Conference Agenda

Recently, there has been a trend to use diode lasers emitting in the near infrared spectral range instead of the more common CO2 lasers for powder bed fusion of polymers. However, it is important to note that melting of polymer powders with a diode laser typically necessitates the incorporation of additional optical absorbers. The majority of publications have focused on the effects of these absorbers only on the most common polymer utilized in powder bed fusion, namely polyamide. By contrast, this study analyses the absorption and resulting geometry of thermoplastic polyurethane coated with CuS nanoparticles produced by high power laser fragmentation. Monolayer samples were prepared via powder bed fusion at specific energy densities using an 808 nm diode laser setup and the resulting geometry was measured. The results show that CuS nanoparticles could be used as a suitable optical absorber in near infared powder bed fusion.

Laser-based additive manufacturing with diode lasers offers energy efficiency and compact system design but requires powders that absorb near-infrared light. This study explores how the placement of light-absorbing nanoparticles—either embedded in the polymer or attached to its surface—affects processability and part quality.

Surface-modified powders, despite ten times lower absorbance, achieved comparable melting with only 1.5 times higher laser energy. Resulting parts showed increased tensile strength without loss of ductility. Microscopy revealed that surface-localized heating preserves semi-crystalline regions, indicating a distinct melting mechanism compared to embedded absorbers. These crystalline domains likely reinforce the polymer matrix and contribute to improved mechanical properties. The findings highlight that not only the choice, but also the location of absorbers critically influences energy input and performance.

Surface modification, therefore, presents a scalable strategy to tailor powders for diode laser processing—offering new opportunities for efficient, precise, and application-driven polymer printing.

The moon serves as a steppingstone for humanity’s space colonization. Due to high transportation costs, utilizing lunar resources is considered essential for further development in space applications. Lunar regolith and its simulants exhibit a wide range of particle size distributions (PSDs). Simulants prepared under terrestrial conditions retain moisture, requiring pre-drying. Within this work, the influence of these characteristics on the melting process similar to a powder bed fusion process has been investigated.

Simulant powders of different PSDs (particle sizes ≤ 1000 µm) and drying states (undried, 300 °C and 800 °C for 4 h) were processed in a vacuum chamber and the fabricated samples profoundly analyzed. The results show an increase in sample mass with larger particles and higher drying temperatures. No correlation of the PSD and drying temperature on the porosity was observed. Processing undried simulants caused the formation of discontinuous melt tracks and a significant chamber pressure increase.

Laser-based powder bed fusion (PBF-LB/M) of magnesium WE43 shows great potential for lightweight applications due to its low density and high specific strength. Especially complex magnesium structures such as gyroid lattices with a high surface-to-volume ratio are desirable for further weight reduction. However, rapid corrosion is impeding the transfer into industrial applications.

To enhance the corrosion resistance of additively manufactured WE43, a ceramic surface modification by plasma electrolytic oxidation (PEO) has been investigated in previous baseline studies. This contribution addresses PEO of filigree WE43 structures and the evaluation of geometrical requirements like the minimal feature size. Moreover, the microstructure and corrosion resistance of the manufactured parts have been analyzed. In thin-walled specimens as well as gyroid structures, wall sizes down to 150 µm could be manufactured and successfully modified by PEO. In corrosion tests, the untreated specimen dissolved after 12 hours, whereas the modified specimen showed no signs of corrosion.

We report on a study of different hot isostatic pressing (HIP) cycles, improving the mechanical properties of additively manufactured Inconel 718 components. For this, PBF-LB/M built components are post-processed by different HIP-sequences, as gas pressure and processing time are varied, leading to differences in microstructure and material characteristics. Static and dynamic mechanical testing is performed, evaluating the changes in mechanical properties with the ultimate tensile strength and the endurance limit. Furthermore, metallographic analysis is used to investigate the achieved density and microhardness, as thermal post processing, especially HIP, leads to a significant improvement in material characteristics. Microstructural analysis, showing the grain boundaries, is used to define generated phases and precipitations of the material matrix. Moreover, the fracture behaviour is classified by grain deformation during mechanical testing, as differences in microstructure lead to highly different fatigue behaviour.

As lattice structures in various designs are used in additive manufacturing for lightweight components, the mechanical characterisation and fracture behaviour is of upmost importance for the industrial application. In this study, the fatigue behaviour of Inconel 718 lattice structures is evaluated, comparing sole PBF-LB/M to a hybrid additive manufacturing process combining PBF-LB/M with in-situ high-speed milling. At first, the static and dynamic mechanical load behaviour of different packing densities is analysed, determining the compressive strength and the endurance limit. Secondly, such hybrid additive manufactured components are compared to PBF-LB/M built parts with respect to these mechanical properties, revealing improved compressive properties and modified regimes of fatigue. In addition, differences in fracture behaviour are qualified by fractographic and surface analysis. Overall, it can be summarized that the mechanical load characteristics, especially the fatigue behaviour, are improved for hybrid additively manufactured components with a superior surface quality of Ra < 2 µm.