Abstract: Numerically controlled electron discharge machining (NC-EDM) for precision work is the final process of the combined electrical machining technology for 3D closed impellers, and it has a crucial effect on the integral precision of the machining work. Such key techniques as the design of the electrodes and their tracks, the fixtures of the cathodes and the impeller are discussed. A series of technological experiments are made and a qualified 3D-flow closed impeller is machined successfully. The results show that high production efficiency can be obtained by numerically controlled electrochemical machining (NC-ECM) for pre-processing, while the precision and reliability of the machining of a complex integral component can be ensured by NC-EDM for precision work. To sum up, a 3D-flow closed impeller can be machined efficiently, precisely, reliably and integrally with this method.

Key words: 3D-flow, closed impeller, numerical control, electrical discharge machining, electrode design