Through metallic mask electrochemical micromachining of micro-groove with a porous cathode

Abstract

This paper proposes a method of electrochemical micromachining through a metallic mask to reduce the undercutting of micro grooves and improve machining localization. In this method, a metallic mask with through-slit was directly placed on the workpiece instead of using the traditional insulated masks. This decreases the undercutting by reducing the electric field intensity at the edge of micro grooves. In addition, a porous cathode with jet flow mode was employed to allow firm contact of the mask with the workpiece so as to enhance the mass transfer in the machining area. Simulated results show that the metallic mask reduces the current density at the edge of micro groove effectively, and so the undercutting of the profile is evidently reduced. Experimental results indicate that for the same depth, the etch factor (EF) for micro grooves reaches 5.6 by using a metallic mask, and the machining localization is improved significantly. The pulse duty cycle has an important effect on the machining localization and with a pulse duty cycle of 20% a micro groove with better machining localization is obtained. Although a metallic mask improves machining localization of micro grooves, however a low current efficiency is observed with this process as compared to traditional electrochemical micromachining.