SACE scanning process assisted with ultrasonic vibration on quartz glass

Spark-assisted chemical engraving (SACE) is suitable to machine hard and brittle insulating materials such as quartz glass; however, the processing efficiency is quite low for achieving good machining quality. In this research, a scanning process of ultrasonic vibration-assisted SACE (UV-SACE) is proposed for high-efficiency processing on quartz glass without surface microcracks. For revealing the microscope mechanism under different vibration amplitudes, a high-speed camera is used to observe the motion of micro bubbles, morphology of gas films, and instantaneous discharges. Then through the processing experiments with two-factor coupling effect of feed rate and vibration amplitude, it is found that the cutting depth is significantly affected by feed rate due to the effect of ultrasonic vibration. The optimal input conditions are obtained by using the NSGA-II optimization method. Furthermore, the removal mechanism of UV-SACE scanning process on quartz is analyzed and applied: Lower feed rate (scanning speed) as the fully discharging case can improve the material removal rate (MRR), while higher feed rate as the insufficient discharging case can improve the processing accuracy and surface quality. Machining experiments verified the proposed mechanism and the optimized process.