Researchers at Germany’s Fraunhofer Institute for Laser Technology ILT have developed a laser powder bed fusion (LPBF) process that embeds locally permeable or dense zones, complete with graded transitions, directly into metal parts. The method will be showcased at Laser World of Photonics 2025 in Munich, 24–27 June 2025.
Controlled permeability without post-processing
“By changing the process parameters, we can create controlled permeability,” said Andreas Vogelpoth of ILT’s LPBF Process & Systems Engineering group. The approach places porous and dense regions side-by-side, preserving mechanical integrity while allowing gases or liquids to pass where required.
Classic metal foams or fabrics offer similar functions but must be produced and assembled separately, adding seams that raise thermal or electrical resistance. ILT’s in-situ porosity “adds new functions to parts made with 3D printing: permeability as a designable feature,” Vogelpoth noted.
Target applications in aerospace and thermal systems
ILT’s first industrial test case is hydrogen-electrolyzer stacks, which contain several functional layers. Printing these layers with integral permeable regions could cut the number of individual parts, lower material usage and reduce production costs. Beyond hydrogen, the institute is already in talks with partners in turbomachinery, toolmaking, heat-exchanger and filter manufacture, and chemical-processing equipment.
Each of these sectors requires components that combine structural strength with precise fluid or thermal management, making the ability to “dial in” porosity especially valuable. ILT stresses that its open, cross-application approach is intended to give small and medium-sized enterprises access to multifunctional metal AM without major hardware investment.
Computer-tomography tests show the pores are reproducible. Ongoing research aims to let users specify exact permeability values for any region of a part, with Fraunhofer providing the matching design and process parameters.
At the Munich fair the team will display a metallic Fraunhofer ILT logo submerged in water; air forced through its integrated porous zones creates a visible bubble curtain, allowing visitors to “see and feel” the controlled permeability.
Related advances in LPBF porosity control
Earlier this year, Dyndrite joined forces with Elementum 3D to embed the PermiAM permeability-control workflow in Dyndrite LPBF Pro, allowing engineers to print fully dense and highly porous regions within the same metal build. Likewise, researchers from Carnegie Mellon University and the University of Pittsburgh produced a mechanistic model for shrinkage porosity in Inconel 718 and published process-parameter maps to help manufacturers predict and eliminate unwanted pores in LB-PBF parts.
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Feature image shows. Demonstration of the additive manufacturing of porous structures. Image via Fraunhofer ILT.
