A technique of machining micro holes by combining EDM with USM

The purpose of this research is to enhance the machining ability and flexibility of the micro EDM, improve the machining state, and increase the productivity and aspect ratio of the micro holes. Basing on RC pulse power supply and workpiece vibration, the machining experiments of micro holes are carried out by combining micro EDM with USM. The experiment results indicate that with the increase of ultrasonic amplitude, the machining velocity heightens and the aspect ratio of the micro holes augments; at the same time, however, the wear of the electrode and the extensive magnitude of the holes increase. Micro holes of Delta and Y cross-section with accurate profile are drilled steadily. According to the analysis of the machining mechanism, the effects produced by ultrasonic vibration mainly include cavitation, pumping, degassing and entrainment, whereas for the vibration mode of the workpiece, the working liquid flowing is intensified because of the acoustic streaming effect.