TY - CHAP A1 - Franz, Daniel A1 - Roth, Gian-Luca A1 - Rung, Stefan A1 - Esen, Cemal A1 - Hellmann, Ralf T1 - Superimposed beam deflection using acousto-optical deflectors in combination with a galvanometer scanner T2 - Lasers in Manufacturing - LiM 2021 KW - Galvanometer Y1 - 2021 ER - TY - JOUR A1 - Franz, Daniel A1 - Schuster, David A1 - Schwarz, Simon A1 - Rung, Stefan A1 - Esen, Cemal A1 - Hellmann, Ralf T1 - Fabrication and analysis of through-glass vias for glass-based electronic packaging using an ultrashort pulsed laser JF - Optics and Lasers in Engineering KW - Ultrakurzzeitlaser KW - Laserbohren Y1 - 2025 U6 - https://doi.org/10.1016/j.optlaseng.2025.109106 SN - 0143-8166 VL - 193 PB - Elsevier BV ER - TY - JOUR A1 - Franz, Daniel A1 - Yang, Yongting A1 - Esen, Cemal A1 - Hellmann, Ralf ED - Esen, Cemal T1 - Flexible 2D Laser Cutting of Ultra-Thin Glass Using an Ultrashort Pulsed Laser Robotic System JF - Journal of Laser Micro/Nanoengineering KW - Laserschneiden KW - Ultrakurzzeitlaser Y1 - 2026 U6 - https://doi.org/10.2961/jlmn.2026.01.2004 SN - 1880-0688 VL - 21 IS - 1 PB - Japan Laser Processing Society ER - TY - CHAP A1 - Franz, Daniel A1 - Schuster, David A1 - Schwarz, Simon A1 - Rung, Stefan A1 - Esen, Cemal A1 - Hellmann, Ralf T1 - Ultrashort pulsed laser drilling of through-glass vias for glass core packaging T2 - Proceedings of LAMP2025 – the 9th International Congress on Laser Advanced Materials Processing, Ise-City, Japan, June 2025 KW - Ultrakurzzeitlaser KW - Laserbohren Y1 - 2025 ER - TY - CHAP A1 - Sommer, David A1 - Truetsch, Ben A1 - Esen, Cemal A1 - Hellmann, Ralf T1 - Microstructural Fracture Behaviour of PBF-LB/M Inconel 718 Components within different HIP Processes T2 - Lasers in Manufacturing, München, Juni 2025 N2 - We report on a study of different hot isostatic pressing (HIP) cycles, improving the mechanical properties of additively manufactured Inconel 718 components. For this, PBF-LB/M built components are post-processed by different HIP sequences, as gas pressure and processing time are varied, leading to differences in microstructure and material characteristics. Static and dynamic mechanical testing are performed, evaluating the changes in mechanical properties with particular focus on the ultimate tensile strength and endurance limit. Furthermore, metallographic analysis is employed to investigate the achieved density and microhardness. Microstructural analysis, showing the grain boundaries, is used to identify generated phases and precipitations of the material matrix. Moreover, the fracture behaviour is classified by grain deformation during mechanical testing. As the HIP leads to microstructural changes of Inconel 718 components, mechanical properties can be improved significantly, enhancing the ultimate tensile strength and simultaneously the endurance limit. KW - Isostatisches Heißpressen Y1 - 2025 ER - TY - CHAP A1 - Sommer, David A1 - Peters, Maximilian A1 - Esen, Cemal A1 - Hellmann, Ralf T1 - Influence of in-situ high-speed milling within a hybrid additive manufacturing approach on the fatigue behaviour of Inconel 718 lattice structures T2 - Lasers in Manufacturing, München, Juni 2025 N2 - As lattice structures in various designs are used in additive manufacturing for lightweight components, the mechanical characterisation and fracture behaviour is of upmost importance for their industrial application. In this study, the fatigue behaviour of Inconel 718 lattice structures is evaluated, comparing sole PBF-LB/M to a hybrid additive manufacturing process combining PBF-LB/M with in-situ high-speed milling. At first, the static and dynamic mechanical load behaviour of different packing densities is analysed, determining the compressive strength and the endurance limit. Secondly, hybrid additive manufactured components are compared to PBF-LB/M built parts with respect to these mechanical properties, revealing improved compressive properties and modified regimes of fatigue. In addition, differences in fracture behaviour are qualified by fractographic and surface analysis. Overall, it can be summarized that the mechanical load characteristics, especially the fatigue behaviour, are improved for hybrid additively manufactured components with a superior surface quality of Ra < 1 µm. KW - Hochgeschwindigkeitsfräsen Y1 - 2025 ER - TY - CHAP A1 - Bischoff, Kay A1 - Kefer, Stefan A1 - Esen, Cemal A1 - Hellmann, Ralf T1 - Towards entirely ultrashort pulsed laser based process chain to manufacture polymer lab-on-chip systems with electrical, photonic, and microfluidic functionalities T2 - The 5th Smart Laser Processing Conference (SLPC) KW - Ultrakurzzeitlaser Y1 - 2024 UR - https://confit.atlas.jp/guide/event/opic2024/subject/SLPCp-22/date?cryptoId=&lo=fin&eventCode=opic2024 ER - TY - JOUR A1 - Sommer, David A1 - Hornung, Simon A1 - Esen, Cemal A1 - Hellmann, Ralf T1 - In situ high-speed milling and thermal post-processing for the optimization of fatigue behaviour of additive-manufactured IN718 components JF - Journal of Materials Research N2 - We report on the optimization of tensile properties and fatigue behaviour of Laser Powder Bed Fusion (PBF-LB/M)-built IN718 components employing an innovative hybrid additive-subtractive technology and various heat treatments. The hybrid approach comprises PBF-LB/M with in situ high-speed milling. Double Ageing, solution and ageing treatment, as well as Hot Isostatic Pressing are used to improve ultimate tensile strength and endurance limit. As a result, the advantages of the hybrid-machined components are clearly demonstrated by their improved mechanical properties. These enhanced properties are associated to changes in microstructure, which are identified as precipitations of IN718. Furthermore, crack initiation and crack growth for high cycle numbers as well as sudden fractures are determined. KW - Hochgeschwindigkeitsfräsen Y1 - 2025 U6 - https://doi.org/https://doi.org/10.1557/s43578-025-01656-x SN - 0884-2914 VL - 40 IS - 16 SP - 2388 EP - 2401 PB - Springer Science and Business Media LLC ER - TY - JOUR A1 - Sommer, David A1 - Truetsch, Ben A1 - Esen, Cemal A1 - Hellmann, Ralf T1 - Effect of Hot Isostatic Pressing and Sequenced Heat Treatment on the Mechanical Properties of Hybrid Additive Manufactured Inconel 718 Components JF - Journal of Manufacturing and Materials Processing N2 - We report on the effect of hot isostatic pressing combined with solution and ageing treatment in different sequences on the mechanical properties of Inconel 718 specimens, which in turn have been fabricated by a hybrid additive manufacturing approach. The latter combines conventional laser powder bed fusion and in-situ high speed milling, yielding superior surface quality as being quantified by Ra about 1 μm. In a comparative study between hybrid additively manufactured parts and those built without milling, we find that, in general, any combination of heat treatment leads to a higher ultimate tensile strength and an improved endurance limit, while, however, hot isostatic pressing affects these figures of merit most. In addition, metallographic analysis reveals increased density and hardness for hot isostatic pressed parts due to precipitation hardening. These improvements of the mechanical properties are found to be even more pronounced when the printed parts are manufactured by the hybrid additive approach, i.e., for parts with improved surface conditions. KW - Isostatisches Heißpressen Y1 - 2025 U6 - https://doi.org/https://doi.org/10.3390/jmmp9110378 SN - 2504-4494 VL - 9 IS - 11 PB - MDPI AG ER - TY - JOUR A1 - Sommer, David A1 - Peters, Maximilian A1 - Esen, Cemal A1 - Hellmann, Ralf T1 - Enhancing mechanical properties of double-periodic lattice structures using hybrid-additive manufacturing JF - The International Journal of Advanced Manufacturing Technology N2 - We report on a study of the mechanical properties of hybrid-additive manufactured Inconel 718 double-periodic lattice structures. For this, a hybrid approach, combining Laser Powder Bed Fusion (PBF-LB/M) and in-situ high-speed milling, is employed. Within this technique, the PBF-LB/M process is interrupted after several layers, as the milling process starts, enabling a machining of inlaying structures. KW - Hochgeschwindigkeitsfräsen Y1 - 2026 U6 - https://doi.org/https://doi.org/10.1007/s00170-025-17373-y SN - 0268-3768 VL - 142 IS - 7-8 SP - 4065 EP - 4071 PB - Springer Science and Business Media LLC ER - TY - JOUR A1 - Sommer, David A1 - Hornung, Simon A1 - Esen, Cemal A1 - Hellmann, Ralf T1 - Design Guide for Hybrid-Additive Manufacturing of Inconel 718 Combining PBF-LB/M and In Situ High-Speed Milling JF - Journal of Manufacturing and Materials Processing N2 - As the correlation between design rules and process limitations is of the upmost importance for the full exploitation of any manufacturing technology, we report a design guide for hybrid-additive manufacturing of Inconel 718. Basic limitations need to be evaluated for this particular hybrid approach that combines laser powder bed fusion (PBF-LB/M) and in situ high-speed milling. Fundamental geometric limitations are examined with regard to the minimum feasible wall thickness, cylinders, overhanging structures, and chamfers. Furthermore, geometrical restrictions due to the integrated three-axis milling process with respect to inclinations, inner angles, notches, and boreholes are investigated. From these findings, we derive design guidelines for a reliable build process using this hybrid manufacturing. Additionally, a design guideline for the hybrid-additive manufacturing approach is presented, depicting a step-to-step guide for the adjustment of constructions. To demonstrate this, a powder nozzle for a direct energy deposition (DED-LB/M) process is redesigned following the previously defined guidelines. This redesign encompasses analysis of the existing component and identification of problematic areas such as flat angles, leading to a new construction that is suitable for a hybrid-additive manufacturing approach. KW - Hochgeschwindigkeitsfräsen Y1 - 2025 U6 - https://doi.org/https://doi.org/10.3390/jmmp9030088 SN - 2504-4494 VL - 9 IS - 3 PB - MDPI AG ER - TY - JOUR A1 - Bischoff, Kay A1 - Esen, Cemal A1 - Hellmann, Ralf T1 - Femtosecond reductive Laser Sintering under multiple focus conditions for rapid production of conductive copper layers JF - Procedia CIRP N2 - Reductive laser sintering is an advantageous alternative to conventional precious metal- or mask-based processes for the electrification of polymers and has been demonstrated in a variety of sensor applications. Ultrashort pulsed lasers promise precise control of the energy applied during sintering and ablation. Besides fine tracks, microelectronic circuits include wide contact pads, which leads to time-consuming processing with small laser spot sizes. The use of larger focal diameters, which results in wider lines and thus a higher metallization rate, is accompanied by a loss of structure resolution. We show the influence of focusing on the femtosecond reductive laser sintering of copper(II) oxide on cyclic olefin copolymers. While small focus diameters down to 23 µm provide high accuracy, increasing the laser power and the focus diameter up to 400 µm significantly accelerates the process, first by enlarging the line width and second by increasing the scanning speed due to the exposure time. Two-dimensional copper electrodes for 23 µm and 200 µm focal diameters were generated by hatching individual lines and compared with respect to their morphology. The enlarged spot can be used for high-speed generation of electrodes with a surface conductivity of 117 mΩ/sq. Hybrid processes with production under combined focusing conditions are presented for the first time. KW - Laserstrahlsintern KW - Ultrakurzzeitlaser Y1 - 2024 U6 - https://doi.org/10.1016/j.procir.2024.08.189 SN - 2212-8271 VL - 124 IS - 124 SP - 629 EP - 633 PB - Elsevier BV ER - TY - JOUR A1 - Sommer, David A1 - Truetsch, Ben A1 - Esen, Cemal A1 - Hellmann, Ralf T1 - Fractographic Analysis and Fatigue Behavior of Additively Manufactured Ni‐Superalloy Components with Post Processing Heat Treatment and Hot Isostatic Pressing JF - Advanced Engineering Materials N2 - A report is made on a study of mechanical properties and fractographic characteristics of laser powder bed fusion (PBF‐LB/M)‐built Inconel 718, performing heat treatments and hot‐isostatic pressing. For this, tensile components are heat‐treated by different processes, as namely stress relief (SR), SR and double aging (SR + DA), and hot‐isostatic pressing are conducted. For the mechanical testing, the ultimate tensile strength (UTS) as well as the fatigue behavior are evaluated, examining differences in maximum load behavior, elongation, and the different regimes of fatigue. As changes in material structure can be observed, the sole SR leads to a diminished UTS, while the combination of SR + DA develops an UTS of R m  = 1277 MPa. Within the fatigue behavior, the HIP shows a very balanced material structure with an increased high cycle and very high cycle regime, as the texture gets homogenized during the heat treatment. The metallographic analysis can quantify the material changes, as the density and the hardness are improved by virtue of the heat treatments. Furthermore, the fractographic analysis shows the differences in fracture behavior, arising due to the microstructural changes, as crack initiation points, crack propagation, and forced fractures can be categorized by scanning electron microscopy. KW - Nickellegierung KW - Superlegierung Y1 - 2025 U6 - https://doi.org/https://doi.org/10.1002/adem.202500078 SN - 1438-1656 VL - 27 IS - 12 PB - Wiley ER - TY - JOUR A1 - Sommer, David A1 - Hornung, Simon A1 - Esen, Cemal A1 - Hellmann, Ralf T1 - Evaluation of the Impact of Heat Treatment Processes and Surface Conditions on the Mechanical Properties of PBF-LB/M-Built Inconel 718 Components JF - Materials Science Forum N2 - A study of the mechanical properties of hybrid additive manufactured IN718 components is presented, optimising mechanical properties due to an in-situ high-speed milling and different heat treatment processes. At first, the impact of different heat treatment processes is investigated, as the changes in microstructure during the process lead to different mechanical properties. Static and dynamic mechanical load behaviour is tested, quantifying microstructural changes by means of the Ultimate Tensile Strength (UTS) and the endurance limit. Furthermore, sole PBF-LB/M- and hybrid built components are compared, investigating the effect of a surface finish on the static and dynamic load behaviour, as superficial cracks and melting errors diminish the UTS and the endurance limit of PBF-LB/M-built components. Within these experiments, a change of fatigue behaviour for the heat-treatedstates can be observed, compared to the as-built state of the PBF-LB/M, as the development of different phases during heat treatment leads to an improvement of the endurance limit for, e.g., solution and ageing treated components. Additionally, the improvement of the surface quality to Ra = 2 µm leads to a significant increase of the dynamic mechanical load behaviour of hybrid-built components, as superficial cracks and surface defects are reduced. KW - Hochgeschwindigkeitsfräsen Y1 - 2025 U6 - https://doi.org/https://doi.org/10.4028/p-9gR9cI SN - 1662-9752 VL - 1155 SP - 11 EP - 17 PB - Trans Tech Publications, Ltd. ER -