The most productive way to cut external spur and helical gears, splines, sprockets and worm wheels. A hob rotates in a fixed ratio with the workpiece while feeding across its face, so each hob tooth takes a small chip and the involute is generated by the combined motion rather than copied from a formed cutter. Hobbing cannot cut internal gears and needs runout room past the end of the teeth, which limits it next to shoulders.
Hobbing the 52-tooth gears this shift, roughing pass then finish, then they go to heat treat on Thursday.
Also heard as
- gear hobbing
- hob cutting
Related terms
Hob
A gear cutter shaped like a worm with gashes across its threads, used on a hobbing machine.
Gear shaping
Cutting gear teeth with a reciprocating, gear-shaped cutter that rolls with the blank as it strokes.
Scallops
Shop word for the small ridges a hob leaves across and along each tooth flank, visible as a fine texture.
Green
Shop word for a gear in its soft, machined state before heat treatment, as in cut green, finish hard.