Experimental investigation on different cutting tool performances during turning of Inconel 718 at varying cooling strategies

In the last decades, superalloys have found wide applications in space, defence, and energy industries due to their excellent thermal and mechanical properties. One of the most interesting Nickel-based superalloys is Inconel 718, widely used in the aerospace field. More than 50% of produced Inconel 718 is used in aerospace applications; actually, the most important components in modern aero-engines, such as blades, sheets, and disks, are made of this superalloy. Inconel 718 combines ductility with high strength to weight ratios. It is characterized by a yield strength of 550 MPa, a thermal conductivity of 11.04 W/m°C, good mechanical and thermal fatigue properties and outstanding creep resistance at elevated temperatures (up to 760°C). Nevertheless, this material is classified as difficult-to-cut and heat-resistant material which makes its manufacturing arduous and an open challenge for many companies. This thesis work aims to find a strategy to reduce tool wear when machining Inconel 718. To this aim, turning trials were carried out at varying lubricating cooling conditions and cutting tools. Specifically, cryogenic cooling was evaluated as an alternative to conventional flooding. Different cutting tools in terms of shape and materials were investigated as well. The tool wear was inspected by using a scanning electron microscope at different working steps while the surface finish was investigated by using a roughness tester. Results show that a proper combination of tool and cooling strategy can significantly improve both tool life and surface finish.