Electrical discharge drilling assisted with bubbles produced by electrochemical reaction

In EDM drilling, the accumulation of debris is the main factor leading to abnormal discharges and process instability, which prevent the processing of microholes with a high aspect ratio. To fabricate microholes with an ultrahigh aspect ratio, bubbles produced by an electrochemical reaction were applied to assist electrical discharge machining (B-EDM) in tungsten materials. The mechanism and machining performances of the B-EDM method were investigated. The results showed that bubbles produced by electrochemical reaction on both the surface of the electrode and the workpiece prevented the accumulation of debris at the bottom of the hole, which improved machining stability. This process is effective in enhancing drilling performance in deep microholes by improving such parameters as the material removal rate, electrode tool wear, longitudinal section topography, and achieved aspect ratio. Experimental results showed that the processing time and electrode wear of B-EDM were approximately one third those of EDM in the processing of 20 mm through-holes. A hole with a diameter of 0.22 mm and depth of 120 mm was successfully fabricated by B-EDM on tungsten within 130 min.