Laser-based Process Repairs, Coats Metal Components at High Speeds

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Fraunhofer ILT (Institute of Laser Technology), in collaboration with three industrial partners from the EVEREST project, developed an EHLA (extreme high-speed laser material deposition) process and system technology to efficiently repair and coat metal components. The collaborators tested an adaptation of the process on rollers.

Having successfully completed the project, participating researchers hope to establish the freshly minted process chain in industry settings. The goal, they said, is to reliably and efficiently coat long and large rollers and other rotating components with the process in a near-net shape.

Nearly a decade ago, Fraunhofer ILT researchers began development on EHLA, increasing a previous process from a maximum of two meters per minute to several hundred. EVEREST is a current example of that collaboration; along with partners LUNOVU GmbH, BCT GmbH, and Drink & Schlössers GmbH & Co. KG, the Fraunhofer ILT scientists processed parameters and strategies for coating and repair, as well as for hybrid manufacturing of sealing surfaces. In tests, they coated a heating roller 1200 mm in length and 200 mm in diameter with corrosion-resistant powders based on iron, nickel, and cobalt. The coating thicknesses in the project ranged from 50 to 300 μm at process speeds of 20 to 200 m/min.

The system technology — developed by BCT and Fraunhofer ILT for geometry acquisition and process monitoring, as well as for adaptive tool path planning — was instrumental to successfully completing the project. The partners used a specially developed CAM module that semi-automatically corrects geometric deviations from the target state.

“We took a camera-based approach that allows us to follow the coating process from a bird’s-eye view, so to speak, and thus draw conclusions about the stability of the process,” said Gregor Bultel, a scientist at Fraunhofer ILT. “The system technology has proved very successful in the project, and we are now looking for the first users for it.”

Tests conducted at LUNOVU — where the laser systems manufacturer built the process into the demonstrator — integrated the complete workflow from scanning, path planning, and automatic generation of the numerical-control program into the automatic repair process.

“The biggest problem was to combine all the subsystems involved into one process chain,” said LUNOVU application developer Andreas Bartling. “We mastered the challenge: The result was a reliable process chain that not only saves resources, but also has very efficient system technology requiring very few employees to look after it.”

Upcoming work will involve optimizing the powder materials, depositing complex geometries, increasing the final contour proximity, and developing new process strategies for crack-free deposition of very hard coatings, Bultel said. “I’m thinking about linking process chains. We could also combine the coating process with post-processing steps — perhaps even in one and the same machine.”

The project was supported by funds from the European Regional Development Fund.


Published: February 2021
BusinessCoatingsLasersmanufacturingindustrialpartnershipsEVERESTFraunhoferFraunhofer ILTEuropeextreme high-speed laser material depositionMaterialsdepositiondeposition processesTech Pulse

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