Experimental Study of Lubricant Oil Film Behavior on Al6061 Under MQL Milling Process

Abstract

AbstractMinumum Quantity Lubrication (MQL) technology has proven to give better surface roughness and tool life performance compared to conventional lubricating method despite its very little usage of lubricant oil. Therefore, it is crucial to deeply understand the lubricating mechanism of MQL to explain this phenomenon. However, most experimental studies conducted in the past was focused to investigate the relationship between effects of machining parameter to the machining performance. Here, the behavior of lubricant oil from MQL generator during the milling process was investigated in this study by using Laser-Induced Fluorescence method to measure the lubricant oil film thickness. Experiments were conducted during the milling process under different oil viscosity and cutting speed. The average surface roughness of workpiece was also measured to relate the lubricant oil behavior and the machining performance. Overall, lubricant oil film thickness fluctuation was found to dramatically change with decreasing oil viscosity. The oil film thickness was also found to increase with increasing cutting speed up until 24.514 m/min. Moreover, the lubricant oil was found to accumulate on the beginning of the milled area. The lubricant oil film thickness drastically dropped at the position of cutting tool. The average lubricant oil film thickness was found at approximately 2.0 mm for the lowest viscous oil and 0.02 mm for the largest viscous oil. The average surface roughness was found to decrease with increasing cutting speed, which has confirmed the results of lubricant oil film thickness that shows more lubricant supplied on the workpiece gives better surface finishing for the workpiece.KeywordsMinimum quantity lubricationLiquid film thicknessOil viscosityLaser-induced fluorescenceSurface roughness