FORMULATION | FRICTION AND WEAR
Right: This metal/plastic bearing/shaft combination incorporating parts in Witcom’s PPS-2014/316 operates over a temperature range from -40°C to more than 200°C
to achieve the improved lubrication properties needed by its customers, according to Shazia Akhtar, R&D Senior Technologist at the company. These include
long established graphite and blends of synthetic metal sulphides. The company has also been investigating application of graphenes and other 2D nanotechnology additives through a research collaboration with the University of Manchester, where graphene was first isolated and characterised in 2004. Electro-mechanical devices are an important
part of everyday life, whether they raise sun blinds, open the tailgates of cars, or drive the robots that assemble washing machines. All depend on problem-free operation of gears, bearings, guides, and slides working over long periods of time and a broad range of environmental conditions. Witcom Engineering Plastics has developed a
broad range of lubricated engineering plastic compounds for such applications with what it describes as outstanding wear and friction proper- ties. “We see an increasing demand of low wear and friction compounds. In automobiles, buzzing, squeaks and rattles need to be kept to a minimum, as nowadays they are very noticeable, especially in electric vehicles,” says Bram Willemen, the com- pany’s Business Development Manager for Lubricated Compounds. Wear resistance has to be considered alongside other mechanical requirements, according to the company. A recent project for a metal/plastic
bearing/shaft combination assembly incorporating a component in its Witcom PPS-2014/316 grade illustrates this. The compound contains a propri- etary high performance lubricant system in which the coefficient of linear thermal expansion is adjusted to be in the same range as the metal elements. As a result, the bearing/shaft combination remains within the required tight tolerance field over a temperature range from -40°C to over +200°C.
Regulatory compliance Last year, the EU toughened REACH restrictions on use of perfluorooctanoic acid (PFOA), which potentially affects compounds containing PTFE as a lubricant, according to Witcom Product Develop- ment Engineer for Lubricated Compounds Rudi de Telder. “We had to adjust some of our PTFE-con- taining formulations and started a lot of validation projects with our suppliers and customers and have successfully fulfilled all requirements with the new regulations,” he says. “We also initiated the development of more non-halogenated lubricated solutions to provide more eco-conscious options as there will be more environmental pressure on PTFE and PFOA.” The EU 2020/784 regulation was originally intended to limit the amount of PFOA in PTFE micro-powder to 25 parts per billion (ppb) and was due to take effect on 4 July 2020. However, on 8 April 2020 it was superseded by an amendment to another regulation (EU 2019/1021) covering persistent organic pollutants (POPs), which allows for the use of PTFE micro-powders with PFOA at up to 1,000 ppb until 4 July 2022. After that date the limit is expected to revert to the originally pro- posed 25ppb limit. US-based Shamrock Technologies is a global
leader in PTFE micro-powder additives for lubrica- tion and wear resistance modification across a variety of industries. It says it is committed to ensur- ing conformance with the more stringent <25 ppb
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