Laser promise for joining plastics and metal

A new laser-assisted joining process developed at the Fraunhofer Institute for Laser Technology offers the potential to manufacture plastic-metal hybrid materials.

Plastic is increasingly being used as a construction material, which poses the problem of joining dissimilar material classes.

The Liftec joining process works by heating a component, or a part of it, by laser radiation which passes through the plastic joining partner.

The component is pressed onto the plastic part under mechanical pressure, then heated, and finally pushed into the plastic by further mechanical pressure.

Provided that a suitable component geometry has been selected, a solid, positive bond is formed after cooling. It is essential to the process that the component should have a higher melting point than the plastic joining partner. Suitable materials include metals, ceramics and temperature-resistant plastics.

Another approach is being investigated at RWTH Aachen University. In this approach, researchers are examining several irradiation methods, materials, beam sources and pre-treatment methods.

A first series of tests is being carried out to determine the influence of structural density on the joining process. This is being done by producing surface structures with dotted, lined and chequered patterns in stainless steel samples using Nd:YAG laser light.

Subsequently, the structured samples are bonded to the transparent plastic samples by diode laser light in a con-tour or quasi-simultaneous joining process. The resulting bonds are very strong and generally very promising.