Flow Analysis and Experimental Investigation on Micro Electrochemical Drilling of Deep Micro-Holes

Background: Deep micro-holes are important structures which are widely used in many engineering fields. However, deep micro-holes machining, especially on difficult-to-cut materials, has always been a problem. The Electrochemical Micro Machining (EMM) process is a good selection for the fabrication of deep micro-holes on difficult-to-cut materials, and various relevant patents and scientific papers have been discussed. Objective: In order to realize the fabrication of deep micro-holes, an electrochemical drilling process with high-efficiency is introduced. Method: Firstly, a numerical simulation of the gap flow field is carried out. Simulation results show that with the increase of the electrode rotating speed, the gas film, which has a good insulation effect around the electrode increases rapidly, thereby eliminating the taper and improving the machining localization significantly. At the same time, the enhanced mass transfer is performed well, which can improve the machining efficiency significantly. Secondly, the influences of some predominant parameters such as rotating speed, feed rate, applied voltage and pulse frequency on machining localization were analyzed. Results: Finally, a row of deep micro-holes with no taper, which have a diameter of less than 400μm, an aspect ratio of more than 10, are fabricated successfully on the nickel-based superalloy. Conclusion: It is proved that the use of the micro electrochemical drilling process with a high-speed spiral electrode for fabricating deep micro-holes has considerable potential and broad application prospects.