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With increased awareness of environmental issues and regulations, developments for recent automotive engines are progressing towards engines with low fuel consumption. Due to these changes, automotive engine bearings are increasingly used in harsher environments, with higher loading. These operating conditions require bearings with both conformability and fatigue resistance. From the above background, various aluminum alloy bearings have previously been developed, including materials with solid solution treatment to improve their properties, and alloys which can be used with or without an overlay [1, 2, 3]. These materials are known to have good conformability and fatigue resistance. However, while conventional Al-Sn-Si alloy bearings display excellent sliding properties, due to the unceasing trend for engine downsizing, more conformability is required.

As the recent engines are designed for higher performance, piston pin bushing used for small end of connecting rod must endure higher dynamic load and oil temperature conditions. Therefore, the bushing is required higher wear resistance and anti-corrosion. And it is also expected to develop the bushing without lead due to environmental concerns. In this report, lead free copper based bushing alloy was studied. At first, in order to keep the anti-seizure property without lead, we studied the effects of hard particles added into copper based alloy. Second, we evaluated the effect of addition of hard particles on wear resistance and anti-corrosion.

As the recent engines are designed for higher performance and better efficiency, three layers bearings must endure under heavy dynamic load and higher speed conditions. And it is also expected to develop the bearing without lead due to environmental concerns. In this report, a lead free copper based bearing alloy was studied. At first, in order to keep the anti-seizure property without lead, we studied the effects of bismuth and molybdenum carbide particles addition into the copper based bearing alloy. Secondly, we studied the influence of axial bearing relief to keep a conformability under high load condition.