Lasers set to improve processing lightweight materials

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The Fraunhofer Institute for Laser Technology is developing manufacturing techniques for the cutting and joining of lightweight construction materials including aluminium, high-strength steels, magnesium, titanium and fibre-reinforced plastics (FRP).

The research, funded under European Union and German government funded programmes, is aiming to solve the problem of low market penetration by complex lightweight components because their manufacturing costs are very high. For industries such as automotive, lightweight materials would lower fuel consumption and increase vehicles’ operating ranges.

Adhesive bonding and riveting have been used to join these materials but the Institute is lasing the joining zone directly because it is faster. This approach also enables the use of selective reinforcements. The work at Fraunhofer has also realised the joining of plastic and metal using lasers. A two-stage process, first the metallic component is treated with a high-brilliance laser beam, and in a second step it is heated using a diode laser. Softened plastic then penetrates into the structured metal which leads to an excellent mechanical clawing between the joining parts.

Fraunhofer’s work has also looked at cutting, which can include component trimming and the cutting out of holes and sections. One of the key goals of the cutting process is to minimise any damage to the edges of the material. Conventional laser cutting techniques often produce poor results due to the size of the heat affected zone.

Fraunhofer’s researchers are using a short-pulse CO2 laser. With the short pulses they were able to reduce the heat input and were able to significantly reduce the thermal damage inflicted on the material. A nearly complete elimination of thermal damage was also achieved by using a high power ultrashort pulse laser. Even highly sensitive material combinations in aeronautics can be processed economically by these lasers, according to the Institute, with power at up to 500W.

The work is being funded by the EU project FibreChain and the German Federal Ministry of Education and Research’s InProLight. The Institute has also invested in its Laser Lightweight Construction Center, which is currently being set up in the laser machine facility. The Centre will have a machine with 3D capabilities, a CO2 laser for the machining of FRP components and high power ultrashort pulse lasers that are able to process CFRP components.