Cold Heading Terms:
Cut-off: A specific length of wire that is cut off from a coil of wire prior to going into the heading die.
Heading Die: A stationary piece of tooling that has the specific geometry for the part machined into its cavity used to form parts.
Punch: A piece of tooling that moves, striking the cut-off slug to upset material and push it into the heading die.
Knockout Pin: (used for two purposes)
To serve as a support against which the blank rests while it is being headed.
To eject the part out of each die.
Diameter of Upset: The amount of material that can be upset to form a head of a fastener. A length of wire equal to its diameter. The term “1 diameter of upset” only moves a small amount of material to form the head of a fastener. The term “4 ? diameters of upset” involves moving a lot of material to form the head of a fastener. The larger the diameter of upset – the larger the head diameter can be made.
Upsetting: Striking an object on its end causing the existing diameter to increase in size.
Extrusion: Forcing into a die causing the diameter to become smaller
Grain Flow: The grain flow of the existing material is either interrupted (as in machining) or uninterrupted (as in cold heading). A part that has an interrupted grain flow is weaker than a part with uninterrupted grain flow. Cold-formed parts are stronger because the internal grain structure follows the contour of the part.