EHLA 3D: The Next Generation of Extreme High-Speed Laser Material Deposition

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Dr Thomas Schopphoven, of Fraunhofer ILT, provides an update on the development of EHLA for 3D printing applications

Extreme High-Speed Laser Material Deposition (EHLA), developed at the Fraunhofer Institute for Laser Technology ILT, is known as an efficient and environmentally friendly alternative to conventional cladding processes. It offers several significant advantages, particularly for coating metallic components to be protected from corrosion and wear. Scientists at Fraunhofer ILT are continuing to work on the patented process to advance it for additive manufacturing and, thus, expand its possibilities many times over.

Originally created as an alternative to coating processes such as hard chrome plating and thermal spraying, Fraunhofer ILT is working with industry partners to transform this extremely high‐speed form of laser material deposition into a fast and affordable additive manufacturing process. The goal is to push the boundaries of 3D printing and achieve extremely high deposition rates at high resolution.

The perfect foundation

Compared to conventional laser material deposition, EHLA scores in several respects. It is not without reason that the scientists at Fraunhofer ILT won the prestigious Joseph von Fraunhofer- and first Berthold Leibinger Innovationspreis for this. The process they developed improves the feed rate at which the surface is processed from 0.5-2 metres per minute in conventional laser material deposition all the way up to 50-500 metres per minute. A component can, therefore, be coated 100 to 250 times faster today. It is also possible to apply significantly thinner layers. While layers of at least 500 micrometres were state of the art with conventional laser material deposition, a minimum of 50 micrometres is now possible.

‘EHLA 3D’ is a new generation of EHLA that enables high build rates, great flexibility and material diversity, and high precision for 3D printing (Credit: Fraunhofer ILT)

Another advantage is the low heat input. In conventional laser material deposition, the powdered filler material is melted directly on the component surface in a relatively large melt pool in the coating process. However, this can permanently change the material properties and costs a great deal of energy. Not so with EHLA: Here, the solid powder particles are melted by the laser while still in the air. They reach the surface of the component in a liquid state and do not have to be melted further with a high energy input. As a result, the heat-affected zone is reduced to five to ten micrometres, which is only one hundredth of that of the conventional process.

This means that metallurgically incompatible, heat-sensitive material pairings can now be joined and processed together, such as aluminium and titanium. Overall, the component surface also becomes much smoother. Its roughness is only one tenth of that from conventional deposition. For the experts at the Fraunhofer ILT, this provides a perfect basis as technology for additive manufacturing.

New generation of additive manufacturing

For several years the extreme high speeds needed for EHLA had been achieved on fast, lathe-like, kinematic systems for rotationally symmetrical components. But we did not want to limit ourselves to simple round parts when a much wider range of possible applications is conceivable.

For this reason, a team of scientists has been developing a new generation of the process to use the innovative technology for 3D printing. Dubbed ‘EHLA 3D’ this process enables several unique, process-related advantages at once: high build rates, great flexibility and material diversity, and high precision at the same time. Now we are working on complex, filigree structures easily and cost-effectively on a large scale. Individualised components are also conceivable.

First projects started

To make the advantages of EHLA 3D available to a large group of users in the industrial environment, Fraunhofer ILT is conducting targeted research work with various machine builders and end users. In particular, we are working on mastering the process complexity and transferring expert knowledge into machine knowledge. The focus here is, for example, on applying artificial intelligence methods, process simulation as well as process monitoring concepts and automated tool path planning tools. The potential is huge. We are currently only seeing the tip of the iceberg of what is possible, and we're excited to find out more.

Currently, numerous renowned companies from diverse sectors are looking into EHLA 3D. Further bilateral as well as publicly funded consortium projects and feasibility studies are also being planned. The range of possibilities for the production and processing of components will be expanded many times over with EHLA 3D, while at the same time the process becomes more efficient and environmentally compatible.

Dr Thomas Schopphoven is the head of the Laser Material Deposition department at Fraunhofer ILT

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