PLASTIC-FLOW IN ROTARY ULTRASONIC MACHINING OF CERAMICS

Since rotary ultrasonic machining (RUM) appeared some 30 years ago, many experimental studies have been conducted to explore the relations between control variables (such as ultrasonic vibration amplitude, applied static pressure, rotational speed, diamond type, grit size and bond type, etc.) and process outputs (such as material removal rate, tool wear, etc.). However, few investigations into material removal mechanisms of RUM have been published. The material removal in RUM process has been mainly attributed to brittle fracture. In this paper, experimental evidence is presented to show that plastic flow can also be one of the material removal modes in RUM in addition to brittle fracture. To explain the experimental evidence, related work is reviewed and some theoretical analysis is provided