Material removal mechanism in ultrasonic vibration assisted polishing of micro cylindrical surface on SiC

Abstract

In consideration of the high hardness of the mold insert material SiC, ultrasonic vibration was introduced in the abrasive polishing (AP) of the linear micro cylindrical surface aiming to enhance the surface quality while improving the machining efficiency. However, the interaction behavior in between the material and polishing tool under ultrasonic vibration has not been studied so far. In this paper, the material removal mechanism of ultrasonic vibration assisted polishing (UVAP) on micro cylindrical SiC surface was investigated to fulfill a fundamental understanding of this process in comparison to the conventional polishing without employing ultrasonic vibration. The collection method of high frequency friction forces was firstly proposed to analyze the friction behavior on the SiC cylindrical surface. Then the relationship between ultrasonic vibration, friction force and micro cylindrical surface quality was studied respectively. The experimental results indicated that when the ultrasonic vibration was applied, the friction force decreased accordingly corresponding to a better surface quality. In addition, the lubrication condition was discussed in UVAP process based on the establishment of the stribeck curve. Furthermore, the wear coefficients were calculated through measuring the material removal depth, the surface morphologies were measured by a scanning electron microscopy in revealing the different material removal modes under various different polishing parameters. Through computation and analysis, it shows that the lower polishing force and relative lower speed as well as the higher vibration frequency and amplitude could result in a lower surface roughness and less polishing marks of micro cylindrical surface on SiC. Finally, the cylindrical arrays were successfully polished with the optimized parameters on precision diamond ground SiC surfaces.