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A new concept in thrust washers for gasoline and diesel engines has been developed. Traditionally, thrust washers have been made from the same steel-backed bimetal or trimetal materials that are used for connecting rod bearings and crankshaft main bearings. The new concept is a solid aluminum alloy, specifically formulated for optimum performance as a thrust washer material. This alloy has environmental advantages and performance characteristics superior to currently used materials. The composition, manufacturing process, and microstructure of the new concept thrust washer are briefly explained, and the performance characteristics and environmental advantages are presented.

Standard bonded transmission piston design specifies the use of low carbon steel for the piston carrier material. High strength low alloy (HSLA) steel is proposed for applications where load and packaging requirements dictate. The impact of carrier material selection on piston design and manufacturing needs to be comprehensively evaluated in these cases. This paper will discuss considerations for using HSLA steel and make recommendations for its application to bonded transmission pistons.

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.

This paper introduces a new hypereutectic aluminum alloy for piston casting, an improved casting process and a new re-melting procedure. The resulting microstructures improve the fatigue performance of the piston combustion bowl region exposed to severe cyclic thermal and mechanical loading in modern diesel engine applications. It is shown how composition and material properties of the new alloy increase the material's fundamental properties, compared to an existing hypereutectic alloy. The new casting process minimizes the occurrence of fine oxide inclusions which helps to exploit the fundamental material strength. Finally the paper describes the combustion bowl re-melting process and gives engine validation results to illustrate its considerable influence on premature fatigue failure.

Lead is well recognized as having environmental and health risks. The elimination of lead from automotive components has been accelerated by the European End of Life Directive as well as litigation concerns in the U.S. In response to these circumstances, two new lead-free bronze materials have been developed as replacements for SAE 792 (CuSn10Pb10). The two lead free materials are sintered bronzes with nominal compositions CuSn10Bi3 and CuSn8Ni. The characteristics and performance of these materials are compared and contrasted to sintered and cast SAE 792. Fatigue strength, mechanical properties, corrosion resistance, and wear resistance are described and related to the microstructural and application conditions. The CuSn10Bi3 material is preferred for SAE 792 applications having poor lubrication or high-speed conditions, typically in spark ignition connecting rod bushings or highly loaded transmission bushings.