Surface Roughness Prediction in Rotary Ultrasonic Machining of Zirconia Dental Ceramic Using RSM

This paper aims to investigate the factors affecting the surface roughness of dental zirconia ceramic when machined with rotary ultrasonic machining. The experiments were conducted using response surface methodology (RSM), and the effect of control variables on the response was determined using Box–Behnken design. The investigated control variables were cutting speed Vc (70, 135 and 200 m/min), feed rate Fz (25, 50 and 75 mm/min), and ultrasonic frequency Us (20, 23.5, and 27 kHz). The results demonstrate that the interaction between the ultrasonic frequency and the feed rate is the most dominant factor that affects the surface roughness. A threedimensional surface graph was used to plot the responses of control variables. The two factors interaction model where developed. A minimum surface roughness of 0.144 µm was achieved with optimum machining parameters include cutting speed 77.45 m/min, feed rate 73.14 mm/min, ultrasonic frequency 20.36 kHz.