Graded porous structures via metal Additive Manufacturing developed by Fraunhofer ILT
June 5, 2025
Researchers at the Fraunhofer Institute for Laser Technology ILT have developed a method which can be used to additively manufacture metallic materials so that they are locally permeable or dense, with graded transitions between the states.
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The newly developed method is based on the Laser Beam Powder Bed Fusion (PBF-LB) process. Until now, the focus has been on producing components that are as dense and resilient as possible, explains Andreas Vogelpoth from the LPBF Process and Systems Engineering group at Fraunhofer ILT. “But if we allow porosity locally, for example, by changing the process parameters, we can create controlled permeability,” he stated.
The result is completely metallic components that are locally permeable, such as to gases or liquids, while still maintaining the required mechanical integrity. The technique results in areas with different densities combined within one component. The institute can make transitions either with a sharp separation or a graded transition.
Classic metal foams or fabric structures fulfil similar functions, but usually have to be produced separately and incorporated into components. Not only does this take time, but it also limits the design freedom and leads to changes in the physical properties of the component due to seams and joints, e.g. an increase in thermal and electrical resistance. The Fraunhofer solution integrates porous zones directly into the component. Thus, post-processing is not necessary. Even complex geometrical shapes with internal structures can be made in this way.
“We are adding new functions to parts made with 3D printing: permeability as a designable feature,” explains Vogelpoth. The process is particularly interesting wherever gases or liquids need to be distributed, filtered or channelled in a controlled manner.
A key area of application is hydrogen technology, specifically for electrolysers. These consist of complex cell stacks with various functional layers. Fraunhofer ILT is currently investigating whether these layers can be additively manufactured directly, including specific permeable areas. The experts at Fraunhofer ILT aim to reduce the number of individual parts and, thus, improve efficiency while reducing material usage and production costs.
The Fraunhofer ILT team is also already in contact with end users in other areas of applications such as turbomachinery, toolmaking, heat exchangers and filters as well as chemicals. The wide range of possible applications underlines how relevant this development is for high-tech applications.
Fraunhofer ILT will showcase the new Laser Beam Powder Bed Fusion (PBF-LB) applications at this year’s Laser World of Photonics 2025 in Munich from June 24 to 27, 2025.
