Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Nachhaltige Reinigung und Präparation
    ( 2024)
    Uhlmann, Eckart
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    Polte, Julian
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    Burgdorf, Philipp
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    Reder, Waldemar
    In der Fertigungstechnik lautet aktuell die Devise, innovative Wege für mehr Nachhaltigkeit zu entdecken. Für industrielle Reinigungsprozesse ist das CO2-Strahlen auf dem Vormarsch - im Beitrag wird beschrieben, warum.
  • Publication
    Smarte Überwachung elektrischer Großantriebe
    ( 2023)
    Geisert, Claudio
    ;
    Polte, Julian
    ;
    Uhlmann, Eckart
    ;
    Rauch, Hartmut
    ;
    Brach, Karsten
    Die Nutzung von Digitalisierungstechnologien im Kontext von Industrie 4.0 bietet insbesondere für den gesamten Bereich der Wartung und Instandhaltung von elektrischen Großantrieben großes Potenzial zur Schaffung innovativer Serviceangebote. Durch erweiterte Sensorik im elektrischen Antrieb und Intelligenz in der Verarbeitung und Analyse von Daten im Betrieb von Anlagen, kann eine vorausschauende Instandhaltungsstrategie eingeführt werden, die eine höhere Verfügbarkeit der Anlagen ermöglicht und gleichzeitig den Aufwand für Instandhaltungseinsätze reduziert. Um diese Potenziale im Servicegeschäft elektrischer Großantriebe zu erschließen, wird in diesem Beitrag ein hypothesengetriebener Ansatz zur Zustandsüberwachung beschrieben.
  • Publication
    Sharpening mechanism of extremely sharp edges for diamond micro mills
    ( 2022)
    Wu, Y.
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    He, N.
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    Chen, N.
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    Polte, Julian
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    Yan, B.
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    Li, L.
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    Uhlmann, Eckart
    The fabrication of extremely sharp cutting edges for ultra-hard micro mills is crucial for suppressing the severe size effect, restraining burr formation, and improving the surface quality of widely used micro components in micro milling. In this study, a hybrid machining technique, laser-assisted precision grinding, is proposed to improve the grinding efficiency and increase the sharpness of the cutting edges of polycrystalline diamond (PCD) micro end mills. A transient heat model of laser ablation was constructed to investigate the laser-cutting mechanism of PCD with a cobalt binder. Facilitated by suitable heat conduction, cobalt absorbs photon energy to heat itself and transmits thermal energy to the surrounding diamond, resulting in uniform graphitisation and cobalt oxidation on the cut section. Hence, the affected layer on the cut section can be easily ground using a low grinding load. Moreover, the subsequent grinding mechanism of the laser-cut section was demonstrated. The diamond was removed via micro-abrasion without any intercrystalline cracks or grain dislodgement, and the abrasive grain size was optimised to achieve superior ground surface quality. Thus, the uniform graphitization, micro abrasion, and smaller material stress near edge contributed to the extremely sharp edges. Furthermore, PCD micro end mills with a diameter of 400 μm, aspect ratio of 2, and cutting-edge radius of approximately 0.2 μm were fabricated, showing a superior sharpness compared with that of the end mills with an edge radius of 1-5 μm reported hitherto. Subsequently, micro-milling experiments were conducted on oxygen-free high-conductivity copper (OFHC) using the self-fabricated PCD micro end mills. Almost no burrs were observed, and the surface roughness of the machined groove was 19.8 nm, indicating the superior cutting performance of the fabricated PCD micro end mills.
  • Publication
    Harmonization of Heterogeneous Asset Administration Shells
    ( 2022)
    Koutrakis, Nikolaos-Stefanos
    ;
    Gowtham, Varun
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    Pilchau, W.B.P. von
    ;
    Jung, T.J.
    ;
    Polte, Julian
    ;
    Hähner, J.
    ;
    Corici, Marius-Iulian
    ;
    Magedanz, Thomas
    ;
    Uhlmann, Eckart
    In the era of digital transformation of the manufacturing and process industry, heterogeneity of assets is one of the most challenging issues towards digitally integrating components within the Industrial Internet of Things. In this context every participant relies on its proprietary digitalization approach envisioned by Plattform Industrie 4.0. To consolidate these heterogeneous data exchange interfaces, e.g communication protocols, data formats etc., an intermediate step of harmonization is required. Our contribution provides an architecture based on the Asset Administration Shell standard to bring heterogeneous Cyber-Physical-Systems together. We illustrate the functionality through an abstract use-case.
  • Publication
    Flexible Automatisierung mit Virtuellen Agenten
    ( 2022)
    Uhlmann, Eckart
    ;
    Polte, Julian
    ;
    Mühlich, Christopher
    ;
    Lindow, Kai
    The process automation of hybrid assembly systems presents companies with the challenge of integrating people and machines into a collaborative system while taking socio-economic aspects into account. The transfer of biological principles to the design of production processes, in combination with Industry 4.0, enables the development of self-organizing systems. Inspired by this, a decentralized platform solution for flexible automation is presented in order to use human skills to increase productivity in a targeted manner.
  • Publication
    Numerical investigation into cleanability of support structures produced by powder bed fusion technology
    ( 2022)
    Campana, Giampaolo
    ;
    Uhlmann, Eckart
    ;
    Mele, Mattia
    ;
    Raffaelli, Luca
    ;
    Bergmann, André
    ;
    Kochan, Jaroslaw
    ;
    Polte, Julian
    Purpose: Support structures used in laser powder bed fusion are often difficult to clean from unsintered powder at the end of the process. This issue can be significantly reduced through a proper design of these auxiliary structures. This paper aims to investigate preliminary the airflow within differently oriented support structures and to provide design guidelines to enhance their cleanability, especially the depowdering of them. Design/methodology/approach: This study investigates the cleanability of support structures in powder bed fusion technology. Digital models of cleaning operations were designed through computer-aided engineering systems. Simulations of the airflow running into the powder entrapped within the thin walls of auxiliary supports were implemented by computational fluid dynamics. This approach was applied to a set of randomly generated geometrical configurations to determine the air turbulence intensity depending on their design. Findings: The resul ts, which are based on the assumption that a relationship exists between turbulence and powder removal effectiveness, demonstrated that the maximum cleanability is obtainable through specific relative rotations between consecutive support structures. Furthermore, it was possible to highlight the considerable influence of the auxiliary structures next to the fluid inlet. These relevant findings establish optimal design rules for the cleanability of parts manufactured by powder bed fusion processes. Originality/value: This study presents a preliminary investigation into the cleanability of support structures in laser powder bed fusion, which has not been addressed by previous literature. The results allow for a better understanding of the fluid dynamics during cleaning operations. New guidelines to enhance the cleanability of support structures are provided based on the results of simulations.
  • Publication
    High-Performance Electro-Discharge Drilling with a Novel Type of Oxidized Tool Electrode
    ( 2022)
    Uhlmann, Eckart
    ;
    Polte, Julian
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    Streckenbach, Jan
    ;
    Dinh, Ngoc Chuong
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    Yabroudi, Sami
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    Polte, Mitchel
    ;
    Börnstein, Julian
    Electro-discharge drilling is a key technology for manufacturing sophisticated nozzles in a broad range of automotive and aerospace applications. The formation of debris in the working gap leads to arcs and short circuits on the lateral surface when state-of-the-art tool electrodes are used. As a result, limited drilling depth, increased linear tool wear, and the conicity of boreholes are still challenges. In this work, a new approach for the passivation of the lateral surface of copper tool electrodes by oxidation is shown. The comparison with state-of-the-art tool electrodes showed a reduction in the erosion duration by 48% for machining hardened steel. Promising improvements could be achieved by the thermal oxidation of the tool electrodes with the aim of increasing the electrical resistivity of the lateral surface of the tool electrode. However, due to the loss of strength, the high oxide layer thickness, and the partial delamination of the oxide layer, further comprehensive investigations on the influence of the oxidation temperature need to be conducted. Future adjustments with lower oxidation temperatures will be carried out.
  • Publication
    Modeling of the wet immersed tumbling process with the Discrete Element Method (DEM)
    ( 2021)
    Uhlmann, Eckart
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    Fürstenau, J.-P.
    ;
    Kuche, Yves
    ;
    Yabroudi, Sami
    ;
    Polte, Julian
    ;
    Polte, Mitchel
    Immersed tumbling is an industrially established process for finishing of components made of metal, ceramic or plastic. In this process, the components are completely surrounded by a wet, abrasive medium, which allows burrs to be removed and surfaces to be polished. In order to gain specific insights into the influence and flow properties of the abrasive media used in this process, numerical approaches using the Discrete Element Method (DEM) with the Rocky DEM software are presented within these investigations. A complete process simulation could be realised by means of a digital machine tool. The immersed tumbling process with cone-shaped polymer abrasive media is implemented by use of a liquid bridge model. The results were validated by experiments with an industrially used immersed tumbling machine tool and for the first time allow sound statements about the contact conditions and interactions of the abrasive media with the workpiece.
  • Publication
    Agiles Modellieren von Servicetätigkeiten
    ( 2021)
    Uhlmann, Eckart
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    Bösing, Manuel
    ;
    Polte, Julian
    ;
    Kirsch, Lucas
    ;
    Altmann, Ian
    ;
    Emmerling, Roman
    Kontextsensitive Assistenzsysteme bieten ein großes Potenzial zur Optimierung von Arbeitsabläufen. Durch die Einbindung Digitaler Zwillinge können unmittelbar Kontextinformationen zur Verfügung gestellt werden, wobei die Modellierung der Arbeitsabläufe derzeit wenig standardisiert ist. Die in diesem Beitrag vorgestellte Lösung zeigt eine interaktive Software-Applikation für kontextsensitive Assistenzsysteme in Kombination mit Prozesspatterns für die Modellierung von Servicefällen.
  • Publication
    Evaluation of carbon fiber reinforced polymer – CFRP – machining by applying industrial robots
    ( 2021)
    Grisol De Melo, Ever
    ;
    Santos Silva, Jéssica Christina dos
    ;
    Klein, Tiago Borsoi
    ;
    Polte, Julian
    ;
    Uhlmann, Eckart
    ;
    Oliveira Gomes, Jefferson de
    Carbon fiber reinforced polymer (CFRP) is widely used in high-tech industries because of its interesting characteristics and properties. This material presents good strength and stiffness, relatively low density, high damping ability, good dimensional stability, and good corrosion resistance. However, the machinability of composite materials is complex because of the matrix/fiber interface, being a challenging machining material. The CFRP milling process is still necessary to meet dimensional tolerances, the manufacture of difficult-to-mold features like pockets or complexes advance surfaces, finish the edges of laminated composites, or drill holes for the assembly of the components. Besides, the demand for low-cost, reconfigurable manufacturing systems of the industry demonstrates that the application of industrial robots (IRs) in the CFRP milling process becomes an alternative for providing automation and flexibility. Therefore, the objective of this work is to evaluate the performance of the low payload IR KUKA KR60 HA in a milling experiment of CFRP, which indicates its potential application as an alternative to milling process. Furthermore, the influence of the cutting tool geometry as well as the cutting parameters in the machining behavior with IRs is evaluated.