Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • 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
    Diamond burnishing for mould and die industry
    ( 2018)
    Uhlmann, Eckart
    ;
    Oberschmidt, Dirk
    ;
    Guhde, Sebastian
    ;
    Polte, Mitchel
    ;
    Polte, Julian
    Special ultra-precision processes are necessary to machine surfaces for optical applications with required surface roughness Ra < 30 nm. The use of ultra-precision cutting results in low feed f and significantly reduced cost-efficiency. Diamond burnishing can be a cost-effective alternative. The process reduces the surfaces roughness and generates residual stress, which is advantageous for the workpiece's fatigue strength. However, diamond burnishing is mostly used for post-processing of rotating parts. Applications of diamond burnishing by linear motion, e. g. in mould and die making, are not common. The article shows first investigations to manufacture surfaces with optical quality on milled parts made of steel X37CrMoV5-1, copper CW008A, brass CW612N and aluminium 5083. The experiments were carried out on a 5-axis milling machine tool PFM 4024-5D, PRIMACON GMBH, PeiÃenberg, Germany. The feed velocity, the penetration depth, and the stepover were varied as input para meters. Vickers hardness and the surfaces roughness were measured as reference criteria. Thus, the ability for the surface improvement by diamond burnishing of complex shaped surfaces could be shown.
  • Publication
    Manufacturing, replication and assessment of microfluidics for blood plasma separation
    ( 2016)
    Uhlmann, Eckart
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    Hein, Christoph
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    Polte, Mitchel
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    Polte, Julian
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    Spielvogel, Anja
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    Huth-Herms, Katrin
    ;
    Oberschmidt, Dirk
    Point of care diagnostics gain importance with regard to novel diagnostic techniques. Future applications, for example based on cell-free DNA, are prenatal or cancer diagnostics. With regard to these methods a large influence of natural blood degradation during full blood storage and transport before laboratory based separation restricts possible applications. With a point of care plasma separation device, the plasma can be separated from full blood directly after blood collection. Thus, diagnostic markers remain undamaged and allow a highly specific detection. Targeting microfluidics for point-of-care blood plasma separation, this work presents the development of a microfluidic blood plasma separation device along a novel process chain. Besides system design and manufacturing technologies for prototypes, the development of technologies for replication, closure of microfluidics and affecting of surface properties are under the special scope of this investigation.
  • Patent
    Maschinenbaugruppe, Fertigungsmaschine mit Maschinenbaugruppe sowie Verwendung und Verfahren zur Fertigung von Rotationsbauteilen
    ( 2014)
    Oberschmidt, Dirk
    ;
    Uhlmann, Eckart
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    Eßmann, Jörg
    ;
    Herfert, Frank
    ;
    Polte, Mitchel
    Die Erfindung betrifft eine Maschinenbaugruppe 100 zur Verwendung in einer Fertigungsmaschine 1000, insbesondere in horizontaler Ausrichtung einer Drehachse D in einer Horizontal-Fertigungsmaschine, mit - einer an einem Aufnahmeträger 4 angebrachten Werkstückaufnahme 30 mit einer ersten Seite 31 und einer zweiten Seite 32 und - einer ersten und einer zweiten Werkzeugaufnahme 10, 20, wobei - die erste Werkzeugaufnahme 10 auf der ersten Seite 31 der Werkstückaufnahme 30 und die zweite Werkzeugaufnahme 20 auf der zweiten Seite 32 der Werkstückaufnahme 30 angeordnet ist. Erfindungsgemäss ist vorgesehen, dass die Werkstückaufnahme 30 eine Hauptspindel 33 mit einer von der ersten zur zweiten Seite 31, 32 verlaufenden Drehachse D aufweist und die Hauptspindel 33 zur Aufnahme eines Werkstücks entlang der Drehachse D ausgebildet ist.
  • Publication
  • Publication
    Binderless-cBN as cutting material for ultra-precision machining of stainless steel
    ( 2014)
    Polte, Julian
    ;
    Polte, Mitchel
    ;
    Lorenz, David
    ;
    Oberschmidt, Dirk
    ;
    Sturm, Heinz
    ;
    Uhlmann, Eckart
    The ultra-precision cutting of steel materials is possible but needs modifications of machine tools or the workpiece material. One approach of actual research is the development of cutting materials that gives the opportunity for direct cutting of surfaces with ultra-precision quality. Binderless-cBN is here one of the most promising materials. The paper shows results of experimental studies with binderless-cBN as cutting material while turning stainless steel. Various investigations were carried out to determine the wear mechanisms. Furthermore, measurements are shown regarding the surface quality. The achieved results show the high potential ofbinderless-cBN as cutting material for the machining of steel.
  • 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.