EU’s “ComMUnion” project develops industrial processes for mixed metal and polymer matrix composites

Laser textured steel is attached to continuous fiber reinforced thermoplastic ribs and placed with laser-assisted tape to join the structure without the need for adhesives.

In recent years, in response to the need to reduce weight, thereby saving energy and resources, the demand for lighter components for mobility and transportation applications has increased dramatically.

Hybrid parts made of steel and partially functionalized with fiber reinforced plastic combine high mechanical properties with low weight. The demand for cost-effective mass production manufacturing processes that favor such structures is rapidly increasing. In the EU research project “ComMUnion”, two Fraunhofer Institutes in Aachen, Germany – Fraunhofer Institute for Production Technology (IPT) and Fraunhofer Institute for Laser Technology (ILT) – In collaboration with 14 partners from industry, research and academia, we are developing industrial processes and solutions for hybrid lightweight designs by combining metal and polymer matrix composites for automotive and aerospace applications.

The new hybrid manufacturing process is based on a combination of laser texture and laser-assisted tape placement. The component is first pretreated with a laser to provide a specially developed, precisely defined rough surface structure. The textured surface allows continuous fiber reinforced thermoplastic lightweight material, which is then used for hardening, to bond directly to the steel component. The bonding is then mechanical and does not require additional pre-treatment or additional adhesion promoters such as adhesives or adhesives.

The stiffening element is made of a fiber reinforced thermoplastic that is particularly suitable for the intended load and is attached to the component using a tape placement process. The laser locally heats the thermoplastic strip to the steel in the joint region. The matrix material melts and flows into the laser textured cavity. After the molten material solidifies, the tape with the embedded unidirectional fibers adheres to the rough surface of the steel part.

Combined process for mass production

The advantages of combining these two laser processes just emerge when the mechanical properties of the assembly require local improvements without significantly increasing the weight of the components. This method is particularly suitable for large scale production because no further post-treatment steps (such as curing operations) are required after the tape is placed to consolidate the material. In addition, precise local heating reduces deformation and residual stress when joining two materials. The laser texturing process developed at Fraunhofer ILT can also be applied to metal surfaces in a reproducible manner, precisely where the texture is desired. In addition, the laser is not subject to any tool wear.

The first hybrid body part has been completed as a demonstration component

Research partners have now completed the first demonstration component made of high-strength steel and unidirectional fiber reinforced thermoplastic tape to validate the applicability of the process in a proof-of-concept form: two Fraunhofer researchers Kira van der Straeten from Fraunhofer ILT and Tido Peters from Fraunhofer IPT have created a hybrid lightweight rocker arm panel, a body component for the automotive industry, to test and demonstrate the functionality of the process combination as part of the ComMUnion project.

The project partner introduced the “Composite Action Area” organized by AZL to the professional audience at JEC World, a light construction trade fair held in Paris from March 12th to 14th, 2019.

The “ComMUnion” project is funded by the EU Horizon 2020 Research and Innovation Program with the agreement number 680567.

A portion of the hybrid vehicle rocker arm panel is laser-assisted for placement for localized functionality. Source | ComMUnion Fraunhofer IPT

European partner of the ComMUnion research project
Aciturri Engineering SL, Spain
Germany AFPT GmbH
Spain Ai Men Technology Center (Coordinator)
Autotech Engineering, AIE, part of the Spanish Gestamp Group
CASP SA, Greece
ESI Group, France
Fraunhofer Institute of Laser Technology, ILT, Germany
Fraunhofer Institute for Production Technology, Germany IPT
Manufacturing Systems and Automation Labs (LMS) – University of Patras, Greece
Lunovu GmbH, Germany
Missler Software, France
Motofil Robotics, SA, Portugal
Spanish new infrared technology company SL
Philips Photonics GmbH, Germany
Tecnatom SA, Spain
University of Coimbra, Portugal