The Bell System Technical Journal 



April, 1927 



Developments in the Manufacture of Copper Wire^ 



By JOHN R. SHEA and SAMUEL McMULLAN 



Synopsis: This paper describes a new copper rod and wire mill located 

 at the Western Electric Company's Plant at Chicago. It includes a brief 

 survey of the copper rolling and wire drawing art at the time the investiga- 

 tion was started; a summary of tests made in varying the practice in rod 

 rolling and wire drawing; and an outline of the work done by the Western 

 Electric Company engineers in developing and designing new types of wire 

 drawing machinery. 



The rod mill is converting 225 pound wire bars into J^" rod in fourteen 

 instead of the usual eighteen passes. This is accomplished by making heav- 

 ier reductions in the first four passes while the copper is hot. The new wire 

 mill incorporates many novel features, and the wire drawing machines are 

 more compact in design and of considerably higher speed than those in 

 general use. 



The design of the wire mill was undertaken following a comprehensive 

 survey of wire drawing processes and equipment used in this country and 

 abroad. Part of this survey consisted of a study of the manufacture of 

 diamond dies, it having been found that dies suitable for high speed drawing 

 required a differently shaped "approach," a better polish, and a shorter 

 "land," than those which were available for low speed work. The econo- 

 mies in floor space and plant investment due to the use of more compact 

 and higher speed machinery are outlined. Some of the outstanding features 

 in plant arrangement which contribute to more efficient operation are dis- 

 cussed in the concluding pages. 



RAPID growth in the various branches of electrical communication 

 accompanied by widespread research are constantly leading to 

 the more efficient and economical meeting of the increasing demands 

 for service. In this connection, one of the more recent and very in- 

 teresting investigations indicated the possibility of effecting substantial 

 improvement in the process of manufacturing copper wire. Accord- 

 ingly, a comprehensive study of all the factors concerned was under- 

 taken which resulted in the construction of a rod and wire mill at 

 Chicago embodying many unique and improved features. A sche- 

 matic layout is given in Fig. 1. 



At the outset the sources of copper and its transportation were 

 studied and it was found more economical to ship wire bars to Chicago 

 for conversion into wire than to locate a wire mill near some of the large 

 refineries and ship wire to the factory. It was also considered that 

 this plan would reduce the investment in wire during the process of 

 manufacturing cable and telephone apparatus. 



1 Read before the Midwinter Convention of the A. 1. E. E., New York City, Feb. 

 8, 1927. 



13 187 



