Abstract: In order to solve the difficult problem of how to machine a complex curved cavity of a difficult-to-cut material in a 3D-flow closed impeller, a new process of combined electrical machining and digitized manufacturing technology is put forward, which is a combination of numerically controlled electrochemical machining (NC-ECM) and numerically controlled electrical discharge machining (NC-EDM). Its overall scheme design and key technology are discussed in this article, including the overall process design, the design of cathodes and their tracks in pre-processing by NC-ECM, the design of electrodes and their tracks in precision work by NC-EDM, fixtures design, and the technological parameter selection and optimization. A 3D-flow closed impeller is machined successfully by this method, and the test results show that the combined electrical machining is useful in the production of 3D-flow closed impellers.

Key words: 3D-flow, closed impeller, combined electrical machining, numerical control systems, electrochemical machining, electrical discharge machining