The cold heading machine is mainly different according to the process requirements of material modification process and the sequence of pre and post heat treatment. It is mainly divided into: steel heat treatment, central heat treatment and wire rod treatment. Steel heat treatment is applicable to hot rolled steel before cold drawing. Preheat treatment. Its purpose is to improve the original structure of steel, reduce the hardness of steel, improve the plasticity of steel and meet the needs of cold drawing deformation. For carbon structural steels smaller than medium carbon steel (C ≤ 0.25%) and some low alloy structural steels, the hardness is low and the plasticity is high. Therefore, if there are no other defects, preheating is not usually carried out.