A 5-DOF controlled maglev local actuator and its application to electrical discharge machining

This paper describes a wide-bandwidth, high-precision, millimeter-stroke maglev local actuator controllable in five degrees of freedom (5-DOF), which is used to maintain a suitable distance between the electrode and the workpiece in electrical discharge machining (EDM). The actuator is sufficiently compact to be attached to conventional electrical discharge machines. It possesses a submicron and micro-radian positioning resolution, bandwidths greater than 100 Hz in the 5-DOF directions, and a positioning stroke of 2 mm in the thrust direction. The maglev local actuator can be levitated stably and positioned precisely, even under electrical discharge conditions generating electrical noise. Using this actuator, multi directional holes can be micromachined. The machining speed and electrical discharge stability are improved compared with conventional EDM. Moreover, by a planetary motion of the electrode, the diameter of the machined hole can be regulated.