Abstract:

This Data Item provides guidance on the selection of the appropriate lubricant class for tribological applications. For this purpose lubricants are divided into four classes, namely oils (liquids), greases (semi-solids), solids and gases. As a preliminary to making a selection, however, guidance is also given on identifying those applications in which the use of a separate lubricant can be avoided, for example, by the use of appropriate contact materials or by using a process fluid as a lubricant. The first part of the Item provides a strategy for the preliminary selection of tribological devices, such as bearings and drives, aimed at avoiding or, at least, minimising the need for additional lubrication and associated support equipment and maintenance. This selection procedure is discussed with particular reference to rotary bearing systems but similar considerations apply to other tribological devices, such as drives and dynamic seals. Later sections of the Item present further strategies applicable when additional lubrication cannot be avoided. These strategies allow the lubricant class to be chosen based on analysis of the tribological system and on knowledge of normal practice in similar or related devices. The broad characteristics of the various lubricant classes are discussed as well as some of the systems that might be used to supply them. The primary requirements of the lubrication system and the usual choice of system for some specific components are also discussed.