An investigation into wire electrochemical micro machining of pure tungsten

• Wire electrochemical micro machining (WEMM) was employed for the micro machining of pure tungsten, and tungsten-based microstructures with high aspect ratio were produced.
• The process for WEMM of pure tungsten with low alkaline electrolyte concentration and small pulse duration was investigated.
• Multi-wire electrochemical micro machining of tungsten was introduced to improve productivity in the machining of multi-slit microstructures.

Tungsten-based microstructures have attracted great interest in many industrial advanced applications. Nevertheless, with a disadvantageous combination of high hardness, toughness and brittleness, the micro machining of pure tungsten poses significant difficulty. In this paper, an investigation into the wire electrochemical micro machining (WEMM) of pure tungsten at low alkaline electrolyte concentration and small pulse duration is presented. Under the optimal machining conditions, tungsten-based microstructures with a side gap of 4 μm, slit width of 18 μm and aspect ratio of 5.6, as well as with a side gap of 5 μm, slit width of 20 μm and aspect ratio of 15, were obtained. In order to improve productivity in the machining of multi-slit microstructures, multi-wire electrochemical micro machining of tungsten was introduced. Using a 3-wire electrode, a 9-slit microstructure with a slit width of approximately 24 μm was produced and the machining efficiency was improved by a factor of three. The results revealed that it was a promising method for the fabrication of tungsten-based periodic or quasi-periodic microstructures, such as the gratings used in the X-ray absorption contrast system of imaging.