1. High plasticity and low hardness are required.
Since tangential tensile stress acts on the lateral surface of the workpiece during cold heading-making it prone to longitudinal surface cracking-materials specifically characterized by high plasticity and low hardness must be used. For steel, the surface hardness is generally required to be in the range of 75–85 HRB.
2. Strict surface quality requirements.
As the cold heading process is primarily used to manufacture standard parts (such as screws and bolts) that typically undergo no subsequent machining, and because the shanks of these parts experience minimal deformation during the process-thereby retaining the raw material's original surface-the raw material must possess low surface roughness and be free from surface defects such as scratches, pitting, or rust.
