ADDITIVES | SURFACE MODIFICATION
Table 2: Tribological properties of the new Star L POM DW1 compound compared to 15% PTFE filled POM PRODUCT
POM +15% PTFE
TRIBOLOGICAL PROPERTIES / ASTM G133 Friction Coefficient (25N ASTM G133) – Static Friction Coefficient (25N ASTM G133) – Dynamic Wear Rate (25 N ASTM G133) – (10^6xmm3 Low noise
Source: Eurostar Engineering Plastics
while 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.
Below: Internal lubricants must improve slip and wear without compromising mechanical performance
“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. Ensinger, another company specialising in high performance plastics, had one of its spotlight exhibits at Fakuma last year on compounds based on polyetheretherketone (PEEK), including types with special tribological properties. These compounds may contain PTFE and also mineral additives for lubrication. “At Ensinger, the demand for optimised PEEK
formulations has grown continuously in recent years,” says Thomas Wallner, Head of Compounds Sales & Marketing. “Originally, the focus was on compounds with improved sliding and friction properties for the automotive industry or mechanical engineering. But also in other sectors, such as the food and electrical industries or medical technology, the requirements in production are increasing and thus the need for innovative solutions.”
Ensinger has developed compound
formulations for very high loads for components in the automotive industry and in plant and mechanical engineering. It says components made of Tecacomp PEEK TRM “exhibit the lowest possible wear and friction as a sliding element.” The company has also developed materials that provide increased mechanical strength.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.agcce.com AGC Chemicals Europe �
www.shamrocktechnologies.com �
www.tribotecc.at �
www.colloids.co.uk �
www.lehvoss.de �
www.eurostar-ep.com �
www.ensingerplastics.com
24 COMPOUNDING WORLD | February 2019
www.compoundingworld.com /N.m)
0.21 0.25 7
++ Star L POM DW1
0.09 0.13 4.8
+++
PHOTO: SHUTTERSTOCK
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