Univ. Prof. Dr. Ing.

Bergs, Thomas

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Now showing 1 - 10 of 21
  • Publication
    Determination of the Level of Automation for Additive Manufacturing Process Chains
    ( 2021)
    Horstkotte, Rainer
    ;
    Bruning, Benedikt
    ;
    Prümmer, Marcel
    ;
    Arntz, Kristian
    ;
    Bergs, Thomas
    Industrial manufacturing is confronted with increased cost pressure due to international competition. The use of automation solutions can help to optimally exploit existing potentials and react to market competitors. In particular, increased productivity and shorter cycle times lead to reduced costs and increased capabilities. New manufacturing technologies can also help to achieve an advantage over market competitors. In recent years, additive manufacturing technologies in particular have gained in importance. Laser Powder Bed Fusion (L-PBF) is an additive manufacturing (AM) technology that enables the production of highly complex and individualized metal components. A significant disadvantage of L-PBF is the required post-processing of additive manufactured parts, which is necessary to remove auxiliary structures, separate the workpieces from the substrate plate and obtain high precision as well as low surface roughness. Automation of these post-processes is a crucial factor for increasing productivity and thus for further industrialization of L-PBF. In order to exploit this potential optimally, the level of automation has to be determined. In this paper, a methodology is presented that enables the determination of the level of automation for the additive process chain with L-BPF. The focus is on evaluating the level of automation of individual manufacturing technologies due to consideration of technology-specific requirements and characteristics. The scope of the analysis is not limited to technologies; handling processes are also taken into account. A differentiated e valuation of the level of automation is enabled by the definition of technology-specific and cross-technology sub-tasks.
  • Publication
    Generation and evaluation of automation concepts of additive process chains with Laser Powder Bed Fusion (L-PBF)
    ( 2021)
    Horstkotte, Rainer
    ;
    Heinrich, Florian
    ;
    Prümmer, Marcel
    ;
    Arntz, Kristian
    ;
    Bergs, Thomas
    Laser Powder Bed Fusion (L-PBF) is an additive manufacturing (AM) technology that plays a major role in the production of mass customized metal components and products. A significant disadvantage of AM is the required post-processing of the additive manufactured parts, which is necessary to remove auxiliary structures, separate the workpieces from the substrate plate and achieve high precision as well as low surface roughness. Automation of these post-processes is a crucial factor for increasing productivity and thus for further industrialization of L-PBF. This paper presents a methodology to model and evaluate the manufacturing process chain of post-processing with regard to automation. For this purpose, a uniform notation is introduced to model the sequence of manufacturing processes and handling operations. The notation allows the representation of different automation concepts and integrates typical post-processes for L-PBF manufactured parts. A reference scale is used to evaluate different concepts with regard to their level of automation. The focus on lead time estimation enables the methodology to generate and evaluate different automation concepts.
  • Publication
    Methodology for integrated additive-subtractive process chain generation
    ( 2021)
    Wollbrink, Moritz
    ;
    Dannen, Tammo
    ;
    Arntz, Kristian
    ;
    Prümmer, Marcel
    ;
    Bergs, Thomas
    The production share of laser powder bed fusion increases in industrial application and single piece and small series production are core markets. Still, many process steps in the field of additive manufacturing are manually operated, especially in post-processing. Additionally, it is not possible to achieve tight dimensional tolerances or low surface roughness which are necessary for typical mechanical parts. Hence, a process chain has to be set up to combine the design flexibility and function integration capabilities of AM with further machining technologies to achieve workpiece requirements. As L-PBF has some particular properties and process parameters influencing post-processing, an individual approach for process chain generation is needed. These properties and parameters are, in particular, support structures and free positioning options within the build chamber of the AM machine. Both properties have a major influence to post-processing and have to be addressed in machine selection, clamping options, processing steps and workpiece description. The approach shows how an additive manufactured workpiece can be described taking into account the complex part consisting of workpiece, support structures and substrate plate. Further, kinematic limitations for further processing are added as meta-information and workpiece requirements and machine performances are compared for a manufacturing process selection for further processing. Based on technological and economical parameters a manufacturing process selection is performed. Finally, improved parameters are suggested to optimize the L-PBF process with regard to further processing. So, the L-PBF process design can combine AM parameters with further processing parameters to improve the whole process chain. The methodology shall be implemented in a software tool to simplify the practical application.
  • Publication
    Development of handling system concepts for additive process chains with Laser Powder Bed Fusion (L-PBF)
    ( 2021)
    Horstkotte, Rainer
    ;
    Heinrich, Florian
    ;
    Prümmer, Marcel
    ;
    Arntz, Kristian
    ;
    Bergs, Thomas
    Laser Powder Bed Fusion (L-PBF) is an additive manufacturing (AM) technology that enables the production of highly complex and individualized metal components. Since these components need post-processing, L-PBF is usually utilized within a manufacturing process chain. The automation of this process chain is a crucial step towards the industrialization of L-PBF. This paper presents a methodology for the conceptual design of handling systems for the automated handling of L-PBF components. It includes the selection of gripping and clamping devices, robots and other peripheral systems. Restrictions that arise from the complexity of the components and the technologies are considered.
  • Publication
    Development of a voxelization tool for the calculation of vector-based workpiece representations
    ( 2021)
    Bergs, Thomas
    ;
    Henrichs, Oliver
    ;
    Wilms, Marcel
    ;
    Prümmer, Marcel
    ;
    Arntz, Kristian
    While voxelization techniques are quite common in domains like medical imaging and computer games, they still have a lot of untapped potential when applied to CAD-models. As a discretized 3D representation, they have a significant potential for new approaches in the fields of knowledge management, workpiece classification and subsequently process planning - especially when enriched with Product Manufacturing Information (PMI). We developed a voxelization tool for colored 3D-mesh representations of workpiece geometries that allows for the structured, dimensionality-reducing storage of geometry information and PMI. The tool creates voxel-representations of triangular mesh representations by recursively splitting the space in which a mesh representation resides into eight equal cubes and checking for intersections with the mesh. If such a cube intersects with the mesh, it is again split. This process continues until a threshold cube size or recursion depth is reached. After termination, the voxelized 3D model is represented by the subset of resulting cubes containing exactly the cubes intersecting with the model's surface. Additional functionalities have been implemented to accommodate data-centric use cases; that is, for watertight, closed meshes the tool discriminates inside and outside voxels and can include them accordingly. The calculated voxelization can also be arbitrarily sampled to a fixed voxel count - allowing to represent the 3D model by a vector of fixed length. This, for example, enables the application of AI/Machine Learning methods, the training of which typically requires a large amount of input vectors of a fixed length. Finally, we developed a plugin for the CAD application software Rhinoceros© that uses its 3D-canvas to display calculated voxelizations for visualization purposes. Going forward, data-centric applications can use workpiece information encoded inside the voxelization representation for a multitude of purposes such as similarity search or clustering.
  • Publication
    Pulsed Laser Influence on Temperature Distribution during Dual Beam Laser Metal Deposition
    ( 2020)
    Gipperich, Marius
    ;
    Riepe, Jan
    ;
    Arntz, Kristian
    ;
    Bergs, Thomas
    Wire-based Laser Metal Deposition (LMD-w) is a suitable manufacturing technology for a wide range of applications such as repairing, coating, or additive manufacturing. Employing a pulsed wave (pw) laser additionally to the continuous wave (cw) process laser has several positive effects on the LMD process stability. The pw-plasma has an influence on the cw-absorption and thus the temperature distribution in the workpiece. In this article, several experiments are described aiming to characterize the heat input during dual beam LMD. In the first setup, small aluminum and steel disks are heated up either by only cw or by combined cw and pw radiation. The absorbed energy is then determined by dropping the samples into water at ambient temperature and measuring the waters temperature rise. I n a second experiment, the temperature distribution in the deposition zone under real process conditions is examined by two-color pyrometer measurements. According to the results, the pw plasma leads to an increase of the effective absorption coeffcient by more than 20%. The aim of this work is to achieve a deeper understanding of the physical phenomena acting during dual beam LMD and to deploy them selectively for a better and more flexible process control.
  • Publication
    Clamping and substrate plate system for continuous additive build-up and post-processing of metal parts
    ( 2020)
    Wollbrink, Moritz
    ;
    Maslo, Semir
    ;
    Zimmer, Daniel
    ;
    Abbas, Karim
    ;
    Arntz, Kristian
    ;
    Bergs, Thomas
    The manufacturing share of laser powder bed fusion (L-PBF) increases in industrial application, but still many process steps are manually operated. Additionally, it is not possible to achieve tight dimensional tolerances or low surfaces roughness. Hence, a process chain has to be set up to combine additive manufacturing (AM) with further machining technologies. To achieve a continuous workpiece flow as basis for further industrialization of L-PBF, the paper presents a novel substrate system and its application on L-PBF machines and post-processing. The substrate system consists of a zero-point clamping system and a matrix-like interface of contact pins to be substantially connected to the workpiece within the L-PBF process.
  • Publication
    Interoperabilität als Erfolgsfaktor für die vernetzte, adaptive Produktion
    ( 2020)
    Kiesel, Raphael
    ;
    Pothen, Mario
    ;
    Arntz, Kristian
    ;
    Bergs, Thomas
    ;
    Schmitt, Robert H.
    Das Wertschöpfungspotential der digitalisierten Produktion in Deutschland ist unumstritten. Um dieses Potential auszuschöpfen ist die Interoperabilität aller Akteure elementar. Zum einen bedarf es einer organisatorischen Interoperabilität, welche die Rollen aller beteiligten Akteure definiert. Zum anderen ist eine semantische Interoperabilität, welche das Vokabular eindeutig festlegt, notwendig. Ein Ansatz für eine erfolgreiche Interoperabilität wird in diesem Artikel dargestellt.
  • Publication
    Durchgängige Bearbeitung von 3D-gedruckten Metallteilen
    ( 2020)
    Wollbrink, Moritz
    ;
    Maslo, Semir
    ;
    Arntz, Kristian
    ;
    Bergs, Thomas
    Der Fertigungsanteil der additiven Fertigung (AM) und besonders des pulverbettbasierten Laserstrahlschmelzens (L-PBF) nimmt in der industriellen Anwendung weiter zu. Allein mit AM lassen sich jedoch oft keine engen Maßtoleranzen oder geringen Oberflächenrauheiten erzielen. Daher muss eine Prozesskette generiert werden, die die additive Fertigung mit weiteren Bearbeitungstechnologien kombiniert. Um einen kontinuierlichen Werkstückfluss als Basis für die weitere Industrialisierung von L-PBF zu erreichen, wird ein neuartiges Substratplattensystem sowie dessen Anwendung in L-PBF-Maschinen und bei der Weiterbearbeitung vorgestellt. Das Substratplattensystem besteht aus einem Nullpunkt-Spannsystem und matrixartig angeordneten Verbindungsstiften, welche die werkstückseitige Verbindung sehr flexibel ermöglichen.
  • Publication
    Individuelle Prozessketten im Werkzeugbau durch daten- und modellbasierte Prognosen
    ( 2020)
    Bergs, Thomas
    ;
    Arntz, Kristian
    ;
    Prümmer, Marcel
    ;
    Wilms, Marcel
    Konnte sich der Werkzeugbau in der Vergangenheit durch die eigene Innovationskraft vom globalen Markt differenzieren, so muss er sich heutzutage durch die Effizienzsteigerung in der Fertigung und die Senkung der Produktionskosten vom Markt abgrenzen. Der heterogene Einsatz verschiedenster Fertigungstechnologien erzeugt einen hohen Planungsaufwand in der Unikatfertigung und erfordert technologieübergreifendes Prozess-verständnis. Auf Basis dieser Komplexität resultieren starke Abweichungen der prognostizierten und tatsächlichen Bearbeitungszeiten, sowohl auf Einzeltechnologieebene als auch technologieübergreifend. Dies hat zur Folge, dass deutliche Potenziale in der Fertigung liegen gelassen werden. Ein möglicher Lösungsansatz diese Potenziale zu nutzen, liegt in der Implementierung von individuellen und adaptiven Prozessketten, sodass bei Störungen wie bspw. einem Maschinenausfall oder Eilaufträgen, auch technologieüber-greifend umgeplant werden kann. Zur Integration von individuellen Prozessketten müssen jedoch einige Herausforderungen überwunden werden, wie bspw. die Erhöhung der Prognosefähigkeit und die Klassifizierung von Bauteilen in der Unikatfertigung. Durch die Kopplung von modell- und datenbasierten Methoden kann die Anzahl an benötigten Daten reduziert und die Prognosefähigkeit gesteigert werden. Darüber hinaus ist die Maschinendatenverfügbarkeit und -verarbeitung entscheidend um weiteres Prozesswissen für die Entscheidungsfindung und Arbeitsplanerstellung zu generieren.