Investigation of Atomized Droplet Characteristics and Heat Transfer Performance in Minimum Quantity Lubrication Cutting Technology

Abstract

Minimum quantity lubrication (MQL) cutting technology is ecologically friendly and efficient in terms of cooling and lubrication. It has be.en widely used in recent years. The atomization effect of the MQL system was characterized by the average diameter of atomized droplets in this study. Second, the MQL heat transfer experimental platform was built, and the cooling experiments were carried out under different MQL parameters. The heat flux density is linearly related to the heat source temperature under steady-state conditions, and the nozzle target distance has the greatest influence on the cooling effectiveness. The flow state of the lubricating oil is liquid film flow when the heat source temperature is lower than 120°C. The flow state of the lubricating oil is ditch flow when the heat source temperature is higher than 180°C. The average droplet diameter decreased by 43.7% when the pressure was 0.4 MPa compared with 0.2 MPa. An increase in gas supply pressure can improve the cooling effect of MQL. With the increase in flow rate, the average droplet diameter and steady-state heat flux do not change significantly. At 270°C, the steady-state heat flux at a flow rate of 90 mL/h was only 2.99% lower than that at 18 mL/h. The average droplet diameter is the smallest, and the cooling effect is the best when the nozzle diameter is 1.5 mm. The heat transfer effect is the best when the nozzle distance is 20 mm at different temperatures. When the nozzle distance is between 20 and 40 mm, the heat transfer capacity of MQL is the most stable. The heat transfer performance of MQL is helpful to improving the efficiency and quality of cutting, and promoting the implementation of a green manufacturing and sustainable development strategy.