Techniques to Upgrade Heavy Duty Aluminum Pistons
The demands on aluminum pistons from increasing diesel engine BMEP levels and longer expected service life are at the point that classical piston alloys processed with conventional casting techniques are no longer adequate. New processes and material enhancements are needed to upgrade heavy duty pistons. The application of the squeeze casting process to densify material improves the fatigue properties of aluminum alloys. This process also allows the use of fiber reinforcing to further improve the physical characteristics of squeeze cast diesel pistons. Metallurgical and physical test data on permanent mold, squeeze cast and squeeze cast metal matrix composite systems show significant differences in high temperature properties such as fatigue, tensile and thermal expansion. Wear characteristics are also compared. The property improvements observed will contribute to the continued use of aluminum pistons in heavy duty diesel engines.