Hollow die rolling is an efficient and resource-saving forming process that offers significant advantages over conventional methods, especially in the production of complex hollow structures. At EuroBlech 2024, IWU presented the BPPflexROLL, a system for the highly efficient production of bipolar plates (BPP) for fuel cells or heat exchanger plates. Now, the flexROLLmax expands the production spectrum to large-format components such as electrolyzer plates. As the 'big sister' of the BPPflexROLL, it opens up new areas of the sheet metal sector for the stamping of components. Sheets with material thicknesses of up to 0.5 mm and component sizes of up to 1.2 m edge length are no problem for it.
The flexROLLmax complements the machine spectrum at Fraunhofer IWU, which already possesses unique expertise in processes and machines for embossing reliefs on metallic surfaces. Together with interested partners, the Chemnitz research institute will be able to expand hollow die rolling to completely new product groups. Structural and functional components for household and building technology and the electrical industry are just a glimpse of possible application examples. The main advantages of hollow die rolling include:
High production rates and cost-effectiveness
In contrast to discontinuous processes such as classical hollow stamping or high-pressure sheet forming, where one component is produced per press stroke and process pauses occur, hollow die rolling takes place continuously through a pair of rollers. This allows for a significant increase in output and leads to economies of scale. Ultimately, this results in significantly lower manufacturing costs per component, promoting the marketability of industrial products.
Reduced process forces, compact plant layout
Hollow die rolling, due to the incremental nature of the process (forming in small, successive forming steps), leads to a significant reduction in process forces – on average by a factor of 10 compared to conventional hollow stamping. Lower process forces mean that the required plant technology can be designed smaller, lighter, and more cost-effectively. This reduces investment costs, space requirements, and energy consumption.
Flexibility and adaptability
Both the BPPflexROLL and the flexROLLmax are designed to be modular and flexible, allowing them to be easily relocated and reconfigured as compact machines. The number of required roller sets can be individually adjusted depending on the specific component geometry. This increases flexibility in production and allows for the manufacturing of different geometries on the same system with minimal setup effort.
Potential for process monitoring and quality control
Fraunhofer IWU is working to further develop hollow die rolling into a 'cognitive forming process.' By integrating sensors and intelligent algorithms, it is possible to monitor or ensure the quality of components during the ongoing process and minimize scrap.
flexROLLmax: Premiere at Fraunhofer IWU I B2B Production Forum
Fraunhofer IWU and fourteen partners are organizing the B2B Production Forum on September 16 and 17, 2025, in Chemnitz for researchers and professionals from the industry. The flexROLLmax is a highlight in the complex 'Profile Processing in Sheet and Bulk Forming.'
Other focal points in impulses, workshops, and live demonstrations particularly concern:
- Fine machining and grinding: Development trends and new processes.
- Digitalization in production: Seamless integration of processes, cloud services, and industrial services, with process monitoring in cutting machine tools and 'Hands On - Shopfloor Digitalization.'
- Hydrogen system production: Latest manufacturing technologies, design, and application of hydrogen systems.
- Precision tool manufacturing and functional surfaces: Material removal processes for tool manufacturing and the design of functional surfaces.
- CNC robotics: Easy integration of robots into the manufacturing process.
- Automated assembly and disassembly: Efficient design of assembly and disassembly processes.
- 3D printing: Dynamics and precision for industrial 3D printing of plastics and metals.
- Batix New Work: Digitalization in production technology.
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