A New Family of Lead-Free Aluminum-Base Engine Bearing Alloys

One of the most successful aluminum-base engine bearing alloys in recent years has been a variation on the SAE 788 alloy that contains 8% tin, 3% silicon and 1.5 to 2% lead. This paper presents two new lead-free aluminum materials derived from this alloy, recently released for general use. These materials are AlSn10Si3 and AlSn6Si4. They have performance characteristics designed for specific applications, the former for lighter loads and higher sliding speeds such as bushings and main bearings, and the latter for higher loaded applications such as rod bearings. Material description and performance data is presented. This paper also presents two additional lead-free alloy developments soon to be released, one alloy designed for even higher loading conditions and one alloy designed for unfavorable geometric conditions such as misalignment.