Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Wolframschmelzcarbidbasierte MMC-Schichten für den industriellen Einsatz im Formenbau
    ( 2022)
    Langebeck, Anika
    ;
    Jahnke, Christian
    ;
    Wünderlich, Tim
    ;
    Hein, Christoph
    ;
    Bohlen, Annika
    ;
    Uhlmann, Eckart
    Zur Steigerung der abrasiven Verschleißbeständigkeit können Oberflächen lokal mit Hartpartikeln verstärkt werden. Diese sogenannten Metal-Matrix-Composit(MMC)-Schichten können mittels Laserstrahldispergieren gefertigt und durch Mikrofräsen nachbearbeitet werden. Im hier vorgestellten Forschungsvorhaben wurde als Grundwerkstoff verwendete Aluminiumbronze (CuAl10Ni5Fe4) mit Wolframschmelzcarbid verstärkt. Der Hartpartikelgehalt kann dabei durch eine Steigerung des Pulvermassenstroms bis zur Packungsdichte des unverarbeiteten Pulvers erhöht werden. Über eine temperaturbasierte Leistungsregelung kann eine gleichbleibend homogene MMC-Schicht mit konstanter Dicke und Tiefe dispergiert werden. Durch das Mikrofräsen mit optimierten Parametern können qualitativ hochwertige MMC-Oberflächen für den industriellen Einsatz in Spritzgusswerkzeugen hergestellt werden. Dabei wurde vor allem der Zahnvorschub fz als kritischer Prozessparameter identifiziert.
  • Publication
    Heat treatment of SLM-LMD hybrid components
    ( 2019)
    Uhlmann, Eckart
    ;
    Düchting, Jan
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    Petrat, Torsten
    ;
    Graf, Benjamin
    ;
    Rethmeier, Michael
    Additive manufacturing is no longer just used for the production of prototypes but already found its way into the industrial production. However, the fabrication of massive metallic parts with high geometrical complexity is still too time-consuming to be economically viable. The combination of the powder bed-based selective laser melting process (SLM), 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 process duration. For the industrial application of the SLM-LMD hybrid process chain it is necessary to investigate the interaction of the processes and its effect on the material properties to guarantee part quality and prevent component failure. Therefore, hybrid components are manufactured and examined before and after the heat treatment regarding the microstructure and the hardness in the SLM-LMD transition zone. The experiments are conducted using the nickel-based alloy Inconel 718.
  • Publication
    In-Situ-Kraftmessung bei variablen Werkzeugwinkeln
    ( 2019)
    Uhlmann, Eckart
    ;
    Uhlemann, Sebastian
    ;
    Kochan, Jaroslaw
    Werkzeugentwicklungen sind von iterativen Anpassungen und aufwendigen Versuchsreihen mit einer Vielzahl von Prototypen geprägt. In einem Forschungsprojekt wurde ein sensorisch instrumentiertes Fräswerkzeug mit verstellbaren Schneiden entwickelt und mittels SLM (Selective Laser Melting) aufgebaut. Mit dieser Entwicklung liegt ein Instrument vor, das im Fräsprozess unmittelbar an den Schneiden Belastungen erfassen kann und durch nachgestellte FEM (Finite Elemente Methode)-Analysen und Optimierungsroutinen ein enormes Potenzial für die Auslegung optimierter Werkzeuggeometrien bietet.
  • Publication
    Wear behaviour of HIPIMS coated micro-milling tools with cutting edge preparation for machining steel moulds
    ( 2018)
    Uhlmann, Eckart
    ;
    Kuche, Yves
    ;
    Polte, Julian
    ;
    Polte, Mitchel
    Micro-milling is an appropriate process for the industrial production of precision parts in the mould and die industry. Decisive for a long tool life is the wear resistance, which can be improved by cutting edge preparation technologies and tool coatings. Especially the improvement of the coating technology with the high power impulse magnetron sputtering (HIPIMS) provides improved tool wear behaviour and longer path length lc. Further studies compare two different HIPIMS-coatings of micro-milling tools for machining the mould steel X13NiMnCuAl4-2-1-1. Furthermore, the tool wear could be reduced due to cutting edge preparation using immersed tumbling process. In consequence of the increased cutting edge radii rβ the measured active forces Fa increased slightly. Best results were achieved for micro-milling tools with cutting edge preparation and AlTiN coating.
  • Publication
    Potentials and limitations of simulation based artefact correction in computed tomography
    ( 2018)
    Uhlmann, Eckart
    ;
    Polte, Julian
    ;
    Melnik, Steffen
    In computed Tomography common artefact correction methods generally address one type of artefacts, thus in praxis usually a combination of different methods is used. Without expert knowledge the user of 3D X-ray scanners is frequently over-challenged figuring out what kind of correction method should be used and when. Simulation based artefact correction in contrast is capable of dealing with multiple kinds of artefacts simultaneously. This includes e.g. beam hardening, partial volume artefacts, off-focal radiation and scatter. The simulation based approach uses prior knowledge about the specimen and the X-ray parameters for calculation of artificial projection images. While in medicine the structure of the specimen (patient) is generally unknown, in field of none destructive testing and quality assurance specimens often exists in form of design data. During simulation based artefact correction artificial images are calculated for every measured projection. Aim is the identification and correction of corrupted projection integrals. A common example is scatter correction, where scatter distribution is determined by Monte-Carlo simulation. For correction the scatter is subtracted from measured projection data, resulting in reduced inconsistencies and enhanced signal-to-noise ratio (SNR). Subsequently, the corrected image data is used for 3Dreconstruction. Although simulation based artefact correction is capable of enhancing 3D image quality, physically correct simulation of projection data can be challenging in terms of accuracy and runtime. Especially when the simulation includes a large variety of artefacts. The aim of this paper is to show the potentials and limitations of simulation based artefact correction algorithms and to discuss the need for full Monte-Carlo method. Furthermore, the requirements for optimal simulation results are determined.
  • Publication
    Boron-doped CVD diamond micro-end mills for machining titanium
    ( 2018)
    Uhlmann, Eckart
    ;
    Polte, Mitchel
    ;
    Polte, Julian
    ;
    Oberschmidt, Dirk
    In industry micro-milling tools made of cemented carbide are widely used. However, these micro-milling tools suffer from fast and random tool breakage during the machining of hard to machine materials. Therefore, in preliminary work micro-milling tools with cutting edges made of boron doped chemical vapour deposition (bdCVD) diamond were developed. In this work new micro-milling tools were successfully applied for machining titanium grade 2. Comprehensive cutting tests were carried out to analyse the influence of the spindle speed n, the feed per tooth ft, and the depth of cut ap on the surface roughness. Further experiments addressed the wear behaviour of the developed micro-milling tools. After a path length lc of 10 m a maximum width of flank wear land VBmax of 29 µm were observed.
  • Publication
    Ductile machining of brittle materials for manufacturing micro-optic components
    ( 2018)
    Uhlmann, Eckart
    ;
    Oberschmidt, Dirk
    ;
    Rolon, D.A.
    ;
    Kühne, S.
    ;
    Jagodzinski, M.
    ;
    Malcher, M.
    Due to the geometry and specification of micro-optic components, these may not be ground or polished, therefore they demand other manufacturing processes such as ultra-precision (UP) machining with defined cutting edge tools. Despite previous studies, the machining of brittle materials remains a challenge for manufacturing those components in UP processes. For example, ductile machining of silicon is extensively studied, however, ductile machining of materials such as Zerodur®, GaP, U.L.E.® and glass is still a challenge to overcome. Therefore, this paper aims at reporting the ductile or part-ductile machining of silicon and Zerodur® pieces in UP processes. Experiments were carried out using UP-shaping and plane turning processes in an UP-machine tool. Moreover, monocrystalline diamond tools were employed. During UP-turning experiments, the process forces were measured. The machining results were obtained by White Light Interferometer (WLI) of the representative mach ined surfaces. In order to complement the experiments, simulations were performed in finite element software to comprehend the influences of the rake angle on ductile machining of those materials. After the UP-shaping experiments, the depth of cut was determined for each of the mentioned materials together with the main influence of each process parameter. Furthermore, a reduction of parameter ranges for UPturning experiments was accomplished. Using Design of Experiments for UP-turning tests, the main influences of process parameters were observed and detailed, together with tool geometry optimization and recommendation for further experiments. The local optimum of process parameters was found as well as the accomplishment of ductile removal during the machining tests. These results and simulation models are going to be further used for a more detailed process description, as analogous tests and optimization of UP processes such as micro-milling.