Minimizing tool marks in deterministic microgrinding

In deterministic microgrinding of glass optics with metal bond diamond ring tools, optical surfaces exhibit residual cutting tool marks that can significantly affect the efficiency of the finish polishing process. The tool marks for spherical surface generation appear as curves that follow contact lines between the tool and workpiece from the center to the edge of the workpiece. The tool marks are circumferentially periodic and the number is typically equal to the k-ratio, i.e. the ratio of grinding tool speed to workpiece speed. This paper describes the effect of the k-ratio, the tool cutting face width, and their interaction on tool mark generation. We introduce a new parameter equal to the ratio of tool cutting face width to the k-ratio spacing. Experimental results indicate that this ratio is the critical factor for tool mark generation. For ratios greater than a critical value, the amplitude of tool marks will be reduced to a level not detectable by interferometry. The influences of vibration and tool roughness are also discussed. The model presented provides new insight into the generation of tool marks and optimization of deterministic microgrinding processes.