Material removal mechanism and grinding force modelling of ultrasonic vibration assisted grinding for SiC ceramics

In this paper, a varied-depth nano-scratch test of single grain is carried out on a nano indentation system. The critical depth of the elastic-plastic transition for SiC ceramics is 7.27 nm, as calculated by Hertz contact theory, and the critical depth of the brittle-to-ductile transition is 76.304 nm, as measured by AFM and SEM. Based on the varied-depth nano scratch test and the grain trajectory of ultrasonic vibration assisted grinding (UVAG), a theoretical model of the normal grinding force is acquired using the material removal in unit time as a bridge. The single factor experiment illustrates that the grinding force increases with the increase of the grinding depth, feed rate, and amplitude, while it decreases with the increase of the spindle speed. The contrast experiment results show that UVAG is beneficial for improving the surface quality and reducing the subsurface damage depth compared with common grinding (CG). A four-level and four-factor orthogonal experiment is designed, on the basis of which theoretical model of the normal grinding force for SiC ceramics is obtained using genetic algorithm. The tangential grinding force is obtained from the normal grinding force using the least square method. The experimental results show that the theoretical model is reliable.