A study on droplets sizes, their distribution and heat exchange for minimum quantity cooling lubrication (MQCL)

The paper analyses the influence of emulsion mist formation parameters and the nozzle distance from the tool-chip interface, on the droplet velocity at the nozzle outlet, on active medium atomization angle as well as on the diameter and number of droplets supplied to the cutting zone. The deformation coefficient of the droplets falling on the surface and the wetting angle have also been determined. In the work it has been proved that the strongest influence on the droplets diameter have the air flow and the distance of the nozzle from the cutting zone. It has been shown that larger angle of the stream splitting ensures that the droplets do not join each other in the air, and consequently assures small diameter on the surface. Additionally, the results show that the emulsion mass flow does not change the droplets diameters by more than 12%. It has been determined that smaller the droplets diameter is, higher content of active compounds in the tribofilms formed on the machined surface is present. In this way the paper presents the analysis and directions of MQCL adjustment trends needed to improve the machining performance.