Measurement of Lubricant Oil Film Thickness upon Minimum Quantity Lubrication Drilling Process

Most of the investigations on the Minimum Quantity Lubrication (MQL) drilling process are focusing on the effects of drilling conditions such as tool wear and temperature generated. However, these effects are mainly depending on the behaviour of the MQL lubricant oil which had been ignored by most of the researchers. Challenging procedure and complex setup are one of the reasons why there are lack of investigation on this area. In this study, a non-intrusive method, Laser-Induced Fluorescence (LIF) method will be used to analyze the lubricant oil film thickness in order to avoid disruption on the natural behaviour of liquid. LIF is a method that is using fluorescence light intensity of the diode laser to measure the thickness of the lubricant oil film. A crucial calibration will be carried out to correlate fluorescence light intensity and lubricant oil film thickness. Besides, surface roughness of the cutting zone also will be measured. The results show that when the drilling speed increases, the thinner the lubricant oil film thickness. As well as the MQL flow rates, the higher the MQL flow rates is set, the thinner the lubricant oil film thickness. For the surface roughness of drilling zone, the surface roughness is getting better when the drilling speed and MQL flow rates increase.