A review of near dry machining/minimum quantity lubrication machining of difficult to machine alloys

Cutting fluids cool and lubricate the cutting tool and machined area, wash away chips thereby increasing material removal rate, lengthen tool life and improve dimensional accuracy. However, strict environmental regulations prohibit liberal use of conventional coolants due to environment, health hazards and economic reasons. But, dry cutting although environmental friendly is not feasible under all machining applications. Some materials, when machined dry, tend to stick to tool face, spoiling tool and machined surface finish, can be efficiently machined under near dry machining (NDM) or under minimum quantity lubrication (MQL) conditions; in which cooling and lubrication in the cutting zone can be achieved by a tiny amount of cutting oil applied to tool tip with compressed air in mist form, thereby addressing the negative impact of flooded coolant machining. This paper, attempts to critically review research progress and current state of affairs in machining of difficult to machine alloys under NDM/MQL.