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A sintered aluminum-lead alloy of the bimetal type was manufactured in Japan (1977), and has been widely used in main and crankpin bearings for automobile engines. However, the recent trend of automobile engines toward high power output, light-weight and compact construction increases the bearing load. As a result, the margin of fatigue strength of the conventional sintered aluminum-lead alloy has been diminishing. In this paper, a new method of manufacturing bearing material by the hot extrusion process is reported. The new method makes it possible to produce the optimum lead grain distribution and strong adhesion between powder particles. The new manufacturing method produces the aluminum-lead bearing material which has 30% or more increase in fatigue strength over the conventional sintered aluminum-lead bearing material.

Recent engine bearings are operating under severe conditions to support such engine requirements as lower fuel consumption, longer life and protection of global environment. On Al-Sn-Si alloy bearings, it has some issue that fatigue may occur on the bearing alloy under severe condition such as in automotive diesel engines. Higher strength of alloy, which allows the fatigue resistance, can be obtained by solid solution treatment at higher temperature in general. But at the same time it makes intermetallic compounds with less bonding strength between intermediate layer and steel backing. A new bearing without lead has been developed by applying the heat treatment of bimetal and adequate intermediate layer for the process, consequently concluded to have the higher fatigue strength, with usual property on Al-Sn-Si alloy bearings.