Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Manufacturing of graphite electrodes with high geometrical requirements
    ( 2019)
    Uhlmann, E.
    ;
    Kuche, Y.
    ;
    Polte, J.
    ;
    Polte, M.
    Graphite is widely used for the die-sinking electrical discharge machining (EDM) process, especially for the roughing process. For the manufacturing of graphite electrodes the milling process is mainly used. The process enables fast processing times tP and high geometrical flexibility. In consequence of the cutting behaviour of graphite micro-components with geometrical features can be manufactured. In this contribution the manufacturing of micro-pins and bridges with aspect ratios of A = 1:50 were machined with diamond coated milling tools. By variation of the depth of cut ap and the width of cut ae it can be shown that the influence of the depth of cut ap is quite bigger than the influence of the width of cut ae. This results in consequence of the higher stability of the geometrical features by improved force distribution.
  • Publication
    Cutting force prediction in micro-milling considering the cutting edge micro-geometry
    ( 2019)
    Uhlmann, E.
    ;
    Polte, J.
    ;
    Wiesner, H.M.
    ;
    Kuche, Y.
    ;
    Polte, M.
    The micro-milling process is used for a wide range of materials and enables the manufacturing of complex geometries with micro-features. One important factor for the tool life is the cutting force Fc, which depends on the applied technology, process parameters and cutting edge micro-geometry. High cutting forces Fc can lead to tool breakage in the transition between the shank and the cutting part of cemented carbide end mills. The prediction of cutting forces Fc in micro-milling processes through cutting force models could potentially decrease the hazard of tool breakage. By including the cutting edge radius rv into the prediction model, additional correction factors can be avoided. Therefore, further knowledge about the applicability of those models for the micro-milling process with chip thickness h < 0.01 mm is needed. In this investigation, the cutting force model of KOTSCHENREUTHER [1], which takes the cutting edge radius rv into account is used for the cutting force prediction in micro-milling. In order to validate this model, an innovative lead free copper alloy CuZn21Si3P is machined. Cemented carbide micro-milling tools with tool diameter D = 1 mm were used. The manufacturing of different cutting edge radii rv was realised with the immersed tumbling process. During milling experiments with a five-axis high precision machine tool the cutting forces Fc were measured. Cutting forces in a range of 6 N < Fc < 26 N were detected. The results show good correlations between the predicted and experimental determined cutting forces Fc. Furthermore, the measured cutting edge radii rv show a high influence on the deviation of the measured and predicted cutting forces Fc.
  • Publication
    Mikrofräswerkzeuge mit Schneiden aus cBN
    ( 2018)
    Uhlmann, E.
    ;
    Polte, J.
    ;
    Polte, M.
    ;
    Kuche, Y.
    ;
    Wiesner, H.
    Die Mikrozerspanung ist eine Kerntechnologie bei der Fertigung von Mikrospritzgussformen. Die hohen Ansprüche an die geometrische Genauigkeit und Oberflächenrauheit erfordern den Einsatz hochfester Werkstoffe. Jedoch unterliegen aktuelle Fräswerkzeuge bei der Mikrozerspanung einem hohen Verschleiß. Einen Lösungsansatz bietet der erfolgreich in der Makrozerspanung eingesetzte Schneidstoff kubisch-kristallinesBornitrid(cBN). Ziel der Untersuchungen war es daher, detaillierte Informationen zur Bearbeitung von gehärtetem Stahl mit cBN-Mikrofräswerkzeugen bereitstellen zu können.
  • 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
    Droplet removal from PVD-coated micro-milling tools with the immersed tumbling process
    ( 2017)
    Uhlmann, E.
    ;
    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.