Physics-based analysis of minimum quantity lubrication grinding

Abstract

Minimum quantity lubrication (MQL), which is to apply a minimum amount of lubricant directly into the contact zone, is a promising alternative to substantially reduce the lubricant cost caused by conventional flood cooling. In order to advance the MQL technique into grinding situations, understanding of the process and evaluation of the performance is necessary. Most documented studies thus far concerning MQL grinding are built upon experimental observations with individual and separate treatment of grinding performance measures such as grinding force, temperature, wheel wear, and surface roughness. This paper develops the analytical understanding of mechanical and thermal effects of MQL in grinding and profiles the MQL performance as functions of process and fluid application parameters. Physics-based predictive models are formulated to quantitatively describe the grinding force considering the lubrication effect of MQL. The friction coefficient under MQL condition is first predicted based on boundary lubrication theory, followed by the single grit force and grit distribution analysis. Further, surface roughness is calculated from the results of undeformed chip thickness distribution through probabilistic analysis. Additionally, energy partition and temperature distribution in the workpiece have been developed based on the moving heat source model. Material constitutive model are utilized to capture the influence of temperature and strain rate on the material flow stress. Experimental measurements of force, temperature, and surface roughness have also been pursued to calibrate and validate the predictive models.