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Composite bearings of PTFE as the base material have been widely used for automotive parts. However, in recent years, due to downsizing, faster sliding speeds, and tendency to increase the bearing load with high performance, particularly for boundary lubrication conditions, the PTFE-based composite bearing is often worn, making it difficult to apply to some applications. A high strength polymer was selected as an alternative to PTFE base material, and the mechanical properties and performance in a start-stop test, reciprocating sliding test and seizure test were evaluated. Focusing on the characteristics of high strength, by applying a PEEK resin, in each evaluation, it was confirmed that superior performance was achieved compared with a conventional PTFE based composite bearing.

A copper based bushing alloy is used under boundary lubrication for the sliding part of a fuel injection pump etc. for automotive diesel engines. Lead is added to a copper based alloy bushing, because seizure resistant property is an important factor under boundary lubrication. However reducing the use of lead, an environmental pollutant, is required from environmental concerns. Therefore, a lead free bushing alloy was studied in this paper. Concept of material design is to prevent adhesion between a bushing alloy and a mating shaft leading to less wear under the boundary lubrication. The tested material is basically copper-based alloy to which low melting metal instead of lead, hard particles and solid lubricant are added. Tribological and mechanical properties of the material were evaluated in terms of seizure resistance, fatigue strength, conformability and cavitation resistance.

The bearing is used for the sliding part of automotive parts, for example the brake pedal and the seat. As many of these bearings are aimed for maintenance free, the polymer based bearing that can be used under no lubrication is applied. This bearing material has three layer structures consisting of steel-backing and a porous copper alloy interlayer impregnated and covered with the polymer composite, which consists of poly-tetrafluoroethylene (PTFE), lead and others (1), (2). Lead has the characteristic to form the transferred film of PTFE to the countershaft, and this phenomenon improves the wear resistance. This bearing material shows the excellent bearing performance by the characteristic of lead under no lubrication. However, because lead has been designated as one of the environmental pollutants, the addition to the bearing material is being restricted in recent years. Therefore, lead free polymer based bearing that can be used under no lubrication was developed in this study.

Recently, as for the rod guide bush bearing materials for shock absorbers, lower friction and the improvement of durability are required along with ride quality and longer life of automobile. Usually, lead is contained in bearing materials. However, the addition of the lead in bearing material is being restricted from the earth environmental problem. Bearing materials for shock absorbers are composite material consists of steel backing and covered with polymer surface layer. This basic material structure hasn't been changed till now, though it has been improved by changing its components and compositions based on the customer's requirement. Bearing material with both lower friction and excellent wear resistance has been developed in this study.