Influence of the Pulse Width on the Lateral Gap in Pulsed Electrochemical Machining

Abstract Pulsed electrochemical machining (PECM) is often applied for the machining of complex shapes in difficult to cut materials. The anodic metal dissolution mechanism results in complex interactions between the workpiece material, the process parameters and the design of the removal device. The final shape of the workpiece in various applications is defined by the shape of the cathode and the resulting lateral gap. However, the influence of pulse width on the formation of the lateral gap and the resulting shape accuracy has not yet been sufficiently quantified. First, the material removal characteristics of AISI 304 were characterized for pulse widths between 1 ms and 4 ms. Subsequently, systematic PECM experiments with a cylindrical cathode were conducted to determine the resulting lateral gap, frontal gap, shape accuracy, equilibrium current, and transferred charge. A slight decrease in lateral gap was observed with decreasing pulse width, whereas no significant influence on frontal gap or shape accuracy was found. The voltage and the current density in the frontal gap were identified as the dominant factors regarding the formation of the lateral gap. The effects were found to scale approximately linearly with the pulse width. In addition, a previously developed analytical model for predicting the lateral gap was applied and validated for all investigated pulse widths. The results provide new insight into the effects of the pulse-width and support a model-based design of PECM processes.