Electrical Upsetting Machines

A high density of electric current at very low voltage is made to pass through a portion of the end of the bar stock, which is held against an anvil and clamped between two jaws, to generate sufficient heat to make the portion red hot and plastic. An upsetting force is applied axially on the rod against the anvil making the portion, which is in plastic stage to deform into a bulb shape and to gather the required volume.

This process is usually followed with a forging operation to get the required shape.