Analysis of the roundness error elimination in counter-rotating electrochemical machining

Roundness error plays an important role in numerous science and engineering fields, and it seriously affects the surface machining accuracy of revolving parts. Counter-rotating electrochemical machining (CRECM) has huge advantages in eliminating the roundness error of the blank, especially for thin-walled casings. In this study, a simulation model is established using the finite element method to analyze the mechanism of the elimination of roundness errors during CRECM. The rotation and feed motion of the electrodes are realized by kinematic equations, and the characteristics of material removal on the workpiece surface are explained. The simulation results show that due to the uneven surface of the revolving part, the current density presents a varying distribution, and the electric field is concentrated at raised points. The material removal rate at raised points is thus much greater than that at sunken points, and the raised points require more power during the material removal process. By optimizing the simulation parameters, the minimal interelectrode gap can be maintained substantially constant. The reliability of the simulation methodology is verified by experiments. The machined thin walled parts are found to have good consistency of wall thickness, and an error is only around 0.028 mm.