MAHLE piston ring sets: piston rings that stop leaks

Piston rings made by MAHLE are found in every leading vehicle brand worldwide. Together with engine manufacturers, MAHLE engineers develop and test the optimal ring set for pistons in new engines. The piston, piston rings, and cylinder wall must be coordinated perfectly so that the engine will function optimally for a long time.

The demands on our piston rings are pretty tough

Over 2,000°C heat, more than 200 bar pressure in diesel engines, and friction—these are the working conditions for piston rings. In order to meet these requirements, piston rings must make contact with the cylinder wall over their entire circumference, even if the cylinder deviates slightly from its ideal shape. Due to high inertia forces and combustion pressures, along with severe wear stresses, piston rings must meet tough requirements with respect to the piston ring material (strength at elevated temperatures), surface quality, and shape.

The material piston rings are made of

Materials: for the safety of people, engines, and the environment—only the best

In newer engines with greater power output per litre, the stresses on the rings are naturally greater. At the same time, they need to be smaller than ever in order to save weight, minimize friction, and improve fuel consumption and throttle response of the engine. Some of the latest piston rings are as thin as a sheet of paper. This is why MAHLE uses high-quality steel made from castings with embedded graphite, nodular cast iron, or wound rolled steel profiles.

Often the entire surface is also coated with tin or phosphate. MAHLE also finishes the running surfaces with a thin, 100–200 µm nitrite, chromium, chromium-ceramic, multilayer, or molybdenum coating. Tiny pores or grooves in the superhard surface take up oil and ensure sufficient lubrication. But even if this is missing, the material can still hold up for a long time.

The ideal ring set for every piston

We offer a wide range of piston ring set designs—in original equipment quality, or specially designed for older engines in order to reduce compression losses and normalise oil consumption. We can provide piston ring sets for nearly all passenger car petrol and diesel engines as well as commercial vehicle diesel engines with diameters from 60 to 160 mm.

It is essential that the TOP identification is observed. Rings with TOP identification are fitted with the marking facing upwards in the direction of the piston crown.

The MAHLE “N” piston ring set includes the same piston rings that are installed in original equipment. MAHLE “V” piston ring sets are specially designed for use in older engines.

Research and development for the repair shop: so that you can continue to install safe products in the future

Innovative developments: PVD nanotechnology

MAHLE engineers have developed a method for coating motorsport piston rings that is now applied to series production: PVD nanotechnology (Physical Vapour Deposition). Several layers of diamond-hard carbon are deposited on the steel in a high vacuum. This makes the running surfaces smoother and more wear-resistant, so that the rings can be made even thinner.

There are two ways to optimise piston rings. With NanoBium vacuum vapour, up to 6,000 layers of CrN and Nbn ceramic are applied, which results in a coating that is only 60 µm thick. The alternative is called CeramSlide: here free amorphous carbon particles are embedded in a ceramic surface with grains about 30 nm in size. That is really quite small; structural steel grains, for example are a thousand times bigger.

Both processes have only recently been developed to production maturity. In the MAHLE Tech Center, however, progress never stands still—now they are researching whether and how superstrong carbon nanotubes can be used in pistons and bearings.

Ring set with PVD-coated compression ring, Napier ring, and three-piece oil control ring.

Piston ring fitting [PDF; 2404 KB]
Fitting recommendations [PDF; 523 KB]