112 BELL SYSTEM TECHNICAL JOURNAL 



quantity of wire can be obtained from high speeds as from low speeds if 

 (1) the dies are made to definite specifications, (2) the dies are matched into 

 sets, and (3) the drawing machine factors are the same. 



The drawing machines have been designed and are maintained with the 

 view of overcoming some of the serious causes of short die life. Long die 

 life is not only obtained by good die shop practice but also control of the 

 following machine factors; (1) smooth drawing capstans and minimum 

 slip, (2) minimum whip of wire entering dies, (3) adequate lubrication of 

 capstans and cooling of dies, and (4) elimination of foreign particles from 

 the drawing compound. 



Fig. 17 — Schematic showing cross-section of diamond die used in high speed wire drawing 



Drawing Compound and Equipment 



A one-story building is used for manufacturing wire. In the basement 

 the drawing compound tanks, piping, heat exchangers, pumps, power serv- 

 ices and controls are installed. The compound solution used to lubricate 

 and cool the capstans and dies in the drawing machines consists of a homo- 

 genized solution of soap, fat and oil mixed with water. This compound 

 returns to a self-cleaning distributing launder in an enclosed steel tank. 

 The launder consists of a pipe with slots evenly depositing the compound 

 over the entire width of the tank. The copper sludge settles to the bottom 

 and the lighter impurities rise to the surface to be held back by a skimmer 

 plate. The clarified super-natant solution rises over a dam into the pump 

 suction chamber to be pumped at the rate of 200 gallons per minute to each 

 No. 1 machine and 100 gallons per minute to each No. 2 machine. The 



