Wear mechanisms of coated tungsten carbide when machining Inconel 718 under cryogenic and dry conditions

This study presents the investigation on tool wear mechanisms of PVD TiAlN coated tungsten carbide inserts during high-speed turning Inconel 718 under cryogenic and dry conditions. For cryogenic, the coolant used is liquid carbon dioxide (CO2) applied at a fixed flow rate and pressure. The investigated cutting parameters for the experiment are: cutting speed, Vc=70 and 110 m/min, feed rate, f=0.075 mm/rev and depth of cut, ap=0.1 mm. The experimental results showed that the lower cutting speed resulted with longer tool life with the cryogenic machining reduced the tool wear progression of nose wear slower compared to dry cutting. The wear criterions found in both cutting conditions were scratched marks, build-up edge (BUE), notching and catastrophic fracture through mechanisms which were abrasion and adhesion. As observed, the cryogenic machining helped to reduce the fracture and chip welding on the rake face of the tool which were found severe in dry cutting. The consistent cooling effect of the cryogenic CO2 was believed to efficiently reduce the cutting temperature and caused the mentioned improvement.