Cam and Follower lubrication is one of the most challenging tribological problems. It is considered as a typical transient mixed lubrication problem. Most of the lubrication phenomena such as physical wedge effect, squeeze film, elastic deformation of contacting surfaces, sidal leakage, thermal effects and variation of lubricant properties with pressure and temperature play an important role in this problem. Moreover, in this research the surface roughness effects such as thermal generation due to asperity friction, surface roughness pattern and running-in process is also investigated besides the above mentioned factors. In this thesis, a tribometer is designed and manufactured to simulate the cam and flat follower movement and also measure the frictional and normal force applying on the contact area. This tribometer can also be used to investigate the wear and roughness variation during the time. The numerical simulation founding is validated by comparing to the experimental results of tribometer. Results of numerical simulation show the considerable effect of lubricant entrainment velocity, roughness and thermal consideration on the tribological parameters such as lubricant film thickness and frictional behavior. Increasing the entraining velocityas can be achieved by a roller follower instead of flat one is also investigated which shows a drasticaly improvement in film thickness and frictional force. Increasing the roughness height forms a thicker film thickness. But, when the roughnesses go higher the film thickness parameter decreases which declare a more severe lubrication condition and increasing in frictional force. Film temperature is increasing by viscous dissipation and asperity frictional heating which results ina lower viscosity of lubricant and decreasing in lubricant film thickness. The effects of surface roughness pattern is investigated by comparing longitudinal and transverse pattern which the longitudinal pattern shows the better performance. This study also investigates the surface roughness variation during running-in and its effect on the friction coefficient. The results show that the effect of running-in process cannot be neglected. Keywords: Cam and follower mechanism, Lubrication, Elastohydrodynamic, Mixed, Surface roughness, Tribometer
