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Engineering Plastics


Stevenage, July 31, 2007

Cooling-water pipe of DuPont™ Zytel® resists heat, pressure and anti-freezing agent

Cooling-water pipes are exposed to high temperatures and aggressive environment. At the same time they are required to provide long-term leak resistance despite internal pressures of almost two bar. Consequently they have been traditionally manufactured from metal. As an alternative, Hutchinson of Mannheim (Germany) – in close cooperation with Volkswagen – developed a polymer pipe, made of a heat- and hydrolysis-stabilized grade of DuPont™ Zytel® nylon, and manufactured using gas-assisted injection moulding. Used in the 1.6 litre petrol engines from the Volkswagen Group, the pipe fits neatly into the available package space, facilitating the smooth flow of the cooling agent. The pipe made of Zytel® requires substantially less manufacturing expenditure than its metal counterpart, without any restrictions in terms of reliability. Thanks to its exact fit, its elasticity and the ability to integrate fixing plates and branch connections in the moulded part – rather than additional, separate parts – the pipe’s production cost is reduced considerably, while it is also approximately 50 percent lighter than its predecessor.

“We were seeking a polymer that could replace metal in these applications without limitations,” explains Olivier Nicolas, polymer technology manager at Hutchinson. “We compared a number of polyamides, as they have already proven their value in similar fluid transfer systems for the engine- compartment over a number of years. In the end, tests conducted at our laboratory showed that Zytel® EFE7392 from DuPont met all of our requirements – as well as those of Volkswagen. It combines, for example, high glycol resistance with good ageing resistance, high burst strength at temperatures up to 135°C and high creep resistance. Using this material we were able to achieve short cycle times when producing the 650mm-long pipe (when stretched), as well as highly uniform and repeatable wall thicknesses.”

Zytel® EFE7392 is a polyamide 66, reinforced with 33 wt. % glass fibres, which provides high stiffness, dimensional stability and hydrolysis resistance,” adds Laurent Zielezinski, a member of the European automotive development team at DuPont. “The material was not only optimised for the specific application, but was specially developed for gas-assisted injection moulding. Whereas most standard PA 66 grades may not be so well-suited to this processing technique, this specialty grade assists the formation of particularly smooth internal surfaces and uniform wall thicknesses, a prerequisite for flow with minimized pressure loss.”

Volkswagen uses the cooling-water pipe across its group, thus it can be found not only in the VW Golf, Jetta and New Beetle, but also in vehicles from Audi, Seat and Skoda. Nicolas concludes: “We worked closely with DuPont during system development and with regards to processing optimization and material validation. Since the pipe went into serial production, we have had very positive experiences with gas-assisted injection moulding and Zytel® EFE7392, a material optimized for this process. It was therefore a simple decision for Hutchinson to adopt the combined processing and material benefits, in terms of time, weight and cost, for its ongoing development projects.”

Hutchinson is a subsidiary of the Total Group with representations in Europe, America and Asia, and is one of the world’s leading suppliers to the automotive industry. The product portfolio includes components for vibrations technologies, drivetrain systems, sealants and adhesives, fluid transfer systems (low and high pressure), body parts and sealing systems as well as precision seals and moulded parts. The German facility in Mannheim is a competency centre for the development and manufacture of components for the transfer of media (cooling agent, charge air, fuel and oil).

The DuPont Engineering Polymers business manufactures and sells Crastin® PBT and Rynite® PET thermoplastic polyester resins, Delrin® acetal resins, Hytrel® thermoplastic polyester elastomers, DuPont™ ETPV engineering thermoplastic vulcanizates, Minlon® mineral reinforced nylon resins, Thermx® PCT polycyclohexylene dimethyl terephthalate, Tynex® filaments, Vespel® parts and shapes, Zenite® LCP liquid crystal polymers, Zytel® nylon resins and Zytel® HTN high-performance polyamides. These products serve global markets in the aerospace, appliance, automotive, consumer, electrical, electronic, industrial, sporting goods and many other diversified industries.

DuPont is a science-based products and services company. Founded in 1802, DuPont puts science to work by creating sustainable solutions essential to a better, safer, healthier life for people everywhere. Operating in more than 70 countries, DuPont offers a wide range of innovative products and services for markets including agriculture and food; building and construction; communications; and transportation.

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July 2007

This press release was prepared with input provided by:

Hutchinson GmbH
Hansastraße 66
D-68169 Mannheim, Germany
Contact: Olivier Nicolas
Telephone: +49 (0) 621 39 71 - 1 72

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Photo: DuPont
Water used to cool Volkswagen’s 1.6 litre petrol engine flows through a pipe made of heat- and hydrolysis stabilized grade of Zytel® nylon from DuPont. Hutchinson manufactures this part using gas-assisted injection moulding. The technology enables considerable savings in terms of both weight and cost versus previous metal counterparts, without compromising the performance or resistance of the moulded part.

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