Production of gears requires special accessories and cutters for use with standard machine tools in low volume production or special machines for high volume production.
Gear cutting is divided into three types: (1) generating, in which there is relative rolling between the cutter and gear blank and in which the tooth is formed; (2) non-generating, in which cutters are formed in the shape of spaces between the desired teeth; and (3) profiling or tracing, in which templates are used to guide the cutting tool.
Modern high-production gear cutting demands the use of a generating process while other processes are used for small lots and experimental gears. As an example, a modern gear hobbing machine loads and unloads, adjusts the machine for pitch diameter controls, shifts the hob to distribute cutter wear, and sorts the finished gears without any operator attention.
To ensure correct operation, many gears are further finished after they are cut. Shaving, in which a minimum amount of metal is removed, can be used to achieve correct finish and required profile. Grinding, burnishing, and lapping are also used to finish gears. Gear rolling, in which the finished gear, especially a spline, is cold formed from solid stock, is applied in much the same manner as thread rolling.