Aluminium is extensively used in the transport sector. Heading the list of advantages are its unique combination of strength and lightness, corrosion resistance, excellent recyclability, improved safety and design flexibility. Today, aluminium is widely used in cars, trucks, buses, coaches, trains, metros, ships, ferries, aircraft and bicycles.
The combination of lightness, strength and formability make aluminium the ideal material for any transport application. The initial investment in energy is repaid many times over in fuel savings and gains during recycling of most vehicles.
It takes force to move something. Therefore, the lighter the relevant thing is, the less force it takes. A truck, car, train, boat or plane can be moved with less force or carry more cargo at the same force if the vehicle itself is lightened.
Let's not forget non-motorised transport -bicycles, scooters, roller blades- nor mobility aids -wheelchairs, walking frames and chairlifts- all of which also benefit from the properties of aluminium.
The potential of aluminium as a mass reduction material becomes obvious when looking at its specific weight (2.7 grams per cubic centimetre), which is less than half of that of iron (7.8 g/cm3) and copper (8.9 g/cm3). Of course this is a simplistic view, since application-specific design and performance criteria have to be considered for every vehicle component but nevertheless shows the potential of weight saving by replacing other materials with aluminium.
As well as direct weight reduction by material substitution, there are additional possibilities for component light-weighting. Aluminium-specific fabrication techniques, such as complex, multi-hollow extrusions or thin-walled, high-strength, vacuum die castings, enable new design solutions, which lead to further weight reductions.
Safety is the most important factor in the design and customer choice of a vehicle. In the development of the car body structure, it is most important to find a suitable compromise between stiffness, crash performance and further body requirements, such as styling and package restrictions. Aluminium is well suited to reach these goals with maximum performance at the lowest possible mass.
The most important advantage of aluminium for the design of lightweight and cost-efficient structures is its ease of formability. Elaborate sheet panels can be efficiently formed using different methods ranging from high productivity stamping processes to low tooling cost technologies for low volume production.
An interesting aspect compared to competing materials is the availability of extruded, open and closed profiles, with intricate shapes, in different wall thicknesses. Net-shaped and near net-shaped aluminium parts can be produced using forging and other massive forming techniques, but in particular by various casting processes.
As vehicle manufacturers apply aluminium to lightweight their vehicles, the focus is increasingly directed toward the system cost and life cycle cost analysis to obtain the desired outcome of an improved driving performance, reduced fuel consumption or reduced emissions. The manufacture is increasingly considering how to exploit fully the weight reduction in one or more parts, and allow this weight reduction to offer further weight or cost savings in other vehicle components.
Aluminium from transport applications is part of an established recycling system. Recycled aluminium can be utilized for almost all applications, preserving raw materials, reducing emissions and leading to considerable energy savings. Currently, metals, aluminium being the most significant, play an important role in funding the end-of-life processing of vehicles, through their high scrap value.
It is no surprise that some of the most stylish vehicles of the last two centuries, have employed aluminium – both for its functional and also for its aesthetic properties; its durability, formability and wide range of finishes.
The Airstream trailer, London’s Eros, Philippe Starck’s 1006 chair, the iPod, the BMW 328 racing car – all make full use of aluminium’s light weight, strength and durability and are at the same time transformed from functional objects to cultural icons through their stylish look and feel.
Aluminium -even unpainted and uncoated- resists corrosion by water and road salt and, in non-cosmetically critical parts, its use can avoid the substantial extra costs of galvanizing, coating and painting required for some competing materials. Aluminium does not rust if the paint is scratched or chipped. Nor is it weakened or embrittled by desert heat, northern cold, or the ultraviolet radiation in sunlight.
Text: European Aluminium Assosiation, International Aluminium Institute
Photos: Austal, autoblog, Boeing