Those offering different materials to the automotive marketplace now need to argue a considerably more complex case than mere physical characteristics and price

Anyone tracing the history of material use in the automotive industry will find that what historians term the ‘Whig approach’ will not do. There’s simply not a simple timeline tracing a clear direction, with the past merely being a build-up to the present, and progress moving in one direction.

Instead, a more complex reality reveals manufacturers and suppliers juggling competitive pressure, customer demands, legislative constraints, alternative processing technologies and cost pressures. Choices that make commercial sense at one point are quickly reversed when a new processing method becomes viable, or relative material costs change. When looking at the industry over the past decade, we certainly need to abandon the simple notion that metals are giving way to plastics, as if the materials could simply be substituted one for the other, with cost the only driver. Nor is there much hope that end users will appreciate the contribution that particular materials make to the increasing sophistication and refinement of finished vehicles. The plastics that have had such an impact on reliability and performance will, as likely as not, still be presumed as evidence of cost-cutting, whereas the contribution rubber makes to the refinement and suppleness of the their vehicles will be as poorly understood.

Back to the future The role of plastic has been traditionally evaluated against a template suggesting it was a competitive ‘substitute’ material. Analysts would look at vehicle components made of traditional materials and ask: ‘could this be produced cheaper and lighter using a plastic or composite material?’ Each innovation would be hailed as plastics making inroads into areas dominated by metallic parts. The greatest excitement, though, was reserved for those occasions where a technological development produced plastics with the durability and temperature resistance suitable for use in drivetrain or power units, rather than rocker covers and sump pans. The past decade has shown the falsity of this simple model, with trends reversing on occasion. New environmental concerns have altered the balance between materials, with metals sometimes even replacing plastics. Sophisticated lifecycle analyses of the environmental impact of products and processes have upset many of the simple assumptions about environmental costs, while recent energy and feedstock prices have eroded any positive forward motion. Those offering different materials to the marketplace now need to argue a considerably more complex case than mere physical characteristics and price. Perhaps typical of the companies challenging the notion of plastics as mere substitutes is JSP, leaders in the production and development of expanded polypropylene with its ARPRO brand. Work undertaken with Volvo illustrates the point. By tailoring the use of ARPRO to specific seat systems, the company can exploit the full potential of what might otherwise seem a simple, basic material. The high strength-to-weight ratio of its engineered foam, with its ability to return to its original shape following dynamic stress, has important usage implications. As a substitute for existing materials, it may offer advantages of weight and resilience, but for its real potential, designers are asked to stretch their imaginations and rethink seating systems and related floorpan areas.

Sensitive material can add value downstream
Traditionally, the anti-submarine ramp has been a part of the body-in-white process involving complex, carefully formed pressings and expensive tooling changes. Working with a leading interiors integrator, JSP found that using ARPRO to integrate the anti-submarine ramp into the seat, a simplified, consistently-shaped floorpan structure could be used. This had important knock-on production benefits, as the requirements of different body variants could now be met using a common floorpan configuration. As is so often the case, incorporating a new material generates change in the way the component is configured, with repercussions and benefits across designs and even whole model ranges.

The task then for the plastics supplier is to move its customers away from simple cost comparisons between likefor- like products – the substitution logic of a previous phase – moving on towards an appreciation of the complex way in which sensitive material choice can add value downstream. JSP finds its customers more than responsive to these possibilities.

Competitive pressure now ensures that even the most cautious manufacturer and component supplier has a flexible approach. Paul Compton, Executive Vice President and Chief Operating Officer of JSP describes the company’s key strengths: an ability to react quickly to any design challenge, be proactive in realising opportunities, with clear and decisive evaluation.

A wide range of suppliers have developed sophisticated, modular approaches, offering carmakers fully-integrated solutions to specific vehicle areas. Plastics have been a key element of these developments, and the attraction of these modules fitting vehicles across common platforms is obvious. Comparable development in automotive glazing has recently emerged, with suppliers such as SABIC Innovative Plastics encouraging designers to fully exploit the potential of functional integration within glazing systems using injection-moulded polycarbonates.

Lightweight glazing technologies using polycarbonates address the apparent conflict between establishing high levels of crash performance and passenger safety, while offering the levels of visibility that customers demand. Highperformance Lexan polycarbonate allows new flexibility in the generation of aesthetically-pleasing roof and window shapes. SABIC worked with Land Rover to assist in the development of the LRX concept vehicle, a popular attraction at the 2008 British International Motor Show. Bayer MaterialScience offers its BayVision concept, providing manufacturers with a single-source service, encompassing the entire process chain. Using its Makrolon polycarbonate products, Bayer speaks of weight savings of up to 50 per cent and a freedom from many of the design constraints imposed when using glass.

Working with software developers
Essential to any innovative use of new materials in automotive design is the performance data and modelling information needed to allow engineers to explore a material’s potential. This is where traditional materials with stable structures can gain a head start. To counter this, those promoting new materials have increasingly sought to work with software developers and others to ensure that their materials can be analysed from both a performance and process perspective.

Moldflow provides plastic simulation software that allows engineers to analyse and optimise their plastic injection moulding designs for the manufacturing process. The ability to model different processes, improve warpage predictions and provide venting analysis of thermoset materials are among the capabilities that ensure designers can get the best from the materials and processes they choose.

Executives in the plastics industry, perhaps more than most, feel the need to maintain a clear commercial focus. While headline-grabbing ideas and hi-tech partnerships with academic and research organisations are essential components of a developing and challenging industry, long-term growth will still require the correct commercial decisions. Yet, the more adventurous exploration of future plastics – or any material for that matter - cannot be left solely to those involved in the industry. Wherever governments have sought to encourage hi-tech developments, they have found it favourable to promote joint industry-academia-government collaboration on projects with a speculative edge. For some in the industry, there is a degree of scepticism about these collaborations, as they do not always have the commercial impact their promoters would like.

Yet even those most comfortable with the belief that markets can generate the product innovations necessary for commercial success will usually agree that the complex environmental agendas coming to the fore may demand more than pure market triggers if they are to be addressed. Bioplastics are a case in point. Japan, for example, is home to the new ‘Mazda Bioplastic Project’, in which the carmaker has signed a collaborative research agreement with Hiroshima University to develop non-food based cellulosic biomass for use in vehicle construction within five years. Using non-edible plant matter, including plant waste and wood shavings, a carbon-neutral bioplastic would conserve food resources, while moving away from a reliance on increasingly costly and problematic fossil fuels.

Waste not, want not
Following Mazda’s pioneering research into biomass technology and the production of heat-resistant bioplastic, the potential applications for this new material include vehicle bumpers, interior panels and a range of other components. A 100 per cent plant-derived fabric is already used in the interior of the Mazda Premacy Hydrogen RE Hybrid, available through a commercial leasing programme scheduled to begin this year.

Both Toyota and Mazda, and their associated suppliers, have expressed optimism about the potential of bioplastics derived from corn. However, the use of foodstock for bioethanol has led to increasing maize prices, leading to concerns over the practice and the effect it is having on basic living standards. It is the cause-effect linkages of this sort that emphasise the climate of uncertainty in which technological development is currently taking place. With the conventional wisdoms of economic development and progress being increasingly challenged, and dramatic shifts in the geography of industrial production and vehicle usage, technological possibilities can no longer simply be measured against a price matrix. Instead, complex social, environmental and political influences have to be factored in to the equation.

New possibilities with nanotechnology
In nanotechnology – the study and manipulation of materials at dimensions of less than one hundred nanometres, or 0.0000001m - a new range of possibilities has arisen, with advances in the properties of thermoplastic resins and more resilient coatings and body paints having been revealed. Polymer nanocomposite materials have been developed that possess significant electrical conductivity, which in the future will have potential in wiring and the use of metallic components, while nanoclays and nanocomposite fillers already outperform conventional reinforcements and fillers in a variety of thermoplastics.

The US Society of the Plastics Industry highlights the research that is being done in ‘Nanohybrid’ plastics, offering the possibility of new plastics with an engineered decomposition profile, rapid decomposition addressing the associated environmental concerns. The organisation points towards the challenges of advanced energy storage as a source of new commercial possibilities and applications. The automotive sector dominates the rubber market, with approximately 90 per cent of natural rubber and 45 per cent of synthetic rubber going into new tyre production. Extra automotive uses include hoses, belts, bushings, sealants, flooring and seating.

Bonding rubber
In automotive use, rubber is almost invariably coexisting and co-dependent on other materials. Arguably the most important developments with this material in recent years have come in the bonding processes used to make the rubbers adhere to other materials and components, with more sophisticated understanding of the requirements generated by seal behaviour in particular conditions. Pirelli, for example, points to work done over many years to enhance the adhesion properties of steel cord used in tyre construction by means of new coating technologies and drawing processes. Environmental concerns have led to detailed lifecycle analyses of the impact of tyre construction and performance.

This in turn has focused efforts to reduce rolling resistance, generally seen to have the greatest effect in reducing energy usage and environmental impact. Tyre construction techniques have their part to play but for the past decade or two, new high-performance silica fillers have also played a role. More recently, Rhodia Silcea has introduced a new Zeosil Premium range of high surfacearea silica filler options that promise a further marked reduction in rolling resistance, alongside other benefits. Perhaps significantly, the two most widely-noted challenges to traditional rubber tyres have, to date, made relatively modest progress since their initial introduction. The Michelin ‘Tweel’ project encountered vibrations and noise difficulties when used on passenger cars and development has seen commercial progress restricted to low-speed vehicles and niche markets. Similarly, the Amerityre project using polyurethanes has been confined to low-speed agricultural and utility vehicles.

Moulds and foams
Developments in moulding technologies offer opportunities for the innovative use of rubbers. Newly-developed selective self-adhesive silicone rubbers can be co-moulded with nylons, polycarbonates and PBT-type polyesters in ways designed to eliminate assembly operations. Likewise, co-moulded silicones are replacing natural rubbers in a range of automotive applications.

In the short term, there is increasing interest in rubber foam products. Lightweight, open cell foamed rubber has a range of uses within the automotive sector. Silicone foam rubbers offering high compressibility, such as the MTI Leewood Magnifoam and MagniCell products, lend themselves to sound attenuation and vibration reduction. Materials such as Thermoplastic Polyurethane (TPU) serve to bridge the gap between plastics and rubber. Huntsman, for example, offers a wide range of soft elastic TPUs suitable for high-temperature applications, while the company’s Advanced Materials Division has developed resin transfer moulding processes that allow the production of complex composite parts in a single process to high degrees of accuracy.

Alternative challenges
At least one recent study has identified the use of alternative power sources as a major challenge to the rubber industry, suggesting that these developments are likely to offer less, rather than more, potential for the use of rubber because of the reduction of inherent vibration and the absence of traditional cooling systems. Whether future automotive power sources will open any new applications for rubber, only time will tell.

If the complex interactions that form the environmental impact of particular material choices are one part of the equation, the challenges now become even more severe with unstable energy and raw material prices. The effect of rising energy costs have been severe, but the unstable nature of raw material costs have posed particular problems for the rubber industry.

The paradox is that in times of uncertainty, the inclination is always to choose familiar and traditional materials. Yet environmental and competitive pressures now mean that designers can no longer simply play it safe if they want to preserve market share and enhance product appeal. End users may remain indifferent and unaware of what materials are used in their vehicles, but technologists and designers are sure to be faced with ever more complex choices.