Mechanism and suppression method of grain burial in laser sharpening of bronze-bond diamond wheels

Abstract

Laser technology is increasingly being applied to the dressing of diamond wheels, not only enabling high profile accuracy but also enhancing its grinding performance. However, diamond wheel is a super-hard composite material, diamond exhibits significantly different thermophysical properties from the bond. This disparity introduces considerable uncertainties in the laser processing of diamond grinding wheels. In this study, the phenomenon of grain burial was first observed in a nanosecond laser sharpening bronze-bonded diamond wheel. Even with sufficient removal depth of the bronze bond, the diamond grains did not protrude as expected but instead ended up below the bond plane. It caused unstable grinding behavior, increased wheel clogging, and reduced grinding quality. Through detailed analysis of the changes in the wheel's surface morphology, the mechanism of laser sharpening was uncovered and the reason for grain burial was identified. This phenomenon is strongly influenced by the laser power input and the differences in thermophysical properties between diamond and bronze. Further increasing the laser power to 30 W, exceeding the theoretical value, effectively addressed the grain burial issue. At last, the subsequent strategy using a 5 W low-power laser cleaning was also proposed to mitigate the associated thermal effects resulting from high power.