Processing and machining mechanism of ultrasonic vibration-assisted grinding on sapphire

Owing to outstanding mechanical, optical, thermal stability and chemical stability properties, sapphire has widespread use in semiconductors, aerospace and other fields. However, it is difficult to machine it efficiently and precisely because of its brittleness and hardness. In this work, the processing and mechanism of machining sapphire using ultrasonic vibration-assisted grinding technology have been investigated via experiment. The machining factors have been analyzed, including the condition of machined surface, specific grinding energy, force and force ratio. Referring to conventional grinding, the application of ultrasonic vibration reduces the force, force ratio, specific energy, and the reduction ratio is direction dependent. The effect on surface roughness and morphology is also anisotropic. Regarding the smoothness of the surface, the suitable directions were axial and tangential, while there was no noticeable improvement in the radial direction. Our results and insights could be beneficial for the precise machining of brittle materials and quality management.