Machinability assessment of NiTinol shape memory alloy in electrochemical machining

Abstract

NiTi shape memory alloys (SMAs) attract researchers because of their myriad applications in areas such as aerospace, medicine, and robotics. The current study focuses on the machining (drilling) of high-temperature Ni56Ti44 SMA by electro chemical machining (ECM) process. Machining quality features like rate of material removal (RMR), overcut, taper angle and circularity error are investigated by considering the different electrodes (copper, brass and tungsten) and the current (I), voltage (V) and inter electrode gap (IEG) as controllable parameters. Parametric analysis of machining characteristics is performed by conducting experiments following the response surface methodology (RSM) approach-based Box-Behnken design. A multi-objective optimisation for the desired output responses is also accomplished using the utility method. It was found that better RMR is achieved via the desirability analysis using RSM whereas the utility method led to improved result for the all-other performance measures. The study of the scanning electron microscope (SEM) micrographs revealed that among the three electrodes under consideration, the tungsten electrode is the most suitable for the machining of the present NiTi SMA.