High-speed cladding coats industrial rollers at 200m/min
Extreme high-speed laser material cladding (EHLA) has been shown to coat heating rollers at speeds of up to 200m/min.
The coating test was carried out as part of the concluded project Everest, in which the Fraunhofer ILT and three industrial partners have been developing process strategies and system technology to efficiently repair and coat components.
Together with Lunovu, BCT and Drink & Schlössers, the ILT scientists want to establish their newly developed process chain in industry to coat long and large rollers, as well as other rotating components. The partners are therefore now looking for industry users to adopt the EHLA process chain.
EHLA is capable of speeds 10 times faster than traditional laser metal deposition (LMD) in terms of surface coverage rate. The process has proven capable of achieving coating speeds above 300m/min and surface coverage rates of 250-1,000cm2 for rotationally systematic components.
The process was successfully tested by Lunovu on a heating roller (length: 1,200mm, diameter: 200mm) by coating it with corrosion-resistant powders based on iron, nickel and cobalt. The coating thicknesses in the project ranged from 50 to 300µm – at process speeds of 20 to 200m/min.
The system technology developed by BCT and Fraunhofer ILT for geometry acquisition, process monitoring and adaptive tool path planning played an important role in the project. A CAM module was developed that corrects geometric deviations from the target state in a semi-automated manner. ‘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,’ explained ILT scientist Gregor Bultel.
In the future, suitable system technology will allow very large, long rollers with a diameter of up to 3,000mm to be reliably coated close to the final contour. (Image: Drink & Schlössers)
The result was a reliable process chain that not only saves resources, but also has very efficient system technology that requires very few employees to look after it.
‘The system technology has proved very successful in the project, and we are now looking for the first users for it,’ said Bultel.
Roll manufacturer Drink & Schlössers has also tested the process with success. ‘With the process and the system technology used, the component surfaces could be processed well,’ confirmed managing director Kurt Beckers. ‘We were able to produce the surfaces exactly as we had imagined.’ Seeing good opportunities for EHLA, Beckers hopes that the process technology can be developed even further, which will also allow very large, long rollers with diameters up to 3,000mm to be reliably coated close to the final contour.
Future work on the new process chain will involve optimising the powder materials, depositing complex geometries, increasing the final contour proximity, and developing new process strategies for crack-free deposition of very hard coatings. In addition, Bultel is thinking about linking process chains: ‘We could also combine the coating process with post-processing steps – perhaps even in one and the same machine,’ he suggested.
The Everest project was supported by the European Regional Development Fund (ERDF).