Investigation of grinding modes in horizontal surface grinding of optical glass BK7

Grinding is one of the most important processes to manufacture hard-brittle materials such as optical glass. It is often desired to increase the material removal rate while maintaining the desired surface quality. The success of this approach relies on the better understanding of the relationship between the grinding modes and the characteristics of surface and subsurface integrities. Based on the kinematic analysis of horizontal surface grinding as well as the features of grinding-induced cracks, four grinding modes were proposed. They are brittle mode, semi-brittle mode, semi-ductile mode and ductile mode. The horizontal surface grinding of optical glass BK7 has been studied using diamond grinding wheel. The four different grinding modes have been investigated with the characteristics of surface morphologies before and after etching, surface roughness, subsurface damages as well as indentation depth. It was found that the level of surface roughness and depth of subsurface damage were strongly dependent on grinding mode. This study provides valuable insights into the material removal mechanism and the dependence of surface and subsurface integrities on grinding mode.