Study on the effects of ultrasonic vibration-assisted wire-EDM machining parameters on material removal rate and surface roughness of NiTiV shape memory alloy

Nickel-titanium (NiTi)-based shape memory alloys (SMAs) exhibit remarkable properties, making them increasingly demanding in various engineering and medical applications especially when these SMAs are manufactured with intricate shapes and sizes. This present study examines the machining of Ni₅₀Ti₄₈V₂ SMA using ultrasonic-assisted WEDM with input parameters of pulse ON time (T_ON), pulse OFF time (T_OFF), peek current (I), and servo voltage (SV) along with 20 kHz constant ultrasonic vibration on the responses of material removal rate (MRR) and surface roughness (Ra). RSM-BBD response surface methodology was used to conduct the experiments. It was inferred from analysis of variance (ANOVA) analysis, that as the peak current (I) and pulse ON time (T_ON) increased, the MRR increased by 65.76% and Ra decreased by 54.44%. The confirmation was carried out in USV-WEDM under optimal conditions, which shows that both the predicted and actual MRR and Ra are close to each other. When compared with conventional WEDM, the USV-WEDM shows significant improvement in MRR by 8.6% and also improved surface quality by 6.3%. The surface characteristics of Ni₅₀Ti₄₈V₂ after machining were examined using field-emitted scanning electron microscopy, showing small irreularisation peaks and wavy surface topography at optimised parameter conditions. USV-WEDM showed a lower-order micro-hardness variation due to effective flushing of molten layer re-accumulation as compared to WEDM. When comparing the base and machined samples, the temperatures of austenite and martensite are nearly the same, indicating that shape memory effects are unaffected by the USV-WEDM process.