PISTON RINGS FOR 2-STROKE ENGINES
Daros, Federal-Mogul’s brand for all large bore engine 2 stroke piston rings. Since 1899, formerly named David Robertson’s Engineering became the first factory in the world to specialize in piston rings and, since then, Daros continues working in close cooperation with leading engine manufacturers in order to develop new rings for modern diesel engines.
Daros designs and manufactures rings for all 2-stroke engines being nowadays used and produced, both in marine application as well as in power plants.
Daros Piston Rings are designed in close cooperation with leading engine manufacturers
All material specifications produced by Daros are developed in close co-operation with the leading engine manufacturers. The ability to tailor make the material ensures the best operational resuslts with respect to both performance and component life time of piston rings and liners. The Daros foundry exclusively works with cast iron of various grades and types. The casting process must be controlled in order to ensure high material quality with good repeatability. Chemical composition and temperatures are carefully monitored throughout the casting process. The casting process govern the size, shape and distribution of the graphite, parameters which are of vital importance to strenght and heat conductivity of the piston ring.
The casting process is completely managed internally in order to get the complete control of it and therefore ensure the best possible quality!
PISTON RING COATINGS
In order to further increase the performance of the ring, various types of coatings are applied. Today many types of piston rings are coated, mainly on the running surface. Two main types of coatings can be distinguished; Running-in coatings and wear resistant coating. Running-in coatings are used to shorten or, for some applications, even eliminate the need for running-in. The wear resistant coatings are used to increase TBO or to cope with extreme operational conditions.
All coatings have been developed with engine makers.
PISTON RING GEOMETRY
All piston rings manufactured by Daros are oval turned to create the tension in the ring. The oval shape of the piston ring is designed to offer a circumferential pressure distribution without any leakage or hard contact zones. Daros has developed the OPCORE (Optimised ring end correction) technology in order to minimise the running-in wear and to ensure optimum geometry at the ring opening. The OPCORE technology is based on the true operating conditions for the piston rings, this means that e.g. ther- mal conditions of the piston ring and liner are taken into account in the design model. The results is a piston ring with well determinated redius of curvature and ovality, with the best possible running in and sealing features. The geometry, in terms of joint type, is of vital importance for the majority of the modern engine types, especially those engines equipped with gas tight top rings. For all types of rings the closed gap must allow for some thermal expansion, at the same time the gap has to be kept at minimum in order to reduce the leakage area.