Types of Thread Rolling

There are two types of thread rolling - Infeed and Thrufeed.

All thread rolling machines are capable of both, making for a more versatile machine that can do bolts and studs as well as longer-length threaded pieces.

INFEED ROLLING (PLUNGE)

Infeed rolling uses a timed cycle for increased production.  It's used for general rolling of parts up to the maximum length of dies, and also shouldered or headed work pieces.

• Helix angle ground into the dies
• Work piece and dies are kept parallel on the machine
• Work piece rotates between the dies, but has little or no axial movement

Automatic nut and bolt threading rod thread rolling machine

THRUFEED ROLLING

Thrufeed rolling is used for rolling threads that exceed the maximum face width of the dies, as well as for continuous rolling of long threaded bars.

• Typically uses annular ring type die, with the thread form ground on the die in straight rings with no helix.
• Helix angle produced by tilting the spindles on the machine to the same helix as the work piece
• Work piece rides between the dies on a support blade
• Multiple start threads (within range of machine) can be rolled by increasing helix angle tilt on the machine
• Speed-up dies are used for high-speed rolling