The Curvic coupling from the aviation sector is a critical component used in helicopters. Previously, the external helical gearing was manufactured on one machine and the curvic coupling gearing on a second machine. The external and internal cylindrical grinding was then carried out on a third machine in two consecutive process steps.
When grinding steel parts, the surface of the part can "burn" if too much heat is applied in a short time. Grinding burn refers to all those structural changes in edge zones of steel parts that are caused by grinding processes in steels due to the thermal energy introduced. Grinding burn can mainly occur in the form of tempering zones or new hardening zones.
A significant amount of work is being done to advance the technology of gears specifically for use in electric vehicles. No longer hidden by the noise of the internal combustion engine, the transmission has taken center stage as the noisiest component in most electric-driven cars.
Gear manufacturing involves a number of processes that, intentional or not, affect the residual stress state of the critical surfaces. Stresses, including residual stresses from processing, are commutative, with compressive stresses typically improving fatigue life and crack initiation while tensile stresses do the opposite. Accordingly, gear designers and manufacturers often require compressive residual stresses at the surface on critical geometries such as gear teeth and roots.