CO2 cryogenic milling of Inconel 718: cutting forces and tool wear

Machining Inconel 718 alloy is a challenge due to its low machinability. This thermal resis-tant alloy combines high strength even at high temperatures with strain hardening tendency that causes high forces and extreme cutting temperatures during the machining. These issues force industries to achieve suitable machining processes to deal with this kind of alloys and the high worldwide competitiveness. Nevertheless, environmental considera-tions must to be taken into account due to growing environmental concerns. In the work here presented, cryogenic cooling with external MQL lubrication (CryoMQL) working along with CO2 as internal coolant is proposed for milling Inconel 718 with the aim of not only improving from a technical point of view but also environmental. This technique was com-pared with other lubricooling techniques. The results show that internal CryoMQL improves tool life by 57% in comparison with emulsion coolant, achieving 120% if it is compared with MQL in stand-alone mode. (C) 2020 The Author(s). Published by Elsevier B.V.