Cathode optimization and multi-physics simulation of pulse electrochemical machining for small inner-walled ring grooves

The small inner-walled ring grooves of the injector nozzles of hard-to-cut metallic materials are difficult to machine in aerospace and aviation field. Nowadays, electrical discharge machining (EDM) technology is often employed to machine this kind of structures. However, a time-consuming process of removing the metamorphic layer is needed after EDM process for some important workpieces. To solve this problem, electrochemical machining (ECM) technology for the inner-walled ring grooves of 1J116 corrosion-resistant material is studied. First, four basic tool cathode structures are designed with equal-clearance method and flow field simulations are performed with k-ε turbulence model to optimize their structures to ensure flow field uniformity and machining stability. Simulation results show that the uniformity of flow field distribution and machining stability of structure IV cathode are the best among the four types of cathode structures. Then, electric field characteristics in different machining states between the structure IV cathode and the workpiece are analyzed with multi-physics simulation based on the flow field analysis. Simulation results show that current density can meet the machining requirements of the inner-walled ring grooves of the injector nozzles when voltages vary from 12 to 18 V. Finally, a verification experiment is conducted with the optimized tool cathode and machining parameters. The experimental results show that good machining quality is achieved at voltage of 14 V with structure IV cathode.