Ultrasonic vibration-assisted turning of Titanium alloy Ti-6Al-4V: numerical and experimental investigations

The machining of Titanium alloy, Ti-6Al-4V has got an extensive attention from industries like aerospace, medical, and biomedical plants due its unique properties like high strength at elevated temperature and better strength to weight ratio. Still, properties like reduced thermal conductivity, affinity to react with the tool and work hardening make difficult to cut it by conventional turning process. Ultrasonic vibration-assisted turning (UVAT) is one of the advanced turning method in which tool is allowed to vibrate with ultrasonic frequency (similar to 20 kHz) with small amplitude and hence converting the continuous cutting to an intermittent cutting process. In the present work a horn (acts as an amplifier as well as a tool holder) with inserted tool tip is designed and FEM analysis has been done for its suitability for the process. The dynamic analysis has also been performed to find out the stress distribution in both parts under cyclic loading conditions. It enables to locate the highly stressed nodal regions. Experimental investigation has been carried out for both conventional turning (CT) and UVAT processes to demonstrate effects of various inputs on the output responses like cutting forces, surface roughness, tool wear and temperature rise in UVAT. Additionally, a 3D finite element model for UVAT and CT has been prepared. The simulation results like force and steady state tool tip temperature have also been validated with the experimental results and found to be in good agreement. The advantages of UVAT process have been discovered in terms of reduction in the cutting forces and surface roughness for the used Ti-6Al-4V workpiece.