TY - CHAP A1 - Laumer, Tobias A1 - Appel, Peter A1 - Stichel, Thomas A1 - Amend, Philipp T1 - Untersuchungen zum Absorptionsverhalten von Pulverschüttungen für das Laserstrahlschmelzen von Kunststoffen Conference T2 - Rapid.Tech, 2013, Erfurt N2 - Die Energieeinbringung in Form von elektromagnetischer Strahlung in das Pulverbett beim selektiven Laserstrahlschmelzprozess von Kunststoffen wird maßgeblich durch das Absorptionsverhalten der Pulverwerkstoffe bestimmt. Aufgrund von Vielfachreflexionen an den einzelnen Pulverpartikeln in den Poren weisen Pulverwerkstoffe im Vergleich zu makroskopischen Festkörpern andere Absorptionseigenschaften auf. Im vorliegenden Beitrag wird daher ein geeigneter Messaufbau zur Bestimmung der optischen Materialeigenschaften von verschiedenen Pulverwerkstoffen vorgestellt. Mittels eines Ulbricht-Kugel-Messaufbaus wird der Reflexions-, der Transmissions- und der Absorptionsgrad von pulverförmigen Werkstoffen bei einer Wellenlänge von 10,6 µm eines CO2-Lasers und unterschiedlichen Schichtstärken ermittelt. Neben den Werkstoffen Polyamid 12 und Polyethylen im reinen Zustand werden Mischungen mit Additiven, wie beispielsweise Graphit, analysiert und verglichen. Durch die Beimischungen kann eine für den Schmelzprozess zu geringe Absorption des reinen Kunststoffes wie im Fall von Polyethylen-Pulver bei einer Wellenlänge von 10,6 µm gezielt erhöht werden, wodurch die Entwicklung neuer Pulverwerkstoffe erleichtert wird. KW - Additive Fertigung KW - Laserstrahlschmelzen von Kunststoffen KW - Werkstoffqualifizierung Y1 - 2013 UR - https://www.researchgate.net/publication/274250200_Untersuchungen_zum_Absorptionsverhalten_von_Pulverschuttungen_fur_das_Laserstrahlschmelzen_von_Kunststoffen ER - TY - CHAP A1 - Laumer, Tobias A1 - Koopmann, Jonas A1 - Stichel, Thomas A1 - Amend, Philipp T1 - Generation of multi-material parts with alternating material layers by Simultaneous Laser Beam Meltingof polymers T2 - International Conference on Additive Technologies, 15 - 17 Oct 2014, Wien N2 - By using Additive Manufacturing technologies, like Laser Beam Melting (LBM) of polymers, parts can be realized within single days and necessary modifications can be quickly adapted. With increasing complexity, products are often made out of different polymer materials and the need for multi-material parts is an increasing industry requirement, which cannot be fulfilled by the single material parts realizable by LBM. Therefore, Simultaneous Laser Beam Melting (SLBM) as a new Additive Manufacturing technology offers the possibility to build parts consisting of different polymer materials. The realizable parts combine different material properties, like differing stiffness or chemical resistances, within a single part. Up to now, different materials are deposited next to each other on the building platform, thus the boundary surface between the different polymers is orientated perpendicular to the building direction. For this paper, the polymer powders are alternated in building direction. Thus, the boundary surface is orientated horizontally and is larger, both influencing the boundary surface and resulting part properties, which are analyzed by a high-resolution thermal imaging system and by cross sections. KW - additive manufacturing KW - Multi-Material Parts KW - Simultaneous Laser Beam Melting Y1 - 2014 UR - https://www.researchgate.net/publication/274250275_Generation_of_multi-material_parts_with_alternating_material_layers_by_Simultaneous_Laser_Beam_Meltingof_polymers ER - TY - CHAP A1 - Stichel, Thomas A1 - Amend, Philipp A1 - Laumer, Tobias A1 - Roth, Stephan T1 - Electrostatic Multi-Material Powder Deposition for Simultaneous Laser Beam Melting T2 - International Conference on Information, Communication and Automation Technologies (ICAT), 2014, Wien N2 - In this paper, the use of electrostatic polymer powder transfer methods for the preparation of multi-material layers is discussed with respect to the application in Simultaneous Laser Beam Melting (SLBM). Therefore, the basic principles of the single process steps as well as the challenges in combination with SLBM are considered verifying the critical process steps. On that base, process concepts are developed which might enable the fabrication of high quality multi-material parts in the future. Moreover, since the polymer powders typically used with Laser Beam Melting differ strongly from common toners for e. g. electrophotographic printing, an experimental setup was built to study the powder transfer with an electrically chargeable transfer plate using polyamide 12 powder. The results of this study show that transfer of powders usable for Laser Beam Melting can be achieved, but depends on the electric field strength which is a function of the gap between transfer and substrate plate and the intermediate electric potential. Y1 - 2014 UR - https://www.researchgate.net/publication/280154608_Electrostatic_Multi-Material_Powder_Deposition_for_Simultaneous_Laser_Beam_Melting ER -