Wire electrochemical micromachining of Ni-based metallic glass using bipolar nanosecond pulses

Abstract

The up-and-coming trend of product miniaturization alongwith application of novel materials with extreme properties has created a challenge for machining industry. Newly developed wire electrochemical micromachining (WECMM), as an important nontraditional micromachining technique, has been identified as a promising method for fabrication of microcomponents on a wide range of conductive materials. However, in many cases, the processing performance is typically limited by the properties of tool cathode and the mass transport rate in the interelectrode, which plays a crucial role in further development of this technique. Herein, the use of bipolar nanosecond pulses is innovatively proposed to help reduce the deposition of electrolysis products on the tool electrode and the underlying mechanism is systematically analyzed. Helical carbon nanotube fiber (CNF) was used as a new tool cathode in vibration-assisted WECMM to enhance the mass transport rate. The microshaping characteristics of the proposed method using bipolar nanosecond pulses were then investigated using a Ni-based metallic glass that exhibits typical passivation behavior in dilute acidic electrolytes as a representative example. Compared with traditional unipolar pulses, the use of bipolar pulses could effectively inhibit passive film growth on the machining surface of metallic glasses. In addition, no tool wear occurred for CNF that the original surface morphology became rougher only at excessive negative voltages. Finally, functional microcomponents were successfully fabricated with overall improved processing performance.