ABSTRACT
There is an increasing requirement for testing the performance of bearing
materials, lubricants, lubricant additives, and solid lubricants. For bearings
running on ideal full oil films, the viscosity is the only important lubricant
property that affects the friction. However, in practice most machines are
subjected to variable conditions, vibrations and disturbances and occasional oil
starvation. For these reasons, even bearings designed to operate with a full fluid
film will have occasional contact, resulting in a rubbing of surfaces under
boundary lubrication conditions and, under certain circumstances, even under
dry friction conditions. Many types of oil additives, greases, and solid lubricants
have been developed to reduce friction and wear under boundary friction. Users
require effective tests to compare the effectiveness of boundary lubricants as well
as of bearing materials for their specific purpose.
