hobbed

Hobbed is an adjective or past participle used to describe a part that has been produced by hobbing, a gear-cutting process. In this context, a hob is a specialized cutting tool with multiple helical flutes. A hobbed component is formed when a rotating hob engages a gear blank and progressively cuts teeth as the two pieces rotate in a precisely coordinated manner.

The process involves mounting the hob on a machine spindle and the gear blank on another. The blank is rotated while the hob advances axially, so that new tooth spaces are generated along the circumference. The tooth geometry is defined by the hob’s profile and the pitch of the gear. Hobbing can produce a range of external gears, including spur and helical gears, as well as sprockets and splines; internal gears can also be produced with specialized tooling. The method is valued for its high material removal rate and suitability for high-volume production.

After hobbing, parts are frequently finished by shaving, grinding, or lapping to improve surface finish and tighten tooth tolerances. The resulting gear teeth typically reflect the hob’s profile, which is standardized to meet industry gear pitches and module specifications.

In practice, “hobbed” appears in manufacturing documentation and catalogs to denote gears and related components that were produced by hobbing rather than by milling, shaping, or grinding alone. Hobbed gears are common in automotive transmissions, industrial gearboxes, and other high-volume gear applications.

See also: gear hobbing, gear manufacturing, gear finishing.