Experimental Study on the Fabrication of 3D Microelectrodes for Electrochemical Micromachining

The use of three-dimensional (3D) microelectrodes to machine micro-cavities in electrochemical micromachining (ECMM) can greatly improve processing efficiency. The 3D microelectrodes that are difficult to fabricate by traditional methods can be prepared by laminated object manufacturing and vacuum thermal diffusion bonding (VTDB). However, the VTDB process is very time-consuming, resulting in a long preparation cycle. To solve this problem, the present study proposed an approach combining wire electrochemical micromachining (WECMM) with micro-electric resistance slip welding to fabricate 3D microelectrodes. The machining surface quality and dimensional accuracy of 2D microstructures under different WECMM conditions were investigated. Moreover, the effects of the welding parameters on the bonding quality were studied. The experimental results show that with a 6 V machining voltage, 1.33 μm/s feed rate, and 30 μm movement amplitude for the wire electrode, the machining gap was approximately 10 μm and the machining surface was flat when using a tungsten wire 8 μm in diameter to machine 30 μm thick #304 stainless steel foils by WECMM. Under a 0.3 V welding voltage, 0.2 MPa welding pressure, 20 ms welding time and 160 times slip welding discharge, the error in 3D microelectrodes in lamination direction was smaller than 3 μm. Based on the proposed approach, two typical 3D microelectrodes were successfully fabricated and subsequently applied in ECMM to machine 3D micro-cavities in nickel plates.