In the present work, turning performance of Inconel 825 superalloy is studied under Nanofluid Minimum Quantity Lubrication (NFMQL). Nanofluid used is nano-Al₂O₃ dispersed distilled water. The tool insert used in this study is PVD multi-layered (TiN/ TiCN/ TiN) coated cermet. The following machiningperformance indicators: tangential cutting force, tool-tip temperature, wear morphologies of the tool insert, macro/ micro-morphologies of chips produced, etc. are studied. It is observed that dry machining environment causes vibration signals of random nature whose frequency and amplitude of acceleration are highly timevariant. On the contrary, periodic vibration signal with lower amplitude of acceleration is detected in case of NFMQL machining. Consequently, NFMQL exhibits lower cutting force, reduced tool-tip temperature, and less severe tool wear than that of dry machining. NFMQL produces thinner chips with shorter segmentation spacing and wider shear angle than dry machining.

In the present work, the machinability of difficult-to-cut Inconel 718 aerospace superalloy is studied under vegetable oil-based minimum quantity lubrication (MQL) in consideration with different cutting tool materials. MQL environment is produced by supplying air-oil mist in which biodegradable sunflower oil is used.In comparison with uncoated carbide tool, performances of MT-CVD multi-layered TiCN-Al₂O₃-TiOCN coated and MT-CVD double-layered TiCN-Al₂O₃ coated carbide inserts are assessed during longitudinal turning of Inconel 718. Coating materials are characterized by average thickness of individual coating layer, elemental composition and frictional coefficient. With constant feed and depth-of-cut (0.1 mm/rev and 0.25 mm respectively), quantitative responses such as tangential cutting force, tool-tip temperature and width of tool flank wearare considered as machinability assessment criteria under varied cutting speed condition (v = 60, 80, 100 and 130 m/min). Notable reduction in tool-tip temperature (25.6% and 30.4%) and reduction in cutting forces (10.6% and 22.3%) are obtained for coated tool [T1] and coated tool [T2] respectively, when compared to uncoated counterpart. Detailed analysis on tool wear modes is carried out followed by chip’s macro/micromorphology. Apart from chip’s micro-morphological parameters, morphologies of chip’s back and free surfacesand chip microhardness are studied.