TY - JOUR A1 - Blümel, Christina A1 - Sachs, Marius A1 - Laumer, Tobias A1 - Winzer, Bettina A1 - Schmidt, Jochen A1 - Schmidt, Michael A1 - Peukert, Wolfgang A1 - Wirth, Karl-Ernst T1 - Increasing flowability and bulk density of PE-HD powders by a dry particle coating process and impact on LBM processes JF - Rapid Prototyping Journal N2 - Purpose – The purpose of this paper is to demonstrate the processability of cohesive PE-HD particles in laser beam melting processes (LBM) of polymers. Furthermore, we present a characterization method for polymer particles, which can predict the quality of the powder deposition via LBM processes. Design/methodology/approach – This study focuses on the application of dry particle coating processes to increase flowability and bulk density of PE-HD particles. Both has been measured and afterwards validated via powder deposition of PE-HD particles in a LBM machine. Findings – For efficient coating in a dry particle coating process, the PE-HD particles and the attached nanoparticles need to show similar surface chemistry, i.e. both need to behave either hydrophobic or hydrophilic. It is demonstrated that dry particle coating is appropriate to enhance flowability and bulk density of PE-HD particles and hence considerably improves LBM processes and the resulting product quality. Originality/value – At present, in LBM processes mainly polyamide (PA), 12 particles are used, which are so far quite expensive in comparison to, for example, PE-HD particles. This work provides a unique and versatile method for nanoparticulate surface modification which may be applied to a wide variety of materials. After the coating, the particles are applicable for the LBM process. Our results provide a correlation between flowability and bulk density and the resulting product quality. KW - Polymers KW - Bulk density KW - Dry particle coating KW - Flowability KW - Hydrophilic KW - Hydrophobic Y1 - 2015 U6 - https://doi.org/10.1108/RPJ-07-2013-0074 SN - 1758-7670 SN - 1355-2546 VL - 21 IS - 6 SP - 697 EP - 704 PB - Emerald ER - TY - CHAP A1 - Laumer, Tobias A1 - Stichel, T. A1 - Sachs, Marius A1 - Amend, Philipp A1 - Schmidt, Michael ED - Bártolo, Paulo T1 - Qualification and modification of new polymer powders for laser beam melting using Ulbricht spheres T2 - High value manufacturing : Advanced research in virtual and rapid prototyping ; Proceedings of the 6th International Conference on Advanced Research and Rapid Prototyping, Leiraia, Portugal, 1-5 October, 2013 N2 - The restricted amount of available materials for Laser Beam Melting (LBM) of polymers is one of the main limitations for expanding the technology. Current qualification methods deal with problems like inadequate powder flowability or high part porosities among others but do not offer a detailed analysis of the important beam-matter-interaction between powder particles and electro-magnetic laser radiation. In this paper, polyethylene powder is qualified for the LBM process and specifically analyzed regarding the optical material properties of the powder for a wavelength of 10.6 μm. By admixing graphite as absorption intensifier the change of the optical material properties and the thereby connected processing parameters are analyzed. Furthermore an explanation approach is given to explain the relation between different transmittances of different powder particles and the optical material properties of the polymer powders. Y1 - 2014 UR - https://www.researchgate.net/publication/286311000_Qualification_and_modification_of_new_polymer_powders_for_laser_beam_melting_using_Ulbricht_spheres SN - 978-1-138-00137-4 SN - 1138001376 SP - 255 EP - 260 PB - CRC Press CY - Boca Raton ER -