Experimental evaluation of minimum quantity lubrication in near micro-milling

Abstract

This paper presents the performance of the minimum quantity lubrication (MQL) technique in near micro-milling with respect to dry cutting on the basis of tool wear, surface roughness and burr formation. The effects of tool materials, oil flow rate and air flow rate on tool performance in MQL cutting are also studied. It is found that the application of MQL will significantly improve the tool life, surface roughness and burr formation compared to those in dry cutting based on slotting tests with micro-end mills on a meso-scale machine tool. It is also observed that the values of surface roughness are close related to the tool-wear conditions in micro-cutting. Based on the experimental results, it is presumed that the maximum allowable tool flank wear of the 600-μm micro-tool is 80 μm while the surface finish quickly deteriorates after the tool flank wear reaches 80 μm and the tool breaks soon after the tool wear reaches 100 μm. The optimal lubrication conditions in this study are oil flow rate of 1.88 ml/h and air flow rate of 40 l/min. It is also found that the air flow rate has a more significant influence on tool life than the oil flow rate under MQL conditions in this study.