Study on Thermal Stress Removal Mechanisms of Hard and Brittle Materials During Ultrasonic Vibration Assisted EDM in Gas

The principle of Ultrasonic vibration assisted electrical discharge machining in gas medium (UEDM in gas) was proposed in this work and experimental equipment was designed. Hard and brittle materials such as cemented carbide and sintered Nd-Fe-B magnetic materials were machined using the experimental equipment of UEDM in gas. The thermal stress removal mechanisms of hard and brittle materials machined by UEDM in gas medium were discussed in detail. The process of thermal stress removal during UEDM in gas can be divided four steps, which are the formation of thermal stress, the formation of micro cracks, grain breaks and particles strips.