TY - JOUR A1 - Hofmann, A. A1 - Hierl, Stefan T1 - Kontrolliertes Laserdurchstrahlschweißen JF - Kunststoffe N2 - Obwohl das Laserdurchstrahlschweißen sehr reproduzierbar arbeitet, können Fehler aus den Vorprozessen Compoundieren, Spritzgießen etc. das Schweißergebnis negativ beeinflussen. Dem Anwender steht inzwischen eine breite Palette an Prozessüberwachungsmethoden zur Verfügung, um eine gleich bleibende Produktqualität zu erzielen. Y1 - 2005 UR - https://res.cloudinary.com/sternwald-systems/raw/upload/v1/hugoprd/ARTIKEL_ATTACH/0023FE89_2E241FF70B1C/cf76c9103f760b78d6a3d1b7ecab28f0903541fb/KU_2005_06_Qualitaetssicherung-Kontrolliertes-Laserdurchstrahlschweissen.pdf VL - 95 IS - 6 SP - 36 EP - 38 PB - Hanser ER - TY - JOUR A1 - Dzafic, Adelisa A1 - Maiwald, Frederik A1 - Hierl, Stefan T1 - Messung der Schmelzefließgeschwindigkeit beim Laser-Durchstrahlschweißen von Kunststoffen JF - Werkstoffe in der Fertigung KW - Laserdurchstrahlschweissen KW - Kunststoff KW - Schmelzen KW - Fließgeschwindigkeit Y1 - 2021 SN - 0939-2629 VL - 57 IS - 3 SP - 31 EP - 33 PB - HW-Verl. CY - Mering ER - TY - JOUR A1 - Hüntelmann, Sven A1 - Hierl, Stefan T1 - AM-gerechte Bauteilgestaltung BT - Erarbeitung eines methodischen Vorgehens für die Topologieoptimierung additiv gefertigter Bauteile JF - additive - Das Magazin für generative Fertigung Y1 - 2020 UR - https://additive.industrie.de/forschung/am-gerechte-bauteilgestaltung/#slider-intro-2 IS - 01 SP - 57 ER - TY - CHAP A1 - Schmailzl, Anton A1 - Quandt, Benjamin A1 - Hierl, Stefan A1 - Schmidt, Michael T1 - Correlation between Joint Strength and Process Temperature in Quasi-Simultaneous Laser Transmission Welding of Polyamide 6 T2 - Proceedings of LiM2019 - Lasers in Manufacturing (23 June 2019, Munich) N2 - The joint strength is gaining importance in quasi -simultaneous laser transmission welds, especially in structural components. A correlation between the joint strength and a process characteristic is a basic requirement for selecting the best process parameter setting. In this work, the temperature is measured during welding polyamide 6 by using a scanner-integrated pyrometer with an InGaAs-detector. The filtering of the heat radiation in the upper joining partner is taken into account by calibrating the mea surement system. By this, the measured temperature signal represents the temperature in the joining zone. A correlation is found between the measured temperature and the resulting joint strength. Moreover, high joint strengths are also seen for welds with short welding times, as far as the temperature is sufficiently high. With this knowledge, a process window can be derived easily in order to produce welds with high strength and short welding times. Y1 - 2019 SP - 1 EP - 10 PB - Wissenschaftliche Gesellschaft Lasertechnik e.V. ER - TY - CHAP A1 - Quandt, Benjamin A1 - Schröcker, Korbinian A1 - Hierl, Stefan ED - Huber, Otto ED - Bicker, Marc ED - Patzelt, Peter T1 - Prozessüberwachung beim quasi-simultanen Laser-Durchstrahlschweißen glasfaserverstärkter Thermoplaste T2 - 9. Landshuter Leichtbau-Colloquium: Leichtbau in Forschung und industrieller Anwendung von der Nano- bis zur Makroebene, 27. / 28. Februar 2019 Hochschule Landshut, Tagungsband zum Colloquium Y1 - 2019 SP - 56 EP - 64 PB - LC-Verlag CY - Landshut ER - TY - JOUR A1 - Maiwald, Frederik A1 - Roider, Clemens A1 - Schmidt, Michael A1 - Hierl, Stefan T1 - Optical Coherence Tomography for 3D Weld Seam Localization in Absorber-Free Laser Transmission Welding JF - Applied Sciences N2 - Quality and reliability are of the utmost importance for manufacturing in the optical and medical industries. Absorber-free laser transmission welding enables the precise joining of identical polymers without additives or adhesives and is well-suited to meet the demands of the aforementioned industries. To attain sufficient absorption of laser energy without absorbent additives, thulium fiber lasers, which emit in the polymers’ intrinsic absorption spectrum, are used. Focusing the laser beam with a high numerical aperture provides significant intensity gradients inside the workpiece and enables selective fusing of the internal joining zone without affecting the surface of the device. Because seam size and position are crucial, the high-quality requirements demand internal weld seam monitoring. In this work, we propose a novel method to determine weld seam location and size using optical coherence tomography. Changes in optical material properties because of melting and re-solidification during welding allow for weld seam differentiation from the injection-molded base material. Automatic processing of the optical coherence tomography data enables the identification and measurement of the weld seam geometry. The results from our technique are consistent with microscopic images of microtome sections and demonstrate that weld seam localization in polyamide 6 is possible with an accuracy better than a tenth of a millimeter. KW - image processing KW - laser transmission welding KW - optical coherence tomography KW - process monitoring KW - transparent polymers Y1 - 2022 U6 - https://doi.org/10.3390/app12052718 N1 - Corresponding author: Frederik Maiwald VL - 12 IS - 5 SP - 1 EP - 11 PB - MPDI CY - Basel ER - TY - GEN A1 - Maiwald, Frederik A1 - Dzafic, Adelisa A1 - Hierl, Stefan T1 - Messung der Schmelzefließgeschwindigkeit beim Laser-Durchstrahlschweißen von Kunststoffen T2 - Laser in der Elektronikproduktion & Feinwerktechnik - LEF 2021, Erlangen, 22.04.2021 KW - Laserdurchstrahlschweissen KW - Kunststoff KW - Schmelzen KW - Fließgeschwindigkeit Y1 - 2021 ER - TY - JOUR A1 - Schmailzl, Anton A1 - Käsbauer, Johannes A1 - Martan, Jiří A1 - Honnerová, Petra A1 - Schäfer, Felix A1 - Fichtl, Maximilian A1 - Lehrer, Tobias A1 - Prušáková, L. A1 - Tesař, Jiří A1 - Skála, J. A1 - Honner, Milan A1 - Hierl, Stefan T1 - Measurement of Core Temperature through Semi-Transparent Polyamide 6 using Scanner-Integrated Pyrometer in Laser Welding JF - International Journal of Heat and Mass Transfer N2 - Predicting the core temperature during welding is an ambitious aim in many research works. In this work, a 3D-scanner with integrated pyrometer is characterized and used to measure the temperature during quasi-simultaneous laser transmission welding of polyamide 6. However, due to welding in an overlap configuration, the heat radiation emitted from the joining zone of a laser transmission weld has to pass through the upper polymer, which is itself a semi-transparent emitter. Therefore, the spectral filtering of the heat radiation in the upper polymer is taken into account by calibrating the pyrometer for the measurement task. Thermal process simulations are performed to compare the temperature field with the measured temperature signal. The absorption coefficients of the polymers are measured, in order to get precise results from the computation. The temperature signals during welding are in good agreement with the computed mean temperature inside the detection spot, located in the joining area. This is also true for varying laser power, laser beam diameter and the carbon black content in the lower polymer. Both, the computed mean temperature and the temperature signal are representing the core temperature. In order to evaluate the spatial sensitivity of the measurement system, the emitted heat radiation from both polymers is calculated on basis of the computed temperature field. Hereby it is found, that more than 90 percent of the detected heat radiation comes from the joining area, which is a crucial information for contact-free temperature measurement tasks on semi-transparent polymers. KW - Semi-transparent polymer KW - Pyrometer KW - Laser transmission welding KW - Temperature KW - measurement Y1 - 2020 U6 - https://doi.org/10.1016/j.ijheatmasstransfer.2019.118814 VL - 146 IS - January PB - Elsevier ER - TY - CHAP A1 - Maiwald, Frederik A1 - Englmaier, Stephan A1 - Hierl, Stefan T1 - Absorber-free Laser Transmission Welding of Transparent Polymers using Fixed Focus Optics and 3D Laser Scanner T2 - Procedia CIRP N2 - Laser transmission welding is a well-known joining technology for thermoplastics, providing reliable and hermetical sealing without adhesives or particle formation. The main advantages of laser-based energy input - high precision, no additional adhesive and no particle emission - are essential for medical and optical applications. To obtain sufficient absorption in visually transparent polymers, thulium fibre lasers emitting in the polymers’ intrinsic absorption spectrum are used. Optics with high numerical aperture provide large intensity gradients inside the specimen, enabling selective fusing in the joining zone. Although the basic feasibility has already been demonstrated, the welding process lacks stability and productivity. Aim of this work is the determination of optimized settings for a fast and reliable welding process. Thus, the interplay of process parameters as well as their impact on the seam are analysed by thermal simulations. Calculated settings are verified by welding tests with COC, PA6 and PETG, using a fixed-focus optics and a 3D laser scanner with up to 200 mm/s feed rate. Y1 - 2020 U6 - https://doi.org/10.1016/j.procir.2020.09.117 VL - 94 SP - 686 EP - 690 ER - TY - CHAP A1 - Käsbauer, Johannes A1 - Schmailzl, Anton A1 - Prehm, Jens A1 - Loose, Tobias A1 - Hierl, Stefan T1 - Simulation of Quasi-Simultaneous Laser Transmission Welding of Plastics BT - Optimization of Material Parameters in Broad Temperature Range T2 - Procedia CIRP N2 - Thermo-mechanical simulation offers great opportunities to optimize welding processes of plastics. For realistic simulation, the temperature dependent mechanical properties need to be implemented from ambient temperature to temperatures above the flow temperature. Standard test methods are insufficient for characterization in the entire temperature range because close to the flow temperature the material is too soft for tensile tests and too stiff for rheometry. Therefore, an optimization strategy is developed, that determines unknown material parameters by testing in welding simulations. The unknown parameters are iteratively adjusted to minimize the mismatch between computed and measured set-paths. Thus, important process characteristics are calculated realistically, enabling the computer aided assessment of the weld quality. KW - plastics welding KW - simulation KW - material modelling KW - optimization KW - parameterization KW - Kunststoffschweißen KW - Thermomechanische Eigenschaft KW - Simulation Y1 - 2020 U6 - https://doi.org/10.1016/j.procir.2020.09.136 VL - 94 SP - 737 EP - 741 ER - TY - GEN A1 - Käsbauer, Johannes A1 - Schmailzl, Anton A1 - Loose, Tobias A1 - Hierl, Stefan T1 - Thermo-Mechanical Modeling of Quasi-Simultaneous Laser Transmission Welding using LS-DYNA with Focus on Accuracy of Heat Input Calculation T2 - Technology Day 2020 - Plastics on the test rig, Traboch, 04.03.2020 Y1 - 2020 ER - TY - JOUR A1 - Käsbauer, Johannes A1 - Schmailzl, Anton A1 - Weber, Ulrich A1 - Hierl, Stefan A1 - Jaus, Tobias A1 - Schwalme, Michael T1 - Simulationsgestützte Evaluierung von Strahloszillationsmustern beim quasi-simultanen Laser-Durchstrahlschweißen JF - JOINING PLASTICS - Fügen von Kunststoffen Y1 - 2019 VL - 13 IS - 2 SP - 102 EP - 109 ER - TY - GEN A1 - Käsbauer, Johannes A1 - Schmailzl, Anton A1 - Loose, Tobias A1 - Hierl, Stefan T1 - Potentials of the EFG-Method for Modeling Quasi-Simultaneous Laser Transmission Welding Considering the Melt Flow T2 - Simulationsforum 2019 - Schweißen und Wärmebehandlung, Weimar Y1 - 2019 ER - TY - CHAP A1 - Käsbauer, Johannes A1 - Schmailzl, Anton A1 - Hierl, Stefan T1 - Simulationsgestützte Prozessentwicklung beim Laser Durchstrahlschweißen von Thermoplasten ohne absorbierende Füllstoffe T2 - 36. CADFEM ANSYS Simulation Conference, 10.-12. Oktober 2018, Leipzig Y1 - 2018 SP - 1 EP - 9 ER - TY - CHAP A1 - Hüntelmann, Sven A1 - Hierl, Stefan T1 - Methodisches Vorgehen bei der Topologieoptimierung additiv gefertigter Bauteile T2 - Technikforum 3D Druck - Innovative Ansätze für Bauteiloptimierung, Design und Konstruktion. Technologie Centrum Westbayern, 27.11.2018 Y1 - 2018 ER - TY - GEN A1 - Maiwald, Frederik A1 - Hierl, Stefan T1 - Absorberfreies Laser-Durchstrahlschweißen transparenter Kunststoffe T2 - InnovationForum Medizintechnik, Tuttlingen, 24.10.2019 Y1 - 2019 ER - TY - RPRT A1 - Schillinger, Moritz A1 - Görlach, Julien A1 - Hierl, Stefan ED - Baier, Wolfgang T1 - Erstellung eines Konstruktionskatalogs für die additive Fertigung T2 - Forschung 2018 N2 - Die additive Fertigung bietet vielfältige Möglichkeiten hinsichtlich der Bauteilgestaltung. Jedoch sind auch bei den generativen Fertigungsverfahren konstruktive Randbedingungen zu beachten, um Bauteile kostengünstig und mit optimalen Eigenschaften herzustellen. Es ist bereits umfangreiche Fachliteratur erhältlich, die entsprechende Konstruktionsempfehlungen gibt. Um Produktentwickler bedarfsgerecht zu unterstützen, ist jedoch ein Nachschlagewerk erforderlich, das mit geeigneter Systematik Konstruktionsvorschläge ausgibt, die zur aktuellen Problemstellung passen. Aufbauend auf dem Stand der Technik, eigenen Analysen und experimentellen Untersuchungen werden erste Ansätze für ein solches Nachschlagewerk vorgestellt. KW - Rapid prototyping KW - Methodisches Konstruieren KW - Konstruktionskatalog Y1 - 2018 UR - https://doi.org/10.35096/othr/pub-1382 SP - 70 EP - 71 ER - TY - RPRT A1 - Hierl, Stefan ED - Baier, Wolfgang T1 - Forschungsschwerpunkte im Labor Lasermaterialbearbeitung T2 - Forschungsbericht 2017 N2 - Durch das Laserkunststoffschweißen können sowohl filigrane Nähte in der Mikrotechnik als auchtragfähige Verbindungen für Strukturbauteile hergestellt werden. In der Automotiv- oder der Medizintechnik-Industrie ist diese Fügetechnologie mittlerweile etabliert, jedoch sind die Anwen-dungsmöglichkeiten bei Weitem noch nicht ausgeschöpft. In kürzlich gestarteten Forschungsprojekten mit regionalen Industrieunternehmen und internationalen Forschungspartnern werden im Labor Lasermaterialbearbeitung weitere Potenziale gehoben. KW - Laserschweissen KW - Kunststoff Y1 - 2017 UR - https://doi.org/10.35096/othr/pub-1383 SP - 56 EP - 57 ER - TY - CHAP A1 - Schmailzl, Anton A1 - Steger, Sebastian A1 - Hierl, Stefan ED - bayern photonics e.V., ED - Bayerisches Laserzentrum GmbH, T1 - Herausforderungen bei der Integration einer pyrometrischen Temperaturmesstechnik in 3D-Laserscansysteme T2 - Photonikseminar Kalibrierung des 2D- und 3D-Arbeitsfeldes von Laser-Scan-Systemen, 31.Mai 2017 Y1 - 2017 SP - 48 EP - 56 CY - Nürnberg ER - TY - JOUR A1 - Quandt, Benjamin A1 - Schäfer, Felix A1 - Hierl, Stefan T1 - Heiße Infos aus schwachem Temperatursignal BT - Scanner-integrierte, pyrometrische Temperaturmessung für verstärkte Kunststoffe JF - Kunststoffe Y1 - 2018 SN - 0945-0084 IS - 12 SP - 65 EP - 68 PB - Hanser CY - München ER -