Study of oil-water ratio and flow rate of MQL fluid in high speed milling of Inconel 718

High speed milling of Inconel 718 by carbide tool aided by MQL of various oil-water ratios and flow rates of the fluid was investigated. Tool wear and cutting force were taken to assess the effectiveness of the fluids. The action of the fluid in machining Inconel 718 under MQL was also studied. EDX analysis of the rake face of the tool shows that the fluid has penetrated into the chip-tool interface and works as the diffusion barrier as well. The results reveal that the amounts of fluid penetration and wetting area are essential for effective fluid action. Tool wear and cutting force are found to decrease with increasing flow rate of the fluid irrespective of oil-water ratio. But the improvements are negligible as compared with those resulted from the flow rates of 100 ml/hr and 60 ml/hr. This can also be confirmed by the little difference of wetting area beyond the flow rate of 60 ml/hr. Based on this study, it is concluded that the most appropriate oil-water ratio and flow rate of the fluid used in MQL in high speed milling of Inconel 718 are 60:40 and 60 ml/hr, respectively.