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Engineering Materials

Enhancing timing drive system performance and sustainability

Government mandates have put automotive brands under pressure to meet stringent CO2 emission targets. To reduce fuel consumption, OEMs are developing timing drive systems that improve the efficiency of internal combustion engines (ICE) in conventional and hybrid drivetrains.

Key timing drive system components need to be made from materials offering excellent wear and friction behavior. Timing chain guides require low friction to optimize fuel economy, and excellent resistance to abrasive and pitting wear that can cause premature part failure. Support arms must offer high stiffness and fatigue resistance to keep chains in place, even at high speeds.

A common way to enhance materials used for timing drive systems is to add polytetrafluoroethylene (PTFE) – a synthetic fluoropolymer of tetrafluoroethylene. When added to polymers as a micro-powder, the additive substantially improves the material’s friction and wear properties. Yet, environmental and safety concerns regarding PTFE have emerged. Some PTFE manufacturing processes produce perfluorooctanoic acid (PFOA), which is linked to serious health risks. PFOA is very bio-resistant and can easily contaminate drinking water and accumulate in wild fish. As a result, regulatory bodies in several countries are expected to fully ban materials containing PFOA by 2022.  

It’s important to consider the risks of using PFTE with even trace amounts of PFOA in materials for your timing drive system. Once production begins, you are committed to supporting the solution throughout the lifetime of the engine it’s used in, which may be up to seven years after launch. Thus, you may be forced to switch to a new version of the low friction material. Switching materials requires you to go through lengthy and expensive production part approval processes (PPAP) to verify its compliance with OEM requirements. These risks can easily be avoided by leveraging PFOA-free materials. 

Advanced PFOA-free material science 

DSM’s Stanyl® PA46 is the industry’s leading material solution for timing drive systems. In 2017, a major car brand replaced the polyamide 66 (PA66) used in its timing drive system components with Stanyl HGR2. The switch enabled V8 engines to achieve a 0.5Nm friction torque reduction, which improved fuel economy by 0.4% and led to DSM and partners winning the Society of Plastics Engineers (SPE) Automotive Innovation Award. PFOA levels in each Stanyl grade we offer, including HGR2, are well below the detectable limit, and we provide all customers with letters of conformity certifying the material’s compliance with regulations.

Proven wear and friction properties 

Due to its high crystallinity, Stanyl provides unmatched performance in under-the-hood applications subject to high torque levels. Compared to PA66, Stanyl achieves a 10-20% lower coefficient of friction in chain guides, which enables manufacturers to reduce CO₂ emissions by up to 1 gram per kilometer. The material’s outstanding resistance to pitting and abrasion wear ensures parts remain highly durable throughout the lifetime of engines. Stanyl-based support arms deliver excellent stiffness and fatigue resistance in high-temperature engines, as well as substantial material cost savings since the final parts can be lighter without compromising mechanical strength. 

Driving sustainability goals 

As part of DSM's commitment to supporting a more sustainable future, our team is developing bio-based alternatives for our entire engineering plastics portfolio for launch by 2030. Our new bio-based mass balanced solution Stanyl HGR3-W demonstrates ultra-low friction properties and improved torque loss reduction to bring fuel savings to the next level. In accordance with the International Sustainability & Carbon Certification (ISCC), the material leaves a smaller CO2 footprint and lower molded part scrap rate compared to Stanyl HGR2. DSM is also leveraging renewable energy sources in facilities worldwide to make our operations more eco-friendly.

Today, Stanyl is used in timing chain systems applied to 50% of newly built cars. DSM works closely with automotive OEMs and Tier 1 suppliers to evolve our material solutions so that they respond to market trends, comply with changing industry regulations and drive best-in-class part performance and reliability. Our global services teams provide comprehensive material, design and application expertise. This enables our customers to manufacture products that exceed the expectations of OEMs and support a healthier future for the planet.

Click here or visit Plastics Finder today to learn more.

Jippe van Ruiten

Application Development Manager Automotive at DSM Engineering Materials

Published on

30 March 2021

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ABOUT THE AUTHOR

Jippe van Ruiten

Application Development Manager Automotive at DSM Engineering Materials

Jippe Van Ruiten is Application Development Manager Automotive at DSM Engineering Materials. He studied polymer physics at University of Groningen and after graduation started his career at DSM in 1988.

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