Thermal-assisted machining of Inconel 718: Impact of tool rake angles on specific cutting energy, carbon emission, and chip formation

Industries are forced to reduce energy use and carbon emissions while machining difficult to machine alloys like an Inconel 718 due to cost saving and environmental purposes. Introducing heat during machining like thermal-assisted machining (TAM) may improve the machinability of Inconel 718, while research in quantifying its impact on specific energy and carbon emissions is still limited. This study begins by obtaining the temperature properties of Inconel 718, then using finite-element analysis to design a local heating model that softens the material to reduce machining difficulty issues. Machining experiments at a cutting speed of 66 m/min are conducted under various thermal-assisted temperatures and rake angle combinations. The findings reveal that TAM reduces specific cutting energy by 14% to 30% compared to dry cutting. Notably, thermal-assisted processing technology can effectively reduce carbon emissions, and at a −5° rake angle and 500 °C, it can reduce 99.06 μg, but the increase in rake angle will counteract this effect. When using TAM, the chip morphology will change from serrated chips to smooth continuous chips as the heat-assisted temperature increases, and the increase in rake angle will resist this change. These results indicate that the combination of thermal-assisted technology and the selection of the rake angle of the cutting tool can reduce carbon emissions and achieve dual sustainability benefits in terms of economy and environment. This provides a promising approach for improving energy efficiency and supporting low-carbon processing strategies for aerospace high-temperature alloys.