This standard is included in DIN Handbook 198. As during the useful life of a machine, an apparatus or an instrument, the geometrical form of a sliding region included in it must not change at all or only to an insignificant extent due to wear, care is, if possible, to be taken by suitable design of sliding region and corresponding choice of lubricant that the sliding partners used are separated from each other by a bearing lubricant film. In the case of such operating conditions, above all, the strength and heat properties of the anti-friction materials are playing a role such as hardness, compressive strength, fatigue strength, coefficient of expansion.