Continuous Generating Grinding of Gears

Only grinding can simultaneously deliver high surface finish and high precision geometry

Grinding is a metal cutting process that, due to innumerable cutting edges and high operating speed, can simultaneously deliver high material removal rate, superior surface finish and very precise geometry. The grinding process is particularly suitable for hard materials such as case hardened gears. Generally, this process is referred to as hard finishing.

The Reishauer continuous generating grinding process is based on a multi-axes high performance grinding machine equipped with dressable, vitrified bonded grinding worms also called threaded wheels. This union of machine and tooling ensures the resulting high-quality gears ground with very short cycle times. The abrasive grain used in the threaded wheels consists of fused or sintered aluminium oxides that are markedly harder than the case hardened steel of the gears to be ground. The constant profile accuracy and permanent free-cutting properties of the threaded wheels are  maintained by diamond dressing tools mounted within the grinding machine.

Put simply, the kinematics of continuous generating grinding can be understood as a worm drive with additional abrasive machining properties, consisting of an infeed X to set the depth of cut, a vertical feed-rate Z, and the lateral shifting motion Y that ensures that the abrasive worm shifts continuously sideways by a small amount for each mm of vertical feed-rate. In this manner, the grinding always takes place with fresh, unused abrasive grits that determine the material removal rates, surface finishes and profile holding.