Research on counter-rotating electrochemical machining of convex structures with different heights

Counter-rotating electrochemical machining (CRECM) is an alternative method for the manufacture of aero-engine casing parts with complex convex structures. In previous studies, the revolving part with hollow windows was used as the cathode tool. However, only convex structures with the same height could be machined. In practice, there are usually differences in height between different convex structures on the surface of most casing parts. To machine convex structures of different heights by using CRECM, a specific cathode with concave cavities has been designed. The bottom surfaces of concave cavities are conductive, and the depths of concave cavities are changed according to the height of convex structures. The material of the workpiece in this study is Inconel 718. Forming processes of convex structures with the cathode are simulated by using the finite element method. Results show that during the processing, the top surface of the convex structure is gradually changed from stray corrosion at low current density to normal dissolution at high current density. The height of the convex structure increases and then approximately keeps constant with increasing amount of feed, and it also can be controlled by changing the depth of the concave cavity. Finally, convex structures of different heights on the cylindrical workpiece are machined experimentally, verifying the feasibility of the method.