Influence of energy input parameters on wire feed rate and surface characteristics during WECM of Nitinol SMA

Abstract

Nitinol shape memory alloy (SMA) has outstanding chemical and mechanical properties which make the machining of Nitinol SMA more difficult than other materials due to super-elasticity and multiphase transformation. Wire electrochemical machining (WECM) is a nontraditional process, which removes conductive material through anodic dissolution despite of material’s properties. In this paper, the mathematical model is presented for slit width calculation for the influence of different parameters using vibration-assisted nozzle jet flushing. In this experimental investigation, the effect of prominent energy input parameters on wire feed rate to achieve better homogeneity, machining accuracy, and surface quality with a 300 µm thick sheet of Nitinol SMA micro-slits has been presented using an in-house developed WECM set-up. Experimental results revealed that the wire feed rate and surface roughness drastically increases with an increase in the most influencing energy input parameter, that is, pulse voltage with minimum average surface roughness (Ra) of 0.1076 µm and 123.60 µm average slit width at 7 V pulse voltage. Finally, the curved complex micro-feature of a 120 µm thick sheet of Nitinol SMA was fabricated successfully with a 137.795 µm average slit width under the controlled process parameter combination using WECM.