Parameter Identification of Equivalent Circuit for Pulsed Electrochemical Machining Based on Experimentally Obtained Current Waveforms

Abstract

Pulsed electrochemical machining (PECM) has significant advantages for processing difficult-to-cut metal materials. Since the charge and discharge behavior of the electric double layer (EDL) in PECM greatly influences machining characteristics, an easy-to-use and time-saving method to simulate the ECM phenomenon with equivalent circuit and identify the circuit parameters (such as EDL capacitance and Faradaic resistance) is helpful for understanding the material removal rate and machining accuracy. However, identification of circuit parameters usually requires specialized equipment (such as an electrochemical workstation) to perform impedance measurements, which are cost and time consuming. In this study, an equivalent circuit model of ECM was established, and a simple method was adopted to identify the circuit parameters by analyzing time variation of the voltage and current waveforms between the workpiece and tool. The obtained circuit parameters were applied to the equivalent circuit model in the circuit simulation software, and the simulated current waveforms were compared with the experimentally obtained waveforms to verify the reliability of parameter identification. Furthermore, the established model was applied to ECM with a diode, which was usually inserted to the circuit to suppress the reverse current and reduce the tool wear in PECM. The Faradaic current and capacitive current of the workpiece anode were discussed in the simulated model, which helped understanding the material removal rate and machining accuracy in PECM.