EHD FILM THICKNESS IN NONSTEADY STATE CONTACTS

This paper describes a study of EHD film thickness in non-steady state contact conditions. A modification of ultrathin film interferometry i s employed which is able to measure both central film thickness and fi lm thickness profiles 50 times a second. Film thickness with two perfl uoropolyethers and two mineral base oils are investigated in a number of different types of non-steady state motion, including acceleration/ deceleration, stop/start and reciprocation. The results demonstrate a range of transient behaviors of EHD film whose thicknesses deviate fro m those in steady state conditions.