@inproceedings{LaumerStichelAmendetal., author = {Laumer, Tobias and Stichel, Thomas and Amend, Philipp and Roth, Stephan and Schmidt, Michael}, title = {Analysis of Temperature Gradients during Simultaneous Laser Beam Melting of Polymers}, series = {Physics Procedia}, volume = {56}, booktitle = {Physics Procedia}, publisher = {Elsevier}, doi = {10.1016/j.phpro.2014.08.159}, pages = {167 -- 175}, abstract = {By simultaneous laser beam melting (SLBM), different polymer powders can be processed to multi-material parts, which offers the potential to enlarge the field of application for conventional LBM. In a SLBM process, a powder bed consisting of different polymers and therefore with different melting and crystallization temperatures is deposited. Besides the use of infrared emitters for preheating the lower melting polymer, a CO2 laser distributes the necessary preheating temperature of the higher melting polymer. In the last step, a thulium fibre laser distributes the energy necessary for melting the two preheated powders simultaneously. In order to analyze the temperature gradients of the process on the powder surface and in deeper layers, a high-resolution thermal imaging system and thermocouples are used.}, language = {en} } @inproceedings{LaumerRothSticheletal., author = {Laumer, Tobias and Roth, Stephan and Stichel, Thomas and Schmidt, Michael}, title = {Strategien zur Erzeugung von dreidimensionalen Multi-Material-Bauteilen}, series = {4. Industriekolloquium des Sonderforschungsbereichs 814 - Additive Fertigung 814, 2015, N{\"u}rnberg}, booktitle = {4. Industriekolloquium des Sonderforschungsbereichs 814 - Additive Fertigung 814, 2015, N{\"u}rnberg}, organization = {Friedrich-Alexander-Universit{\"a}t Erlangen-N{\"u}rnberg, Sonderforschungsbereich 814 Additive Fertigung}, isbn = {978-3931864651}, language = {de} } @inproceedings{AmendMrotzekLaumeretal., author = {Amend, Philipp and Mrotzek, Tino and Laumer, Tobias and Wolf, Michel and Roth, Stephan and Gude, Maik and Schmidt, Michael}, title = {Experimental Investigations on Laser-based Hot-melt Bonding and Injection Molding for Laser-structured Metal Plastic Hybrids}, series = {Laser in Manufacturing (LIM 2017), Munich, Germany}, booktitle = {Laser in Manufacturing (LIM 2017), Munich, Germany}, isbn = {978-3-87525-428-0}, abstract = {The use of thermoplastics in lightweight construction is continuing to grow. This implies the need for suitable joining techniques to combine thermoplastics with other materials, such as metals, to gain tailored multi-material parts. In this paper latest results of experimental investigations on laser-based hot-melt bonding and injection molding for laser-structured metal plastic hybrids are presented. As materials stainless steel and short-fiber reinforced polyamide are used. The stainless steel surface is structured with a nanosecond pulse laser before joining to improve the mechanical adhesion between the dissimilar materials. Thereby, different structure depths in the range between 16.6 ± 1.2 µm and 66.5 ± 2.5 µm as well as different hatch distances between 70 and 300 µm are realized. The laser-based joining process is carried out irradiating the metallic surface multiple times. Positioned below the metal in T-joint configuration, the thermoplastic melts as a result of heat transfer and acts as hot-melt cohesive. Besides, hybrid joints are manufactured using injection molding. For experiments, the mold temperature as well as the melt temperature are varied. Regardless of the joining process, the hybrid joints are mechanically characterized by tensile tests. The results demonstrate that for both joining processes strong laser-structured metal plastic hybrids can be realized.}, language = {en} } @inproceedings{AmendLaumerRothetal., author = {Amend, Philipp and Laumer, Tobias and Roth, Stephan and Baat, Florian and Schmidt, Michael}, title = {Investigations on Laser-based Hot-melt Bonding of Additive Manufactured Plastic Parts to Metal Sheets for Strong and Tight Multi-material Joints}, series = {Laser in Manufacturing (LIM 2017), Munich, Germany}, booktitle = {Laser in Manufacturing (LIM 2017), Munich, Germany}, abstract = {In this paper, first results regarding the realization of laser-based hot-melt bonding of additive manufactured plastics parts to metal sheets for strong and tight multi-material joints are presented. Compared to earlier investigations, in which nearly solely extruded plastic materials were applied, the use of additive manufactured plastics complements the research field with a promising approach. Besides the typical advantages of multi-material joints regarding weight reduction and high strengths, such parts can meet the needs of constructional freedom and the avoiding of tool costs. Materials used for this paper are aluminum (AlMg3), stainless steel (1.4301) and polyamide 12 (PA12). The performed experiments resulting in multi-material joints between metal and polyamide. The realized specimens undergo a tensile shear test and a tightness test, in which the characteristics of the joints are determined.}, language = {en} } @article{LaumerWudyDrexleretal., author = {Laumer, Tobias and Wudy, Katrin and Drexler, Maximilian and Amend, Philipp and Roth, Stephan and Drummer, Dietmar and Schmidt, Michael}, title = {Fundamental investigation of laser beam melting of polymers for additive manufacture}, series = {Journal of Laser Applications}, volume = {26}, journal = {Journal of Laser Applications}, number = {4}, publisher = {AIP Publishing}, issn = {1938-1387}, doi = {10.2351/1.4892848}, abstract = {By selective laser sintering (SLS), polymer powders are molten layer by layer to build conventional prototypes or parts in small series with geometrical freedom that cannot be achieved by other manufacturing technologies. The SLS process is mainly defined by the beam-matter interaction between powder material, laser radiation and different material characteristics by itself. However the determination of these different material characteristics is problematic because powder material imposes certain requirements that cannot sufficiently be provided by conventional measurement methods. Hence new fundamental investigation methods to determine the optical and thermal material characteristics like the thermal diffusivity, thermal conductivity, or the influence of different heating rates on the melting behavior are presented in this paper. The different analysis methods altogether improve the process of understanding to allow recommendations for the future process controlling.}, language = {en} }