Cold forming is a manufacturing process in which the blanks of the component being made are shaped by pressure without any application of heat. A blank is placed between a die and punch and then pressed with considerable force to cold form the part. The die and punch have hollow spaces, and the blank is formed by being forced into these spaces when pressed. If the die has a stepped diameter, the process is called reduction or forward extrusion.
In the reduction process, the blank is lengthened by one diameter step. If there is a hollow space between the inside of the die and the punch into which the material can flow, a corresponding hollow space will be created on the blank. The punch’s penetration of the blank is called cup extrusion. Depending on the material flow inside the dies, the process is called forward or backward extrusion.