Research on Surface Formation Mechanism in Elliptical Ultrasonic Assisted Grinding (EUAG) of Monocrystal Sapphire Using Structure Function Fractal Method

Abstract

This study investigates surface formation characteristics in elliptical ultrasonic assisted grinding (EUAG) of monocrystal sapphire using structure function fractal method. During the EUAG process, the workpiece is imposed to ultrasonically vibrate in two directions, i.e., vertical and parallel to work-surface, by using an elliptical ultrasonic vibrator. To clarify the work-surface formation characteristics in EUAG of sapphire material, grinding experiments are carried out involving sapphire substrate. In experiments, work-surface roughness is measured, and the ground work-surface morphology is examined by scanning electron microscope (SEM) and its fractal dimension was calculated by structure function method. The fractal dimension of ground surface in EUAG is bigger than that in conventional grinding (CG), meaning that the ground surface in EUAG is more exquisite and better than that in CG. Therefore, the fractal analysis method has the potential to reveal the ground surface characteristics in EUAG of monocrystal sapphire.