Why is it called hobbing?

The term "hobbing" is closely related to the unique cutting tool and the manufacturing process used in gear production.

The name "hobbing" is directly derived from the specialized cutting tool called a "hob". A hob has a distinct appearance, resembling a worm - like structure with helically - arranged cutting teeth. This tool is the key element in the hobbing process. Historically, as the process of using this specific tool to create gears evolved, it was named after the tool itself. The word "hob" might have originated from the similarity of the tool's shape to a hobnail or some other pre - existing object with a spiral or screw - like form in the early days of mechanical engineering. As the manufacturing technology developed, the process of using a hob to cut gear teeth became standardized and was named "hobbing".

In terms of the manufacturing process, hobbing involves the meshing motion between the hob and the gear blank. This motion is crucial for generating the gear teeth. When the hob rotates, it is equivalent to the linear movement of a rack in the meshing process. The hob's continuous rotation and axial movement along the gear blank, while the gear blank rotates at a synchronized speed according to the gear - rack meshing ratio, gradually cut and form the gear teeth around the circumference of the gear blank. The unique and characteristic nature of this process, which is centered around the use of the hob, led to it being named "hobbing". It is a way to describe the entire gear - cutting operation that is distinct from other gear - manufacturing processes like milling or shaping. For example, compared to gear milling where a different type of cutter is used to cut each tooth space one by one, hobbing with its unique hob - based meshing motion stands out, and thus the name "hobbing" was coined to clearly define this particular gear - production method.