Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Chapter 4: Micro-electrical Discharge Machining
    ( 2015)
    Uhlmann, E.
    ;
    Röhner, M.
    ;
    Langmack, M.
    ;
    Schimmelpfennig, T.-M.
    Within this chapter, the procedure of one single discharge during four phases is explained. Besides addressing the differences between electrical discharge machining and micro-electrical discharge machining, it also compares several established processes based on which different process parameters are discussed as well as applications and merits of each process.
  • Publication
    Application of PCD and boron doped CVD diamond tool electrodes in micro EDM
    ( 2010)
    Uhlmann, E.
    ;
    Röhner, M.
    ;
    Domingos, D.C.
  • Publication
    Influence of coatings in micro-EDM
    ( 2010)
    Uhlmann, E.
    ;
    Röhner, M.
    ;
    Rosiwal, S.
    ;
    Domingos, D.C.
    Micro-Electrical Discharge Machining ( - EDM) means the modification of process technologies and machine tools for the manufacturing of micro and miniature parts and structures [ 1 -3]. Compared to conventional die sinking EDM the relative wear can rise up to more than 30% , especially when relaxation generators are used. To achieve shape accuracies in the range of a few microns, it is common to use several tool electrodes for roughing and finishing. In order to reduce the wear and therewith the number of tool electrodes and to enhance the machining results, coated electrodes can be applied. The paper presents results of investigations on wear behaviour of various coatings on tool electrode materials.
  • Publication
    Turbomaschinen in Berlin-Brandenburg
    (Regioverlag, 2010)
    Besinger, F.
    ;
    Lichtfuß, H.-J.
    ;
    Röhner, M.
    ;
    Uhlmann, E.
    Experten haben vor dem Hintergrund einer neuen Studie über Turbomaschinen auf die bedeutende Rolle der Hauptstadtregion als Industriestandort hingewiesen. Mit über 8.000 Arbeitsplätzen und einem Jahresumsatz von 1,8 Milliarden Euro sei die Turbomaschinenindustrie inklusive Zulieferer ein wichtiger Bestandteil des Zukunftsfelds Energietechnik in Berlin-Brandenburg, sagte am Mittwoch ein Sprecher der privaten Technologiestiftung Berlin (TSB), die die Studie in Auftrag gegeben hatte. Turbomaschinen wandeln Wärme in Drehbewegungen um und werden unter anderem als Flugzeug- oder Kraftwerksturbinen eingesetzt. «Der Markt der Turbomaschinen wächst. Die Hauptstadtregion hat das Potenzial, ihre Wettbewerbsfähigkeit und die Wertschöpfung in der Region zu steigern», sagte Christian Hammel, Leiter des Bereichs Technologie und Innovation bei der TSB und Herausgeber der Studie. Mit den Unternehmen Alstom, MAN, MTU, Rolls-Royce und Siemens seien gleich fünf führende Turbomaschinenhersteller in Berlin-Brandenburg vertreten. Die Region sei sogar Europas größter Produktionsstandort für Gasturbinen. «Der Bereich der Turbomaschinen zeigt exemplarisch das große Potenzial der Hauptstadtregion», sagte Berlins Wirtschaftssenator Harald Wolf (Linke). Die exzellente Wissenschafts- und Forschungslandschaft gebe Impulse für technologische Innovationen, die zum Wachstumsmotor für Berlin und Brandenburg würden. Allerdings müsse künftig noch mehr getan werden, um Forschung und Entwicklung der Industrieunternehmen besser zu vernetzen.
  • Publication
    Micro-EDM
    ( 2010)
    Uhlmann, E.
    ;
    Röhner, M.
    ;
    Langmack, M.
  • Publication
    Influence of grain size on wear behavior of CVD-diamond coatings in micro-EDM
    ( 2010)
    Uhlmann, E.
    ;
    Rosiwal, S.
    ;
    Bayerlein, K.
    ;
    Röhner, M.
    In order to reduce wear and therewith enhance the microelectrical discharge machining (µ-EDM) results, a coated electrode was used. The paper presents the results of investigations into the influence of grain size of the boron-doped CVD diamond coating on the wear behavior in microsinking EDM. Experimental investigations show that nanocrystalline coatings exhibited smaller discharge craters compared to those for microcrystalline diamond coatings, and microcrystalline coating showed melted material around the discharge crater. The finding will be subjected to further investigations.
  • Publication
  • Publication
    Machining of micro rotational parts using electrical discharge machining
    ( 2007)
    Piltz, S.
    ;
    Röhner, M.
    ;
    Uhlmann, E.
    Micro rotational parts are used in several industrial sectors. Well-known applications are micro shafts of gears, ejector pins in forming tools, pin electrodes for micro ED-drilling or micro stamping dies. Depending on the geometric complexity of micro rotational parts different process variants of micro electrical discharge machining characterized by a rotating workpiece can be used: 1. Wire Electrical Discharge Grinding (WEDG) with fine wire electrodes (50 microns). 2. Electrical Discharge Turning (EDT) with micro structured tool electrode. 3. Cylindrical Electrical Discharge Grinding (CEDG) with micro profiled disk electrode. Characteristic to these process variants is the superimposed relative motion between the rotating electrodes and the feed. This relative motion can be varied in a wide circumferential velocity range to improve the material removal process. The paper gives an introduction to the analysis of electrical, thermal, and hydrodynamic effects (amongst others: FEM and CFD results) influencing the process behavior with respect to technological requirements of micromachining. The investigations about the role of the relative movement according to the process behaviour of Micro Electrical Discharge Machining led to conclusion that several heat-conductive, hydrodynamic or pulse-electric effects must be taken into account. It has been determined, that the relative movement between both electrodes does not cause a premature break down of the spark, but leads to pulsating current. The assumption of a stationary discharge channel can be derived from this. The influence of the relative movement on the heat conduction is, however, only relevant on circumferential speed above v(ind u) = 2 m.s(exp -1) or on discharge duration longer than t(ind e) = 10 micro s, as the FEM-simulations have shown. Optical based measurements of single discharges confirmed the tendency of decreasing crater size with rising velocity of the relative movement. In contrast, the surface roughness produced by series of discharges increases with rising speed. This result led to the further assumption, that improved flushing conditions because of the relative movement effect an increase of the power density and the process efficiency respectively. CFD simulations clarified the increase of the flow rate with rising velocity. But the dielectric fluid flows produce also a substantial change of the hydrodynamic pressure, thus a removal process free of machining forces can no longer be assumed. According to the current state of the investigations the conclusion follows, that a relative movement with high circumferential speed should be used only for removal-intensive machining operations. Entnommen aus TEMA