Effect of chip sliding velocity and temperature on the wear behaviour of PVD AlCrN and AlTiN coated mixed alumina cutting tools during turning of hardened steel

The present study investigates the performance of mono-layered AlCrN and multi-layered AlTiN PVD coatings on mixed alumina inserts in turning of hardened AISI 52100 steel. The performance of the cutting tools was evaluated by cutting tool wear and correlated in terms of material's build-up and friction at the chip-tool interface, chip sliding velocity and cutting zone temperature. The results revealed increment of material's build-up with feed rate whereas it decreased with the increase of cutting speed and chip sliding velocity. The sliding velocity increased with the increase of cutting speed resulting in lower contact time between the tool and the chip, and thus, the adhesion reduced with an increment of cutting speed. On the other hand, an increase of contact area in combination with higher cutting zone temperature and lower sliding velocities resulted in an increase of material's build-up with feed rate. AlTiN coated cutting tools exhibited superior anti-oxidation, anti-adhesion and anti-abrasive properties as compared to AlCrN coated and uncoated cutting tools. However, the AlCrN coating exhibited superior machining behavior at higher cutting speeds indicating the suitability of the coating at elevated machining speeds.