The flank load carrying capacity of case-hardened gears is significantly influenced by the condition of the case properties. A negatively influenced case, e.g. due to grinding burn, may result in a significantly reduced load carrying capacity of the tooth flank. On the other hand, additional finishing methods such as shot peening and superfinishing allow a positive influence on the case properties, resulting in a further increase of the tooth flank load carrying capacity. The variation of the case properties is not adequately taken into account by the current standards DIN 3990 / ISO 6336.
This paper summarizes the results of the FVA research project 521 I. This project investigated the effects of shot peening and superfinishing on the tooth flank load carrying capacity. Based on the experimental results, an extension of the calculation method for the permissible contact stress σHP is proposed.