The automotive industry is on the brink of a revolution, and the plastics industry poised to play a major role. The real plastics revolution in automotive industry began in 1950 when thermoplastics made their debut, starting with ABS and going on to polyamide, polyacetal and polycarbonate together with introduction of alloys and blends of various polymers. The ongoing development of advanced, high-performance polymers has dramatically increased their usage. Originally plastics were specified because they offered good mechanical properties combined with excellent appearance, including the possibility of self-colouring. The application of plastic components in the automotive industry has been increasing over the last decades. Nowadays, the plastics are used mainly to make cars more energy efficient by reducing weight, together with providing durability, corrosion resistance, toughness, design flexibility, resiliency and high performance at low cost.
The average vehicle uses about 150 kg of plastics and plastic composites versus 1163 kg of iron and steel – currently it is moving around 10-15 % of total weight of the car.
Increasing use of plastic in automotive industry
The automotive industry uses engineered polymer composites and plastics in a wide range of applications, as the second most common class of automotive materials after ferrous metals and alloys (cast iron, steel, nickel) which represent 68% by weight; other non-ferrous metals used include copper, zinc, aluminium, magnesium, titanium and their alloys. The plastics contents of commercial vehicles comprise about 50 % of all interior components, including safety subsystems, door and seat assemblies.
Many types of polymers are used in more than thousand different parts of all shapes and sizes. A quick look inside any model of the car shows that plastics are now used in exterior and interior components such as bumpers, doors, safety and windows, headlight and side view mirror housing, trunk lids, hoods, grilles and wheel covers.
PP – Polypropylene is extremely chemically resistant and almost completely impervious to water. Black has the best UV resistance and is increasingly used in the construction industry.
Application: Automotive bumpers, chemical tanks, cable insulation, battery boxes, bottles, petrol cans, indoor and outdoor carpets, carpet fibres.
PUR – Polyurethane materials are widely used in high resiliency flexible foam seating, rigid foam insulation panels, microcellular foam seals and gaskets, durable elastomeric wheels and tires, automotive suspension bushings, electrical potting compounds, hard plastic parts (such as for electronic instruments), cushions.
PVC – Poly-vinyl-chloride has good resistance to chemical and solvent attack. Its vinyl content gives it good tensile strength and some grades are flexible. Colored or clear material is available.
Application: Automobile instruments panels, sheathing of electrical cables, pipes, doors, waterproof clothing, chemical tanks.
ABS – Acrylonitrile-butadiene-styrene is a durable thermoplastic, resistant to weather and some chemicals, popular for vacuum formed components. It is a rigid plastic with rubber like characteristics, which gives it good impact resistance.
Application: Car dashboards, covers.
PA – Polyamide is known as nylon 6.6 or nylon 6. Both these nylons have high resistance to abrasion, low friction characteristics and good chemical resistance. They also absorb water easily and components in wet or humid conditions will expand, precluding their use in applications where dimensional stability is required.
Application: Gears, bushes, cams, bearings, weather proof coatings.
PS – Polystyrene is very popular, ease to manufacture, but has poor resistance to UV light.
Application: Equipments housings, buttons, car fittings, display bases.
PE – Polyethylene has good chemical resistance. Two types are used, low density polyethylene (LDPE) and high density polyethylene (HDPE) can be manufactured in a range 30 of densities.
Application: Glass reinforced for car bodies, electrical insulation, packaging, where strength and aesthetics are important.
POM – Polyoxymethylene (also know as polyacetal or polyformaldehyde) has big stiffness, rigidity and excellent yield, which are stable in low temperatures as well. Very good chemical and fuel resistance.
Application: Interior and exterior trims, fuel systems, small gears.
PC – Polycarbonate has good weather and UV resistance, with transparency levels almost good as acrylic.
Application: Security screens, aircraft panels, bumpers, spectacle lenses, headlamp lenses.
PMMA – Acrylic is more transparent than glass, has reasonable tensile strength (shatter proof grades are available) and good UV and weather resistance, high optical quality and surface finish with a huge colour range. Application: Windows, displays, screens.
ASA – acrylonitrile styrene acrylate material has great toughness and rigidity, good chemical resistance and thermal stability, outstanding resistance to weather, aging and yellowing, and high gloss.
Application: Housings, profiles, interior parts and outdoor applications.
In automotive design, plastics have contributed to a multitude of innovations in safety, performance and fuel efficiency, but it requires never-ending research and improvement. Leading experts say that the easiest and least expensive way to reduce the energy consumption and emissions of a vehicle is to reduce the weight of the vehicle. It is estimated that every 10% reduction in vehicle weight results in 5% to 7% fuel saving. Thus for every kilogram of vehicle weight reduction, there is the potential to reduce carbon dioxide emissions by 20kg. The incorporation of the lightweight materials in automotives is a necessity and our common need.
Technology activities and priorities
Plastics industry is very important in supporting the automotive industry. Automobile engineers are working together closely to optimize other systems, integrating injection and blow moulded parts offering a better product without expensive assembly work. Plastics are also finding their way into the structural design of the cars (the most complicated design problem the tank fuel system has been solved thanks to plastics).
There are four areas requires highest-priority research and development with plastics. These are:
Body and exterior
Interior – priorities for improving safety in the passenger compartment include making safety advances affordable through innovative design and more efficient manufacturing capabilities, designing for increased vehicle compatibility, accommodating an aging driver population, including more safety features in reduced package space, and enhancing safety belt designs .
Body & Exterior – from bumpers to body panels, laminated safety glass to rear parking assists, research activities must include energy management technologies that resist vehicle intrusion, impede roof crush, and reduce body and exterior weight without compromising safety performance.
Powertrain & Chassis – research in this area focuses on components that generate and deliver power and include the frame and its working parts. R&D priorities include pursuing significant advancements in engineering and research capabilities for designing with plastics, exploring new ways to optimize safety and fuel efficiency, expanding predictive modeling capabilities for composite materials, and developing the new safety components that will be required for future alternative vehicles and powertrain options.
Light weighting – for example the marketplace offers new ultra light-weight wheel trims successfully, which provides innovation in products with high rigidity and low weight (these components had to put through high testing due to control of resistance to the weather conditions and long lifetime). Continuous development of new PP types allows the replacement of steel in automotive in the near future as well (for example new type GB 266 WG is hard, light material with perfect heat resistance and mechanical properties; suitable for products used in high stress areas). The transition to lightweight materials from conventional ones requires research activities that will increase the overall value of plastics in automobiles; develop new, high performance components that lower the center of gravity of a vehicle; improve crash avoidance and performance systems; and enhance pedestrian safety.
Reinforced thermosetting resins also have a key part to play. While there is nearly fifty years of experience of the use of glass fibre-reinforced resins in production of bodywork, this has tended to be restricted by the nature of the material to low-volume production (of sports cars and ‘special’). However great strides have been made in the development of processes for moulding fibre-reinforced polyesters and polyurethanes at mass-production levels, there is an increasing number of exterior bodywork panels and bumper systems that are produced in volume in these thermosetting materials.
Focusing on safety of travellers is also a very important area plastics playing part in. As the population of older drivers increases, improved counter measures and crash performance systems will be needed to keep these passengers safe. Many older drivers have lower biomechanical tolerances and require special safety features to avoid injury. With targeted research, highly versatile plastics may enable important advances in safety features that are needed to protect the 65-and-older population. The greatest challenge to plastics in the automotive sector is in recycling (automotive industry has probably the best record of all industries when it comes to recycling its materials – with an average of around 75%, but the expectations are continuously increasing). Fortunately, automakers continue to devise new uses of recycled materials.