Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Design and hard machining of a high performance ceramic impeller
    ( 2020)
    Uhlmann, Eckart
    ;
    Polte, Julian
    ;
    Koprowski, S
    ;
    Kochan, Jaroslaw
    ;
    Borsoi Klein, T.
    The constant development and improvement of mechanical and chemical properties of high performance ceramics allows the expansion of its actual applications. In comparison to metal materials, the use of novel high performance components can offer numerous advantages. In turbomachinery, a full ceramic impeller can fulfil the requirements of efficiency and high turbine inlet temperatures combined with lower cooling requirements, reduced combustion emissions and fuel consumption. This is feasible not only thanks to the properties of the ceramics, but also by the interaction of this with simulation, design optimization, manufacturing processes and a high quality finishing by hard machining. However, the machining of brittle material components with complex geometries remains a challenge in terms of resultant surface characteristics, tribological properties, geometric accuracy and process costs. In this scenario, 5-axis grinding with mounted points and innovative strategies p rovide new possibilities for the manufacturing of these complexes components. The current work aims at a practice-oriented design and the following hard machining of a hot isostatically pressed silicon nitride (HIPSN) impeller with complex geometry and high requirements, gathering low geometrical deviations, reduced brittle fractures and roughness at the ground part. To achieve these objectives, different machining strategies and parameters are tested and correlated with the resulting quality of the component. Simulation techniques are also shown to ensure optimum operating conditions for the ceramic component.
  • Publication
    NC-form grinding of carbon fibre reinforced silicon carbide composite
    ( 2013)
    Uhlmann, E.
    ;
    Borsoi Klein, T.
    ;
    Schweitzer, L.
    ;
    Neubrand, A.
    This paper presents an approach for the development and optimization of the NC-form grinding technology for an efficient machining of carbon fibre reinforced silicon carbide composite (C/SiC). The C/SiC properties, the importance and the necessity of the application of a high performance grinding process for the machining of this innovative composite material are introduced first. Then, the methodologies and the experimental investigations of NC-form grinding with the application of several machining parameters and three distinct bond types (vitrified, metal and synthetic resin) of diamond mounted points for the abrasive machining of C/SiC are presented. In order to monitor and analyze the process, grinding forces, surface integrity of ground workpieces and grinding wheel wear are investigated. The results of this paper provide new information regarding the wear behavior of grinding tools and the optimized conditions for grinding of C/SiC.
  • Publication
    Double face grinding of carbon fibre reinforced silicon carbide composite
    ( 2011)
    Uhlmann, Eckart
    ;
    Hoghe, T.
    ;
    Borsoi Klein, T.
    High performance ceramics are already being produced for rolling and sliding bearings, brake disks and medical implants. Due to their high hardness and wear resistance, these materials only can be machined using abrasive tools with diamond grains. Requirements such as high quality of components and low production costs complicate the development, selection and optimization of finishing processes for the machining of advanced ceramics. Carbon fibre reinforced silicon carbide composite (C/SiC) has the potential to be used in high performance brake applications because of its low density and superior friction performances at increased temperatures. This article gives an overview of an innovative grinding concept, the double face grinding with planetary kinematics, for an efficient machining of C/SiC components. Using high speed double face grinding with planetary kinematics in C/SiC machining, the material removal rate can be increased and the contact forces can be reduced. As a result of increased cutting speeds, the chip formation mechanisms can be changed and the thermal damage of the machined workpiece can be reduced.