Flow visualization and characterization for optimized MQL machining of composites

Limited information is available on the effect of Minimum Quantity Lubrication (MQL) parameters (oil flow rate OFR, air flow rate AFR, nozzle orientation and distance from the cutting zone) on flow characteristics. ‘Particle Image Velocimetry’ and ‘Phase Doppler Anemometry’ flow visualization methods were used to define the optimal MQL jet for better penetration and cooling/lubrication; coherent, small magnitude/number of vorticities, and small droplets of high velocity. Effect of flow characteristics on cutting forces, temperature, tool wear and geometric errors was examined in CFRP milling. Optimum AFR, OFR and nozzle distance from the cutting zone were established and compared to flood, pressurized air, and dry machining.