Ultrasonic inspection technique aids downsizing for diesels30 May 2012
Federal-Mogul Corporation is using a novel two-dimensional (2D) ultrasonic analysis system to produce high performance pistons that enable a substantial further step in diesel engine downsizing. In its first application, the greatly improved cooling capability of the company's "raised gallery" piston allowed a Federal-Mogul customer to introduce a series of measures that achieved a CO2 reduction of up to 30% compared with the previous generation engine without raised gallery pistons.
The first production application of Federal-Mogul's raised gallery piston also delivers a specific power increase of 25%, keeping the piston at temperatures much lower than the acceptable limit of 400°C. In the same conditions, a standard piston's bowl rim stresses are 43% higher and its temperature reaches 440°C, close to the metal's melting point.
"Diesel downsizing increases specific power output in order to improve fuel economy and CO2 emissions and also increases the thermal and mechanical loads that diesel pistons must withstand," says Gian Maria Olivetti, Federal-Mogul's vice president for technology and innovation, powertrain energy.
"With the development of new highly-loaded engines, the risk of piston failure has increased substantially as past improvements in materials, design and cooling concepts have reached their physical limits. Federal-Mogul's innovation in advanced testing techniques, materials science and manufacturing processes greatly reduces the limitations placed on diesel downsizing strategies."
Modern diesel pistons have a cooling gallery, through which oil flows continuously. The position and design of the gallery have a significant impact on the component's operating temperature and durability. The closer the gallery is to the piston bowl, the more heat that can be removed, allowing engine manufacturers to increase combustion temperatures and pressures to improve fuel economy and CO2 emissions.
Standard, one-dimensional ultrasonic testing can identify defects but cannot quantify their size and position.
Federal-Mogul's 2D ultrasonic process, however, provides 125,000 data points in 30 seconds. The technique enables Federal-Mogul engineers to accurately determine the size and position of defects, providing valuable data for casting process development. The detailed information provided also ensures consistent quality in the finished high-precision components.
Federal Mogul Ltd
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