Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Fabrication of smooth surfaces in hardened tool to steel using my-EDM technology
    ( 2012)
    Uhlmann, Eckart
    ;
    Domingos, David C.
    In this paper a process optimization was conducted to enable the achievement of smoothest surfaces in hardened tool steel using my-EDM technology. The trials were carried out using DoE-methods, aiming therefore the limitation on the number of experiments. The paper gives detailed information on the experimental procedure applied and on the achieved results, considering surface roughness and sub-surface damage as well as crack formation on the work piece surface.
  • Publication
    A time domain simulation approach for micro milling processes
    ( 2012)
    Uhlmann, Eckart
    ;
    Mahr, Frederik
    Prediction of Process Machine Interactions (PMI) can be achieved using models for conventional milling processes in the time and frequency domain. However, instabilities such as regenerative chatter can also be observed in micro milling processes using filigree cemented carbide end mills. The dominant chatter frequencies are basically related to the end mills eigenfrequencies. Nevertheless, the dynamic characteristics of the machine tool structure and the work piece must not be neglected. In this paper a comprehensive time domain process model is presented. The machine tool dynamics are considered as non-coupled oscillators based on measured frequency response functions at the tool holder. The end mill is modeled as rotating Euler-Bernoulli beam with variable boundary conditions at the tool clamping. At first, the parameter identification for a geometric cutting force model is described. It contains the cutting edge radius as a time-depended parameter. Thereafter, the modeling and parameter identification of the structural parts are presented. A stability criterion is defined with special regard to the tool deflection at the TCP. Finally, simulation results at different stable and unstable operating points for full immersion cutting are discussed in detail and compared to experimental tests.