Lightweight design

Composite materials are playing an increasingly important role in the automotive and aerospace industries. For that reason, Dieffenbacher, a mechanical engineering and plant construction company, joined forces with the Fraunhofer Institute for Chemical Technology (ICT) to develop a production line for the economical series production of locally reinforced thermoplastic components.

Due to their low weight, composite materials are popular, particularly in the automotive and aerospace industries. Structures made of carbon-fiber reinforced polymer (CFRP), for example, are up to 70 percent lighter than steel and 30 percent lighter than aluminum. At the same time, they are extremely durable and resistant to corrosion.

 

Mechanical engineering and plant construction company Dieffenbacher recognized the potential inherent in glass-fiber or carbon-fiber-reinforced materials (GFRP and CFRP). Its Composites business unit manufactures presses and production plants and is also involved in developing methods to produce fiber-reinforced plastic parts. 

Dieffenbacher has worked with the Fraunhofer Institute for Chemical Technology (Fraunhofer ICT) in this field for more than 25 years. The independent research institute based in Pfinztal near Karlsruhe, Germany, brings together a wide variety of chemical technology research topics under one roof, including polymer research and lightweight design. It is this background that guided Dieffenbacher’s decision to work with Fraunhofer ICT to develop a new type of production line.

 

Made up of the Fiberforge and Fibercon systems, the tailored blank line produces tape layups from lightweight materials and then uses heat to join them (consolidation) to create a formable laminate. This laminate can then be used as underbody paneling for cars, for example: It reduces the overall weight of the vehicle, and at the same time is stable enough to withstand the impact of rocks.

 

In the Fiberforge, the glass-fiber or carbon-fiber-reinforced tapes are reeled off, cut to size, and set down on a rotary table in a set pattern. What is special about the Fiberforge is that it can accommodate a total of four reels, allowing for hybrid layups and laying of tapes with various widths and thicknesses. “A completely new material is produced that can even be used as an economical substitute for metals,” says Dr. Sebastian Baumgärtner, team leader for thermoplastic processing at Fraunhofer ICT. The Fiberforge is already being used in the large-scale production of locally reinforced thermoplastic components for the automotive and aerospace industries.

Precise coordination of 27 axes

The greatest challenge facing the Fiberforge was how to control and coordinate all of its 27 axes. With the Simatic S7-1517TF technology CPU, however, this functions smoothly: The integrated motion control functions ensure exact positioning of the tape, even at high speeds.

 

Felix Manger, a development engineer in the Composites business unit at Dieffenbacher, has been working closely with the ICT on the evolution of the Fiberforge system for many years. “Many customers want the components installed in a system to come from a single source,” he explains. “We therefore offer them a consistent automation concept that is easier to operate and maintain.”

 

Our machines also have long lifetimes, so it is important that faulty components can be reordered and replaced even after many years. That makes Siemens our ideal supplier.
Felix Manger, a development engineer in the business unit Composites at Dieffenbacher

Vacuum technology guarantees high quality

Thanks to an in-depth analysis of the entire process chain, from the tape to the final thermoplastic fiber composite part, researchers at the Fraunhofer ICT identified a bottleneck process: the consolidation of the tape layup. This step ensures the high quality of the final component and achieves reproducibility in forming the tape.

 

“We looked closely at a number of technologies, but ended up developing our own vacuum consolidation technology,” explains Baumgärtner. As a supplementary process line for the Fiberforge, Dieffenbacher developed Fibercon, which is suitable for large-scale production. It is used to consolidate the tape layup supplied by Fiberforge to produce a laminate. A vacuum-assisted process minimizes voids and imperfections in the material and suppresses oxidation processes. This ensures an excellent laminate quality. 

Thermoplastic components in large-scale production

Fibercon and Fiberforge were finally combined to form a tailored blank line for the large-scale production of locally reinforced thermoplastic components. Together with the downstream systems such as handling robots and forming presses, the production line enables the manufacture of more than a million parts a year.

 

Picture credits: Siemens AG

With more than 1,700 employees and 16 production and distribution sites around the world, Dieffenbacher, headquartered in Eppingen, Baden-Württemberg, Germany, is a leading manufacturer of press systems and complete production systems for the wood composite, recycling, automotive, and aerospace industries. Dieffenbacher’s Composites business unit specializes in the automotive and aerospace industries.

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