A forging process in which a length of wire is sheared off and upset in one or more die stations to form the head, shoulders and other features without heating. It turns out hundreds of parts a minute with almost no scrap, and the metal grain flows around the head contour instead of being cut through as in machining. Most fasteners up to about an inch in diameter are cold headed, while larger ones are hot forged.
Cold heading's running the M8 flange bolts at three hundred a minute, so watch for head bursts after the die change.
Headed parts keep their grain flow around the head, one reason headed bolts outlast bolts machined from bar.
Also heard as
- cold forming
- heading
Related terms
Header
The machine that cold heads fasteners, feeding wire, cutting blanks and striking them in a series of dies.
Upset
To thicken part of a wire or bar by squeezing it along its length, the basic move that forms a fastener head.
Head burst
A split on the edge of a cold-headed bolt head, caused by metal being stretched past its ductility.
Thread rolling
Forming threads by squeezing a blank between hardened dies, displacing metal instead of cutting it away.