Steel
Cold Stamping
Cold stamping is a high-speed production process whereby a piece of metal wire is cut to a precise size and then transported in a succession of moulds in which the material is deformed at high speed to obtain the desired geometry – larger diameter/lower length or removal by shearing and/or drilling.
The material is deformed beyond the elastic resistance point and then takes the shape of the mould. However, the material is not pushed beyond the yield point (breaking load) to avoid fractures. The only exceptions are cutting and/or drilling operations. The material does not reach the recrystallisation temperature, but it still undergoes a hardening.
Traditionally, cold stamping has remained at the level of an experience-based technology.
This is changing since electronic data processing allows the use of increasingly sophisticated finite element analysis and simulation programs.
Steels for such uses must have high cold stretch deformability in stamping operations and low yield strength (≈ 190 N/mm2); they therefore fall into the family of soft and extra soft carbon steels.
Other specific requirements are a regular and rounded grain ferritic structure, a content of oxide inclusions well controlled by type, number and distribution; the finished wires must have surfaces free of visible defects at most, due to their aesthetic importance in the finished product.