Study on the micro through holes machining using the electrochemical machining (ECM) method with a graphite electrode

Electrochemical machining is widely used in biomedical, aerospace, automotive, and other fields. The development of electrochemical machining (ECM) is restricted by many factors such as the difficulty of preparing micro-electrode, large machined gap and serious stray corrosion. In this paper, we present a method to fabricate micro-holes by combining micro-graphite electrode with hollow structure. Firstly, a sealed graphite electrode was proposed to guarantee that the sediment can be fully removed by the flowing electrolyte. Then, the effect of machined parameters such as the pulse frequency, machined voltage, electrode feeding speed, and electrolyte concentration on machining quality was studied. By optimizing the machined parameters, the minimum value of micro-hole taper with 0.07 could be obtained. To improve the shape precision of workpiece, this paper designed the hollow structure inside the electrode. With the increasing of the pulse frequency, the machining accuracy of micro-holes increased. The results suggested that the pulse frequency of 100 kHz, the machined voltage of 18 V, the feeding speed of 1 mu m/s, and electrolyte concentration of 5% were more suitable for micro-holes machining with ECM.