ordinarily not pro- 
 nounced and is useful rather than objectionable. 
 
 Tin is sometimes present by accident and sometimes by design. It (jltn 
 increases the elastic limit and hardness of the material somewhat and 
 acts as a deterrent to certain corrosive influences. Other elements are 
 seldom found in the presence of good practice. 
 
 Accurate knowledge of the physical properties of brass and the use 
 of scientific methods in its manufacture have not heretofore been of 
 sufficiently wide employment to have resulted in any generally accepted 
 practice in specifying the qualities of brass required for specific uses or in 
 testing it for the determination of its suitability. As a general rule, 
 therefore, the largest measure of satisfaction can be secured when the 
 brass maker is cognizant of the exact purpose for which material is to be 
 employed and in close cooperation with the user can apply his knowledge 
 and skill to the selection of mixture and treatment best adapted for the 
 purpose. 
 
 Anttmottg 
 Kxstmt 
 
 75 
 
The chemical, physical and research laboratories of the Bridgeport 
 Brass Company are in equipment and personnel second to none in their 
 ability to determine and select the most suitable material for any particular 
 usage. 
 
 Sftnppr ^t is equally important, however, that the temperature to which the 
 
 material has been finally annealed, or the temper to which it has been 
 rolled in case a temper is desired, be determined. The former may be 
 ascertained by the ordinary tensile test, altho on thin material this is 
 somewhat uncertain. It may also be determined by microscopic examina- 
 tion as the size of crystal varies, as shown by Figure 85, with varying 
 temperatures of anneal. 
 
 Figure 84. Sample from extruded rod showing niixture of Alplia and Beta crystals. 
 
 ^pprifiratuina 
 
 The iscleroscope and Brinnell tests are also useful in this connection, 
 see Figure 74. The latter in particular is applicable to relatively thick 
 sections. For thin sheet the Erichson machine is very useful. This 
 instrument employs a dome shaped tool to draw sheet into the corres- 
 ponding shape. This drawing action is continued until fracture occurs. 
 The depth of the cup at fracture, which is measured by the machine, is a 
 measure of the ductility of the material. At the same time the smooth- 
 ness or roughness of the drawn cup indicates roughly the size of the 
 crystal structure. 
 
 Comprehensive attempts to draw specifications for various forms of 
 wrought brass have not been conspicuously successful except in isolated 
 instances. This is because of the absence of reliable data of a specific 
 nature relating the various properties of brass to the requirements of 
 individual users. As indicated by the data heretofore given an enormously 
 wide range of physical characteristics can be imparted to brass by varia- 
 tions in composition, heat treatment and manipulation. 
 
 76 
 
Figure 85. Microstructure of brass which has been annealed at various temperatures. Magnified 
 
 85 diameters. 
 
 Figure 86. Microstructure of brass which has received varying amounts of cold rolling. Magnified 
 
 85 diameters. 
 
 77 
 
Qlrgatala 
 
 Sqmltbrtum 
 Btagram 
 
 STRUCTURE 
 
 THE crystallic structure of brass is revealed by the microscope. The 
 crystals are of two kinds, known respectively as the alpha and beta 
 crystals. The crystals shown in Figure 85 are alpha crystals, while 
 Figure 84 shows a mixture of alpha and beta, the light ones being the 
 former and the dark ones the latter. 
 
 Figure 85 shows the effect which varying annealing temperatures 
 have on crystal size in the case of a sample of brass which has been rolled 
 quite hard and then annealed at different temperatures. 
 
 Figure 86 shows the effect upon the crystal structure produced by 
 cold rolling. In this instance a sample of very thoroughly annealed brass 
 has been rolled to several degrees of hardness as stated. 
 
 Some of the useful mixtures are composed entirely of alpha crystals, 
 some of beta crystals and others of a mixture of the two. These crystals 
 separate out of the molten brass as solidification occurs and exist singly 
 or together in any particular mixture according to its composition and 
 temperature. The alpha crystals are relatively weak and ductile while 
 the beta are stronger and less ductile. 
 
 The equilibrium diagram. Figure 87, shows the relations existing 
 between the proportions of copper and zinc, the temperature, and the 
 crystallic structure. The line A.B.C. indicates the temperature at which, 
 for various proportions of copper and spelter, solidification begins as a 
 molten mass cools. The line A b* bi ci C shows the respective tempera- 
 tures at which solidification is corriplete. It will be seen from this diagram 
 that the presence of alpha or beta crystals is a function not alone of the 
 proportions of copper and spelter present but of the temperature- also. 
 A brass containing 70 percent or over of copper will consist only of alpha 
 crystals, whereas one containing 65 percent of copper will, when at a 
 temperature of 700 deg. C. or over, contain some beta. If it is slowly 
 cooled the beta will grow less as the temperature falls and finally dis- 
 appear completely. If, however, it be rapidly cooled as by quenching 
 
 in water there will be insufficient 
 time for the latter transforma- 
 tion to take place and the pres- 
 ence of beta will be found upon 
 microscopic examination. Sim- 
 ilarly a brass containing 60 
 percent of copper will, after 
 highly heating, contain all beta 
 or a mixture of alpha and beta 
 according as it is rapidly or 
 slowly cooled. 
 
 fc700 
 
 2 ■ 
 
 liJ 
 
 1- 
 
 400 
 
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 MOLTEN 
 
 BRASS 
 
 
 i 
 
 
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 bj 
 
 \'\ 
 
 ~°^"^ 
 
 r^ 
 
 
 
 
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 BETA 
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 / 
 
 
 ALPHA 
 
 
 Vlph 
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 V 
 
 
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 e 
 
 90 
 
 50 
 
 Figure 87. 
 
 80 70 60 
 
 PERCENT COPPER BY WEIGHT 8«-e87 
 
 Equilibrium diagram of copper-zinc ailoySc 
 
 78 
 
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 Photographs, Art Work, Engraving and Printing 
 
 under the direction of — 
 
 Ray D. Lillibridge Incorporated 
 
 Technical Advertising 
 
 111 Broadway, New York City