Authorised by Academic Registrar, April 1996
Objectives This subject is designed to develop skills and understanding relating to the effect of lubrication and friction and wear in the design of bearings, gears and cams.
Synopsis Introduction: friction, wear and lubrication. Friction: surface topography, actual contact between surfaces, classical laws of friction. Friction in metals: elastic and elastoplastic contact between surfaces, welding and shearing theory, ploughing and adhesion component of friction. General review of wear. Wear resistance. Types of wear and wear tests. Properties of lubricants. Lubricant rheology. Lubricant additives, greases. Classification and testing of lubricants. Boundary lubrication: P-V factors, influence of surface finish and hardness. Hydrodynamic lubrication: Navier-Stokes equation. Reynolds Equation, solution for two-dimensional isoviscous incompressible flow. Application to pad bearings. Application to journal bearings. Application to thrust bearings. Elastohydrodynamic lubrication: Hertzian contact stress, film thickness parameter, pressure viscosity relationship. Application to gears and rolling element bearings. Bearing selection: rolling element bearings, journal bearings, hydrostatic bearings. Modes of failure: failure modes of bearings and gears. Lubrication practice: lubrication systems, methods of lubrication for industrial plant. Seals: types of seals, materials and applications.
Assessment Examination (3 hours): 50% + Laboratory work, projects, class test: 50%