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Influence of Powder Deposition on Powder Bed and Specimen Properties

1
Institute for Particle Technology, TU Braunschweig, 38104 Braunschweig, Germany
2
Institute for Engineering Design, TU Braunschweig, 38106 Braunschweig, Germany
*
Author to whom correspondence should be addressed.
Materials 2019, 12(2), 297; https://doi.org/10.3390/ma12020297
Received: 19 December 2018 / Revised: 5 January 2019 / Accepted: 14 January 2019 / Published: 18 January 2019
(This article belongs to the Section Materials Physics)
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Abstract

Three-dimensional printing used to be a rapid prototyping process, but nowadays it is establishing as an additive manufacturing (AM) process. One of these AM techniques is selective laser sintering (SLS), which most often involves partial melting of the particles and therefore belongs to the category of powder bed fusion processes. Much progress has been made in this field by research on process parameters like laser power, hatch distance, and scanning speed while still lacking a fundamental understanding of the powder deposition and its influence on parts. A critical issue for economic manufacturing is the building time of parts with good mechanical properties, which can be reduced by lower surface roughness due to less or missing post processing. Therefore, the influence of three blade shapes on powder bed surface roughness has been evaluated for PA12 powder with three different grain size distributions by using advanced X-ray micro computed tomography (XMT) and a confocal laser scanning microscope (LSM). Along with those methods, new techniques for powder characterization were tested and compared. Lowest roughness has been achieved with a flat blade, based on a higher compression due to a larger contact zone between blade and powder bed. Furthermore, an anisotropic effect of the mechanical properties resulting from different building directions has been detected which can be explained by varying amounts of solid contact paths through the powder bed depending on powder application direction. In addition, an optimal combination of process parameters with an even compression of the powder bed leads to low surface roughness, complementing the advantages of additive manufacturing. View Full-Text
Keywords: additive manufacturing; selective laser sintering; surface roughness; blade geometry; powder application direction; PA12 additive manufacturing; selective laser sintering; surface roughness; blade geometry; powder application direction; PA12
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Beitz, S.; Uerlich, R.; Bokelmann, T.; Diener, A.; Vietor, T.; Kwade, A. Influence of Powder Deposition on Powder Bed and Specimen Properties. Materials 2019, 12, 297.

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