Less weight means improved emissions and fuel economy

New research into the substitution of traditional vehicle parts with aluminium components has resulted in a 30% reduction in the overall weight of a typical car. Dean Palmer reports Research into alternative materials for car components has shown that the overall weight of a vehicle can be cut by as much as 30% if design engineers maximise the use of strong, lightweight aluminium rather than traditional steel for many vehicle components and systems. The study, undertaken last year by Aachen University in Germany and commissioned by the European Aluminium Association’s (EAA) Automotive Group, indicated that by maximising the use of aluminium components on their vehicles, manufacturers could cut as much as 400kg off the overall weight of a typical, compact-class steel (monocoque) car. The aptly-named ‘Alumaximised Car’ study involved splitting a hypothetical reference car into sections, then separated into systems and finally into individual components. The theoretical car, which weighed 1,229kg without driver and fuel, was then systematically dismantled and steel parts substituted with aluminium ones. The primary and secondary effect on weight was then calculated. The research team replaced each component, first with proven technology, then latest aluminium technology. In a second phase of the study, additional secondary weight saving effects were taken into account to further optimise potential weight reductions. These included looking at the possible reduction of engine power and size made possible by the weight savings, whilst keeping performance constant. And downsizing the suspension was also considered due to the lower mass of the car, as well as reducing the fuel tank volume whilst keeping the driving distance range constant. Dieter Braun, chairman of the EAA’s Automotive Group, told Eureka: “By maximising the use of aluminium we can help cars be lighter, greener and safer. The Aachen research shows that by alumaximising across the annual production of 16 million cars would lead to a 7.7 million-tonne reduction in CO2 emissions. This would help the European Carmakers’ Association (ACEA) meet their commitment to reduce the amount of carbon dioxide emissions in new cars by 25% in five years and another 14% by 2012.” According to Braun, the study also showed that fuel efficiency would be improved. He explained that in the calculation model used at Aachen, fuel consumption would decrease by around 1.8 litres/100km. More information on the study can be found at www.aluminium.org/transportation/alumaximised.asp Aluminium is already widely used in car manufacturing to aid weight saving. According to the EAA, in 1985, just 4% of the weight of an average car was accounted for by aluminium. But by 2005, it expects this to increase to around 10%. One growth area for the application of aluminium is within the vehicle structure itself. Vehicle OEMs have already taken steps towards using aluminium for welded blanks. Although steel tailor-welded blanks are already an established part of automotive production, Audi and metal giant Corus have recently collaborated to apply this technology to aluminium. The objective is to increase the structural integrity of the car, while reducing vehicle component weight in order to cut fuel consumption and CO2 emissions. Corus says it can tailor-weld two or more sheets of different grades and thickness of aluminium that have been chosen to give the optimum strength, using the least amount of material possible. Both 5000 and 6000 series aluminium alloys are used because of their strong forming capabilities, making them ideal for the vehicle body and chassis. A mono beam laser system provides ‘perfect’ weld quality in both alloy groups. Corus anticipates that in the next 10 years, 25 to 30% of all steel body-in-white car production will include tailor-welded technology. MIFA Aluminium is a Dutch company specialising in supplying precision aluminium profiles and extrusions to the industrial and automotive markets. The firm’s UK area sales manager Rob Van Oene commented: “Aluminium is more expensive to produce than traditional steel and it requires different types of machinery, so we tend to focus on supplying the high-tech, specialist low-to-medium volume auto manufacturers rather than high volume producers such as Ford and Toyota. But we expect the use of aluminium on vehicles to continue to rise in the future.” Oene added that in his experience, aluminium is gaining more credibility for use on car bodies, but is also starting to be used more to finish vehicle interiors.