Investigation of electrochemical micromachining of tungsten microtools

Tungsten tools are used in various advanced manufacturing industries owing to their excellent physical and mechanical properties. However, the material characteristics of tungsten, such as its hardness and brittleness, make it difficult to fabricate tungsten microtools using mechanical methods. Electrochemical micromachining (ECMM) is a potential method for machining tungsten microstructures, because the process is independent of the material physical and mechanical properties. In this paper, an investigation into ECMM of tungsten microtools using a rotary helical electrode is presented. The optimal process conditions, including electrolyte concentration, duty ratio, and frequency of pulsed voltage, are determined experimentally. A quantitative relation between the machining side gap and the applied voltage and electrode feed rate, which can be controlled online during the machining process, is calculated from the experimental results. A contour map is drawn to aid in selecting the optimum process parameters to achieve a specific slit width. Finally, a tungsten array microtool with variable cross-section is fabricated by adjusting the applied voltage online.