A Study of Minimum Quantity Lubrication (MQL) by Nanofluids in Orbital Drilling and Tribological Testing

Abstract

In minimum quantity lubrication (MQL), an aerosol containing a minimum amount of the cutting fluid is delivered to the tool/workpiece interface during the metal cutting operation. The fluid lubrication by the fluid and the cooling by the compressed air in the aerosol improves the cutting process, while the low consumption rate in MQL provides less cleanup and reduces the associated cost. In this paper, molybdenum disulfide (MoS2) and hexagonal boron nitride (hBN) nanoparticles were added to the aerosol for providing a third functionality to the MQL, which is solid lubrication at the interface. Both orbital drilling and tribological testing using a four-ball tester were studied to examine the effectiveness of solid lubrication in MQL. In orbital drilling of titanium with tungsten carbide tools, MQL with nanofluids containing MoS2 nanoparticles resulted in less transfer film buildup on the tool. In four-ball testing, MQL with nanofluids with MoS2 and hBN nanoparticles yielded lower surface temperatures and less variation of frictional torques in titanium.