2. Tools for cutting spiral gears

The advent of multi-axis numerically controlled machines has brought about an evolution in processes. Nowadays, hobbing is carried out in a single cycle [Completing ], and less frequently in separate roughing and finishing operations, except in sectors such as aviation.

There are two main families of tools for this type of gearing:

• one-piece cutters or cutter inserts that cut one tooth completely before retracting to allow splitting. We refer to this family of tools as milling cutters for intermittent dividing cycles. Generally, the crown and pinion forming a couple are made with generation, but for mass production, the crown can be made without generation;

• cutter-knives with blade inserts arranged in sectors, each successively penetrating a tooth hollow in a continuous generating...