There is no shortage of competition between materials in the transportation market. The question is not which specific material to select; in general, the future lies with mixed material designs. The key question is which material is the optimal selection for a specific application, technically and economically; dependent on the type of vehicle, the envisaged design targets, the planned production volume, the existing manufacturing infrastructure and – not least – the available know how and experience.

The crucial step is an integrated design and engineering approach, taking into account the specific properties of the different aluminium alloys and qualities of the various aluminium semis and finished products. Intimate knowledge of the material characteristics, including crash behaviour, enables rapid product development based on computer aided design and engineering methods. Quantitative simulation of the related fabrication processes ensures efficient production of aluminium components and structural modules with consistently high quality.

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. Depending on the applied method, cast aluminium parts can exhibit a wide range of sizes, shapes and properties. Extruded and subsequently machined profiles ,as well as high quality, thin-walled pressure die cast aluminium components, are not only beneficial for load-carrying and/or stiffening functions, but can be applied simultaneously as joining elements. Their proper use enables the development of new, innovative structural design solutions and – as a result – significant weight and cost savings by parts integration and the incorporation of additional functions.

Apart from structural applications, aluminium alloys are also used in transportation for other specific advantages, such as their excellent thermal and electrical properties. The most obvious examples are heat exchangers as well as components for internal combustion engines and electric motors.

A critical factor for success in the transportation market is the assembly step. The assembly tasks range from the joining of individual aluminium components of different alloys and product forms (stamped sheet, castings, machined extrusions, forgings, etc.) to multi-material joining of aluminium to steel, magnesium, plastics and composites. Mixed material designs bring additional complications, since the selection of the applicable joining methods is restricted and other factors such as different thermal expansion coefficients or potential galvanic corrosion effects have to be taken into account. Most of the joining processes developed over many years for steel structures are applicable to aluminium. However, the increasing use of aluminium and, in particular, mixed-material designs has led to the introduction of novel joining techniques, such as laser and friction stir welding, self-piercing riveting and adhesive bonding. As a result, suitable joining methods are today available for all aluminium applications, but the selection of the proper method for optimal technical performance and economical viability is a challenging task.