Experimental evaluation of machinability performance of CNT coated HSS tool during turning of titanium alloy

The present research deals with the deposition of carbon nanotubes (CNT) over the HSS tool, and to evaluate the machining performance of the coated tool with respect to the important machinability aspects like cutting tip temperature, cutting forces, surface roughness and tool wear and life. The plasma enhanced chemical vapour deposition (PECVD) technique was employed to deposit CNTs over the substrate. Microstructural investigations through SEM and Raman spectroscopy were carried out to acknowledge the dense deposition of CNTs. Scratch test was also performed to validate the bonding strength of the coated layer with the substrate. Machining experimental results under three different cutting conditions, concluded that the CNT coated tool is the right potential candidate for turning tougher materials. Drastic depletion in cutting tip temperature and cutting forces to the extent of 70 to 80 % was observed for coated tool due to the excellent mechanical and thermal properties of CNTs. However, there was no significant effect of coating to influence the surface roughness at a lower level of cutting conditions, but considerable improvement has been observed at elevated cutting condition. The tool wear and life analysis explored the steady improvement to a remarkable extent. Very specifically, under elevated machining conditions, tool life investigations concluded the fact that the CNT coated tool has a tool life of more than 60 minutes with negligible failure.