DIAMOND DIES FOR DRAWING OF COPPER WIRE 



31 



materials and the lubrication of the contacting surfaces which in turn is 

 affected by their condition. Considered on this general basis, the die life 

 is proportional to the wire lineal footage. A good criterion for determining 

 the overall diamond die performance is the total useful life in million con- 

 ductor feet. This in turn will be proportional to the number of recuts 

 obtainable before breakage renders the die non-usable. 



Although diamond die life is theoretically a function of wear, actually it 

 is limited by the failure of the die stone by breakage and "chipping out." 

 Due to the peculiar physical properties of diamonds some breakage will 

 always occur. This condition is also affected by fatigue caused by vibra- 



Table II 



Note: Some of the results listed above appear to be inconsistent with the expected 

 trends. This is attributed to the many variables which exist in normal Wire Mill 

 Operations. 



* Based on Kearny's distribution of gauges. 



tion, impact, thermal stresses and other factors. An important element 

 influencing die breakage which is often overlooked is the detrimental effect 

 produced by improper maintenance of the drawing machine parts. An 

 appreciable reduction in die breakage was obtained by proper periodic 

 maintenance checks. 



Kearny's Wire Mill diamond die life data are listed in million conductor 

 feet per die per gauge step in Table II. The finisher and line die life is 

 tabulated separately to account for the allowable oversize diameter limits 

 for each type. No data are available at the present time to permit listing 

 of the total useful life in million conductor feet. 



