The surfaces of laser-sintered and laser beam melted parts are characterized by typical surface effects and thus cause difficulties when using the popular tactile profilometry method and conventional two-dimensional surface parameters for analysis. Therefore, this study shows the potential of a new measurement approach by a confocal microscope and three-dimensional surface parameters. Within this study, a special focus is laid on the classification of different surface orientations and on a special issue in laser sintering: orange peel severity.

The analysis of surface effects in powder bed fusion additive manufacturing is the subject of intensive research activities. The aim of this paper is to provide an overview of the current state of knowledge and to gain a comprehensive understanding of this subject area. The paper is intended to enable researchers to select specific articles for their own further research context. In addition, a bibliometric analysis validates the data base. A discussion of the findings suggests that the criticality of the surface should be considered as a quality factor in the field of additive manufacturing by powder bed fusion processes. An accurate and reliable measurement is crucial for predicting component quality. There is a clear trend from two-dimensional measurements to three-dimensional measurements. Conducting comprehensive research is essential to improve the reliability and comparability of measurement results and to promote broad acceptance and application of this technology in the industry.

The powder bed fusion of metals using a laser beam (PBF-LB/M) is an additive manufacturing process for the direct production of metal parts using powder as a starting material. The PBF-LB/M process consists of two main steps: the application of a new powder layer and the melting of the cross-sections of the parts in each layer. Laser exposure usually takes up a lot of time during a build process; however, the application of powder layers, also taking up a considerable amount of time, offers potential to shorten production times. In this work, a powder test rig that mimics the real flow conditions of a PBF-LB/M system is used to measure the quality of X3NiCoMoTi18-9-5 powder layers applied at different recoater speeds by determining the powder surface roughness. The same recoating settings are then used on a real PBF-LB/M system to produce samples and investigate their densities as a function of recoater speed. The results show that the recoater speed influences the surface of the applied powder bed and has an effect on the density of the manufactured samples. However, this influence decreases if only samples with a high relative density are considered.

Additive manufacturing of pure copper is of interest due to the materials thermal and electrical conductivity, corrosion resistance and ductility, as well as the possibility of creating value through the production of complex structures. Powder bed fusion of copper using an electron beam (PBF-EB) is considered promising due to the vacuum atmosphere, the scalable beam power, and the high reflectivity of copper for IR radiation used in state-of-the-art powder bed fusion of metals using a laser beam (PBF-LB/M) machines. In PBF-EB, spot-based exposure strategies are considered a promising approach to overcome issues resulting from vector-based processing with variable vector length such as lack of fusion, local temperature accumulation, and surface swelling. However, the processing of pure copper using spot-based exposure strategies is widely uncovered. This study investigates the transfer of exposure parameters from vector- to spot-based processing of pure copper and compares the relative density, microstructure and physical properties. Both applied exposure strategies yielded relative densities exceeding 99.5%, electrical conductivities exceeding 100% IACS, and thermal diffusivities above 1.17 cm ² s ⁻¹ . Variations in microstructure and mechanical properties are analyzed using electron backscatter diffraction method and attributed to differences in local thermal gradients and solidification speed. The results indicate that, in addition to conventional vector-based exposure strategies, spot-based exposure approaches are also applicable for the fabrication of complex components.

One of the most widely used additive manufacturing processes for metals is the powder bed fusion process, using a laser beam to melt powder layer upon layer into complex three-dimensional structures. While this manufacturing technique offers considerable design versatility, it is limited by overhang features that necessitate support structures, with the required angles for these supports varying based on the material, process, and machine used. Overhang features are susceptible to distortion, which compromises process stability. If the overhang feature penetrates into the next layer of powder, the recoater that distributes the loosened powder can be damaged, which can lead to a total loss of the parts in severe cases. In this work, the effect of the laser path, the hatching, on the overhang displacement was investigated. Overhang specimens were built using different hatching strategies, orientations of the hatching sequence toward the gas flow, hatch lengths, and altered hatching in differently sized areas in the overhang. Among other implications, it was found, for the hatching, that the hatch length should be maximized to reduce overheating effects and displacement in overhang regions. The findings and their practical implications offer an overview of the overhang displacement and the influence of various hatching strategies and parameters. This research serves as a foundation for more advanced optimized hatching strategies that will reduce overhang displacement, increase process stability, and even further increase the freedom of design in additive manufacturing.