@inproceedings{LaumerKargSchmidt, author = {Laumer, Tobias and Karg, Michael Cornelius Hermann and Schmidt, Michael}, title = {Additive Manufacturing of Gradient and Multimaterial Components}, series = {International Conference on Competitive Manufacturing COMA, 2013, Stellenbosch}, booktitle = {International Conference on Competitive Manufacturing COMA, 2013, Stellenbosch}, abstract = {In the paper first results regarding the realisation of gradient and multi-material parts manufactured by Laser Beam Melting in powder bed of metals and polymers are published. Gradient properties of additively manufactured metal parts can be achieved by varying the composition of alloying components in the powder and adapting process strategies. As an alternative to atomizing pre-alloyed materials, mixtures of different powders are investigated. For realizing multi-material-parts from polymers, at first relevant material properties concerning compatibility have to be analysed. Therefore the paper shows the main requirements for compatibility between different materials and also first results regarding the compatibility of polymer powders and possible combinations for the manufacturing of multi-material components by laser beam melting of polymers.}, language = {en} } @inproceedings{LaumerKoopmannSticheletal., author = {Laumer, Tobias and Koopmann, Jonas and Stichel, Thomas and Amend, Philipp}, title = {Generation of multi-material parts with alternating material layers by Simultaneous Laser Beam Meltingof polymers}, series = {International Conference on Additive Technologies, 15 - 17 Oct 2014, Wien}, booktitle = {International Conference on Additive Technologies, 15 - 17 Oct 2014, Wien}, abstract = {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.}, language = {en} } @inproceedings{LaumerSchmidtStichel, author = {Laumer, Tobias and Schmidt, Michael and Stichel, Thomas}, title = {Influence of temperature gradients on the part properties for the simultaneous laser beam melting of polymers}, series = {Proceedings of Laser in Manfacturing Conference 2015, June 22 - June 25, 2015 Munich, Germany}, booktitle = {Proceedings of Laser in Manfacturing Conference 2015, June 22 - June 25, 2015 Munich, Germany}, organization = {German Scientific Laser Society (WLT e.V.)}, abstract = {By Laser Beam Melting of polymers (LBM), parts with almost any geometry can be built directly out of CAD files without the need for additional tools. Thus, prototypes or parts in small series production can be generated within short times. Up to now, no multi-material parts have been built by LBM, which is a major limitation of the technology. To realize multi-material parts, new mechanisms for depositing different polymer powders as well as a new irradiation strategy are needed, by which polymers with different melting temperatures can be warmed to their specific preheating temperatures and be molten simultaneously. This is achieved by simultaneous laser beam melting (SLBM). In the process, two different materials are deposited next to each other and preheated a few degrees below their melting temperatures by infrared emitters and laser radiation (λ = 10.60 µm), before in the last step the two preheated powders are molten simultaneously by an additional laser (λ = 1.94 µm). So far, multi-material tensile bars have been realized and analyzed regarding their boundary zone between both materials. The experiments showed that the temperature gradients in the boundary zone and along the building direction seem to be of great importance for the process stability and the resulting part properties. Therefore, a detailed analysis of the occurring temperature gradients during the process is needed to identify adequate process adjustments regarding the temperature controlling. To analyze the temperature gradients, thermocouples positioned inside the powder bed are used. By varying the temperature of the building platform, the influence of different temperature gradients on the resulting part properties is shown.}, 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} } @inproceedings{Laumer, author = {Laumer, Tobias}, title = {The influence of micro-sized structures on the compound strength of multi-material components built by Simultaneous Laser Beam Melting of Polymers}, series = {Proceedings of LPM2016 - the 17th International Symposium on Laser Precision Microfabrication, 2016, Xian, China}, booktitle = {Proceedings of LPM2016 - the 17th International Symposium on Laser Precision Microfabrication, 2016, Xian, China}, abstract = {Simultaneous laser beam melting (SLBM) allows the direct realization of multi-material components consisting of different polymer materials by a single Additive Manufacturing (AM) process. To achieve a high compound strength between different materials by adhesive bonding, a common boundary zone based on diffusion of the macromolecules is necessary and thus, both materials needs to be compatible regarding their specific adhesion compatibility. However, by SLBM also incompatible polymers can be processed to multi-material parts. If two incompatible polymers are processed, a positive locking between the different materials is necessary to achieve a connection between the materials. The positive locking results of a random mixture process of the different powder materials during the powder deposition process by a two chamber recoater system, which leads to the forming of undercuts of one material in the other during the melting and recrystallization. In this paper, thermoplastic elastomer (TPE) and polypropylene (PP) powders, which are incompatible, are processed to multi-material specimens. By qualifying basic material properties, their influence on the process and especially on the forming of undercuts in the boundary zone is analyzed. To also allow the analysis of the influence of both material and process parameters on the resulting part properties, tensile test specimens are built and their tensile strength is determined. Additionally, cross sections of the boundary zone are prepared and analyzed by microscope images.}, language = {en} }