This paper deals with the residual stress depth profiles in case-carburized gears, their effects on the fatigue behavior as well as the enhancement of ISO/TS 6336-4 to include the consideration of tensile residual stresses in the tooth core area. For this purpose, an equation is also presented with which these tensile residual stresses can be estimated so that they can be used in the enhanced evaluation of TFF risk.

Standardized methods, like AGMA 2001-D04 or ISO 6336 for the calculation of the load carrying capacities of gears are intentionally conservative to ensure broad applicability in industrial practice. However, new applications and higher requirements often demand more detailed design calculations nowadays; for example: long operating lives in wind power gearboxes or fewer gear stages and higher speeds in e-mobility applications result in higher load cycles per tooth in a gearbox.