Micro Machining by Wire-Preposed Jet Electrochemical Machining

Abstract

Jet Electrochemical Machining (Jet-ECM) is a manufacturing technology which is based upon anodic dissolution. This method enables a fast production of complex micro structures and therefore it has been widely used in many fields such as aerospace, medicine and electronic. However, there are also some drawbacks needing further improvement. The problem is that with the increase of the machining depth, the current density will gradually decrease, the material removal rate will decrease as well. Moreover, the lateral size of the feature will slowly increase with the increase of time. Therefore, there is a limitation for high aspect ratio structure machining in Jet-ECM. In addition, the current density distribution of the electrolyte jet flow is not concentrated enough, which also affects the shape accuracy. Hence, a wire-preposed Jet-ECM (WPJet-ECM) method is proposed, in which a wire electrode is put in the high-speed jet and passes through the nozzle. The electrode can feed into the structure to follow the dissolution of workpiece so that a high aspect ratio will be ensured. The current density is confined to the end face of the electrode to improve the shape accuracy by insulating the side wall of the electrode. An electric field simulation model is established to simulate the distribution of current density. The simulation results indicate that wire-preposed method can concentrate the current density effectively. Concave processing experiments by wire-preposed method are also performed to verify the effectiveness. The nozzle is kept feeding downward at a constant speed. The results demonstrate that the diameter of the concave is decreased and the depth is increased compared with the condition in which the nozzle stays still. Furthermore, the inner surface quality and edge quality of the concave are also significantly improved.