Nylon cuts rocker cover weight by almost half

The Chrysler Group’s new Dodge Caliber , Jeep Compass and Jeep Patriot models are now rolling off assembly lines with engine rocker covers made from DuPont’s Zytel nylon 6/6.

These rocker covers weigh 40 per cent less compared to traditional covers made from aluminum or thermoset plastics, and are manufactured by Bruss Sealing Systems — a division of Bruss North America Inc. — a producer of thermoplastic (TPO) valve covers.

Gianluigi Molteni, manager of DuPont’s Automotive Powertrain Segment, said this grade of Zytel nylon 6/6 was selected because it can withstand long-term exposure to a harsh, hot-oil environment — testing involves immersion in engine oil for 3,000 hours at 150 degrees Celsius. “The material’s higher melting point, hydrolysis resistance and mechanical property retention, including creep resistance, enable thermoplastic covers to withstand demanding thermal cycling tests used by OEMs to determine system sealability,” he added.

DuPont’s automotive team also joined with Chrysler and Bruss to develop a new design for the vehicles’ air-oil separators, which are housed under the rocker covers. These new air-oil separators pull 90 per cent less oil into a vehicle’s engine, meaning less oil is burned by the catalytic converter, significantly reducing tail-pipe emissions.

“The [Zytel nylon 6/6] was critical in the success of the rocker panel project,” Mike Cuneo, director program management, Bruss North America Inc., said. “It retains mechanical properties, notably creep, and resists aging better than nylon 6 resins when exposed to hot air, hot oil and hot water.” The Zytel nylon 6/6 grade also offers high flow, Cuneo added, helping to reduce production cycle time.

E.I. du Pont Canada Co. — Engineering Polymers Division (Mississauga, Ont.); www.plastics.dupont.com; 905-821-5953