High performance thanks to PVD coating
Stuttgart, September 2008—The piston pin has a great influence on the performance of an engine. For very highly stressed engines, MAHLE has therefore developed piston pins with PVD coatings, which allow reduced weight of the piston group, and also reduce friction.
Piston pins made of case-hardened steels and nitrided steels ensure high fatigue, wear, and seizure resistance when in contact with the piston and connecting rod. Bushings in the bores of the pistons and connecting rods further improve the tribological conditions, but also increase both weight and cost. MAHLE's coated piston pins provide the best tribological conditions, allow the elimination of bushings, and thus the weight of the piston and connecting rod to be reduced.
Coatings based on PVD (Physical Vapor Deposition, a high-vacuum vaporization process) have long been proven in motorsport. Diamond-like carbon coatings (DLC) are often used in this context. Friction losses drop significantly with such coatings. Coatings based on chromium nitride are also possible.
For coating temperatures of up to 230 degrees Celsius, casehardened steels can be used as the pin material, for higher temperatures, nitrided steels have better properties. Besides single-layer coatings, MAHLE is also working on multi-layer coating composition. Tests show that a PVD-coated piston pin consistently has greater wear and seizure resistance, with reduced oil lubrication and friction.
Piston pins with PVD coatings have been shipped to different MAHLE customers and used successfully in engines as series parts since 2006.
The MAHLE Group is one of the 30 largest companies in the automotive supply industry worldwide. As a leading manufacturer of components and systems for the combustion engine and related products, MAHLE ranks among the top 3 systems suppliers for piston systems, cylinder components, valve train systems, air management systems, and liquid management systems. MAHLE employs around 48,000 people at 110 production plants and eight research and development centers. In 2007, MAHLE achieved sales of over EUR 5 billion (USD 7.5 billion).