Towards Understanding Subsurface Characteristics in Burn Process of Gear Profile Grinding

In gear profile grinding, the grinding burn will greatly influence the anti-fatigue performance of gears. However, the influence of microstructure change caused by grinding burn on gear surface integrity is still unclear. In this paper, full-factor experiments of gear profile grinding are conducted and the grinding temperature is measured during the experiments. Furthermore, the tooth surface integrity including microstructure, residual stress, microhardness, and surface morphology is characterized. The relationship between grinding parameters, grinding burns and subsurface layer properties is analyzed by systematical test results. Radial grinding depths of more than 20 μm matched with wheel speeds below 30 m/s will result in severe grinding burns. The effect of grinding burns on the grain state mainly results in the breakdown of high strength martensite and the formation of inhomogeneous secondary tempered sorbite. The recovery and recrystallization of the microstructure of the tooth subsurface layer after grinding burns is the root cause of the substantial reduction in compressive residual stress and nano-hardness. The occurrence of grinding burns is mainly due to the unreasonable matching of process parameters rather than being influenced by a single grinding parameter alone. The risk of burn can be significantly reduced at greater wheel speeds and lower radial grinding depth. This study presents an insight into the mechanism of the effect of gear profile grinding burns on the surface integrity of the tooth flank.