Efficiency Improvement of Electrochemical Discharge Machining by a Magnetic Field-assisted Approach

Electrochemical discharge machining (ECDM) is an effective spark-based machining method for the low-cost machining of microholes and microchannels in non-conducting materials, such as glass, quartz and some ceramics. However, since the spark discharge performance becomes unpredictable as the machining depth increases, ECDM drilling is hard to achieve precision geometry and efficient machining rate. One of the mainly factors for this is the difficulty of sustaining an adequate electrolyte flow in the narrow gap between the tool and the workpiece. Since electrolysis is conducted with a magnetic field, Lorenz force induces a magneto hydrodynamic (MHD) convection. As in ECDM process, the surface of electrolysis bubbles would suffuse charged ions. The Lorenz force induces a movement of charged ions and further pushes the electrolysis bubble moving toward the magnetic field direction. This effect of mechanism, which is in place of a mechanical disturbance, can stir an electrolyte even in a narrow gap when in higher machining depth. In this study, MHD convection was induced to enhance electrolyte circulation in the microhole and prevent deterioration of gas film quality; and so as to enhance the machining accuracy and efficiency by aid of a magnetic field during ECDM. The improvement in machining accuracy thus achieved was 23. 8% while that in efficiency reached 57. 4%.