Analysis on the Effects of Grinding Wheel Speed on Removal Behavior of Brittle Optical Materials

It is often desired to increase the machining rate while maintaining the desired surface and subsurface integrity during fabricating high-quality optical glass components. This paper proposed a high-speed high-efficiency low-damage grinding technology for machining brittle optical materials, which consists of three grinding processes: rough grinding, semifinishing grinding, and finishing grinding. Grinding characteristics are investigated with respect to grinding forces, specific cutting energy, surface roughness, ground surface quality, subsurface damage, and material removal mechanisms in grinding of fused silica optical glasses with this technology at grinding speeds of up to 150 m/s. These indications are thoroughly discussed by contacting the undeformed chip thickness. The results indicate that the level of these indications is significantly improved with an increase in the wheel speed due to the decrease of the undeformed chip thickness. It is also found that the improvement of ground surface quality is limited when the wheel speed increases from 120 m/s to 150 m/s, which may be due to the influence of vibration caused by the higher wheel speed. For different grinding processes, these results are also substantially improved with the change of grinding conditions. It is found that the material removal mechanism is dominated by brittle fracture at rough and semifinishing grinding processes, while ductile flow mode can be observed at the finishing grinding process. There are some differences between the experimental results and the previous predicted model of subsurface damage depth.