Micro sinking electro-discharge machining of complex 3D micro-cavity using in-situ milled graphite microform electrode

This paper develops a new combined technology to fabricate complex 3D microstructure based on micro milling and micro sinking electro-discharge machining (micro-SEDM). Graphite microform electrode is in-situ prepared by micro milling and subsequently used for micro-SEDM, integrating the advantages of two processes. Material removal rate (MRR) and electrode wear ratio (EWR) are experimentally investigated to determine proper parameters for different micro-SEDM performances. Three different machining strategies including single, double and treble micro-SEDM are adopted to fabricate 3D microstructure. The surface roughness, size accuracy, machining duration and cost of micro-cavities, and electrode wear under different strategies have been compared. The results show that treble micro-SEDM produces superior surface quality with 0.83 μm Ra and size accuracy with ≤ 28.05 μm tolerance. The proposed method broadens the machining flexibility and capability of micro-fabrication techniques.