Technological Innovation in the Plastics Industry Brings Dramatic Changes for European Auto Makers

By Laura Carrabine, Editor

In the last decade, the use of plastic components in the automobile industry has grown exponentially. Since today's consumers want vehicles that are safer, more comfortable, fuel efficient, affordable, stylish and environmentally friendly, the use of plastics is key to providing technological innovation. Plastic materials are strong yet lightweight, versatile and flexible, allowing technological innovation and design freedom.

Automotive engineers seek materials that can adapt to sophisticated aesthetics, safety, comfort, fuel efficiency, engineering demands and electronic performance at a cost-effective price. Implementing plastics helps auto manufacturers meet these demands. The use of plastics per automobile has grown from a few kilograms to approximately 105 kilograms according to figures from the European Plastics Converters (EuPC) consortium.

During the last 20 years, the advantages of using plastics have changed. Originally, plastics were specified because they offered good mechanical properties combined with excellent appearance, including the possibility of self-coloring. As the automobile industry developed, plastic suppliers have responded to legislation, manufacturers and consumers.

Rising costs are being addressed by the ability of plastics to be molded into components of complex geometries that often replace several parts made of other materials, thus simplifying assemblies and reducing costs. Plastics' light weight characteristic also helps reduce the overall weight per vehicle, which reduces fuel consumption and allows for more sophisticated systems and components - including safety systems - to be included in today's vehicles without adding to the overall weight. This phenomenon has facilitated more sophisticated heating/ventilation/air conditioning systems, in-car entertainment systems and additional airbags without incurring additional weight. Without plastics, today's car could weigh an additional 200-300 kilograms. Plastic panels on Daimler-Chrysler's "Smart Car" are strong but lightweight, improving fuel efficiency. On average, the car uses only 4.8 liters of fuel every 100 kilometers and emits less than 120 grams of carbon dioxide per kilometer. In addition, substituting conventional materials with plastics leads to a direct primary weight reduction.

Many types of polymers are used in more than 1,000 different automotive parts of all shapes and sizes. While up to 13 different polymers may be used in a single car model, three distinct types make up 65 percent of the total plastics used per vehicle: polypropylene (32 percent), polyurethane (17 percent), and PVC (16 percent).

Car interiors reveal a wide use of plastics, including instrument panels, interior trim and upholstery. Aside from the passenger compartment, lighting, bumper systems, fuel storage and delivery systems, ducts, fenders, exterior body panels and engine components are increasingly made of plastics. The new VW Beetle, for instance, is entirely modern, from plastic bumper to plastic bumper. Advances in polymer technology have improved plastics' heat resistance so that large car components such as bumpers remain in perfect shape, even at high-temperature processing. The VW Beetle is one of the first high-volume vehicles to benefit from this technology, allowing its plastic bumpers to be integrated into the painting process. Plastics' versatility allows for advanced shapes and forms without compromising the safety, comfort or stability of a car. Their strength and durability play an important role in expanding the average life cycle of a car to more than 12 years by providing better protection against corrosion. The new rear bumper on General Motors' Saturn coupe is a single molded part called a solitary beam. It replaces the function of 13 parts in the former aluminum bumper system. Approximately 100 kilograms of plastic replace 200-300 kilograms of traditional materials in today's vehicles.

Other innovations include the use of computers to control engine performance, creating innovative applications for plastics where metal parts could not perform. As cars change from mechanical to more electronic machines, the need for car components to provide electronic shielding and heat and chemical resistance increases. The result is greater demand for thermoplastics. In smaller, advanced applications, new engineering plastics such as polybutyleterephthalate, aliphatic polyketone, and liquid crystal polymers are increasingly used in new, highly demanding applications including connectors and housing for electrical components.

Because of plastics' strength and impact properties, they provide essential safety features from shock absorption for bumpers to air bags, side impact protection and seat belts. The Opel Astra T3000 incorporates impact resistant plastics in each side door. This enhances passenger safety in the event of a side impact because the plastic does not splinter or break. Plastics have replaced glass in the headlights of the Mercedes Benz S Class vehicles, allowing greater design freedom and offering a clean, easy to fit, scratch resistant and stronger alternative. Renault's new Clio takes advantage of plastics versatility. Plastics account for more than 10 percent of the car's total weight. Their use in the car's wings has dramatically increased shock resistance. They have also enabled better design of the intake manifold and a more cost-efficient fuel system.

By using plastics, car makers have reduced vehicle assembly time and costs. Bumpers, fenders and dashboards can be molded as single parts. Plastics are also beginning to replace conventional materials in throttle bodies, and a number of companies are now leading the development of polyetherimide throttle housings that are 40 percent lighter than the aluminum equivalent and cost up to 40 percent less.

A greater use of plastics is vital to producing more energy efficient vehicles. Strict government regulations demand that automobile manufacturers produce products that minimize negative environmental effects, and save natural resources. The nylon air-intake manifold in the new Porsche Boxster, for example, weighs 50-60 percent less than its aluminum alternative. The low flow resistance on inner walls improves fuel economy and performance. Simultaneously, the nylon components offer low thermal conductivity and are recyclable. Initiatives by many European cities to reduce carbon monoxide emissions and improve air quality have led to greater focus on battery-powered vehicles. These cars use increasingly more plastics in their basic structural components to reduce weight and help make the limited power sources last longer. General Motors' Electric Vehicle (EV1) uses plastics throughout its body, including the battery and rear suspension. Electric cars of the future will use fuel cells made of plastic.

Another challenge for automobile manufacturers is the increasing demand for plastics recycling. While the automotive industry has a good record for recycling materials - an average of approximately 75 percent - the requirements established by the European Union set even higher standards. The plastics industry has demonstrated that thermoplastics can be readily recycled by conventional melt processing and its thermosetting composites can be handled by grinding them to powder and reuse in new compounds. Most automotive groups, in partnership with plastic material suppliers and key automotive molders, have developed 'closed loop' approaches, in which certain parts are designated to be recycled to produce other parts. In addition, technologies are being introduced that will permit mixed and contaminated plastic parts to be broken down chemically for reformulation as new plastics. The challenge for the automotive industry and plastics suppliers is to work together to develop new assemblies that meet cost/performance requirements and allow easier dismantling and recycling.

A study by Mavel, commissioned by APME, examined the use of plastics in the automotive industry in France, Germany and Italy compared to the Western Europe average. In the 1970s, German car manufacturers led the way in exploiting plastics' advantages of cost efficiency and design, using approximately 40 percent more plastics in an average car than Italian and French manufacturers. Through the 1980s, Italian carmakers used more and more plastics in the design of their cars. By the 1990s, manufacturers across these countries had adopted many of the same techniques, with plastics becoming a key material.

A Case in Point: Audi switched from aluminum to plastic to manufacture this cylinder head cover. The switch to plastic resulted in 20 percent savings in cost and 30 percent savings in weight compared to aluminum. The company used Moldflow software to optimize the wall thickness of the new plastic part. Building CAE simulation into the design-to-manufacture process eliminated the need for mold changes and significantly reduced development time.