Comparative Thermal Analysis of TiN-Coated and Uncoated Carbide Cutting Tools

This study investigates the thermal influence of titanium nitride (TiN) coatings on tungsten carbide-cobalt (WC-Co) cutting tools during orthogonal machining of gray cast iron. Although such coatings are widely employed for mechanical protection of the substrate and to enhance the tribological performance of the cutting process by reducing friction and improving tool life, their thermal behavior during operation remains insufficiently understood. Considering that TiN coatings are extremely thin (typically \((1-10 \mu)\)m) in comparison to the substrate thickness (\((5-10)\) mm), a key question arises: do these coatings function as thermal barriers, or are the observed reductions in cutting zone temperature solely attributed to their mechanical behaviors? To address this, thermal properties of coated and uncoated cemented carbide tools were characterized. Experimental measurements were performed during orthogonal cutting of gray cast iron. Heat flux and tool-chip interface temperatures were estimated using inverse heat conduction methods. The results showed that uncoated tools exhibited significantly higher interface temperatures, with an average increase of approximately \((300^0C)\) compared to coated tools. The findings suggest that the mechanical benefits of the TiN coating are primarily responsible for the reduction in interface temperature, while its thermal barrier effect is comparatively limited.