Helical Carbon Nanotube Fiber Tool Cathode for Wire Electrochemical Micromachining

Abstract

Helical carbon nanotube fibers (CNFs), proposed as lightweight, high-strength, electrically conducting cables, have potential as tool cathodes in wire electrochemical micromachining (WECMM). WECMM has increasingly become recognized as a versatile technique for producing planar contour micro-features, and holds great advantages for micro-shaping of difficult-to-machine materials. However, the processing performance is affected by the mass transport rate in the narrow inter-electrode gap. Therefore, a helical CNF with superior hydrophilicity and high tensile strength is proposed as a new tool cathode for WECMM. Moreover, the electroplating technique is proposed as a means to improve the electrical conductivity of the CNF electrode. The synthesis of a Cu-CNF electrode had a two orders of magnitude enhanced electrical conductivity of about 2.0 × 107 S/m and a tensile strength of about 1350 MPa. An overall improvement of processing performance for WECMM was achieved. The machining accuracy in terms of slit width and its standard deviation were 38.8 μm and 0.2 μm, respectively. The surface average roughness of side wall was 0.022 μm. Finally, the five-layered micro tenon structures on Ni-based metallic glass were fabricated successfully by using three helical CNF electrodes simultaneously. The total machining efficiency in terms of feed rate attained 9.0 μm/s.