Effect of Flushing on Electrochemical Micromachining of Copper and Inconel 718 Alloy

Electrochemical micromachining (ECMM) is used on conductive materials to make complex features on the workpiece. The application of ECMM process has been limited due to factors such as overcut and taper formation during the machining of microholes. Passivation layer formation is an important issue in ECMM. During electrochemical micromachining process, metal hydroxides are formed at the workpiece–tool interface and get accumulated between the tool and the workpiece which forms a passivation layer. This passivation layer widens the flow of current and affects the accuracy of the machined hole. In this research work, an attempt has been made to improve the circularity of the machined hole by effectively removing the passivation layer formed at the workpiece tool interface using electrolyte flushing technique (EFT). Using EFT, copper and Inconel 718 alloy were machined with brass and copper tool electrodes, respectively. Material removal rate (MRR), circularity and taper angle were considered as primary output response parameters. Various flushing flow rates of electrolyte were taken as input parameters to study the effect of oxide layers formed in and around the tool–workpiece interface. Single-factor experiment optimization techniques were used for the fabrication of microholes. The result clearly shows that the usage of EFT on micromachining removes the passivation layer under different flow rates.