End Surface Grinding Machinability of Zirconia Ceramics via Longitudinal–Torsional Coupled Vibration Rotary Ultrasonic Machining

Zirconia (ZrO₂) ceramics are advanced structural materials that exhibit exceptional performance in aerospace and other heavy-duty applications. Since conventional machining of ZrO₂ ceramics presents significant challenges, this study employs the longitudinal-torsional coupled rotary ultrasonic machining (LTC-RUM) method for end surface grinding of ZrO₂ ceramics. To elucidate the material removal mechanism of LTC-RUM, an analysis was conducted from the perspective of individual abrasive grains. Subsequently, LTC-RUM experiments were carried out on ZrO₂ ceramic samples to investigate the effects of processing parameters on cutting force, surface roughness, and surface morphology. The results show that cutting force decreases with lower spindle speed and ultrasonic power, but increases with higher feed rate and cutting depth. The surface roughness decreases with increasing spindle speed, yet increases with feed rate. Moreover, the surface roughness initially decreases and then increases with increasing ultrasonic power and cutting depth. Compared to conventional machining methods, LTC-RUM significantly reduces cutting force and surface roughness, thereby improving workpiece surface quality. This study provides valuable insights into the application of LTC-RUM for machining ZrO₂ ceramics and other hard and brittle materials.