A 3-DOF Controlled, High-Speed, High-Precision Local Actuator for Micro Electrical Discharge Machining

Abstract

In conventional Electrical Discharge Machining (EDM), the speed and accuracy are limited by probability and efficiency of the electrical discharges. To improve the machining speed and accuracy, we developed a high-speed, high-precision, 3-DOF controlled local actuator. For the actuator, a voice coil motor type of magnetic bearing having a positioning stroke of a few millimeters is used to control the motion of an electrode in the thrust direction in order to speedily maintain a suitable distance from the workpiece. Moreover, two piezoelectric devices having high response speed and high precision are used to achieve the vibration of the electrode in the radial directions to immediately remove the debris between the electrode and the workpiece. The positioning performance of the actuator was evaluated through experiments, and the experimental results show that the actuator possesses a positioning resolution of the order of micrometer, a bandwidth greater than 120Hz and a positioning stroke of 2mm.