Work hardening
The cold-working process uses the pressure and speed of a mechanical or hydraulic press. The press takes a metal ‘blank’ and shapes it using a ‘punch’ and ‘die’ set. Basically, the punch is the tool used for shaping, and the ‘die’ is the clamp that holds the metal. When these metals are cold worked, permanent defects change their crystalline makeup. These defects reduce the ability of crystals to move within the metal structure and the metal becomes more resistant to further deformation. The resulting metal product has improved tensile strength and hardness, but less ductility.