To reduce weight and save energy and resources, the transportation industry has seen a sharp increase in demand for lighter weight components in recent years. The fiber-reinforced composite material is used to partially functionalize the steel mixed material parts, and achieves high mechanical properties with a light weight. As a result, the automotive industry's demand for low-cost, large-scale production processes is rapidly increasing. In the "ComMUion" EU research project, the Fraunhofer Institute for Production Technology ("IPT") and the Fraunhofer Institute for Laser Technology ("ILT") collaborated with 14 companies from industry and academia Partners to develop industrial production processes and solutions for automotive and aerospace applications to enable hybrid lightweight design of steel and polymer-based composites.
The new process is a combination of laser texturing and laser-assisted placement. Pretreatment of steel parts with laser can obtain the required rough textured surface structure. This textured structure allows continuous fiber-reinforced thermoplastic composites to be directly connected to the surface of steel components without the need for additional processing or the use of adhesives.
The laying process is used to attach a thermoplastic composite reinforcement capable of withstanding a certain load to a steel surface. The thermoplastic tape is heated by laser, and the melted matrix resin can flow into the laser-etched texture groove. After the resin is cured, the thermoplastic tape can be connected to the steel surface as a whole.
Combined process suitable for mass production
When it is necessary to improve the layout mechanical properties of components without increasing weight, the advantages of the combined laser process become apparent. Since no post-cure treatment is required, this process is particularly suitable for mass production. In addition, precise local heating reduces deformation and residual stresses that occur when joining two materials. The laser texturing process developed by Fraunhofer ILT can also be applied in a repeatable manner precisely where metal surfaces need to be textured.
To verify the suitability of this process, researchers have completed the first demonstration component made of high-strength steel and unidirectional fiber-reinforced thermoplastic strips, a lightweight threshold plate of mixed materials.