Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

Filters

Reset filters

Settings
Now showing 1 - 10 of 497
  • Publication
    Effects on the distortion of Inconel 718 components along a hybrid laser-based additive manufacturing process chain using laser powder bed fusion and laser metal deposition
    ( 2021)
    Uhlmann, E.
    ;
    Düchting, J.
    ;
    Petrat, T.
    ;
    Krohmer, E.
    ;
    Graf, B.
    ;
    Rethmeier, M.
    The combination of laser powder bed fusion (LPBF), known for its geometrical freedom and accuracy, and the nozzle-based laser metal deposition process (LMD), known for its high build-up rates, has great potential to reduce the additive manufacturing times for large metallic parts. For the industrial application of the LPBF-LMD hybrid process chain, it is necessary to investigate the influence of the LMD process on the LPBF substrate. In addition, the build plate material also has a significant impact on the occurrence of distortion along the additive manufacturing process chain. In the literature, steel build plates are often used in laser-based additive manufacturing processes of Inconel 718, since a good metallurgical bonding can be assured whilst reducing costs in the production and restoration of the build plates. This paper examines the distortion caused by LMD material deposition and the influence of the build plate material along the hybrid additive manufacturing process chain. Twin cantilevers are manufactured by LPBF and an additional layer is subsequently deposited with LMD. The distortion is measured in the as-built condition as well as after heat treatment. The effect of different LMD hatch strategies on the distortion is determined. The experiments are conducted using the nickel-base alloy Inconel 718. The results show a significant influence of LMD path strategies on distortion, with shorter tool paths leading to less distortion. The remaining distortion after heat treatment is considerably dependent on the material of the build plate.
  • Publication
    Reconfiguring machine tool behavior via smart building block systems
    ( 2019)
    Uhlmann, E.
    ;
    Peukert, B.
    The reconfigurability of manufacturing systems is conventionally increased by utilizing concepts of modularization and platforms. At this moment, the actual reconfigurability is often limited to a priori designed reconfiguration variants for the production within single part families. There is only a little research on reconfiguring the mechanical behavior of machine tool frames. This paper presents an innovative approach for reconfiguring the mechanical behavior based on smart building block systems. Topologically optimized polyhedral building blocks are mechanically bolted to form different machine tool frame configurations. A high grade of modularization allows for the assembly of individualized topologies for different manufacturing scenarios "as needed when needed". The increase in reconfigurability results from the high geometric flexibility of the proposed building block system. However, successful implementation relies on quick and robust simulation approaches for calculating the machine tool frame characteristics before the actual assembly process. Within this paper, a time-efficient approach based on the sub-structuring methodology is utilized. The presented approach consists of forming superelements by performing a GUYAN reduction on the building blocks to extract the stiffness behavior. A Component Mode Synthesis is used to extract modal information. The ANSYS Parametric Design Language is then used to automatically couple the modules according to a customized descriptive machine tool language. A simple joint model is implemented and experimentally fitted with a two-block configuration. The two-block configuration is then extrapolated to a full machine tool frame portal. An example of changing the modal characteristics of this machine tool frame portal is presented in the form of numerical results.
  • Publication
  • Publication
    Verbundprojekt SmartStream: Intelligente Bearbeitung durch die Verwendung schaltbarer Fluide
    ( 2019)
    Schmiedel, C.
    ;
    Bierwisch, C.
    ;
    Uhlmann, E.
    ;
    Menzel, P.
    ;
    Mohseni-Mofidi, S.
    ;
    Breinlinger, T.
    ;
    Nutto, C.
    Strömungsschleifen und Hydroerosiv (HE)-Verrunden sind einzigartige Verfahren, die sich dadurch auszeichnen, dass sie funktionelle Oberflächen im Inneren eines Bauteils bearbeiten können, die sonst mechanisch nicht zugänglich sind. Jedoch unterliegen die Verfahren Begrenzungen aufgrund der Gesetzmäßigkeiten der Strömungsmechanik. Daher können die Verfahren nicht bei allen Anwendungen für eine technisch sowie wirtschaftlich sinnvolle Bearbeitung genutzt werden. Im Verbundprojekt SmartStream werden Möglichkeiten zur Überwindung bisher geltender Verfahrensgrenzen untersucht. Zur lokalen Beeinflussung der Zerspanungsleistung der auf die Oberflächen wirkenden Abrasivmedien werden diese durch ein externes magnetisches Feld schaltbar gemacht. Mit Hilfe des angelegten Magnetfeldes lassen sich zum einen strömungsmechanisch ungünstig gelegene Bereiche des Werkstücks bearbeiten und zum anderen die Zeitspanvolumina lokal gezielt steuern. Im vorliegenden Beitrag werden erreichte Entwicklungsziele am Beispiel des Strömungsschleifens vorgestellt.
  • Publication
    Ecological and functional optimization of the pretreatment process for plasma based coatings of cutting tools
    ( 2019)
    Uhlmann, E.
    ;
    Riemer, H.
    ;
    An, S.
    ;
    Fröhlich, M.
    ;
    Paschke, H.
    ;
    Petersen, M.
    Increasing demands in machining of high-tech materials and dry machining lead to higher thermal and mechanical loads on cutting tools. In response to these challenges, enhanced coating solutions are applied to increase performance and life of cutting tools. However, during the production process the cemented carbide substrates are contaminated with grinding oils and residues of organic material. For the subsequent physical vapor deposition (PVD) coating process an intensive and high-quality cleaning process is necessary. In this contribution, plasma electrolytic polishing (PEP) is used as a novel alternative to conventional ecologically harmful cleaning baths. Apart from the ecological advantage, the surface of the substrate can be optimized with regard to the coating adhesion. To examine the performance of the different cleaning processes, machining tests were performed at the IWF to evaluate the layer adhesion and tool life of the tools.
  • Publication
    Thermal and technological aspects of double face grinding of Al2O3 ceramic materials
    ( 2019)
    Deja, M.
    ;
    List, M.
    ;
    Lichtschlag, L.
    ;
    Uhlmann, E.
    Double face grinding with planetary kinematics is a process to manufacture workpieces with plan parallel functional surfaces, such as bearing rings or sealing shims. In order to increase the economic efficiency of this process, it has to be advanced permanently. The temperature in the contact zone of most grinding processes has a huge influence on the process efficiency and the workpiece qualities. In contrast to most grinding processes these influences are unknown in double face grinding with planetary kinematics. The application of standard measuring equipment is only possible with high effort due to the inaccessibility of the working space during the machining process. Furthermore, measurement of the workpieces temperature in the considered machining system is not reported. Due to that fact, the intensive cooling has so far been the only method to avoid the occurrence of thermal defects especially in case of brittle ceramic materials. The influence of the mean cutting speed, the tools' cutting performance and the coolant flow on the temperature change of the workpieces made of Al2O3 ceramic materials was investigated with the use of a newly developed method. The first empirical approach to predict the change in temperature of the ceramic workpieces while processing is proposed. The developed measuring method can be used for obtaining experimental temperature data in other processes, such as polishing and lapping for which only theoretical models exist.
  • Publication
    Modelling of Abrasive Water Jet Cutting with Controlled Depth for Near-Net-Shape Fabrication
    ( 2019)
    Uhlmann, E.
    ;
    Männel, C.
    Near-net-shape fabrication of difficult to machine materials is a promising application for the abrasive water jet technology. An effective implementation can be achieved by controlling the kerf depth and cutting off defined material fragments. A model for controlled cutting is introduced to make the machining process design more effective for different materials. An empirical model was combined with the process' physical behavior, allowing the prediction of the kerf geometry using a minimum number of predictors and thus initial trials. The model tested with metal matrix composites, reveals the capability of transferring knowledge to new materials using few initial trials.
  • Publication
    Manufacturing of graphite electrodes with high geometrical requirements
    ( 2019)
    Uhlmann, E.
    ;
    Kuche, Y.
    ;
    Polte, J.
    ;
    Polte, M.
    Graphite is widely used for the die-sinking electrical discharge machining (EDM) process, especially for the roughing process. For the manufacturing of graphite electrodes the milling process is mainly used. The process enables fast processing times tP and high geometrical flexibility. In consequence of the cutting behaviour of graphite micro-components with geometrical features can be manufactured. In this contribution the manufacturing of micro-pins and bridges with aspect ratios of A = 1:50 were machined with diamond coated milling tools. By variation of the depth of cut ap and the width of cut ae it can be shown that the influence of the depth of cut ap is quite bigger than the influence of the width of cut ae. This results in consequence of the higher stability of the geometrical features by improved force distribution.
  • Publication
    Elektromechanisches Glattwalzen von Stahllegierungen
    ( 2019)
    Uhlmann, E.
    ;
    Thom, S.
    ;
    Prasol, L.
    ;
    Haberbosch, K.
    ;
    Drieux, S.