NEW COPPER WIRE DRAWING PLANT 



111 



PART II— EQUIPPING AND OPERATING THE NEW WIRE MILL 



By J. E. WILTRAKIS 



Alloy and Diamond Dies 



The experience gained in operating the older Hawthorne and Point 

 Breeze wire mills demonstrated the importance of providing and main- 

 taining dies of high quality. The hardest materials, alloys such as tung- 

 sten carbide and flawless diamonds, are used in these dies. 



The alloy dies are used in the No. 1 drawing machine where the wire 

 surface and resulting die wear are relatively small per pound of wire pro- 

 duced. 



Diamond dies are used exclusively in the No. 2 machine. Definite 

 ])roblems were solved in maintaining dies to rigid specifications which 

 include correct die contours, a finely polished surface, and definite die pull 

 values. 



The cross section of a diamond die, Fig. 17, illustrates the general contour 

 found to be most satisfactory for high speed wire drawing. The approach 

 blends smoothly into the reduction angle where the wire is reduced in 

 diameter one AW gage. The bearing is approximately 40% of the wire 

 diameter. With the use of a contour projector, lOOX enlargements of die 

 impressions are periodically made to control the process. 



Well graded diamond dust is used to enlarge the hole in the die and for 

 polishing operations. Dust graded by flotation methods, closely checked, 

 offers the best results. 



For final polishing 6 micron diameter dust is used. A 30X wide angle 

 binocular microscope is used to check the various stages of die making 

 operations and of inspection as shown in Fig. 18. 



The following die pull requirements have been set up for each gage when 

 reducing wire one AW gage size: 



After grouping dies of a certain diameter according to the pounds pull 

 required, they are matched into sets for use in the No. 2 drawing machines. 

 Records are kept of the characteristics and output of each die. 



The increase in speeds up to 12,000 f.p.m. does not appear to have an 

 appreciable effect on die wear. In other words, the same quality and 



