Multiscale multiphysics simulation of a pulsed electrochemical machining process with oscillating cathode for microstructuring of impact extrusion punches

The pulsed electrochemical machining (PECM) with oscillating cathode is a manufacturing technology which is used for shaping and surface structuring of different workpieces, e.g. impact extrusion punches. The principle behind the ECM-process is the controlled anodic dissolution of the workpiece material without any thermal or mechanical impact and independent from workpiece material hardness. In this study, a new multi-scale approach for the modelling of PECM with oscillating cathode was created integrating the short and long time scale physical phenomena. In the short time scale simulation step (t < 0.02 s) the physical processes (current density distribution, motion of cathode, heat and hydrogen generation) during one single oscillation were analyzed. An averaged dissolution speed at the anode boundary over the small time range was calculated. The averaged values were imported as initial and boundary conditions into the long times scale simulation step (t > 10 s). Within this simulation step, the anodic dissolution was simulated by deforming the geometry. This approach allows simulations for long overall time ranges (t > 1000 s) while considering the short times scale processes in combination with a relatively small computational effort. This multiscale and multiphysics model helps to analyze the differences between front and lateral working gap and supports the process design for the pulsed electrochemical machining with oscillating cathode.