The BMW Group has a „live wire” for the innovative production of automotive components in the WAAM process.
- Additive manufacturing by wire arc achieves metal parts with optimal stiffness-to-weight ratio
- After laboratory tests, the first vehicle tests will take place from 2025 onwards
Munich At the additive manufacturing complex in Oberschleissheim, the BMW Group uses an innovative „live wire” system for the additive manufacturing of metal components and tools for vehicles. In wire arc additive manufacturing (WAAM), a wire made of aluminum or a similar material is melted by an electric arc. A software-controlled robot then precisely places a large number of welds, one on top of the other, until the entire joint is complete. Since the part is formed layer by layer, there is no need to focus on demouldability, hollow structures with an optimal ratio between stiffness and weight are possible.
This means that the components are lighter and stiffer than comparable die-casting parts currently produced in series production. They are produced more sustainably due to low energy consumption and low material waste. In the future, it is planned to use components manufactured using the WAAM process in BMW Group production vehicles.
The WAAM process is particularly suitable for large components.
The large width and height of the single weld means that components can be made very quickly using WAAM. Unlike laser beam fusion, which is already used in prototype and small series production at the BMW Group, WAAM is more suitable for large components. Typical wall thicknesses are suitable for components in the body, drivetrain and chassis areas. However, tools and equipment can be manufactured using this high-tech process, which is also used in the aviation industry.
Development in additive manufacturing complex
The BMW Group is testing this process at the Additive Manufacturing Campus in Oberschleishheim, where it has brought production, research and training activities under one roof. With over 30 years of experience, the company is a pioneer in the field of additive manufacturing, commonly known as 3D printing. BMW Group employees have been focusing on the WAAM process, also known as construction welding, since 2015. WAAM cell for production of test components is in use from 2021. One of these example applications is the support of a shock absorber, which, in extensive tests on a test bench, has been compared with series production components made of die-cast aluminium. „At this early stage it is already clear that the WAAM process will reduce emissions in the manufacturing process. The light weight of the component, its favorable material utilization rate and the option to use renewable energy can make the component more efficient,” said Jens Ertel, Head of Additive Manufacturing at BMW. The next stage of development on the road to series production is testing the components in the vehicle, which will begin in the near future.
Wide welds in WAAM process component surfaces are not smooth but slightly wavy and must be finished in critical areas. However, BMW Group engineers were able to demonstrate that WAAM components can be used for higher loads. Optimum process parameters are critical to ensure durability straight from production, so the combination of welding process and robot path planning must be optimally coordinated.
Configuration with generative design and algorithms
To get the most out of the components produced in the WAAM process, it is necessary to combine the manufacturing process with a new overall component design. To this end, the BMW Group continues to accelerate the use of production design. Here, the system uses algorithms to design optimal components based on specific requirements. These mechanisms are developed in close collaboration with intermediate groups and are partly inspired by the evolutionary processes of nature. As with bionic structures, the first step is to use only the material that is actually needed for the component topology, and while fine-tuning in the second step, the component is reinforced only where needed. The result is lighter and stiffer components, greater performance and improved vehicle dynamics.
„It is interesting to see how WAAM technology has evolved from research to become a flexible tool not only for test components, but also for series production components. The use of generative design methods allows the freedom of design to be fully exploited. The potential of the technology was unthinkable just a few years ago,” said Carol, Head of Automotive Research, BMW Group. Vircic said.
Production processes can complement each other
Different additive manufacturing processes are not necessarily in competition with each other, but rather they should be considered complementary. For example, laser beam fusion is consistently more advantageous than the WAAM process in terms of greater detail resolution. However, in terms of potential component size and deposition speed, wire arc additive manufacturing is superior. The BMW Group initially plans centralized production of WAAM components in Oberschleissheim, with possible use of the technology by manufacturing and suppliers elsewhere in the future. Also, it would be conceivable to use this process to produce individual components directly on an assembly line, and to produce different parts by changing software, without the need for new tooling. Sustainability can be further improved by increasing the use of recycled metals.