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Volvo’s next-generation electric car will feature integrated die-cast rear floor components Engineers are working on ingenious processes for making chassis components, and new designs for entire body components and aluminum platforms are starting to attract attention with new looks. Does this mean that the next spring of light metals is coming? Volvo has invested heavily in its main Swedish plant in Torslanda, announcing it will use an aluminium die-casting process to produce entire body components for its next-generation electric car. This can be seen both as a solid step forward in the development of aluminium by Volvo, and as a symbol of its pioneering new frontiers in lightweighting and body structure. Today, Volvo, another heavyweight traditional OEM other than Tesla, will adopt a new approach as an alternative to trying and testing the board-shell construction approach. A process known as gigacasting in the Tesla environment, Volvo calls it megacasting. This process mainly uses special aluminum alloys to produce the entire body parts under high pressure. The purpose is to get rid of the multiple component structures commonly found in steel structures, and to reduce the number of processes and robots used in the body manufacturing process, while reducing the weight of electric vehicles. Target. Whether this will actually lead to advantages in business management and weight loss remains to be seen. However, as Professor Volker of the Technical University of Munich said in an interview with the magazine “Automobile Production”, when it comes to car body construction, aluminum die casting can play a role in some targeted greenfield projects. For the first time, aluminum has made career progress in chassis components. Materials such as forged aluminium wrought alloys or ductile cast aluminium alloys with low silicon content have been used for some time to reduce the weight of steering knuckles, wishbones or wheel frames, previously made from cast iron or forged steel. Long Chip Problems in Aluminum Machining In the field of chassis parts machining, as precision and cutting tool manufacturer Walter AG knows, the machining speed of aluminum alloys is completely different from that of conventional cast iron or steel materials, and different machining strategies are required. According to Fabien Hubine, components and project manager for the transport department at Walther AG, long chips are a major risk factor in aluminium machining. In addition, a built-up edge quickly forms on the cutting edge of the tool, which quickly becomes difficult to maintain the specified tolerances on fit dimensions and surface quality.
Hybrid tools for tapered seat holes are used for chassis components (image via Walter) Full holes are particularly challenging, according to Hubine. While pre-forged grooves are usually drilled into the hub, smaller holes, such as on wishbone, are drilled through the material. According to the tool specialist from Tübingen, Germany, it is not only necessary to simply drill holes, but also to apply defined flat surfaces or chamfers. Up to five processing steps are derived from this statement. But the experts quickly found a solution in the form of a hybrid tool that allows for different machining steps with just one cutter body. Forgeable and thermohardenable wrought aluminium alloys containing magnesium and silicon place particularly high demands on the cutting edge. In addition, wrought aluminum alloys can form long chips or even flowing chips. According to Walter, these chips can seriously jeopardize the smooth running of the machining process. Therefore, the indexable inserts developed for aluminium machining have special geometries and coatings. With the help of the HiPIMS coating (stands for: High Power Pulsed Magnetron Sputtering), the aim is to provide an extremely smooth and droplet-free surface and prevent build-up edges from forming. As a success story, a tooling specialist from Walther AG speaks of a customer who was able to achieve a cutting speed of over 1300 m/min at a rotation of 0.11 mm when drilling a wishbone with a hybrid cutter with a diameter of 50 mm during the drilling phase . BMW strengthens competitiveness in aluminium moulds Another tool innovation comes from BMW. Specifically, experts at BMW’s Light Metals Foundry in Landshut, Germany, have come up with a multi-plate mold technology that promises to reduce carbon dioxide during machining and reduce weight when looking at castings. “With the development of new gating and demolding systems through direct gating in multi-plate mold technology, part designs optimized in terms of function rather than runners can be achieved in the die casting process. In addition, in the case of constant functional performance The weight of the components can be reduced by 20 percent,” explains Klaus Summer, Head of Tooling, Maintenance and Pre-development at Landshut Light Metal Foundry.
Using the multi-template technology developed by BMW Landshut, it is possible to open multiple feed channels to the mold cavity (picture from BMW Group) Improvements in this process allow the material to be optimized for use in product design and transformed into alloys with lower CO2 emissions in a weight-neutral manner. BMW said that the existing facilities at the Landshut foundry could also be used to cast structural parts in the future. In addition, BMW experts spoke about the sustainable optimization of CO2 emissions during the production and utilization phases. The light metal foundry at the BMW plant in Landshut is the largest production area of the components plant in Lower Bavaria and produces light metal engine, chassis and body structure castings. In 2021 alone, the team produced 3.1 million castings with a total weight of nearly 67,000 tons. The Polestar 5 has a glued aluminum platform Volvo AG’s electric performance brand is going all out with aluminium for the new Polestar 5 model. The Swedish company recently announced that the four-door electric GT will have an all-new, bespoke platform made of glued aluminium that is expected to offer performance and environmental benefits. Such systems are almost never used in mass production cars without compromising quality, Polestar said. The UK R&D team from Coventry, UK, has now developed a production-ready and faster manufacturing process for the OEM in which the body and platform are built together. “The chassis and body are designed together,” explains Swift, head of vehicle engineering at Polestar UK R&D. Many of the exterior and interior panels are glued as an integral part of the overall structure. During the production process, various types of aluminum and manufacturing methods are used. There are some intellectual property issues involved, so no further information can be disclosed. But the head of development revealed: “The structure of glued aluminium has several advantages. The two most important points are that we can reduce weight and increase stiffness”.
The role of aluminium in car manufacturing is gaining new attention with custom aluminium platforms like the Polestar 5 For now, Swift is only specifying the platform and process to make it easier to prototype and start physical testing earlier. “This gives us more time to optimize and performance match our virtual models, and we can reduce production time”. He added that the molds required for early prototypes are cheaper and more efficient than similar molds for traditional steel platforms. This saves costs and makes the production of prototypes much faster. The Polestar 5’s body-in-white is also said to be lighter than smaller vehicles and provide the torsional rigidity of a two-door. When asked about the ease of repair and recycling of aluminum systems, Swift said: “That’s why we’ve included new methods of controlling recycled content in the recently released Polestar O2 concept car and improving the availability of metal components. Recyclability.” As a result, different grades of aluminum are used throughout the chassis. Different grades of products are labelled to help them be recycled more efficiently and retain their properties. Swift has been tight-lipped about further quantitative statements: “At this time, we cannot release any details about the investment and planned unit counts.” will play a key role in enhancing R&D capabilities. |
