Modern engines and state-of-the-art piston designs present a challenge for the tribological load capacity of the piston skirt. The skirt coating system NANOFRIKS developed by KS Kolbenschmidt to minimize friction and wear fully meets these requirements. The latest findings of nanotechnology were applied for the first time to this skirt coating.
Tribometer measurements have shown that the NANOFRIKS coating reduces both dry friction coefficient and wear by more than 50 % compared with conventional production coatings. Thanks to a well matched combination of nano-particles, binder, solid lubricant and additives, NANOFRIKS is setting new standards. A further improvement in the wear resistance of NANOFRIKS can be achieved by the additional integration of carbon fibres.
The high wear resistance attained with NANOFRIKS allows higher maximum surface pressures to be applied to the piston skirt. This offers greater flexibility in generating a piston design with low hydrodynamic friction. This philosophy has already been consistently and successfully applied in the development of the low friction LITEKS 2 concept.
The advantage of the NANOFRIKS coating in terms of reduced friction loss was successfully demonstrated using a fired single cylinder engine (floating liner principle). Significant mixed friction improvements are obtained near the dead centres, especially in the maximum cylinder pressure region, compared with the standard coating LOFRIKS 2. Depending on the operating condition, friction could be reduced by 4 ? 9 %.
NANOFRIKS thus offers a sustainable solution for meeting the current customer requirements for reduced fuel consumption and good reliability in engine operation. The successful series production launch of NANOFRIKS at a large European carmaker in 2008 bears evidence to the performance and reliability achieved with the new coating system and underlines the leading role of KS Kolbenschmidt in the area of piston coating technologies.