The role of aluminum in vehicle construction is receiving renewed attention with custom-built aluminum pallets such as those in the Polestar 5. Weight reduction and machining processes are at the core of many activities in the industry. (Photo: Polestar)
Volvo’s announcement that complete body parts for the next generation of electric cars will be produced using an aluminum casting process and that it will invest significant sums in the main Swedish plant in Torsland can be seen as a real commitment to aluminum as a material – And as one of the lightweight construction and bravery to break new ground in body building. In addition to Tesla, an important OEM that can be described as a classic is currently on stage, which offers a promising, if not easy to master, process as an alternative to the tried and tested sheet metal housing construction.
What is referred to as massive broadcasting in a Tesla environment is called massive broadcasting by Volvo. It describes a process in which entire body parts are manufactured under high pressure into giant stamps with the help of specially designed aluminum alloys. The goal is to avoid the multi-part nature of components common in steel construction, to reduce processes and robotics in chassis construction, and of course reduce the weight of electronic cars.
It remains to be seen if this will really lead to the desired benefits in terms of running the business and reducing weight. Body building aluminum casting can still make a career in target quantity lane in green field projects, As Professor Wolfram Falk of the Technical University of Munich says in an interview with Automobil Production. Aluminum initially took its first professional steps with components for the chassis. For some time now, materials such as forged aluminum alloy or ductile cast aluminum alloy with low silicon content have been used to reduce the weight of steering knuckles, wishbones or wheel carriers, which were previously made of cast iron or forged steel.
The aluminum problem is long chips
Especially in the field of chassis parts processing, you hear new things from the tool industry these days. Precision manufacturer Walter cutting tools. According to experts, aluminum alloys can be formed at completely different speeds than traditional cast or steel materials, but this does not mean that the processes are easier. Long chips are a major risk factor, explains Fabian Huebner, Walter’s director of components and projects. “Additionally, compound edges can quickly form on the cutting edges of tools. It quickly becomes difficult to comply with specified tolerances for installation dimensions and surface qualityexpert says.
According to Huebner, complete cavities are particularly challenging. While pre-rigged indents are often drilled for the wheel hub bore on the wheel mount, smaller bores, for example on the wishbone, are made into the solid. According to Tübingen tooling experts, it takes more than just drilling a hole: Specific flat surfaces or edges must also be applied, Walter emphasizes. This quickly leads to up to five processing steps. Experts have found a solution in the form of the so-called hybrid gadgets. This means that the tool body enables different manufacturing steps.
Forged, heat-resistant wrought aluminum alloys with magnesium and silicon put a lot of stress on cutting edges in particular. Wrought aluminum alloys also form long chips or even flux chips, which, according to Walter, can significantly jeopardize the smooth manufacturing process. For this purpose, indexable inserts developed for aluminum fabrication have a special geometry and coating. With the help of the so-called HiPIMS Coating (for: High Energy Magnetic Spray) One wants to provide an extremely smooth, drip-free surface that prevents so-called build-up edge formation. As an example of their success, tool experts talk about a customer who was able to achieve cutting speeds of more than 1,300 m/min with a revolution feed rate of 0.11 mm when drilling holes in the wishbone with a hybrid tool in the drilling stage using a diameter of 50 mm.
BMW enhances the efficiency of aluminum use in tools
Another tool innovation coming from BMW these days. Specifically, the experts at the Light Metal Foundry at the Landshut site introduce what’s called a multi-panel die technology that promises to reduce CO2 in the process and reduce weight when looking at the components. “By developing new gate systems and de-moulding using a direct gate in multi-plate molding technology, component designs that are optimized for function rather than flow path optimization can be achieved in the die casting process. In addition, component weight can be reduced by up to 20 percent with the same functionality‘,” says Klaus Summer, Head of Tool Manufacturing, Maintenance and Advanced Development at the Light Metal Foundry in Landshut.
Process optimization makes product designs with optimal use of materials and a weight-neutral conversion to alloys with lower CO2 emissions possible. As you can hear from the OEM, Landshut’s existing systems can also be used to cast structural components in the future. BMW experts also talk about the sustainable improvement of CO2 emissions in the production and use phase. light metal foundry From the BMW site in Landshut is the largest production area of the Lower Bavarian Components Plant, which manufactures lightweight cast metal engine, body and body components. In 2021 alone, the team there produced 3.1 million cast components with a total weight of nearly 67,000 tons.
Polestar 5 has an annealed aluminum platform
Volvo’s electric performance brand is going big when it comes to aluminum with the new Polestar 5 model. The Swedes recently announced that the four-door GT electric car will feature an all-new, bespoke aluminum platform that promises performance and environmental benefits. According to Polestar, such a system is rarely used in mass production of vehicles without any quality loss. A British R&D team from Coventry, England has now developed a faster production process suitable for mass production, in which both the chassis and platform are manufactured together.
Chassis and bodywork are built together, explains Steve Swift, Head of Vehicle Engineering, Polestar UK R&D, for Automobil Production. Numerous external and internal panels are attached as an integral part of the overall structure. In addition, a variety of aluminum types and production methods were used. Some may represent intellectual property, which is why one cannot reveal more at this time. This head of development reveals a lot: “The bonded aluminum structure has various advantages. Most importantly, it allows us to reduce weight and increase rigidity.“
About the platform and Swift currently wants to define the process only insofar as it makes it possible to more easily create prototypes and start physical tests early. “This gives us more time to optimize and match performance to our virtual models, and we can shorten production time.In addition, the tools required for prototyping are cheaper and more efficient than similar tools for a traditional steel platform. This saves costs and the prototype can be produced faster.
The Polestar 5’s body structure should also weigh less than one for smaller vehicle classes and provide torsional rigidity for a two-door model. When asked about the ease of repair and recycling of an aluminum system, Swift describes: “That’s why we’ve incorporated a new method for controlling recycled content and improving the circularity of metal components into the recently announced Polestar O2 Concept.“Different types of aluminum are used throughout the chassis. The different qualities are highlighted so that it can be recycled more effectively and maintain its properties.
When it comes to more quantitative data, Swift keeps a low profile: “We are currently unable to publish any details about the planned investments and volumes.In any case, the team will be expanded in the coming months from currently 280 to around 500 engineers, who will then play a key role in improving research and development capabilities.