Surface Grinding of Optical BK7/K9 Glass Using Rotary Ultrasonic Machining: An Experimental Study

BK7/K9 glass is regarded as a difficult-to-machine material due to its high hardness and high brittleness properties as well as high tool wear rate during machining. Facing to these challenges, an efficient and effective rotary ultrasonic machining (RUM) process, consisting of grinding process and ultrasonic machining process, was provided to process BK7/K9 glass. In this investigation, the effects of ultrasonic power on cutting forces, torque, and edge chipping of surface grinding in RUM of BK7/K9 glass were studied. Results showed that, by introducing ultrasonic vibration to surface grinding process, both cutting forces in feeding direction and in axial direction as well as torque values were reduced. The higher the ultrasonic power was, the lower the forces and torque values would be. Edge chipping, which was detrimental to the qualities of machined slots and would cause high machining cost, was significant reduced with the help of ultrasonic vibration.