Tribological properties of the new Star L POM DW1 compound compared to 15% PTFE filled POM
Compounding World Feb 2019
Eurostar Engineering Plastics Technology Manager Alexis Chopin discussed (among other things) its recently developed Star L DW series based on a new self-lubricating technology.
“This family of compounds offers a unique value proposition compared to standard PTFE lubricated compounds,” he says. Chopin highlighted in particular an unfilled POM grade, Star-L POM DW1. “For high performance engineering components requiring good tribological properties, POM is widely used due to its properties such as low friction coefficient, excellent wear properties, good fatigue and creep resistance and exceptional dimensional stability,” he said. “Internal lubrication is often needed especially for high speed/high load long-term applications,” according to Chopin. He says current technologies based on PTFE or silicone oil have various limitations: a high PTFE loading may be required, and PTFE is halogenated (a concern for some specifiers). PTFE also increases density and affects mechanical properties. With silicone oil, there can be issues with migration and contamination.
The new Eurostar self-lubricated POM is halogen-free and is based on a new modifier used at a very low loading (1-4%). Chopin says it provides tribological performance better than POM containing 10-20% PTFE. Wear resistance is higher, CoF is lower, and it is also stable over time. Density of the compound is lower than a PTFE modified POM, and the additive has a “limited effect on compound mechanical and thermal properties.” Chopin said that the additive does not migrate, and mould deposits are low. It also helps reduce noise.
He cites potential uses in gears and bearings, conveyer systems, sliding and moving parts in general, and hinges. Not all are moving away from PTFE, though.