Wettability enhancement of high-speed steel surface with electrostatic flocking method

Abstract

Due to the important role of cutting fluid in lubrication of tools, achieving its better wetting effect on the surface has become a research hotspot. Castor oil is widely used in machining with excellent lubrication, but its poor wettability cannot be ignored. To enhance the wettability of castor oil on the tool surface, grooves were prepared on the surface of high-speed steel (HSS) by laser, then nylon fibers were vertically implanted into the grooves by electrostatic flocking. The optimization experiments of groove sizes, electrostatic voltage and fiber length were performed, then flocking surfaces with enhanced wettability were evaluated through the self-propulsion, and high-temperature wetting tests. The results show that the penetration length of oil in the flocking grooves (5.71 mm) is 2.28 times that of the non-flocking grooves (1.74 mm). Moreover, the dense fibers increase the heat exchange area at a high temperature, resulting in a rapid rise in temperature of droplet. Thereby the viscosity resistance of the oil is reduced, accelerating the penetration of oil droplets, which are completely wetting for only 0.3 s at 80 °C. This study is of reference value and practical significance for the application of flocking surfaces enhancing the wettability of cutting fluid.