Electrical Assisted Grinding of Precision Glass and Ceramic Parts

Abstract

We are developing better ways of making precision glass and ceramic parts. Two recent parts are subsurface damage free SiN MOR bars and RBSiC aspheric optics. If, in the past, we relied on resinoid bonded super abrasives; our focus now is on metal bonded wheels. Already, our experience demonstrates their promise - much better figured and finished parts, and a hazard. The performance is tied to stringent preparation beforehand and in-process dressing to insure free cutting. We grind using a modified Blanchard; the spindle is tilted off axis by 1 degree. The 4 inch cup wheels run up to 6000 SFM. We found less than 0.2 micrometer total axial runout to be a working requirement. Further, the wheels - without appropriate dressing - quickly clog or load with debris. Free cutting requires continuous dressing.