Simulated and measured surface roughness in high-speed grinding of silicon carbide wafers

In this paper, the primary factors affecting surface quality are studied and a theoretical model is developed for surface generation in grinding silicon carbide (SiC). The model takes into account the geometrical kinematics and tool micro-vibration in the grinding operation. The simulated roughness profiles agree reasonably well with experimental results. Spectrum analysis was used to extract three different frequencies from the machined surface topography in the frequency domain: figure error, micro-vibration of the wheel, and workpiece. The wheel synchronous micro-vibration is found to be the dominant mechanism for surface generation. The pattern of vibration marks is found to be dependent on the feed rate and the ratio of the rotational speed of the grinding wheel and the workpiece. In addition, the phase shift denoted in the fractional part of the speed ratio is inevitably induced in the evolution of surface generation in the grinding, which imposes a remarkable effect on surface quality. For a non-integral speed ratio (1500 RPM for the workpiece spindle), the arithmetical mean height of the surface (Sa) is significantly improved to about 0.108 μm. A medium phase shift (about 0.5) can suppress the scallop height so as to achieve a good surface finish (Sa = 0.091 μm). The results provide important means for improving the surface quality in ultra-precision grinding.