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Balancing vehicle performance with sustainability and efficiency
Chris Needes, global market manager, Saint-Gobain, explains how the innovative materials company is helping OEMs hit performance targets
Chris Needes, Saint Gobain
The automotive market has undergone a revolution in recent years. The recession and subsequent economic hardships seriously affected car manufacturers, but now the market is beginning to recover, with European and US vehicle sales predicted to grow for the first time in seven years. However, most of the global growth seen in recent years has come from BRIC nations and other emerging markets. Their buoyant economies and fast-growing consumer markets have led to a surge in demand for luxury passenger vehicles.
Additionally, consumer buying behaviour as it relates to automobiles has changed in recent years, with new concerns about financial constraints and carbon emissions affecting the market globally and locally. More and more, consumers worldwide are selecting vehicles based on safety requirements. Many of these features have been key to purchasing decisions for several years in Europe and Japan, but now there is a growing demand for safety in emerging markets, such as China.
In this climate, manufacturers are redoubling their search for inventive and cost-effective ways to balance consumer and regulatory demands for performance and sustainability in order to thrive in a very competitive market. Often it is the small parts that make a big difference in automobile performance, providing ideal solutions for improved driving experience and efficiency.
Global market trends
Sustainability has been a buzz word in the automotive industry for several years. For example, in the EU, increasingly stringent regulations on car emissions have been introduced by the European Commission over the past decade and new legislation restricting carbon dioxide (CO2) emissions has come into force in 2012, forcing manufacturers to place a greater focus on their environmental credentials, particularly regarding fuel efficiency. To reduce fuel consumption and emissions for environmental reasons, consumers are opting for smaller, lighter cars and vehicles with diesel or hybrid engines.
Cost-effectiveness for both consumers and manufacturers is another major trend. Economic conditions in the US, including rising oil prices and a decline in living standards, are leading consumers to follow their European counterparts in abandoning fuel-reliant cars, such as sports utility vehicles (SUVs) in favour of smaller, more fuel-efficient models. In fact, a recent survey shows that US automotive sales are predicted to top 16 million in 2014 as the industry continues to be driven by small, lightweight vehicles that use less fuel and cost less to run.
Manufacturers, in a bid to drive down costs both for themselves and their customers, are focusing more than ever on achieving production efficiencies, using methods such as Just-In-Time production (JIT) and platform sharing across several models. With JIT production, the focus is on having global suppliers that can provide consistent parts anywhere in the world.
Platform sharing, where major design and component features are shared across several vehicles, allows car companies to reduce costs by sharing car parts and production lines globally. It also allows companies to reduce the number of suppliers and number of plants required, as the same models can be built with the same components anywhere in the world. This new method of manufacture enables car producers to respond more robustly to unforeseen events that may have a negative effect on supply, such as the earthquake in Japan in March 2011 and again, working with global suppliers is crucial.
Other significant trends in the automotive industry are performance and safety. For example, in the BRIC nations, the heart of the worldwide growth in car sales, increasingly affluent consumers are beginning to demand vehicles that offer the same performance and incorporate the same safety and anti-theft features found in cars in developed markets. Cars that offer a reduction in Noise, Vibration, and Harshness (NVH), and incorporate features such as increased deformable space between the bonnet and the engine to protect pedestrians from injury in the event of a collision, or a collapsible wheel column to act as a shock absorber should the driver strike the wheel during a crash, are fast becoming a fixture in car dealerships in these emerging markets.
In order to balance all of these seemingly disparate consumer requirements, manufacturers are searching for solutions that are lightweight to reduce CO2 emissions while meeting cost-effectiveness and performance standards. As well as developing electric and hybrid engines to meet demands for fuel efficiency, manufacturers are using lighter materials in large components, such as replacing steel with high-strength aluminium or magnesium in convertible roof frames, and are replacing even the smallest components with lightweight, high-quality alternatives, for example replacing rolling-element bearings with lighter composite bearings with the a polytetrafluoroethylene (PTFE) liner, offers consistent controlled friction values and excellent dampening properties to decrease vibration inside the vehicle. With these components and materials it is now possible to achieve the same performance values, such as safety, comfort and reduced NVH, while enhancing the smart design of the car through reduced weight, space and thus fuel consumption.
Improving automotive efficiency
In working to improve fuel efficiency, manufacturers must be careful to not jeopardise performance or safety and also consider the cost implications for the manufacturing process. Key to achieving this objective is the use of the ideal components for each application.
In looking at the exterior of a vehicle, manufacturers have started to evaluate the use of magnesium in place of steel in convertible car roof frames. However, using traditional steel-backed bearings in the pivots of a magnesium roof frame may leave the frame at risk of galvanic corrosion, where the more active metal corrodes preferentially to the more noble metal when immersed in an electrolyte, such as rain water. To prevent this, composite bearings backed with a metal of similar galvanic potential must be used. These lightweight, high-strength component alternatives not only extend the life of the roof, they also further reduce weight.
Additionally, reducing the weight of car doors is a focus, with aluminium door hinges increasingly used. However, aluminium is more susceptible to thermal expansion than traditional steel, which can affect the performance of the hinge. To circumvent this problem, steel-backed composite bearings have been developed with a larger outer diameter, creating a stronger press fit to compensate for the expansion of the housing. Improved tolerance compensation achieved through the tailored PTFE liner and material structure ensures consistently perfect fit between mating parts. In addition, aluminium-backed composite bearings can also be used to achieve the same thermal expansion levels as the aluminium housing.
Aluminium-backed composite bearings with the PTFE liner are corrosion- and wear resistant contributing to the long, maintenance-free life of the door hinge and enhancing quality perception of the car.
Manufacturers have also discovered new ways to reduce weight while offering the same performance values in the car interior. To achieve this, manufacturers are now using ultra-high strength steels instead of traditional materials in seat frames, which have enabled them to develop thinner, and therefore lighter, components that are able to bear the same loads as heavier designs. This has had an impact on the design of seat adjustors. The weight reduction in the seat frame has led to an increase in load on the adjustment pivots and on the bearing. To combat this, manufacturers have turned to higher quality composite bearings, which combine a thin design with a robust internal structure, to enable the component to withstand the extra loads created by a slimmer frame design. Thus, the use of innovative composite bearings allows car manufacturers to enhance the smart design of their vehicles with the use of fewer, lighter and smaller components.
We can also look at chassis design for examples of reducing weight in a cost-effective manner while improving safety and performance. Electric power steering systems have been adopted over the past decade to replace traditional hydraulic systems. These motors have traditionally been large and heavy to ensure high performance under high loads. However, more and more manufacturers are developing new smaller electric motors to help them meet weight reduction targets. To maintain the same comfortable, smooth steering experience offered by earlier larger motors, high-performing composite bearings with consistently low friction values are now being used at the interface between the motor and the rackshaft, enabling the smaller motors to turn the shaft as easily as larger models, while giving improved steering response and driver handling.
Thanks to advances in technology, powertrain components have been developed that support consumer weight requirements while offering improved NVH reduction, particularly with regard to the dual mass flywheel. The dual mass flywheel dampens torsional vibrations from the engine to prevent them reaching the gearbox, resulting in a more comfortable driving experience for the motorist, even at low Revolutions per Minute (rpm). The trend towards ‘downsizing’ engine components, such as reducing the number of cylinders, can actually increase the intensity of torsional vibrations. In order to combat this, manufacturers are now using composite bearings in the dual mass flywheel. The low friction values offered by the engineered components with the PTFE liner have led to NVH reduction compared with previous models and therefore contributed to noise-free mechanism performance. This in turn has enabled the development of smaller engines that reduce fuel consumption and CO2 emissions without sacrificing comfort for the driver.
The market trends of recent years are clear and look set to continue well into the future. Rising oil prices and more stringent legislation regarding CO2 emissions are driving weight reduction and other energy saving innovations in the automotive industry. The demand globally is for high-quality vehicles that are affordable yet meet performance and safety demands. With innovative components, manufacturers can respond to these global trends without compromising on quality or cost.