Pulsed power supply for electrochemical machining

In this work, the design, construction and experimental validation of a pulsed power supply are presented. The power supply is based on a high frequency half-bridge topology, specifically designed to be applied in an electrochemical machining process. With the aim to overcome the overcut effect, an experimental procedure was performed on high strength low alloy steel samples, which were drilled with a hollow electrode and NaCl as electrolyte. The tests were conducted with direct current as well as pulse signal with frequencies of 20 and 100 kHz. Results show that biasing the electrode with direct current produces an overcut effect in the drilling of the material; however when a high frequency square signal is applied to the electrode by means the proposed pulsed supply, the overcut effect is noticeably reduced. Moreover, when the electrode is coated with an insulating epoxy resin, the overcut effect is further reduced.