Laser welding of textiles: Perfect seams

„Textile laser welding is still at the very beginning“, says Dr. Edith Claßen from the Hohenstein Institute. „Until now, mainly textiles were welded when accuracy and colour was of no importance – for example in the manufacturing of conveyor belts.“

Principally, the textiles of the same kind can be welded, but it is also possible to weld different materials with the same or similar melting point. Thermoplastics such as polyester and polyamide are suitable. They can be welded without absorber materials, when they have enough colour molecules, which serve as absorber systems. If that is not the case, an absorber system is needed. Before DWI Leibnitz Institute for Interactive Materials (Aachen) together with Hohenstein Institute have been working on this processing technology, US absorber systems has been used. They are green coloured and leave that colour after the welding process on the textiles.

Laser welding of textiles.

Laser welding of textiles.

Now, there has been a change. In Aachen, absorber systems has been developed which are fluid and generate seams without decolouration. When the laser beam meets the absorber systems it will warm up and transfer energy to the adjacent materials. They will melt together and the absorber will burn without any residue. These innovative absorber systems are made out of exotic pigments.

After the DWI Aachen having developed the absorber systems, the Hohenstein Institutes started to realizes seams, to examine and classify them. “Nowadays, longitudinal seams can be produced with high reliability”, so Dr. Claßen. These seams are resistant to liquid, mechanically strong, flexible, elastic and can be realized without decolouration. In a word, laser welding is an alternative, promising welding technology for textiles.

“Now, we have to find companies willing to implant this technique on their machines or to install robots”, explains Dr. Claßen the next step. Laser welding machines and –robots are very suitable to produce three-dimensional forms because of the flexible laser beam. Thus, this processing technique is adapted for the production of technical and medical textiles. Because of the fact, that welded seams are permeable to liquids, it is not necessary to tape it afterwards like you have to do it with traditional seams.

Cross-section of a laser-welded joint between two woven fabrics

Cross-section of a laser-welded joint between two woven fabrics

Over all, a high degree of automation is possible“, says Dr. Claßen. The welding process can automatically be monitored and thus, the parameters will be registered. This is extremely important in the production of high quality products such as medical textiles, protection clothing, outerwear and furniture. Items can be manufactured according to temperature, speed and pressure on the absorber and textiles. It is of no matter whether different textiles will be joined or textiles with zips or reflectors. Optically and mechanically perfect seams will be the result. This is also possible with bright or transparent textiles.

But further solutions are yet to come. The Hohenstein Institute are working together with the ITA at the RWTH Aachen to realize zigzag-seams. The procedure is suitable for the serging of seam edges or for elastic materials. The scientists are now testing the tensile strength of this new type of seams.

Header image: Safety jacket.  All seams were produced by laser welding. Copyright for all pictures: Hohenstein Institute

Kirsten Rein

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