Diamond wear in high speed grinding of silicon nitride

Diamond wear of single layer electroplated wheels was investigated in high speed grinding of silicon nitride. Grinding experiments were conducted at wheel speeds of 85 m/s and 149 m/s with the same material removal rate. Microscopic observations of the wheel surface revealed wear flats on the active grains that were mainly developed and increased by attrious wear. This attrious wear has been found to lead to an increase in grinding forces and energy and thereby to shorten the useful wheel life. A statistical model previously developed to characterize the change in wheel topography during grinding in terms of active cutting grains was used to estimate an average wear volume of a single active grain for a given sliding distance. The normal force per active grain calculated from the measured normal grinding force was found to proportionally increase with the corresponding sliding distance. Using the above relationships for wear volume of single grain and normal force per grain, the wear coefficient, K, was obtained. The K at the high wheel speed of 149 m/s decreases From about 10(-2) where high initial run-in wear occurs down to 10(-7) at near the end of the useful wheel life, and is somewhat larger than that obtained at the lower wheel speed of 85 m/s.