Diamond Dies for the High-Speed Drawing of Copper Wire* 



By H, N. PADOWICZ 



ESSENTIAL to the drawing of copper wire at any speed are the dies to 

 effect the desired reduction steps. It can be readily surmised that this 

 item is one of major importance at drawing speeds of 10,000 and 12,000 feet 

 per minute which are being used in the copper wire drawing plants at the 

 Kearny Works and the Baltimore Works of the Western Electric Company.^ 

 In these machines diamond dies are used to draft 12 and 14 A.W.G. supply 

 wire to the final sizes of 19, 22, 24 and 26 A.W.G., respectively. As pointed 

 out in the paper^ describing these machines in the above noted plants, the 

 maximum possible drawing speed is limited by the stresses set up in the 

 take-up reel rims. Drawing dies in themselves should not place any limita- 

 tions on the wire drawing speeds if the factors of heat generated and the 

 rapid movement of lineal wire surfaces are logically considered and provided 

 for. 



In 1924 the manufacture of copper wire at a drawing speed of 2500 feet 

 per minute in a new type of wire drawing machinery, developed and designed 

 by the Western Electric Company, was started in its Chicago plant.^ At 

 that time copper wire was being generally produced at speeds ranging from 

 800 to 1200 feet per minute. A study of the manufacture of diamond dies 

 for use in these machines developed that dies suitable for this work required 

 a differently shaped "approach," a better polish and a shorter "land" than 

 those that were available for low-speed operation. These same factors are 

 still the important items which must be considered for today's drawing speed 

 of 10,000 and 12,000 feet per minute. 



The technique of making diamond dies for the drawing machines which 

 operate up to about 5,000 feet per minute is now well established. The 

 specifications covering the dies for this purpose are known and available 

 to the trade which is well qualified to produce them. However, the oppor- 

 tunity and necessity for diamond dies to draw copper wire at the noted high 

 speeds did not exist prior to the recent development of these high-speed 

 machines and for this reason the industry was not familiar with the necessary 

 die requirements. 



The Kearny Wire Mill was set up to purchase finished mounted dies from 

 outside suppliers and to recut them when oversize. These dies are usually 

 acquired at the smaller final sizes as governed by production schedule re- 

 quirements and enlarged to the larger sizes for both finisher and line die use. 



* Published in Wire and Wire Products, October, 1941. 



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