Surface Grinding of ZTA Parts Fabricated by Laser Engineered Net Shaping Process: Effects of ZrO₂ Content and Ultrasonic Vibration

The zirconia toughened alumina (ZTA) parts fabricated by laser engineered net shaping (LENS) process demonstrate problems resulted from poor surface quality. To improve surface quality and to reduce related problems, rotary ultrasonic machining (RUM) process, which combines both grinding process and ultrasonic machining process, has been introduced. In this investigation, the effects of ZrO₂ content and ultrasonic vibration on flatness, surface roughness, microhardness, and cutting force in feeding direction of LENS-fabricated ZTA parts have been studied. Results showed that with the ZrO₂ content increasing, the flatness value increased, the surface roughness value decreased, and the microhardness value firstly increased then decreased. Compared with LENS-fabricated parts, the parts processed by RUM machine exhibited better surface quality with significantly reduced flatness value and surface roughness value. In RUM process, the introduction of ultrasonic vibration was beneficial for reducing cutting force.