Join Plastics With Magnesium Sheets By Injection Molding

2023 Author : Hannah Pearcy | [email protected] . Last modified: 2023-06-01 01:49

The multi-material construction of thermally joined plastic-metal hybrid connections uses different materials that are adapted to local loads, which could make new ways of weight optimization possible. Due to the physical and chemical inequality of the materials, this design is a particular challenge for the connection technology , especially when using plastics and metals

Kira van der Straeten, research assistant in the microfuging group at Fraunhofer ILT, explains: “In addition, different material properties - such as. For example, thermal expansion and corrosive infiltration - hybrid connections are highly stressed.”The aging behavior of the connection is therefore important for the long-term stability of hybrid components.

Microstructured magnesium sheets achieve tensile shear strengths of over 28 MPa

Together with the Institute for Plastics Processing (IKV) in Industry and Handicrafts at RWTH Aachen University, the scientists from the Fraunhofer Institute for Laser Technology ILT developed a process for joining plastics with magnesium sheets. Magnesium sheets are microstructured with fiber laser radiation under an argon atmosphere and placed in an injection mold. The plastic is then connected to the magnesium sheet by back injection, the plastic forming an adhesive bond with the sheet by filling the microstructures. This form-fit also enables chemically different materials to be easily connected to one another .

The tests showed that the method can be used to achieve tensile shear strengths of over 28 MPa by adapting the structural geometry and arrangement. These values are significantly higher than the usual strengths for structural bonds, which are usually used in bonding agent-based joining processes, which are usually approx. 10 MPa. At the JEC, the Aacheners will show how extremely light components can be manufactured using injection molding and laser microstructuring.

In the project, the scientists also examined various surface pretreatments, joining processes and material combinations. Climate change and corrosion tests gave statements about the long-term stability of the connections. "The results clearly demonstrate that the process is competitive compared to other joining technologies and is ideally suited for a large number of plastic-metal hybrid connections," says van der Straeten.

Facts about the JEC World

JEC World - Trade Fair for Composites takes place from March 3rd to 5th, 2020 in Paris-Nord Villipinte. With 1,350 exhibitors and more than 43,500 expected trade visitors from 112 countries, JEC World has established itself as the leading international composite materials trade fair over the years.

Program highlights

Robot-guided laser beam drills CFRP preforms

In Paris, the Aacheners will also show how 3D-shaped CFRP semi-finished products (preforms) can be drilled reliably and efficiently with a robot-guided ultrashort pulse laser (UKP laser). As part of the publicly funded Carbo Lase project, five project partners from research and industry have developed a robot cell with an automated process chain for the production of laser-processed preforms at the Institute for Textile Technology (ITA) at RWTH Aachen University.

The UKP laser beam is guided from the beam source via a hollow core fiber to a galvo scanner mounted on the articulated arm robot. Thanks to the stabilized laser beam, the mirrorless beam guidance can easily follow the very dynamic movements of the scanner via the CFRP preform.

The robot-guided UKP laser can drill precise holes through the defect-free and precise laser ablation, e.g. B. for inserts. The final matrix infusion creates a reliable and reliable multi-material connection even without adhesive. In tests in the Carbo-Lase project, the inserts directly connected to the matrix material achieved a maximum extraction force that was up to 50% higher than that of conventionally manufactured components with glued inserts.

"The dynamic UKP laser drilling process is particularly interesting for lightweight components for aviation and automotive engineering," says Stefan Janssen, scientist in the micro and nanostructuring group at Fraunhofer ILT. "The process, which can be automated very well, can reduce the effort for materials and costs in the production of CFRP components due to the greater strength of the connecting elements."

Seminar tip

The seminar on lightweight materials in construction teaches methods, design principles and construction methods for lightweight structures. The participants get an overview of different lightweight materials, learn about criteria for the selection of materials and learn about the advantages, disadvantages and risks of the different materials.