Cold Heading, Thread Rolling & Tapping

Cold Heading, sometimes also referred to as cold forming, is a manufacturing process for changing the geometry of metal parts by using high speed and pressure, forcing metal into the shape of the die used. The cold heading process can be used to form a variety of shapes, although it is most commonly for heads of screws.

Thread rolling is a secondary process of creating helical threads by rolling instead of cutting a shaft into the shape of the threads. Two cylindrical dies made of hardened steel with the thread pattern are spun and the shaft to be threaded is fed in between them, with tight spacing so the shaft contacts each die simultaneously. Since the shaft is made of the softer material, it takes the shape of the dies, forming a thread as for far as the shaft is fed into the dies.

Tapping is the process used to turn holes into female threads using a grooved rod called a tap. The tap is fed into a similarly sized hole and rotated, cutting away material to form helical threads. The tap size can vary based on the desired threading, and three different tap types (bottoming, plug, and taper taps) are used to form different features of the threads.