Film Thickness Lubrication Review

Film Thickness Lubrication Review

The preceding discussion is a very simplified attempt to provide a basic description of the principles involved in hydrodynamic lubrication. For a more precise, rigorous interpretation refer to American Society for Metals Handbook Volume 18, listed in the Appendix A. Simplified equations have been developed to provide approximations of film thickness with a considerable degree of precision. Regardless of how film thickness is calculated, it is a function of viscosity, velocity, and load. As viscosity or velocity increases, the film thickness increases. When these two variables decrease, the film thickness also decreases. Film thickness varies inversely with the load; as the load increases, film thickness decreases. Viscosity, velocity, and operating temperature are also interrelated. If the oil viscosity is increased the operating temperature will increase, and this in turn has a tendency to reduce viscosity. Thus, an increase in viscosity tends to neutralize itself somewhat. Velocity increases also cause temperature increases that subsequently result in viscosity reduction.