Now showing 1 - 9 of 9
  • Publication
    Droplet removal from PVD-coated micro-milling tools with the immersed tumbling process
    ( 2017)
    Uhlmann, E.
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    Kuche, Y.
    ;
    Oberschmidt, D.
    ;
    Polte, J.
    The physical vapour deposition (PVD) process is widely used for the coating of cutting tools. The increased hardness and temperature stability permitted a higher cutting speed and longer tool life in comparison to uncoated tools. Within the PVD-process droplets of the target can be deposited on the coated surface. The consequence is an inhomogeneous surface of the cutting tools with an increased surface roughness. In this study, the immersed tumbling process is used for the droplet removal of micro-milling tools. The results show the functionality of the process for the droplet removal depending of the lapping media and process parameters in connection with the amount and size of the droplets.
  • Publication
    Wear behaviour of diamond coated micro-milling tools during micro machining
    ( 2017)
    Uhlmann, E.
    ;
    Kuche, Y.
    ;
    Oberschmidt, D.
    ;
    Polte, J.
    Graphite electrodes are used in the die sinking process for manufacturing of micro structured tools in the die and mould fabrication. They are machined using the micro-milling process. During the cutting process graphite grains have strong abrasive effects on the cutting edges and lead to high tool wear. Consequences are short path length lc and geometrical errors. One approach to reduce tool wear is the tool coating with diamond. The diamond coating changes the cutting edge micro geometry which has influences on the process behaviour. In this paper, the wear behaviour of micro-milling tools with diameter D = 0.5 mm and different micro geometries is analysed and discussed. The results show better wear behaviour for prepared and coated tools.
  • Publication
    Cutting forces while machining STAVAX ESU with binderless-cBN
    ( 2017)
    Uhlmann, E.
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    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.
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    Oberschmidt, D.
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    Polte, M.
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    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
    Liquid covered micro-milling
    ( 2017)
    Uhlmann, E.
    ;
    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
    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
    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.
  • Publication
    Mikrozerspanung von rostfreiem Stahl mit PcBNoB
    ( 2015)
    Uhlmann, E.
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    Oberschmidt, D.
    ;
    Polte, J.
    Zur Fertigung präziser Bauteile mit optischen Oberflächen unter höchster Anforderung an Maß- und Formtoleranz wird monokristalliner Diamant als Schneidstoff verwendet. Bei der Bearbeitung von Stahlwerkstoffen unterliegt der Diamant exzessivem Verschleiß. Eine Möglichkeit Verschleiß zu reduzieren ist die vibrationsunterstützte Bearbeitung, die bereits vielfach untersucht wurde. Ziel der dargestellten Untersuchungen ist es, durch Substitution des Schneidstoffes eine ultrapräzise Bearbeitung von Stahlwerkstoffen zu ermöglichen. Hierzu wurde das Verhalten von polykristallinem kubischem Bornitrid ohne Bindephase (PcBNoB) während der Zerspanung analysiert und bewertet.
  • Publication
    Zellaufschluss für die Biotechnologie
    ( 2013)
    Uhlmann, E.
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    Oberschmidt, D.
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    Spielvogel, A.
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    Polte, M.
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    Polte, J.
    ;
    Herms, K.
    Die in der Industrie und Forschung angewandten Zellaufschlusstechnologien sind vielfältig und untergliedern sich in biologische, chemische und physikalische Technologien. Der vorliegende Beitrag beschreibt einen am Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik entwickelten Lösungsansatz zum kontinuierlichen Zellaufschluss mit definierten Aufschlussraten und Einstellparametern. Anschließend werden die sich durch den Einsatz im Produktionsmaßstab ergebenden Potenziale und Einsatzmöglichkeiten des entwickelten Aufbaus erläutert.