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 - TY - CHAP A1 - Schmailzl, Anton A1 - Steger, Sebastian A1 - Dostalek, Michael A1 - Hierl, Stefan ED - Klotzbach, U. ED - Washio, K. ED - Arnold, C. B. T1 - Online process monitoring at quasi-simultaneous laser transmission welding using a 3D-scanner with integrated pyrometer T2 - Proc. SPIE, Laser-based Micro- and Nanoprocessing X, SPIE LASE 2016, San Francisco, California, United States N2 - Quasi-simultaneous laser transmission welding is a well-known joining technique for thermoplastics and mainly used in the automotive as well as in the medical industry. For process control usually the so called set-path monitoring is used, where the weld is specified as "good" if the irradiation time is inside a defined confidence interval. However, the detection of small-sized gaps or thermal damaged zones is not possible with this technique. The analyzation of the weld seam temperature during welding offers the possibility to overcome this problem. In this approach a 3D-scanner is used instead of a scanner with flat-field optic. By using a pyrometer in combination with a 3D-scanner no color-corrected optic is needed in order to provide that laser- and detection-spot are concentric. Experimental studies on polyethylene T-joints have shown that the quality of the signal is adequate, despite the use of an optical setup with a long working distance and a small optical aperture. The effects on temperature are studied for defects like a gap in the joining zone. Therefore a notch was milled into the absorbent polymer. In case of producing housings for electronic parts the effect of an electrical wire between the joining partners is also investigated. Both defects can be identified by a local temperature deviation even at a feed rate of four meters per second. Furthermore a strategy for signal-processing is demonstrated. By this, remaining defects can be identified. Consequently an online detection of local defects is possible, which makes a dynamic process control feasible. KW - Defect detection KW - Fiber lasers KW - Laser ablation KW - Laser processing KW - Laser welding KW - Mirrors KW - Process control KW - Pyrometry KW - Scanners KW - Signal processing KW - Temperature metrology KW - Polymers Y1 - 2016 U6 - https://doi.org/10.1117/12.2211705 IS - 97361J SP - 1 EP - 7 ER - TY - CHAP A1 - Schmailzl, Anton A1 - Hierl, Stefan ED - CADFEM GmbH, ED - ANSYS Germany GmbH, T1 - Rechenzeitoptimierte Temperaturfeldberechnung beim quasisimultanen Laser-Durchstrahlschweißen T2 - ANSYS Conference & 33. CADFEM Users' Meeting 2015, 24.-26. Juni 2015, Bremen, Germany N2 - Beim quasisimultanen Laser-Durchstrahlschweißen von Kunststoffen wird bisher die FEM-Simulation wegen der Vielzahl von Umläufen des Laserstrahls und der damit verbundenen hohen Rechenzeit kaum eingesetzt. Um die Temperaturfeldberechnung zur Prozessauslegung und -optimierung praktikabel nutzen zu können, ist eine Reduktion der Rechenzeit zwingend erforderlich. Zur Simulation von Schweißvorgängen in ANSYS-CLASSIC werden die thermischen Lasten mithilfe von Ersatzwärmequellen auf Basis von APDL-Routinen berechnet. Im Gegensatz dazu wird in dieser Arbeit eine analytische Lastfunktion zur Berechnung der thermischen Last für das quasismultane Laser-Durchstrahlschweißen vorgestellt. Im Vergleich zur Temperaturfeldberechnung mit Ersatzwärmequelle kann bei der Berechnung eines dreidimensionalen Modells die Rechenzeit von mehreren Wochen auf wenige Stunden und für ein zweidimensionales auf nur wenige Minuten reduziert werden. Y1 - 2015 UR - http://www.cae-wiki.info/wikiplus/images/6/6a/UM2015-2.04.03.pdf N1 - DVD-ROM SP - 1 EP - 15 CY - Grafing bei München ER - TY - RPRT A1 - Steger, Sebastian A1 - Schmailzl, Anton A1 - Dostalek, Michael A1 - Armbruster, Dominik A1 - Hierl, Stefan ED - Baier, Wolfgang T1 - Entwicklung einer Systemtechnik für das quasisimultane Laser-Durchstrahlschweißen von 3D-Kunststoffbauteilen mit Temperaturmessung und Spanndruckregelung T2 - OTH Forschungsbericht 2016 Y1 - 2016 UR - https://doi.org/10.35096/othr/pub-1384 SP - 37 EP - 38 PB - Inixmedia GmbH CY - Kiel ER - TY - CHAP A1 - Schmailzl, Anton A1 - Armbruster, Dominik A1 - Dostalek, Michael A1 - Steger, Sebastian A1 - Hierl, Stefan ED - Falter, Thomas T1 - Strahlführungs- und -formungskonzept zur koaxialen Temperaturmessung beim scanner-basierten Laser-Durchstrahlschweißen T2 - 2. OTH-Clusterkonferenz, 18. Januar 2017, Techbase, Regensburg, Tagungsband Y1 - 2016 SP - 201 EP - 204 PB - Weber Druck CY - Regensburg ER - TY - CHAP A1 - Armbruster, Dominik A1 - Hierl, Stefan T1 - Berechnung des Messstrahlengangs für die in einen 3D-Scanner integrierte, pyrometrische Temperaturmessung beim quasisimultanen Laserdurchstrahlschweißen von Kunststoffen T2 - DVS Congress 2016, Große Schweißtechnische Tagung, DVS Studentenkongress. Vorträge der Veranstaltungen in Leipzig am 19. und 20. September 2016 Y1 - 2016 SP - 165 EP - 169 PB - DVS Media CY - Düsseldorf ER - TY - CHAP A1 - Schmailzl, Anton A1 - Hierl, Stefan ED - Schmidt, Michael ED - Roth, S. T1 - Scanner-integrierte Temperaturmesstechnik beim Laser-Durchstrahlschweißen T2 - Laser in der Elektronikproduktion & Feinwerktechnik - LEF 2017, Tagungsband des 20. Seminars LEF 2017, 07.-08. März 2017 Y1 - 2017 N1 - CD-ROM SP - 181 EP - 192 CY - Fürth ER - TY - RPRT A1 - Schmailzl, Anton A1 - Hierl, Stefan ED - Baier, Wolfgang T1 - Rechenzeitoptimierte Temperaturfeldberechnung zur virtuellen Prozessauslegung des quasisimultanen Laser-Durchstrahlschweißens T2 - Forschungsbericht 2014 / Ostbayerische Technische Hochschule Regensburg Y1 - 2015 SP - 75 EP - 77 PB - Inixmedia GmbH CY - Kiel ER - TY - JOUR A1 - Schmailzl, Anton A1 - Steger, Sebastian A1 - Hierl, Stefan T1 - Process monitoring at laser welding of Thermoplastics BT - 3D-scanner with integrated pyrometer enables online temperature monitoring at quasi-simultaneous laser transmission welding JF - Laser Technik Journal N2 - A pyrometer, integrated into a 3D‐scanner, offers the possibility to measure the weld seam temperature at quasi‐simultaneous laser transmission welding. Experimental studies have shown that gaps located in the joining zone can be identified by a temperature rise even at a high scanning velocity. This enables the implementation of algorithms for observation and control strategies. Y1 - 2015 U6 - https://doi.org/10.1002/latj.201500029 VL - 12 IS - 4 SP - 34 EP - 37 ER - TY - JOUR A1 - Dostalek, Michael A1 - Steger, Sebastian A1 - Schmailzl, Anton A1 - Hierl, Stefan T1 - Detecting Defects Reliably BT - Pyrometer-Based Temperature Measurement during Quasi-Simultaneous Laser Transmission Welding JF - Kunststoffe International N2 - The integration of a broadband pyrometer in a 3-D scanner enables a continuous and local temperature measurement during the quasi-simultaneous laser transmission welding process. Welding tests on polyethylene samples show that defects can be clearly identified based on the temperature signal, despite a high scanning velocity. Y1 - 2015 VL - 105 IS - 12 SP - 37 EP - 40 ER - TY - GEN A1 - Schmailzl, Anton A1 - Hierl, Stefan ED - CADFEM GmbH, ED - ANSYS Germany GmbH, T1 - FE-Modellbildung der Strahl-Stoff-Wechselwirkung beim Laser-Durchstrahlschweißen in ANSYS 14.0 T2 - ANSYS Conference & 32th CADFEM Users' Meeting 2014, 04.-06. Juni, Nürnberg Y1 - 2014 N1 - DVD-ROM SP - 1 EP - 15 CY - Grafing bei München ER - TY - RPRT A1 - Talbot, Sebastian A1 - Hierl, Stefan A1 - Schmailzl, Anton ED - Baier, Wolfgang T1 - Thermische FEM-Simulation des Laser-Durchstrahlschweißens T2 - Forschungsbericht 2013 Y1 - 2014 UR - https://doi.org/10.35096/othr/pub-799 SP - 45 EP - 46 CY - Kiel ER - TY - JOUR A1 - Steger, Sebastian A1 - Dostalek, Michael A1 - Schmailzl, Anton A1 - Hierl, Stefan T1 - Fehlstellen sicher erkennen BT - Pyrometerbasierte Temperaturmessung beim quasi-simultanen Laser-Durchstrahlschweißen JF - Kunststoffe Y1 - 2015 VL - 105 IS - 12 SP - 55 EP - 58 ER - TY - CHAP A1 - Hierl, Stefan ED - Meran, Cemal T1 - Laser Transmission Welding of Plastics BT - Principles, Applications and Process Monitoring T2 - 15th International Materials Symposium - IMSP'2014, Denizli, 2014 Y1 - 2014 SP - 1084 EP - 1093 ER - TY - CHAP A1 - Schmailzl, Anton A1 - Hüntelmann, Sven A1 - Loose, Tobias A1 - Käsbauer, Johannes A1 - Maiwald, Frederik A1 - Hierl, Stefan ED - Sommitsch, Christof ED - Enzinger, Norbert ED - Mayr, Peter T1 - Potentials of the ALE-Method for Modeling Plastics Welding Processes, in Particular for the Quasi-Simultaneous Laser Transmission Welding T2 - Mathematical Modelling of Weld Phenomena 12 N2 - The Arbitrary-Lagrangian-Eulerian-Method (ALE-Method) offers the possibility to model the quasi-simultaneous laser transmission welding of plastics, in which a squeeze-flow of molten plastic occurs. It is of great interest to get a deeper understanding of the fluid-structure-interactions in the welding zone, since the occurring squeeze-flow transports heated material out of the joining zone, causinga temperature decrease inside.In addition, the numerical modelling offers the possibility to investigate the flow conditions in the joining zone. The aim of this article is to show the potentials of the ALE-Method to simulatethe quasi-simultaneous laser transmission welding with the commercially available software LS-DYNA. The central challenge is to realize a bi-directionalthermo-mechanically coupled simulation,which considers the comparatively high thermal expansion and calculates the interactions of solid and melted plastic correctly. Finally, the potentials of the ALE element formulations for the mathematical description of welding processesare shown, especially for those with a squeeze-flow. Y1 - 2018 U6 - https://doi.org/10.3217/978-3-85125-615-4-51 SP - 965 EP - 975 PB - Verlag der Technischen Universität Graz CY - Graz ER - TY - CHAP A1 - Schmailzl, Anton A1 - Hierl, Stefan A1 - Schmidt, Michael ED - Schmidt, Michael T1 - Gap-Bridging during Quasi-Simultaneous Laser Transmission Welding T2 - Physics Procedia N2 - Tightness is often the main requirement for quasi-simultaneous laser transmission welds. However, remaining gaps cannot be detected by the used set-path monitoring. By using a pyrometer in combination with a 3D-scanner, weld seam interruptions can be localized precisely while welding, due to temperature deviations along the weld contour. To analyze the temperature signal in correlation to the progress of gap-bridging, T-joint samples with predefined gaps are welded. The set-path is measured synchronously. Additionally, the temperature distribution and the influence of the thermal expansion of the polymers are studied by a thermo-mechanical FEM-process simulation. On top of that, the melt blow-out of the welded samples is analyzed using μCT-measurements. The experiments have shown that closing of a gap can be identified reliably by the temperature signal and that the squeezed melt flow into the gap and the thermal expansion in the gap zone accelerates gap-bridging. Furthermore the inserted heat can be adapted in the fault zone, in order to avoid thermal damage. Y1 - 2016 U6 - https://doi.org/10.1016/j.phpro.2016.08.113 SN - 1875-3892 SN - 1875-3884 VL - 83 SP - 1073 EP - 1082 PB - Elsevier CY - Amsterdam [u.a.] ER - TY - CHAP A1 - Schmailzl, Anton A1 - Amann, Thomas A1 - Glockner, Markus A1 - Fandanelli, Martin A1 - Wagner, Marcus A1 - Hierl, Stefan ED - CADFEM GmbH, ED - ANSYS Germany GmbH, T1 - Finite element analysis of thermoplastic probes under tensile load using ls-dyna compared to ansys workbench 14 in correlation to experimental investigations T2 - ANSYS Conference & 30th CADFEM Users' Meeting - ACUM, 24.-26- Oktober 2012, Kassel N2 - Joining thermoplastic requisitions is a popular technique to build sophisticated plastic applications. Therefore the laser-transmission welding process is used to join thermoplastic polymers in visible regions. The clamping force in this case plays a decisive role when it comes to the weld quality. Simulating the clamping pressure with finite element techniques is therefore highly attractive to understand the principal of the process. Thermoplastic polymers under tensile load often show a brittle behavior coupled with softening. Simulating such materials is quite difficult for FEM programs. In this case a finite element study of the tensile test in LS-DYNA and ANSYS Wb 14 with respect to the material models was analysed. The experimental data get validated in comparison with the FEM solution for a tensile test. The material models and the problems in simulating softening behavior for thermoplastic polymers were discussed Y1 - 2012 UR - https://www.oth-regensburg.de/fileadmin/media/fakultaeten/m/labore/FEM/pdf/fb-2012_paper_acum.pdf N1 - DVD-ROM SP - 1 EP - 10 CY - Grafing bei München ER - TY - CHAP A1 - Schmailzl, Anton A1 - Quandt, Benjamin A1 - Schmidt, Michael A1 - Hierl, Stefan T1 - In-Situ Process Monitoring during Laser Transmission Welding of PA6-GF30 T2 - Procedia CIRP N2 - Quasi-simultaneous laser transmission welding is preferably used for packaging sensors and electronics. In order to protect the components from moisture, a hermetic encapsulation is needed. However, local weld seam interruptions cannot be identified with the commonly used set-path monitoring. By using a pyrometer, coaxially integrated into a 3D-scanner, gaps between the joining partners can be allocated on basis of the measured temperature. However, the scattering of the heat radiation, especially caused by the fiber reinforcement of the plastics, leads to a reduction of the accessible heat radiation, which makes the identification of gaps considerably more difficult. The herein used experimental setup is characterized by a small detection spot and only by a slight weakening of the heat radiation inside the scanner. Hence, for welding PA6-GF30, the detection of small sized gaps is possible, even if a glass fiber content of 30 percent (wt.) and a weld seam width with approximately 1 mm are given. Y1 - 2018 U6 - https://doi.org/10.1016/j.procir.2018.08.131 VL - 74 SP - 524 EP - 527 ER - TY - CHAP A1 - Schmailzl, Anton A1 - Hierl, Stefan ED - CADFEM GmbH, ED - ANSYS Germany GmbH, T1 - Thermo-mechanische Struktursimulation mit ANSYS Workbench 14.0 am Beispiel des Laser-Durchstrahlschweißens T2 - ANSYS Conference & 31st CADFEM Users' Meeting - ACUM, June 19-21, Mannheim Y1 - 2013 N1 - DVD-ROM SP - 1 EP - 16 CY - Grafing bei München, Darmstadt ER - TY - JOUR A1 - Schmailzl, Anton A1 - Hierl, Stefan A1 - Sieben, Manuel A1 - Brunnecker, Frank T1 - Optimierung der Spanndruckverteilung beim Laserdurchstrahlschweißen komplexer Bauteile mittels FE-Berechnung JF - JOINING PLASTICS Y1 - 2013 VL - 7 IS - 1 SP - 30 EP - 34 ER - TY - CHAP A1 - Schmailzl, Anton A1 - Hierl, Stefan ED - GSI Niederlassung SLV München, T1 - Online-Prozessüberwachung beim Quasi-Simultanen Laser-Durchstrahlschweißen von Kunststoffen T2 - Young Professionals - Jugend forscht und schweisst Y1 - 2013 SP - 1 EP - 7 ER - TY - JOUR A1 - Maiwald, Frederik A1 - Englmaier, Stephan A1 - Hierl, Stefan T1 - Online pyrometry for weld seam localization in absorber-free laser transmission welding of transparent polymers JF - Journal of Laser Micro/Nanoengineering N2 - Production of optical and medical devices makes high demands on cleanliness, precision, visual appearance and reliability. Advantages of laser transmission welding – contactless input of energy, high precision, no adhesives and no particle formation – can be fully exploited for this use. For absorber-free welding, lasers emitting in the polymers’ intrinsic absorption spectrum between 1.6 μm and 2 μm are used. Focusing the laser beam with high NA provides large intensity gradients inside the specimen and enables selective fusing of the joining zone without affecting the surface. Since a molten upper surface leads to visible and palpable irregularities and causes warpage, the verticalexpansion of the weld seam is crucial. To meet the high quality and reliability required in the medical and optical industry, online monitoring of the seam is necessary. The aim of this work is the localization and evaluation of the weld seam using pyrometry. First, the emitted thermal radiation is computed, enabling signal analysis regarding origin and spectrum. Thus, assessment of measurement spectrum and forecast of the signal in dependence on seam shape and position is possible. Finally, welding tests with Topas 8007-04 are performed at 200 mm/s feed rate and monitored with 100 kHz. The comparison of tracked data with thin-cuts demonstrates that weld seam localization by pyrometry is possible, enabling online assessment of the process. KW - Laserdurchstrahlschweissen KW - Kunststoff KW - Transparenz KW - Schweißnaht KW - Wärmestrahlung KW - Pyrometrie KW - Prozessüberwachung Y1 - 2021 U6 - https://doi.org/10.2961/jlmn.2021.01.2002 SN - 1880-0688 VL - Vol. 16 IS - 1 SP - 8 EP - 13 PB - Japan Laser Processing Society ER - TY - JOUR A1 - Maiwald, Frederik A1 - Hierl, Stefan T1 - Pyrometerbasierte Prozessüberwachung beim Laserkunststoffschweißen JF - Photonik KW - Laserschweissen KW - Kunststoff KW - Prozessüberwachung KW - Pryrometer Y1 - 2020 IS - 52 SP - 22 EP - 25 PB - AT-Fachverl. CY - Fellbach ER - TY - JOUR A1 - Maiwald, Frederik A1 - Hierl, Stefan T1 - Absorber-free laser transmission welding of transparent polymers JF - Laser Systems Europe KW - Medical KW - Fibre lasers KW - Welding KW - Plastics Y1 - 2021 UR - https://www.lasersystemseurope.com/analysis-opinion/absorber-free-laser-transmission-welding-transparent-polymers VL - 50 IS - Spring 2021 PB - Europa Science CY - Cambridge ER - TY - JOUR A1 - Reindl, Thomas A1 - Meisner, Dennis A1 - Hierl, Stefan T1 - Benchmarking of plastic-based Additive Manufacturing Processes JF - RTe Journal N2 - Additive Manufacturing (AM) is a future-oriented manufacturing technology that is experiencing an enormous boom in the times of Industry 4.0. As a result, various AM technologies and printer models from different manufacturers are entering the market over a short time span. With the advancing establishment of this manufacturing technology for series applications, the expectations and requirements of the fabricated components are also increasing. However, a major challenge is the application-specific selection of the most suitable AM process due to a lack of comparable data. Furthermore, there needs to be more know-how regarding the geometrical and mechanical characteristics of AM parts. This paper addresses this problem by comparing the three most common plasticbased AM processes in the areas of surface quality, dimensional accuracy, and mechanical properties. Roughness measurements, evaluation of a benchmark artifact, tensile tests, and load increase tests are carried out. Based on the results, the individual possibilities and limitations of the compared AM processes can be detected. KW - Additive Manufacturing KW - benchmark artifact KW - dimensional accuracy KW - Fused Layer Modeling KW - mechanical properties KW - Multi Jet Fusion KW - process benchmark KW - Selective Laser Sintering KW - surface quality Y1 - 2023 UR - https://rtejournal.de/wp-content/uploads/Benchmarking-of-plastic-based-Additive-Manufacturing-Processes.pdf ER - TY - CHAP A1 - Schmailzl, Anton A1 - Geißler, Bastian A1 - Maiwald, Frederik A1 - Laumer, Tobias A1 - Schmidt, Michael A1 - Hierl, Stefan ED - Esen, Cermal T1 - Transformation of Weld Seam Geometry in Laser Transmission Welding by Using an Additional Integrated Thulium Fiber Laser T2 - Lasers in Manufacturing - LIM 2017, Conference Proceedings Y1 - 2017 N1 - CD-ROM SP - 1 EP - 10 CY - München ER - TY - CHAP A1 - Maiwald, Frederik A1 - Tröger, Johannes A1 - Hierl, Stefan T1 - Automated weld seam evaluation and 2D simulation parameter calibration for absorber-free laser transmission welding T2 - Lasers in Manufacturing Conference (LIM 2023), 26. Juni bis 29. Juni 2023, München N2 - Absorber-free laser transmission welding enables clean and precise joining of plastics without additives or adhesives. It is therefore well suited to produce optical and medical devices, which place high demands on cleanliness and accuracy. However, the weld usually has an undesirably large vertical expansion, causing bulges and distortion. To improve this, the intensity distribution of the laser beam as well as the processing strategy must be adapted. Due to the complexity, this is aided by process simulation. However, simulation parameter calibration and verification are usually done considering the seam width and height, which is of limited significance. To overcome this, we propose a new method for image processing of microtome sections, determining the spatially resolved geometry of the weld. Thus, the deviation between experiment and simulation can be calculated pixel by pixel. This spatially resolved value is predestined for the calibration of the simulation parameters: For a parameter field with 18 different settings, the total deviation between experiment and simulation is less than 11 % after calibration. KW - plastics welding KW - image processing KW - simulation KW - optimization Y1 - 2023 UR - https://www.wlt.de/sites/default/files/2023-09/Contribution_122.pdf PB - Wissenschaftliche Gesellschaft Lasertechnik und Photonik e.V. (WLT) ER - TY - BOOK A1 - Schmailzl, Anton ED - Franke, Jörg ED - Hanenkamp, Nico ED - Hausotte, Tino ED - Merklein, Marion ED - Müller, Sebastian ED - Schmidt, Michael ED - Wartzack, Sandro T1 - Festigkeits- und zeitoptimierte Prozessführung beim quasi-simultanen Laser-Durchstrahlschweißen N2 - Mit Blick auf Leichtbauanwendungen ist der Bedarf an thermoplastischen Strukturbauteilen sowohl in der Automobil- als auch in der Luftfahrtindustrie in den letzten Jahren deutlich angestiegen. Das quasi-simultane Laser-Durchstrahlschweißen ist ein etabliertes Kunststoffschweißverfahren, welches jedoch zur Herstellung von tragenden und sicherheitsrelevanten Bauteilen bislang kaum in Betracht gezogen wird. In der vorliegenden Arbeit wird die Korrelation zwischen dem Prozessablauf und der Schweißnahtfestigkeit beim quasi-simultanen Laser-Durchstrahlschweißen von Polyamid 6 (Ultramid B3s) erstmalig untersucht. Zur Prozessanalyse wird ein 3D-Scanner mit integriertem Pyrometer realisiert und für die Messaufgabe kalibriert. Es wird gezeigt, dass die detektierte Wärmestrahlung dem Kern der Schweißnaht zuzuordnen ist. Die Kerntemperatur in der quasi-stationären Prozessphase steht in direkter Korrelation mit der Schweißnahtfestigkeit. Mit steigender Kerntemperatur bzw. Molekülbeweglichkeit erhöht sich die Wahrscheinlichkeit der Bildung von Molekül-Verschlaufungen in der Fügeebene. Zur Ermittlung der Kerntemperatur ist sowohl die in dieser Arbeit entwickelte Temperaturmesstechnik als auch die realisierte numerische Prozesssimulation nutzbar. Die Erkenntnisse in dieser Arbeit sind für eine festigkeits- und zeitoptimierten Prozessführung des quasi-simultanen Laser-Durchstrahlschweißens nutzbar. N2 - The demand on thermoplastic components for lightweight constructions is continuously rising in the automotive as well as in the aerospace industry. The quasi-simultaneous laser transmission welding is an established joining technique in industry, but so far, it is usually not used for high strength applications as well as for safety-relevant components. This is caused by the lack of process understanding in case of producing high strength joints. Especially the temperature in the joining zone is a crucial process characteristic. Up to now, it was not measured in the needed precision. The quasi-simultaneous laser transmission welding of polyamide 6, especially the correlation between process characteristics and the joint strength is analyzed in this work. Therefore, a 3D-scanner with integrated pyrometer was realized and calibrated for the measurement task. It is shown, that the detected heat radiation is mainly coming from the core of the weld seam. The core temperature in the quasi-stationary process state is in direct correlation with the joint strength. The core temperature represents the mobility of the macromolecules in the polymer. An increased mobility leads to a better diffusion, relaxation or retardation of the macromolecules across the joining interface. A process window is defined on basis of the core temperature. The process setting which leads to a high joint strength as well as to the shortest irradiation time is found on the upper corner of the process window. The temperature can be measured with the needed precision by using the herein shown 3D-scanner with integrated pyrometer as well as by using the developed numerical process model. In conclusion, these tools for process diagnostics and the results of this work are useful for the production of welds with high joint strength and short welding times. KW - Laserschweißen KW - Kunststoffe KW - Prozessüberwachung KW - Laserscanner KW - Ingenieurwissenschaften KW - Maschinenbau KW - Produktionstechnik Y1 - 2022 U6 - https://doi.org/10.25593/978-3-96147-584-1 N1 - Zugl.: Diss., FAU Erlangen, 2022 PB - FAU University Press CY - Erlangen ER - TY - CHAP A1 - Maiwald, Frederik A1 - Englmaier, Stephan A1 - Hierl, Stefan T1 - Online pyrometry for weld seam localization in absorber-free laser transmission welding of transparent polymers T2 - 21st International Symposium on Laser Precision Microfabrication: Dresden, 26.06.2020 N2 - Optical and medical devices made of transparent polymers are gaining popularity because of its cost advantages. The manufacturing technology must be able to meet the high demands of these applications. Advantages of laser transmission welding – contactless input of energy, precision, no adhesives and no particle formation – can be exploited here. For absorber-free welding, lasers emitting in the polymers‘ intrinsic absorption spectrum are used. Focusing the laser beam with high NA enables selective fusing of the joining zone. Since a molten upper surface leads to visible and palpable irregularities, the lateral expansion of the weld seam is monitored in this work. Welding tests with 1 mm thick plates of COC are performed and monitored by pyrometry. Distances between seam and surface measured in thin cuts and are compared with the pyrometer signal. This shows that the localization of the weld seam is possible and proper and faulty parts can be distinguished by pyrometry. KW - Laserdurchstrahlschweissen KW - Kunststoff KW - Transparenz KW - Schweißnaht KW - Wärmestrahlung KW - Pyrometrie KW - Prozessüberwachung Y1 - 2020 UR - http://www.jlps.gr.jp/en/proc/lpm/20/073.pdf ER - TY - GEN A1 - Armbruster, Dominik ED - Mottok, Jürgen ED - Reichenberger, Marcus ED - Scharfenberg, Georg ED - Ziemann, Olaf T1 - Optimization of a system technology for coaxial online pyrometry in three-dimensional laser transmission welding BT - Poster Session T2 - Applied Research Conference 2015 ARC 2015 ; 3rd July 2015 Nürnberg Y1 - 2015 SP - 314 EP - 317 PB - pro Business GmbH CY - Berlin ER - TY - CHAP A1 - Dostalek, Michael A1 - Hierl, Stefan ED - Mottok, Jürgen ED - Reichenberger, Marcus ED - Scharfenberg, Georg ED - Ziemann, Olaf T1 - Experimental study to evaluate the influence of clamping pressure variation during laser transmission welding of plastics T2 - Applied Research Conference 2015 ARC 2015; 3rd July 2015 Nürnberg Y1 - 2015 SP - 289 EP - 294 PB - pro Business CY - Berlin ER - TY - CHAP A1 - Preischl, Antonius A1 - Schmailzl, Anton A1 - Hierl, Stefan ED - Ziemann, Olaf ED - Mottok, Jürgen ED - Pforr, Johannes T1 - Experimental study to evaluate the process window for laser transmission welding of plastics T2 - Applied Research Conference 2014 - ARC 2014, 5th July 2014, Ingolstadt Y1 - 2014 SP - 517 EP - 522 PB - Shaker CY - Aachen ER - TY - CHAP A1 - Quandt, Benjamin ED - Mottok, Jürgen ED - Reichenberger, Marcus ED - Bogner, Werner T1 - Effect of the Detection Spot Size on pyrometric Temperature Signal at quasi-simultaneous Laser Transmission Welding T2 - Applied Research Conference 2018, ARC 2018, 10 July 2018, Deggendorf Y1 - 2018 SP - 261 EP - 264 PB - pro Business GmbH CY - Berlin ER - TY - CHAP A1 - Schäfer, Felix ED - Mottok, Jürgen ED - Reichenberger, Marcus ED - Bogner, Werner T1 - Temperature Measurement with Scanner-Integrated Pyrometer during Laser Transmission Welding with Clearweld Absorber T2 - Applied Research Conference 2018, ARC 2018, 10 July 2018, Deggendorf Y1 - 2018 SP - 258 EP - 260 PB - pro Business GmbH CY - Berlin ER - TY - CHAP A1 - Maiwald, Frederik ED - Mottok, Jürgen ED - Reichenberger, Marcus ED - Bogner, Werner T1 - Simulation of Pyrometer Based Temperature Measurement Systems using Non-Sequential Raytracing T2 - Applied Research Conference 2018, ARC 2018, 10 July 2018, Deggendorf Y1 - 2018 SP - 168 EP - 171 PB - pro Business GmbH CY - Berlin ER - TY - CHAP A1 - Schmailzl, Anton A1 - Hierl, Stefan ED - Ziemann, Olaf ED - Bogner, Werner ED - Mottok, Jürgen T1 - Online-process monitoring of laser transmission welding for polymers T2 - Applied Research Conference 2013, ARC 2013 ; 17th and 18th October 2013, Deggendorf Y1 - 2013 SP - 374 EP - 378 PB - Shaker CY - Aachen ER - TY - GEN A1 - Käsbauer, Johannes A1 - Schmailzl, Anton A1 - Hierl, Stefan ED - Klippel, Clemens ED - Mottok, Jürgen ED - Reichenberger, Marcus T1 - Simulative investigation on the influence of material- and process parameter on quasi-simultaneous laser transmission welding BT - Poster Session T2 - Applied Research Conference - ARC 2017, 7 July 2017 München Y1 - 2017 PB - pro Business GmbH CY - Berlin ER - TY - GEN A1 - Maiwald, Frederik A1 - Schmailzl, Anton A1 - Hierl, Stefan ED - Klippel, Clemens ED - Mottok, Jürgen ED - Reichenberger, Marcus T1 - Thermo-mechanical computation of weld seam geometry in laser transmission welding BT - Poster Session T2 - Applied Research Conference - ARC 2017, 7 July 2017, München Y1 - 2017 PB - pro Business GmbH CY - Berlin ER - TY - CHAP A1 - Armbruster, Dominik A1 - Hierl, Stefan ED - Mottok, Jürgen ED - Reichenberger, Marcus ED - Stolle, Reinhard T1 - Simulation of a pyrometer-based temperature measurement system for quasi-simultaneous laser transmission welding regarding the detectable radiant power T2 - Applied Research Conference - ARC 2016, 24 June 2016, Hochschule Augsburg, Germany Y1 - 2016 SP - 314 EP - 317 PB - Shaker CY - Aachen ER - TY - CHAP A1 - Meisner, Dennis A1 - Forstner, Lukas A1 - Kaftiranis, Nikitas A1 - Hierl, Stefan T1 - Investigation of process improvements through laser preheating in extrusion-based additive manufacturing process T2 - Lasers in Manufacturing Conference (LIM 2023), 26. Juni bis 29. Juni 2023, München N2 - Fused layer modeling (FLM) is widely used and is gaining more acceptance in the industry mainly due to its material variety and low costs. However, the usage is limited by a process-related anisotropy of the produced parts. The strength and ductility of the printed parts are significantly lower in the build-up direction than perpendicular to it. This is caused by insufficient interlayer bonding resulting from a reduced surface temperature in the process zone. To overcome this problem, a diode laser is integrated into the conventional FLM process to increase the surface temperature between the already printed surface and the newly applied substrate directly at the deposition zone. The investigations carried out show a significant improvement in the mesostructure, as well as a clear reduction in the anisotropy of the printed test specimens. KW - fused layer modeling KW - laser preheating KW - anisotropy KW - interlayer bonding KW - mesostructure Y1 - 2023 UR - https://www.wlt.de/sites/default/files/2023-09/Contribution_140.pdf PB - Wissenschaftliche Gesellschaft Lasertechnik und Photonik e.V. (WLT) ER -