Application of aluminum alloys for combustion engine bearings

In most cases the choice of proper alloy for combustion engine crank mechanism bearings means a compromise between various requirements. In order to increase the fatigue strength and to enhance the wear resistance the research on new materials, including the aluminium alloys, is being carried out. This paper deals with properties of aluminium bearing materials, requirements relative to their operation as well as tendencies of their future development as the bearing alloys for heavy duty diesels. Interdependences affecting bearing properties, comparison of tested bearing materials fatigue strength, controlled distribution of Si particle size in analysed bearing alloys, comparison of fatigue strength of bearing materials subjected to tests, the wear of analysed bearing alloys after engine tests are illustrated in the paper. The paper concentrates on the problems of properties of aluminium based bearing alloys, tendencies in development of aluminium alloys for highly loaded crank bearings of IC engines. Bearing of Al-Sn-Si alloy operates satisfactorily on an engine and have high fatigue strength (particularly on diesels) and posses high wear resistance, especially for a case of frequently started and stopped engine (gasoline engine) which causes difficulties in formation of continuous oil film at low crankshaft speeds.