Surface Damage Caused by Gear Profile Grinding and Their Effects on Flank Load Carrying Capacity

Abstract

Instances of damage to discontinuous form ground and surface-hardened gears, especially of large scale, have recently increased. This damage may be attributed partly to a faulty grinding process with negative effects on the surface zones and the surface properties. In addition to its high accuracy, discontinuous form grinding is characterized by high material removal because of the line contact between grinding wheel and tooth flank. The efficiency and reliability of the process are affected not only by the use of optimized grinding wheel specifications and machining parameters, but also by the risk of local surface zone damage in the form of grinding burn on the tooth flank. The location and onset of local grinding burn damage have seemed for a long time to be random and unpredictable, for which reason the feed rates and material removal rates have been increased only incrementally in procedures used in industrial practice. The studies reported in the paper are intended to contribute to the knowledge of the interrelationships between surface zone damage and the effects on flank load-carrying capacity for the case of profile grinding. Grinding tests have been conducted in order to investigate more closely the occurrence of surface properties in the form of grinding burn as a function of grinding parameters. Further studies of the flank load carrying capacity of case hardened gears subjected to different surface properties are intended to provide a more detailed analysis of the interrelationship between gear geometry and different surface properties during the grinding process in a first step.