Reducing Engine Cover Weight and Production Cost
Nissan Europe took metal replacement to a new level in engine cover components for its Pathfinder® and Navara® trucks. Using DuPont™ Minlon® mineral-reinforced nylon resin and DuPont™ Zytel® nylon resin to replace two cast-aluminum parts resulted in less weight and cost, without diminishing function or performance.
Rising gasoline prices and more stringent fuel-economy standards put automakers under pressure to lighten cars and improve fuel efficiency. Much has already been done to replace metal parts with lightweight, high-performance polymers, especially the lower-performance metal parts.
Replacing engine cover parts that must endure extremely high temperatures and aggressive chemicals was a harder task. But Nissan Europe saw an opportunity to reduce both engine (and vehicle) weight, and materials and production costs.
Nissan worked with two companies belonging to MCC Mondragon Corporacion Cooperativa, Fagor Ederlan and Maier, to identify innovative solutions. These companies, in turn, worked with material science and application resources at DuPont to help find a lightweight solution to replace two critical high-performance engine cover parts: the cylinder head cover and the front engine cover.
The cylinder head cover is molded from a mineral and glass-fiber reinforced grade of DuPont™ Minlon® nylon-66 that provides high performance in terms of stiffness, strength, dimensional stability and mold shrinkage. These characteristics help create an enclosed sealing system to protect the valve control components, and prevent lubricating oil from escaping. Minlon® reinforced nylon is able to resist operating temperatures of up to 150° degrees and stand exposure to hot oils and other chemicals typically found in these systems.
The front engine cover has slightly different requirements than the cylinder head cover, and is manufactured with a different material. DuPont resources assisted the manufacturer who selected a 30% glass-fiber reinforced grade of Zytel® nylon resin in order to meet the needs for this application. Resistance to heat and chemicals was an important characteristic, as well as its mechanical strength to withstand both the assembly process (bolting to the engine body) and the daily vibrations within the engine bay.
The aluminum cylinder head cover and front engine cover were both replaced with high-performance, lightweight polymer parts. The advantages of replacing the metal parts included:
- Weight saving of 40%
- Cost savings of 30-35%
- No loss of performance
The polymer parts were tested for heat aging, fatigue leakage and mechanical strength. These characteristics were found to be equivalent to those of the original metal parts. Due to the success of these high-performance polymer parts, other metal engine components are being considered for replacement.