Secondary aluminium in series production: BMW iX3 breaks new ground in casting

The company sources wheels and wheel carriers from its network of suppliers. However, at the BMW plant in Landshut two innovative processes have been established that revolutionise the casting of aluminium components. ‘Injector casting’ is used for the housing of the electric motor, which combines the power electronics, transmission, stator, rotor and cooling system in a single unit. ‘This process, which we developed and patented in Landshut, enables the mould to be filled efficiently using an injector, eliminating the need for an additional gating system,’ explains a BMW spokeswoman. The lower melting temperature reduces energy consumption, speeds up solidification and improves mechanical properties. The result is thin-walled structures that can still withstand high loads.

Interaction between robotics and sensor technology

The second key process is ‘integral casting’, which is used to manufacture the rear axle carrier in one piece. This construction method reduces the amount of material used, thereby lowering the weight. ‘This not only saves material but also reduces CO₂ emissions both during production and later vehicle operation,’ said the BMW spokesperson. The rear axle carrier plays a key role in driving dynamics and crash safety – the fact that it can also be made from secondary aluminium is proof of the level of development that has been achieved. BMW did not want to provide specific information on the secondary raw material quotas for individual components.

The manufacturing process itself now resembles a finely choreographed interplay of robotics and sensor technology. The impact of automation on the processes is already evident in the core handling stage: robots pick up sand cores directly from the picking station and place them precisely in the mould. During sieve handling, a needle gripper prevents contaminants from entering the melt – a technique that originally comes from CFRP production. Camera systems check the exact positioning before casting. Automation continues even after casting: robots remove the parts and transfer them to the conveyor system, which transports them to the machining area. Even the furnace lid is now operated automatically.

Lightweight construction expertise at the Landshut site

No special rules apply to recycled material in series production. The BMW spokesperson sums it up: ‘The same high standards of quality, safety and reliability apply to primary and secondary materials.’

Responsibility for the cast parts lies largely in-house. Although BMW checks whether it makes sense to outsource each component, the lightweight construction expertise at the Landshut site allows central cast parts to be manufactured in-house. Suppliers remain part of the process, but the decisive development steps are controlled within the group.

Kick-off for the ‘New Class’

The iX3 is the first representative of the so-called ‘New Class’, which represents the next generation of vehicles for BMW. Secondary materials play a strategic role in this. ‘Based on the four strategic core elements, the focus is on circular product development, in which the use of secondary raw materials is implemented as a guiding principle in development,’ explains the BMW spokesperson. This approach is summarised under the slogan ‘Design for Circularity’ and ranges from materials and ease of disassembly to improved recyclability.

However, implementation is coming up against a barrier that lies outside the factory gates: the availability of suitable secondary materials is limited. As demand increases, so does the pressure on recycling chains. For foundry technology, this means that processes such as injector casting or integral casting are ready to go, but their use always depends on access to high-quality secondary aluminium.

Casting remains a key discipline

The iX3 demonstrates that cast parts made from secondary aluminium can be produced in large series, even when they perform safety-related functions. It also shows that highly automated production with AI-supported control is already a reality. This sends a clear signal to the foundry industry: it remains a key discipline when it comes to reconciling decarbonisation, resource efficiency and large-scale industrial production.

Second-hand aluminium is becoming a building block of a new manufacturing culture – with processes that save energy, keep materials in circulation and create components that can withstand the stresses of tomorrow's mobility.

BMW is also increasingly focusing on innovative materials and the use of secondary materials in the development of other components. For example, 30 per cent of the raw material for the engine compartment cover and the storage compartment under the front flap consists of recycled marine plastic. It comes from old fishing nets and ropes.