Experimental and computational investigations on the effects of deep-temperature emulsion on the turning of Inconel 718 alloy

Nickel-based superalloys, for instance Inconel 718, are applied in extreme conditions due to their excellent high-temperature strength. However, the same thermomechanical properties make the machining of Inconel 718 a challenge. Cutting fluids play a vital role in extending tool life as well as preserving surface integrity. Nevertheless, their effectiveness is naturally restricted by the fluid's heat capacity. In order to improve cooling effectiveness, a new approach has been developed that combines high-pressure fluid supply and high cooling performance through the use of a deep temperature emulsion (DTE). Experimental and computational investigations were carried out on the high-speed turning of Inconel 718. Cutting forces, tool wear, chip formation and surface integrity were monitored. The experiments revealed that the addition of monoethylene glycol (MEG) reduces a cutting fluid's freezing temperature but negatively affects the machining performance. However, the observed deficiencies are compensated by the benefits of cooling the cutting fluid. The cutting fluid at a temperature of T = -10 degrees C leads to comparable results to those of the reference process and even to further improvements in process performance. Therefore, the application of DTE could potentially outperform and ultimately replace conventional cooling strategies. (C) 2020 CIRP.