Study on Micro Litter MQL Machining

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MQL (Minimum Quantity Lubrication) cutting is the most promising environmental conscious machining method with wide applicability. A small amount of cutting oil is sprayed with compressed air to the cutting point. MQL cutting often showed almost the same cutting performance as wet cutting. However, generation of oil mist may cause health hazard and degradation of factory environment. Thus, in this study, machining technology with cutting oil less than 1 ml/h is investigated as an environmental conscious machining of next generation and applied to a difficult-to-machine material, Inconel 718.First, an innovative cutting tool for MQL machining was developed to concentrate oil mist to the cutting point. This tool can guide the oil mist to the tool tip and decrease the tool wear. It was found that in turning, oblique spraying from the side of minor flank face is very effective for reducing the tool wear : tool life using oblique spraying at an oil consumption rate of 1.1 ml/h is almost as long as that of wet cutting.Next, the flow of oil mist was visualized for optimizing the spraying conditions of oil mist. A general-purpose code of computational fluid dynamics and 3D-CAD for shape modeling were used in this analysis and applied to three types of oil mist nozzles : ordinary type, cover type for normal spraying, and cover type for oblique spraying. Velocity, pressure and vorticity of the air calculated for the three nozzles clearly showed that the oblique spraying can carry the oil mist to the cutting point most effectively.