Wear and self-sharpening of vitrified bond diamond wheels during sapphire grinding

Abstract

Vitrified bond diamond wheels were tested during grinding of single crystal sapphire on a precision CNC grinding platform. Self-sharpening, evidenced by the occurrence of cyclic behavior in the machine deflection (grinding force), was observed for wheels made with one bond/diamond composition. These wheels could remove large volumes of sapphire without re-dressing. The self-sharpening effect was reproducible but showed considerable variability in terms of the detailed cycle shape. Wheel failure eventually occurred due to a loss of the self-sharpening action (overloading) or stall-out of the spindle. Process conditions producing increased wheel wear enhanced the self-sharpening action.