An electrochemical discharge drilling method of small deep holes

This paper presents a hybrid electrochemical discharge drilling method in which a metal tube is used as cathode tool and workpiece is used as anode. Liquid with weak conductivity flows at high speed between the metal tube and workpiece. Electrical discharge takes place mainly at the frontal gap, and electrochemical process takes place at both the frontal gap and side gap. The recast layer generated by electrical discharge at the side gap can be removed electrochemically. The machining phenomenon at the gap was observed through a designed transparent clamping fixture, voltage and current waveforms during machining were recorded, and the machining products and removal effect of recast layer were analyzed. The cross section of the hole and machining surface were analyzed, and the tool wear and machining efficiency were compared with those of other processes. Finally, the 4-mm-deep hole of 0.5-mm diameter can be produced with low tool wear and almost no recast layer.