Piston rings with high-value PVD coating for high-speed diesel engines

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Stuttgart, Germany, September 2007—More stringent emissions limits as well as customer expectations require not only a reduction in the lubricating oil consumption, but also engines with even higher specific performance values. This in turn calls for piston rings with higher wear resistance.

Over the last few years, MAHLE successfully introduced the PVD coated (Physical Vapor Deposition) compression ring for diesel engines used in heavy commercial vehicles. The ring is made of nitrided stainless steel and has a ceramic coating (chromium nitride), which is applied by means of the PVD method. MAHLE has now succeeded in additionally depositing the chromium nitride coating on the nodular cast iron ring material. As a result, a cost-efficient compression ring solution is now also available for engines with lower output, offering maximum wear resistance and lower friction.

MAHLE has tested these piston rings in high-speed diesel engines for up to 1,000 hours with excellent results. Further advantages of the PVD coating are the lower friction coefficient and the excellent tribological compatibility with the materials of the cylinder running surface. Thanks to these properties, engine friction and cylinder wear can be reduced. A low-friction ring pack reduces fuel consumption by up to one percent. In addition, the PVD process is very environment-friendly.

The MAHLE Group is one of the 30 largest automotive suppliers worldwide. As the leading manufacturer of components and systems for the internal combustion engine and its peripherals, MAHLE is among the top 3 systems suppliers for piston systems, cylinder components, valve train systems, air management systems, and liquid management systems. With more than 40,000 employees in 110 production plants and seven research and development centers, MAHLE generated sales in excess of EUR 4.3 billion (USD 5.8 billion) in 2006.