Friction bearings are moveable bearings which support and guide machine parts that move relative to each other. They consist of the moveable shaft (bearing pin) and the bearing shell or bushing and can be designed as axial or radial bearings. A fundamental differentiation can be made in the manifold friction bearing applications between systems with and without liquid lubrication. However, in the case of friction bearings, both mechanisms can also be encountered together in the kinetic friction area, depending on the operating conditions. It is therefore important to consider the hydrodynamic behaviour of the partner when creating suitable material combinations. At least one partner should be distinguished by good thermal conductivity, as the lubricating properties of liquids are mainly impaired (e.g. through friction heat).

Low friction coefficients and rates of wear are the main objects of attention during dry running. During so-called hard-soft-matching, it should be ensured that the adapted surface of the hard partner causes as little wear as possible on the soft partner, and the latter in turn should act as a static lubricant and reduce friction through low erosion. Hard partners are metals (including porous sinter metals), ceramic materials or CFC composites, with different carbon materials and plastics acting as soft partners.

An enormous variety of materials is available for manufacturing friction bearings (depending on the application and specification). Use is made of carbon materials such as carbonic graphite, electrographite, impregnated graphite and synthetic resin-bound carbon, ceramic materials such as silicon carbide, aluminium oxide or tungsten carbide, metallic materials and alloys and a variety of polymers.