Fabrication of tungsten micro-rods by ECM using ultra-short-pulse bipolar current

This paper describes tungsten micro-rod machining using a neutral electrolyte and ultra-short-pulse bipolar current supplied by the electrostatic induction feeding method. The tungsten oxide layer can be removed by NaOH generated when the polarity of tungsten electrode is negative. The machining accuracy improves with higher electrolyte concentration, and there is less tool wear when platinum tool electrode is used. A micro-rod with a diameter of 7.1 μm and aspect ratio of 14 was fabricated successfully. The machinable minimum diameter was equivalent to that obtained by EDM. Furthermore, the current waveform could be optimized to increase the material removal rate.