Nissan finds its own path to metal replacement with DuPont high performance polymers
April 2008. In the first development made by Nissan in Europe for metal replacement for under-bonnet applications, the Japanese car manufacturer uses DuPont™ Minlon® and DuPont™ Zytel® for the rocker cover and front cover respectively of its 2.5 litre turbo-diesel engine for the Pathfinder and Navara vehicles.
Both parts were developed by two companies belonging to the MCC Mondragón Corporación Cooperativa: Fagor Ederlan, from Eskoriatza, north of Spain, which has traditionally specialized in engine parts, transmissions and car-body manufacturing either in aluminium or iron, and Maier, a manufacturer of plastic moulded parts for automotive vehicles and other products based in Gernika, Spain. This strategic alliance provides multi-technological (plastic-metal) solutions responding to market demands. By selecting the high performance polymers from DuPont, Maier was able to achieve savings in terms of both cost of production and weight of 30 percent for each of the parts versus their aluminium equivalents, while maintaining performance in line with Nissan’s rigorous demands.
The rocker cover, measuring approximately 47.5 centimetres long by 22.5 centimetres wide and weighing around 1,250 grams, is moulded from a mineral-filled and glass-fibre reinforced grade of Minlon® nylon-66. As a result the cover offers top performance in terms of stiffness, strength, low-warpage and dimensional stability – essential for creating an enclosed seal to protect the valve control system or prevent lubricating oil from escaping. The material is also able to resist operating temperatures of up to 150 °C as well as exposure to hot oils or other chemicals.
The engine front cover, approximately 44 centimetres long and 20 centimetres wide (at its longest parts) and 500 grams, performs similar protective and sealant functions to the rocker cover. Due to its shorter dimensions, whereby stability is less of an issue, a 30 percent glass-fibre reinforced grade of Zytel® nylon resin was used for the front cover’s manufacture. Resistance to heat and chemicals were once more key factors in the material grade’s selection, as well as its mechanical strength to withstand both the assembly process – i.e. its bolting to the engine body – and day-to-day vibrations within the engine bay.
This project was developed by the Maier’s technologic centre MTC, an established supplier to the automotive manufacturer with a reputation for innovative efficiency, and Fagor Ederlan, as a way to show that polymers can at the same time improve cost efficiency and reduce weight versus other alternatives. “By moulding the two parts using high-performance polymers from DuPont, we were able to produce them to the same dimensions and levels of performance as the original cast aluminium parts, yet at a cost saving of 30-35 percent and at a weight saving of 40 percent,” claims Mario Ordoñez, responsible for new materials at Maier. Fagor Ederlan provided the know-how relating to the product’s function, due to their experience in developing aluminium rocker-covers.
Despite the clear benefits, Nissan remained cautious during the two-and-a-half year development period – going as far as developing, in parallel, metal counterparts to be used in case the polymer parts should not withstand, or the process should be delayed by, thorough testing by the automotive testing house IDIADA in Barcelona, Spain, with regards to heat aging, fatigue leakage and mechanical strength. In order to further assure successful compliance with customer requirements, DuPont assisted Maier with comprehensive finite element analysis of the moulded parts, including simulations to improve gate locations, predict material behaviour and provide general processing recommendations.
As a consequence, the injection-moulded parts passed with flying colours and were adopted for serial production on the current 2.5 litre turbo-diesel engine of the Nissan Pathfinder and Navara. These results have made Maier and Fagor Ederlan optimistic about future possibilities to extend metal replacement to other under-bonnet components within the Nissan group, which would in turn help establish its reputation as an innovative and cost-efficient supplier of moulded polymer parts for the powertrain sector.
Fagor Ederlan (www.fagorederlan.es), based in Spain and part of the Automotive Division of MCC (Mondragón Corporación Cooperativa), designs and manufactures parts in aluminium and iron for automotive motors, transmissions and car bodies. With plants in Spain, Slovakia and Brazil, is a supplier to the main car manufacturers. Together with Edertek, its technological centre, it represents a leading company in the development and innovation of different automotive functions. Its plastic engine parts business (Moldatzen) is a joint-venture between Maier and Fagor Ederlan.
Maier, based in Spain and also part of MCC, designs and manufactures plastic components and assemblies for the automotive industry, household appliances and consumer electronics products. The company has plants in Spain, the Czech Republic and the UK, offices in France, Germany, Sweden, Japan and China and joint ventures in Turkey and Japan. In Europe, Maier leads in the development and manufacture of both exterior and interior trim parts for the automotive industry. The company’s products can be found on the vehicles of the world’s top nine automotive companies.
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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The rocker cover (front, left) and front cover (rear, right) for the 2.5 litre turbo-diesel engine of the Nissan Pathfinder and Navara are moulded from DuPont™ Minlon® and DuPont Zytel® respectively. By selecting the high performance polymers from DuPont, the Spanish injection moulder Maier S. Coop was able to achieve savings in terms of both weight and cost and versus their aluminium equivalents, while maintaining performance in line with the Nissan’s rigorous demands.