A Model for Lubricant Flow From Disk to Slider

A model is presented that calculates the equilibrium lubricant thickness on a slider, resulting from a steady state where net inflow from disk evaporation equals net outflow from evaporation back to the disk, and flow to the slider back end from air shear. Based on experimental vapor pressure and viscosity data, and using surface viscosity enhancement factor and disjoining pressure values available in the literature, this model predicts a transition from a flooded regime for molecular weight Mn below 1.5 kDaltons to a starved regime where slider lubricant thickness drops to a value close to zero. At the same time, lubricant accumulation to the slider back end is expected to decrease exponentially.