Effect of minimum quantity lubrication strategies on tribological study of simulated machining operation

The main aim of this paper was to reproduce the frictional behaviour that occurred in milling with a pin-on-cylinder system. Three different tribological tests were conducted reproducing friction phenomenon that happened in three machining conditions: (i) dry rubbing, representing the dry machining condition, (ii) MQL applied to front face rubbing which was similar to milling with MQL applied on the insert rake face and (iii) MQL applied to rear end rubbing which was similar to milling with MQL applied on flank face. Tribological tests were carried out with coated tungsten carbide pins rubbing on X100CrMoV5 steel cylinder. Apparent coefficient of friction, adhesion area and heat flux transmitted to the pin were analysed. It has been shown that MQL rear end rubbing provided a lower adhesion area and lower apparent coefficient of friction than with MQL front face rubbing. Furthermore, MQL rear end rubbing resulted in a greater cooling ability. These findings helped to explain why better results were obtained with MQL flank face lubrication in milling compared to MQL rake face lubrication.