Wire drawing

[1] Of the elemental metals, copper, silver, gold, and platinum are the most ductile and immune from many of the problems associated with cold working.

As the wire is pulled through the die, its volume remains the same, so as the diameter decreases, the length increases.

Usually the wire will require more than one draw, through successively smaller dies, to reach the desired size.

[1][2] The process of wire drawing changes material properties due to cold working.

In a bundle, the wires are separated by a metal with similar properties, but with lower chemical resistance so that it can be removed after drawing.

[citation needed] If the reduction in area is greater than 50%, the process may require an intermediate step of annealing before it can be redrawn.

The block is also tapered, so that the coil of wire may be easily slipped off upwards when finished.

Before the wire can be attached to the block, a sufficient length of it must be pulled through the die; this is effected by a pair of gripping pincers on the end of a chain which is wound around a revolving drum, so drawing the wire until enough can be coiled two or three times on the block, where the end is secured by a small screw clamp or vice.

[6] Lubrication in the drawing process is essential for maintaining good surface finish and long die life.

In some classes of wire the copper is left after the final drawing to serve as a preventive of rust or to allow easy soldering.

The highest strengths available on any steel have been recorded on small-diameter cold-drawn austenitic stainless wire.