Microchannel fabrication on bio-grade Nitinol SMA by μ-ED milling process using sustainable oil for improving the machining performance and biocompatibility

The process of micromachining has garnered attention for its ability to create three-dimensional tiny features, particularly in ultra-hard and exotic materials. The present work investigates the effect of different parameters of the µ-ED milling, such as pulse on time (Ton), pulse off time (Toff), voltage (V), and tool rotation (TR) on the dimensional deviation (DD), material removal rate (MRR), surface roughness (Ra), and machined surface characteristics (analysed by EDS and FESEM). The sesame oil as dielectric and tungsten-copper as tool electrodes were used to maintain the accuracy and improve the machinability of bio-grade Nitinol SMA. Response surface methodology (RSM) and genetic algorithms (GA) were used to optimize the various input parameters of the µ-ED milling process. Artificial neural network (ANN) was combined with GA to find the best parametric combination for microchannel fabrication. The cytotoxicity test was also performed on the machined surface to analyse the biocompatibility of the machined surface. It was found that the cell viability of Nitinol SMA was improved by 85.11% after machining at the optimum condition. The highest MRR was found to be 0.076 gm/min, and the lowest DD and Ra were found to be 16.47 µm and Ra 0.387µm, respectively.