'Cold drawing' is a manufacturing process involving extrusion of a material into a long filament, often for the purpose of increasing the strength of the material.
Cold drawing is primarily used in manufacturing
polymer plastic fibers. The process was discovered by
Julian Hill in
1930 while trying to make fibers from an early
polyester, a precursor to
nylon. It is performed after the material has been "spun" into filaments. Here, spinning does not mean
twisting fine
textile filaments, but rather extrusion of a polymer
melt through pores in
industrial spinnerets. During this process, the individual polymer chains tend to align because of
viscous flow. If subjected to cold drawing afterwards, the fibers align further, increasing their crystallinity,
[1] and the material acquires additional
tensile strength.
[2]
Cold drawing is also used in cable core production. Starting from a 1 cm (0.4 inch) thick
Cu wire, the wire is slowly drawn more and more, and eventually small, thin wires of 1 micrometer in diameter can be obtained.
External links
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Nylon crystallinity
★
Cold drawing of nylon