Base materials Geometry Coatings Tribology


Large bore engines used as the main form of propulsion in marine applications, as well as in power plants, are exposed to severe combustion conditions. Such combustion environments require piston rings that can resist high temperatures: a very corrosive environment and heavy wear: and are capable of creating an optimum oil film between ring and liner.

Daros has mastered the technology of how to develop and manufacture piston rings that provide the best possible performance for the operator, by focusing on four core competences:

Base materials

The base material’s function is to give the ring sufficient strength, the best tribological performance against the liner and the best possible heat transfer (conductivity). The materials we develop at Daros have been well-tested on all engines and liners found in today’s engines.


The geometric shape of the piston ring has a major impact on performance. By optimizing the ring shape and profile, we ensure that the maximum combustion pressure is being transferred to the piston motion and that an optimum oil film is created between ring and liner.


Various different coatings are used to enhance the properties of the base material. Hard coatings are used to increase the time between overhaul (TBO) and the scuffing resistance. We also develop popular coatings for fast running-in and reduced ring groove wear at Daros.


The combustion chamber is a system where the piston rings interact with the liner, lubrication oil, combustion gases and fuel oil. Daros focuses on developing highly competitive piston ring technology in order to optimise performance in the combustion chamber.

Daros Piston Rings P.O. Box 138, SE-435 23 Mölnlycke, Sweden. Phone +46 31 33 84 000