This International Standard specifies a classification and designation system for a selection of the most common unfilled thermoplastic polymers for plain bearings. The unfilled thermoplastic polymers are classified on the basis of appropriate levels of distinctive properties, additives and information about their application for plain bearings. The designation system does not include all properties; thermoplastic polymers having the same designation cannot therefore be interchanged in all cases. It also provides an outline of the properties and applications of the most common unfilled thermoplastic polymers as well as listing some of the fundamental parameters that influence the selection of thermoplastic polymers for use for plain bearings. NOTE In the further course of the work it is intended to prepare standards on "thermosetting polymers" and "mixed polymers" for plain bearings.