Now showing 1 - 7 of 7
  • Publication
    Liquid covered micro-milling
    ( 2017)
    Uhlmann, E.
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    Oberschmidt, D.
    ;
    Polte, M.
    ;
    Polte, J.
    Micro-milling tools made of cemented carbide suffer from fast tool wear and random tool breakage during the machining process. The cutting material cemented carbide is composed of a hard material phase made of tungsten carbide and a binder phase made of cobalt. An allotropical crystal lattice transformation of the binder phase at a temperature TH = 420 °C leads to increased tool wear. Commonly minimum quantity lubrication (MQL) is used as cooling lubricant technology in micro-milling. In this work a new liquid covered cooling lubricant (LCCL) technology and the commonly used MQL technology were compared regarding tool wear of cemented carbide tools for machining the steel STAVAX ESU. In the LCCL technology the cutting process is completely covered with cutting lubricant. It could be concluded that the new LCCL technology offers a high potential to reduce the tool wear in micro-milling of steel with cemented carbide micro-milling tools.
  • Publication
    Cutting forces while machining STAVAX ESU with binderless-cBN
    ( 2017)
    Uhlmann, E.
    ;
    Oberschmidt, D.
    ;
    Polte, J.
    ;
    Polte, M.
    Binderless-cubic-Boron-Nitride(cBN) from the company SUMITOMO CORPORATION, Itami, Japan, provides the opportunity for direct cutting of steel with ultra-precision quality without additional equipment or coating of the workpiece. This work presents the latest results in the field of ultra-precision machining of hardened stainless steel with binderless-cBN. In this paper the influence of the cutting speed vc, the feed f, the depth of cut ap, and the cooling lubricant on the cutting force Fc is shown for turning the stainless steel STAVAX ESU. The cutting speed, the feed and the depth of cut were varied between 3 m/min < vc < 450 m/min, 0.9 mm < f < 9.7 mm, and 5 mm < ap < 30 mm respectively. As cooling lubricants compressed air and W200SL of the company OPORTET, Duisburg, Germany, with a volumetric flow rate & = 1 l/min were used. For measuring the cutting forces Fc the piezoelectric dynamometer MINIDYN 9256C2 from the KISTLER INSTRUMENTE AG, Middlefield, USA, was used. As a result of this work cutting forces Fc < 4.9 N could be observed with an inconstant progression over the varied process parameters.
  • Publication
    Manufacturing of CVD diamond micro-end mills with electrical discharge machining
    ( 2017)
    Uhlmann, E.
    ;
    Oberschmidt, D.
    ;
    Polte, M.
    ;
    Polte, J.
    ;
    Schimmelpfennig, T.-M.
    ;
    Börnstein, J.
    At state of the art micro-milling tools made of cemented carbide are widely used in industry. Nevertheless, these micro-milling tools suffer from fast and random tool breakage while cutting. To improve the wear behaviour of micro-milling tools new cutting materials have to be established. In this work electrical discharge machining (EDM) for manufacturing of micro-milling tools with cutting edges made of boron doped chemical vapour deposition (bdCVD) diamond were investigated. Wire-EDM and die-sinking-EDM were compared regarding the characteristics of the micro-tool´s cutting edges. It could be concluded that the wire-EDM process is suitable for manufacturing of micro-milling tools with cutting edges made of bdCVD diamond. With respect to the elaborated technologies for the wire-EDM process a cutting edge radius rv = 3.9 mm and for the die-sinking-EDM process a cutting edge radius rv = 5.4 mm could be measured.
  • Publication
    Effect of cooling lubricant on surface roughness for turning stainless steel with binderless-cBN
    ( 2016)
    Uhlmann, E.
    ;
    Oberschmidt, D.
    ;
    Polte, J.
    ;
    Polte, M.
    ;
    Huth-Herms, K.
    Binderless-cubic Boron Nitride (cBN) from the company SUMITOMO CORPORATION, Itami, Japan, is one of the most promising cutting materials providing the opportunity for direct cutting of steel with ultra-precision (UP) quality without additional equipment or coating of the workpiece. This work presents the latest development in the field of precision machining of hardened stainless steel with binderless-cBN. In this paper the influence of the feed f and the cooling lubricant on the surface roughness is shown for turning the hardened stainless steel STAVAX ESR (H = 52 HRC) from the company BÖHLER-UDDEHOLM, Düsseldorf, Germany. A surface roughness Ra = 9 nm and Rz = 42 nm could be achieved using binderless-cBN and the cooling lubricant W200SL of the company OPORTET, Duisburg, Germany.
  • Publication
    Geometric deviations in the production of micro-milling tools and their influence on the cutting process
    ( 2016)
    Uhlmann, E.
    ;
    Oberschmidt, D.
    ;
    Kuche, Y.
    ;
    Polte, M.
    For micro-milling tools with decreasing diameter D < 0.5 mm the requirements for the manufacturing rise up and the risk of geometrical deviations of the cutting edges increase. In this investigation industrial produced micro-milling tools with a diameter of D = 0.2 mm made of cemented carbide were analysed. Micro-milling tools with variable macro geometry were selected and used for the machining of mould steel. The influence of the geometrical deviations on the wear behaviour and the surface roughness of the machined steel were examined. It is shown that the variable tool geometry lead to wear of the minor cutting edges S'. Furthermore, an influence on the surface roughness of the machined workpiece is determined.
  • Publication
    High precision milling with a novel compliant machine tool
    ( 2016)
    Uhlmann, E.
    ;
    Oberschmidt, D.
    ;
    Guhde, S.
    ;
    Polte, M.
    For precision milling manufacturing machine tools with high stiffness K and high masses m are state of the art. Usually this will be achieved due to heavy and large machine beds and frames. Hence, a new approach based on the compensation of the dynamic dislocation was investigated. The aim of this new approach was to develop a high dynamic machine tool with a compliant machine frame. Therefore, a novel compliant three- Axes machine tool for high precision milling based on an Ethercat Technology® and the open source ethercat master etherlab machine is developed by the Technische Universität Berlin and the Fraunhofer Institute for Production Systems and Design Technology. For the dynamic dislocation a Kalman-filter is integrated in the machine control which calculates the tool body with respect to the tool-center-point TCP and its velocity v. For the verification milling structures are manufactured with the compliant machine tool.
  • Publication
    CBN-micro-milling tools for machining hardened steel moulds
    ( 2016)
    Uhlmann, E.
    ;
    Oberschmidt, D.
    ;
    Polte, M.
    ;
    Polte, J.
    ;
    Börnstein, J.
    High-precision cutting of hardened steel with geometrical defined cutting edge is restricted due to excessive and random tool wear. For serial production of precision plastic parts hot embossing tools and micro injection moulding tools with high requirements regarding geometrical accuracy and surface roughness are needed. Cutting materials based on cubic Boron Nitride (cBN) are successfully used in macro-machining of hardened steel. In this paper, detailed information about machining hardened steel with micro-milling tools with cutting edges made of cBN are given. An arithmetical mean deviation Ra = 19 nm could be achieved using a high-precision micro-milling machine tool with ball bearing guideways and spindle.