Downsizing diesel engines (increased specific power output) increases the thermal load on the pistons. Recent designs have pushed piston operating temperatures near the upper limit for aluminum pistons.
Diesel pistons have a cooling gallery, which is continuously filled with oil, to reduce piston-operating temperatures. The position and design of the cooling gallery has significant impact on piston temperature and subsequently piston durability. The closer the gallery is located to the bowl, the lower the temperature and the higher the durability.
Federal-Mogul's unique horizontal casting process offers the ability to move the gallery closer to the bowl. However, moving the gallery closer to the bowl poses many challenges in the casting process.
To address these challenges, Federal-Mogul developed a unique non-destructive testing method, called 2-Dimensional Ultrasonic Testing (2dim-US). Through automatic evaluation of amplitude and depth signals, 2dim-US has the ability to detect and record, at line speed, any kind of casting defect. Using statistical analysis of this data Federal-Mogul has improved their casting process thereby improving product quality and reducing scrap.
Enabled by 2dim-US testing method, Federal-Mogul's raised gallery aluminum diesel pistons have enabled its customers to reduce fuel consumption and C02 emissions by approximately 30% while allowing the continued use of aluminum pistons in these high specific power diesel engines.