The machines are generally designed and built to draw intermediate size wire from about Max 3.5 mm to 2.0mm to a finish size of 1.2mm - 0.6mm. and are generally of the so called wet slip type.
There are 2 basic wet slip machine types.
A)
- The machine where the elongation is compensated for by increasing the draw race rpm via the transmission gear ratios. These machines are generally designed to accommodate anywhere from 6-19 dies.
- The cone type machine where the the elongation is compensated for by increasing the draw race diameters sequentially, are generally designed to accommodate anywhere from 12 dies to in some cases as many as 32 dies. This is done by using different machines executions with 2 or 4 or 6 and exceptionally 8 couples of drawing cones each with 5-6 draw races per shaft.
Both machine types as an inherent result of the design have fixed elongation ratio between each die. As a result the die sizes has to be selected so that the area reduction through each die is slightly higher then the theoretical area reduction that would match the fixed elongation. This way the draw race for the second die will pull through more wire than is called for by the 3rd and subsequent drawraces and as a result the wire will constantly slip on the draw races. The slip factor is normally 1-3 %. While the finish diameter can be determined and adjusted by varying the inlet diameter and the reduction taken through the inlet die plus the number of draw races used the slip factor can to a degree also be used to fine tune a draft serie.
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