@inproceedings{47626, author = {{Rüther, Moritz Johannes and Klippstein, Sven Helge and Schmid, Hans-Joachim}}, booktitle = {{PARTEC International Congress on Particle Technology - Book of Abstracts}}, isbn = {{ 978-3-18-990139-9}}, issn = {{0083-5560}}, location = {{Nürnberg}}, pages = {{172 -- 176}}, publisher = {{VDI Verlag GmbH}}, title = {{{Correlation between SLS-Powder processability and particle properties }}}, year = {{2023}}, } @article{43128, author = {{Rüther, Moritz Johannes and Klippstein, Sven Helge and Ponusamy, SathishKumar and Rüther, Torben and Schmid, Hans-Joachim}}, issn = {{0032-5910}}, journal = {{Powder Technology}}, keywords = {{General Chemical Engineering}}, publisher = {{Elsevier BV}}, title = {{{Flowability of polymer powders at elevated temperatures for additive manufacturing}}}, doi = {{10.1016/j.powtec.2023.118460}}, volume = {{422}}, year = {{2023}}, } @article{43046, abstract = {{In the laser sintering technology, the semi-crystalline polymer material is exposed to elevated temperatures during processing, which leads to serious material ageing for most materials. This has already been investigated intensively by various authors. However, the ageing of the material at ambient temperatures during shelf life has not been the focus so far. The need to analyse the shelf life can be derived from an ecological and economic point of view. This work is focusing on the shelf life of PA2200 (PA12). To reduce the potential influences of powder production fluctuations, two different powder batches stored for 5.5 years and 6.5 years are investigated and compared to a reference powder produced 0.5 years before these investigations. Multiple powder analyses and part characterisations have been performed. A significant yellowing and molecular chain length reduction can be derived from the measurement results. Whereas the influence on mechanical part performance was minor, the parts built with the stored powders are more yellowish. As it is most likely that this is due to the consumption of polyamide stabilisers, it can be assumed that these parts will be subject to significantly faster ageing. Therefore, it is still not recommended to use the stored powders for critical parts or light intense and humid environments.}}, author = {{Klippstein, Sven Helge and Kletetzka, Ivo and Sural, Ilknur and Schmid, Hans-Joachim}}, journal = {{The International Journal of Advanced Manufacturing Technology }}, keywords = {{Selective laser sintering, Shelf life, Polyamide 12, powder, PA2200, material ageing}}, publisher = {{Springer}}, title = {{{Influence of a prolonged shelf time on PA12 laser sintering powder and resulting part properties}}}, doi = {{https://doi.org/10.1007/s00170-023-11243-1}}, year = {{2023}}, } @inproceedings{30229, author = {{Klippstein, Sven Helge}}, location = {{Online}}, title = {{{Reproducibility in Polymer Laser Sintering}}}, year = {{2022}}, } @inproceedings{33355, author = {{Klippstein, Sven Helge}}, location = {{Berlin}}, publisher = {{7. AM Forum Berlin}}, title = {{{Neue Polymerwerkstoffe - Der Schlüssel für die Industrialisierung}}}, year = {{2022}}, } @inproceedings{32874, author = {{Kletetzka, Ivo and Klippstein, Sven Helge and Schmid, Hans-Joachim}}, booktitle = {{Proceedings of the 33th Annual International Solid Freeform Fabrication Symposium}}, location = {{Austin}}, publisher = {{Laboratory for Freeform Fabrication and University of Texas}}, title = {{{Shelf Life of Polyamide 12 (PA2200) Laser Sintering Powder}}}, doi = {{http://dx.doi.org/10.26153/tsw/44555}}, volume = {{33}}, year = {{2022}}, } @article{35729, author = {{Rüther, Moritz Johannes and Klippstein, Sven Helge and Ponusamy, SathishKumar and Jesinghausen, Steffen and Schmid, Hans-Joachim}}, journal = {{Werkstoffe}}, pages = {{18 -- 19}}, publisher = {{HW-Verlag}}, title = {{{Innovative Werkstoffherstellung für das Polymer Laser Sintern – Teil 2}}}, volume = {{6}}, year = {{2022}}, } @article{35724, author = {{Rüther, Moritz Johannes and Klippstein, Sven Helge and Ponusamy, SathishKumar and Jesinghausen, Steffen and Schmid, Hans-Joachim}}, journal = {{Werkstoffe}}, pages = {{28--29}}, publisher = {{HW-Verlag}}, title = {{{Innovative Werkstoffherstellung für das Polymer Laser Sintern – Teil 1}}}, volume = {{5}}, year = {{2022}}, } @inproceedings{33695, author = {{Rüther, Moritz Johannes and Klippstein, Sven Helge and Schmid, Hans-Joachim}}, editor = {{Rüther, Moritz Johannes and Klippstein, Sven Helge and Schmid, Hans-Joachim}}, location = {{Madrid}}, title = {{{Flowability of polymer powders at elevated temperatures for additive manufacturing}}}, year = {{2022}}, } @article{30228, abstract = {{Confidence in additive manufacturing technologies is directly related to the predictability of part properties, which is influenced by several factors. To gain confidence, online process monitoring with dedicated and reliable feedback is desirable for every process. In this project, a powder bed monitoring system was developed as a retrofit solution for the EOS P3 laser sintering machines. A high-resolution camera records each layer, which is analyzed by a Region-Based Convolutional Neural Network (Mask R-CNN). Over 2500 images were annotated and classified to train the network in detecting defects in the powder bed at a very high level. Each defect is checked for intersection with exposure areas. To distinguish between acceptable imperfections and critical defects that lead to part rejection, the impact of these imperfections on part properties is investigated.}}, author = {{Klippstein, Sven Helge and Heiny, Florian and Pashikanti,, Nagaraju and Gessler, Monika and Schmid, Hans-Joachim}}, journal = {{JOM - The Journal of The Minerals, Metals & Materials Society (TMS)}}, location = {{Online}}, pages = {{1149–1157}}, publisher = {{Springer}}, title = {{{Powder Spread Process Monitoring in Polymer Laser Sintering and its Influences on Part Properties}}}, doi = {{https://doi.org/10.1007/s11837-021-05042-w }}, volume = {{74}}, year = {{2022}}, } @inproceedings{33356, abstract = {{By monitoring the recoating process within polymer laser sintering production, it was shown that multiple powder-spread-flaws can be detected. Those groove-like flaws are expected to be the result of agglomerates jamming between the recoater and the last powder layer. This work is analyzing the interaction between powder-spread-flaws and part properties, showing the influence of the recoating process on the performance of laser sintering parts. Therefore, artificial powder-spread-flaws are applied to the build jobs of tensile test specimens which are measured and analyzed regarding the elongation at break, strength and fracture position. For the characteristics of the flaws, the artificial grooves are varied in depth and width. Furthermore, the position of the flaw is changed form mid part to close to surface areas. It was shown, that several flaws are visible at the part surface, resulting in stress concentration and reduced performance. But there are as well parts with flaw-layers, which are not visible after the build process on the part. Those parts can have significantly reduced mechanical properties as well.}}, author = {{Klippstein, Sven Helge and Schmid, Hans-Joachim}}, booktitle = {{Proceedings of the 33nd Annual International Solid Freeform Fabrication Symposium}}, keywords = {{Selective Sasersintering, Process Monitoring, Powder Spread}}, title = {{{Powder Spread Flaws in Polymer Laser Sintering and its Influences on Mechanical Performance}}}, year = {{2022}}, } @inproceedings{31871, author = {{Kletetzka, Ivo and Klippstein, Sven Helge}}, booktitle = {{3D-DRUCK HAUTNAH - Der Einfluss einer Zukunftstechnologie auf unser Leben }}, location = {{Paderborn}}, publisher = {{Universität Paderborn}}, title = {{{Pulver im 3D-Druck - von Mascarabürsten bis zum Interieur eines Mini-Coopers (Vortrag)}}}, year = {{2022}}, } @inproceedings{30227, author = {{Klippstein, Sven Helge}}, location = {{Tudolstadt}}, title = {{{Online Monitoring des Beschichtungsprozesses im Laser Sintern, Systementwicklung und Einflussanalyse}}}, year = {{2021}}, } @techreport{24943, author = {{Menge, Dennis and Klippstein, Sven Helge and Schmid, Hans-Joachim}}, pages = {{130}}, title = {{{Additive Leichtbaustrukturen für die Flugzeugkabine}}}, year = {{2020}}, } @inproceedings{22198, abstract = {{Zuverlässige, wiederholbare Bauteileigenschaften sind unabdingbar um das Herstellungsverfahren Polymer Lasersintern im industriellen Prozess-Portfolio vieler Firmen aufnehmen zu können. Einige Unternehmen und Institute haben sich daher in jüngster Zeit mit dem Thema der reproduzierbaren Bauteileigenschaften beschäftigt. Mit der hier vorgestellten und angewandten Methodik wird nicht nur der Prozessablauf vom Bauteil bis zu Nachbearbeitung betrachtet, sondern auch die Maschinenperformance in einem Ringversuch und über einen längeren Zeitraum geprüft. Rückgrat dieser Untersuchung bildet hierbei der aus der Six Sigma Lehre stammende DMAIC (Define - Measure - Analyse - Improve - Control) Verbesserungszyklus. Hierfür wird ein Standard-Prozess definiert. Diesem folgend werden die für die Industrie oder den Anwender interessanten Messungen aufgenommen und analysiert. Anschließend wird der Prozess sowie die Messmethodik optimiert und auch Kontrollmethoden definiert. Für die Anwendung der entwickelten Methodik wird exemplarisch der Maschinentyp EOS P396 mit PA2200 untersucht. Daten für die Bestimmung der Mechanik, der Optik und der Haptik sowie für die Dimensionen und die Bauteildichte werden als Qualitätskriterium aufgenommen und über einen längeren Zeitraum analysiert. Weiteres Ziel ist es, den Messaufwand zu reduzieren und die Qualitätssicherung im Serienbtrieb zu gewährleisten.}}, author = {{Klippstein, Sven Helge and Schmid, Hans-Joachim}}, booktitle = {{Proceedings of the 16th Rapid.Tech Conference}}, title = {{{Methodik zur Qualifizierung des Lasersinter Prozesses für die Serienfertigung}}}, doi = {{10.3139/9783446462441.025}}, year = {{2019}}, } @inproceedings{22202, abstract = {{Structural parts for aviation have very high demands on the development and production process. Therefore, the entire process must be considered in order to produce high-quality AM metal parts. In this case study, a conventional part was selected to be optimized for AM. The process presented includes component selection, design improvement with a novel approach for topology optimization based on the AMendate algorithm as basis of MSC Apex Generative Design,component production on a SLM 250 HL and post-processing including heat treatment and surface smoothing. With the topology optimization a weight reduction of ~60 % could be realized, whereby the stress distribution is more homogeneous. Furthermore, the challenges of support optimization and post-processing have to be addressed, in order to produce competitive parts.}}, author = {{Klippstein, Sven Helge and Duchting, Anne and Reiher, Thomas and Hengsbach, F. and Menge, Dennis and Schmid, Hans-Joachim}}, booktitle = {{30th Annual International Solid Freeform Fabrication Symposium}}, pages = {{1932--1945}}, title = {{{Devolopment, Production and post-processing of a topology optimized aircraft bracket }}}, volume = {{30}}, year = {{2019}}, } @article{17835, author = {{Klippstein, Sven Helge and Hassanin, Hany and Diaz De Cerio Sanchez, Alejandro and Zweiri, Yahya and Seneviratne, Lakmal}}, issn = {{1438-1656}}, journal = {{Advanced Engineering Materials}}, number = {{2}}, title = {{{Additive Manufacturing of Porous Structures for Unmanned Aerial Vehicles Applications}}}, doi = {{10.1002/adem.201800290}}, volume = {{20}}, year = {{2018}}, } @article{16252, abstract = {{Additive Manufacturing (AM) is a game changing production technology for aerospace applications. Fused deposition modeling is one of the most widely used AM technologies and recently has gained much attention in the advancement of many products. This paper introduces an extensive review of fused deposition modeling and its application in the development of high performance unmanned aerial vehicles. The process methodology, materials, post processing, and properties of its products are discussed in details. Successful examples of using this technology for making functional, lightweight, and high endurance unmanned aerial vehicles are also highlighted. In addition, major opportunities, limitations, and outlook of fused deposition modeling are also explored. The paper shows that the emerge of fused deposition modeling as a robust technique for unmanned aerial vehicles represents a good opportunity to produce compact, strong, lightweight structures, and functional parts with embedded electronic.}}, author = {{Klippstein, Sven Helge and Diaz De Cerio Sanchez, Alejandro and Hassanin, Hany and Zweiri, Yahya and Seneviratne, Lakmal}}, issn = {{1438-1656}}, journal = {{Advanced Engineering Materials}}, keywords = {{FDM, Review, UAV}}, title = {{{Fused Deposition Modeling for Unmanned Aerial Vehicles (UAVs): A Review}}}, doi = {{10.1002/adem.201700552}}, year = {{2017}}, }