Analysis of material removal and surface generation mechanism of ultrasonic vibration–assisted EDM

Ultrasonic vibration–assisted EDM (UEDM) has excellent performance on difficult-to-machine materials processing such as titanium alloy, stellite, and nickel-based alloy, and it was hard to describe the material removal process and surface generation mechanism due to the complex physiochemical reactions during UEDM. In the present study, the material removal mechanism is fundamentally studied based on heat transfer theory. The model of microscopic removal volume of single pulse in UEDM is established according to the characteristics of EDM removal mechanism and the interference of ultrasonic vibration energy. The micro-surface topography generating process is described and the influence of ultrasonic vibration on the machined surface is analyzed. Both simulation calculation and experiment validation are executed in order to verify the accuracy of the theoretical derivation. As the experimental results have shown, the surface-generating process is matching well with the theoretical deduction; the carbon deposit area is reduced and the surface roughness is decreased due to the ultrasonic vibration interference. The machined surface quality can be modified by adjusting the matching performance of ultrasonic vibration energy and EDM energy.