Abstract:
Nickel-based superalloys are widely used in the aerospace, automotive, marine and medical
sectors, owing to their high mechanical strength and corrosion resistance. However, they exhibit poor
machinability due to low thermal conductivity, high shear modulus, strain hardening, etc. Various
modifications have been incorporated into existing machining techniques to address these issues.
One such modification is the incorporation of ultrasonic assistance to turning operations. The assisted
process is popularly known as ultrasonic assisted turning (UAT), and uses ultrasonic vibration to the
processing zone to cut the material. The present article investigates the effect of ultrasonic vibration
on coated carbide tool wear for machining Nimonic-90 under dry and wet conditions. UAT and
conventional turning (CT) were performed at constant cutting speed, feed rate and depth of cut. The
results show that the main wear mechanisms were abrasion, chipping, notch wear and adhesion
of the built-up edge in both processes. However, by using a coolant, the formation of the built-up
edge was reduced. CT and UAT under dry conditions showed an approximate reduction of 20% in
the width of flank wear compared to CT and UAT under wet conditions. UAT showed approximate
reductions of 6–20% in cutting force and 13–27% in feed force compared to the CT process. The chips
formed during UAT were thinner, smoother and shorter than those formed during CT.
