Wire electrode insulation method for stray current and overcut reduction during WECM—a novel approach

Wire electrochemical machining (WECM) is a transport-limited dissolving process. The application of various wire electrode coating and insulation methods and the effect of various prominent parameters for reduction of stray current attack and overcut play a more important role in the enhancement of machining accuracy, homogeneity, and surface quality during the fabrication of microfeatures. Therefore, the characteristics of the stray-current attack in WECM were identified through simulation for electrolyte potential, and current density distribution at narrow IEG in the machining zone and overcut model is presented in this paper. Also, the use of synthetic enamel and novel PTFE (polytetrafluoroethylene) tube insulation method was used to reduce the stray current effect and overcut during WECM, and a comparative study has been made with uncoated wire. The stray-current attack and overcut have been greatly reduced by the proposed insulating methods under different parametric conditions. The PTFE pipe tube wire insulation method is proved to be the most prominent method with no stray current attack on fabricated microslits. Also, overcut is reduced to a large extent which is below 5 µm, and a microslit of 100.61 µm average slit width has been fabricated using PTFE tube insulation method with 180° exposed wire angle and 100 µm insulation distance from workpiece upper surface at 40 µm initial interelectrode gap. Further, NiTinol shape memory alloy microslit array was fabricated and analyzed based on SEM and EDX analysis for understanding the effect of PTFE tube wire insulation method during WECM.