Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Application of Micro Structured, Boron Doped CVD-diamond as mEDM Tool Electrodes
    ( 2018)
    Uhlmann, Eckart
    ;
    Oberschmidt, Dirk
    ;
    Bolz, Robert
    High precision cavities are used for micro injection and micro embossing tools in the field of tool making and are mainly used for small batch or mass production of micro parts. In order to fabricate a large quantity of parts, wear resistant tool materials are required. In possession of a high hardness and a high Young's Modulus, such materials are often hard or even impossible to machine by conventional fabrication processes. Being independent of the work piece's mechanical properties, Micro-Electrical Discharge Machining (mEDM) is predestined for this case. mEDM is based on the modification of state of the art process technologies and universal machine tools applied for electrical discharge machining operations [1], [2]. Besides the adjustment of the electrical parameters, the mEDM-process is also determined by the tool electrode's material which has a big influence on the material removal rate VW, the electrode's wear behavior, as well as the process results concerning surface quality and dimensional accuracy [3]. Experimental investigations aim at decreasing the wear of tool electrodes using novel electrode materials. To assure an efficient process, short production times and low tool wear TH are demanded. Therefore, electrodes with excellent electrical and thermal conductivity along with a high mechanical strength have to be used. Boron doped CVD-diamond is fulfilling these criteria. Microstructures within thin CVD-diamond foils are realized by direct structuring utilizing laser ablation and by indirect structuring using micro-structured copper substrates in the CVD-process, which transfer the micro-structure onto the growing diamond layer. Experiments were conducted in order to identify suitable EDM-parameters for different workpiece materials, namely steel 90MnCrV8, silicon carbide SiSiC and tungsten carbide K40F, which lead to lower tool wear TH and high accuracy.
  • Publication
    Development of a versatile and continuously operating cell disruption device
    ( 2013)
    Uhlmann, Eckart
    ;
    Oberschmidt, Dirk
    ;
    Spielvogel, Anja
    ;
    Herms, Katrin
    ;
    Polte, Mitchel
    ;
    Polte, Julian
    ;
    Dumke, A.
    Cell disruption is a recurrent unit operation in biotechnology. Interesting biotechnological products like proteins, lipids or biopolymers are synthesized intracellularly and are often not secreted. Furthermore, cell-free biotechnology uses defined fractions of the cytoplasm for in vitro protein synthesis. Bacteria, yeast, algae and filamentous fungi are surrounded by rigid cell walls that have to be disrupted by physical, chemical or mechanical methods in order to retain the valuable cell content. High pressure homogenization is a widely used procedure to disrupt cells and it has been applied to bacteria, algae and yeast. However, the mode of cell disruption has not been fully elucidated and performance is not predictable, thus time consuming iterative cycles are always necessary to define the best parameters for each microorganism, chemical environment and the corresponding product. Therefore, physical parameters of different biological systems were analyzed and boundary conditions defined in order to construct an adjustable disruption device to allow economical efficient, predictable and adjustable cell disruption processes.