The research team led by Professor Jean Pierre Bergmann, Head of the Production Technology Group at TU Ilmenau, has succeeded in reducing mass loss due to spatter by over 90 per cent using a novel welding process. For the small and medium-sized manufacturing businesses that characterise Thuringia, this means less waste, lower costs and more sustainable production.
To prevent spatter during laser welding, the research team from the Production Technology Group at TU Ilmenau first had to understand what happens inside the workpiece during the welding process – in places the naked eye cannot see. But state-of-the-art techniques such as high-speed cameras, image processing and simulations – and the particle accelerator at the European Synchrotron Radiation Facility in Grenoble, France, a European research institution that functions like a giant, extremely powerful microscope. Using high-energy ‘synchrotron radiation’ – the world’s most intense X-ray light, which is billions of times brighter than conventional X-ray machines – it can penetrate matter and reveal the structure of atoms and molecules down to the smallest detail.
Using high-resolution scans, the Ilmenau researchers were able to observe in real time the extremely rapid processes taking place inside the vapour capillaries – the tiny channels filled with metal vapour that form during deep-seam welding. The images revealed that spatter is caused by a complex interplay of metal vapour, molten pool waves and unstable capillaries. Using computer-aided flow simulations, the research team succeeded for the first time in developing a complete model of these mechanisms.
This in-depth understanding of the processes taking place inside the workpiece during laser welding enabled the researchers to develop targeted countermeasures against spatter formation. Intelligent beam profiles, such as those with superimposed beam shapes, slow down the molten pool flows and thus facilitate the escape of metal vapour – one of the causes of unwanted spatter. In addition, they positioned gas nozzles so precisely that the interaction between the gas and the melt led to a reduction in spatter.
The results of the research and a patent derived from it – ‘made in Thuringia’ – have already been published in specialist journals, enabling high-tech lasers in industry worldwide to operate more precisely, efficiently and cost-effectively.
Contact
Prof. Jean Pierre Bergmann
Head of Production Technology Group
+49 3677 69-2981
jeanpierre.bergmann@tu-ilmenau.de
