Surface formation characteristics in elliptical ultrasonic assisted grinding of monocrystal silicon

The characteristics of surface formation in elliptical ultrasonic assisted grinding (EUAG) of monocrystal silicon were investigated by grinding and single abrasive scratching experiments. In grinding experiments, an elliptical ultrasonic vibrator, on which a thin sheet shaped monocrystal silicon substrate was attached, was installed on a CNC surface grinder equipped with a diamond grinding wheel. By contrast, the vibrator attached with the substrate was set up on a multi-axis CNC controlled machining centre equipped with a single diamond tool to perform the scratching tests. The obtained results show that the grinding forces are reduced by 30%, the surface quality is improved significantly and the surface roughness is decreased by around 25% during EUAG compared with those in conventional grinding without ultrasonic vibration. There is a transition of material removal mode from the permanent contact to the unsuccessive contact between workpiece and abrasive by increasing the ratio of ultrasonic vibration amplitude to the depth of cut.