Study of electrochemical discharge machining technology for slicing non-conductive brittle materials

The electrochemical discharge machining (ECDM) has been proved to be a potential process for the machining of high-strength non-conductive materials. Traveling wire electrochemical discharge machining (TW-ECDM), a newly developed technology, is used to slice the small size (10-30 mm diameter) optical glass and quartz bars. The electrical-thermal etching effect and its feasibility are investigated. The energy release intensities and their physical phenomena under different sizes of discharge wires, power source modulations and methods of electrolyte supply are discussed. The pulsed dc power proves better spark stability and more spark energy release proportion than constant dc power. The input power is modulated to obtain the appropriate frequencies and duty factors for machining glass and quartz materials. The ion translation rate, the electrolyte immersing depth and the concentration of the alkali are found to be the dominant factors of bubbles reaction. Based on the SEM photographs of the workpiece surface, it is noted that the more purple the sparks from the mixed gases of hydrogen and vapor, the better the etching effect is. The V-shape defect occurring at the cut-in and cut-out can be significantly reduced by rotating the workpiece. Finally the appropriate cutting conditions for the quartz and borosilicate optical glass materials are concluded. (C) 2004 Elsevier B.V. All rights reserved.