Understanding the influence of tool coating and cutting environment on the machinability of Nimonic C-263

Nimonic C-263 is subjected to machining difficulties due to their distinctive characteristics such as limited thermal conductivity, and the tendency to undergo work hardening. To overcome the above challenges, the study aims to evaluate and compare the effect of tool coatings (uncoated carbide, chemical vapour deposition (CVD) coated, and physical vapour deposition (PVD) coated) and cutting environments on the machinability of Nimonic C-263. The machinability is analysed using key performance factors, including cutting temperature (CT), surface roughness (SR), cutting force (CF), chip reduction coefficient (CRC), and tool wear. A significant reduction in SR, CT, CF, CRC, and average flank wear was observed with PVD-coated tools (PVD-CT) as compared to CVD-coated (CVD-CT) and uncoated inserts under dry machining conditions. The uncoated carbide under minimum quantity lubrication and flood conditions showed improved performance than the CVD-CT, but lower than the PVD-CT. The results from the present work establish the potential for using a PVD multilayer coating (specifically, TiN/TiAlN) on carbide inserts in the dry machining of Nimonic C-263. This approach eliminates the need for environmentally hazardous flood coolant conditions, promoting sustainability in machining processes.