Fraunhofer Project Center for Coatings in Manufacturing PCCM

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  • Publication
    Repetitive impact test near uncoated and coated cutting edges for assessing their fatigue behavior
    ( 2015)
    Bouzakis, K.-D.
    ;
    Batsiolas, M.
    ;
    Skordaris, G.
    ;
    Stergioudi, F.
    ;
    Michailidis, N.
    The fatigue strength of the cutting edge affects dominantly the tool life, especially in the interrupted material removal processes. The cutting edge fatigue of uncoated and coated tools can be effectively assessed by the repetitive impact test. Cemented carbide inserts of various grain size, surface roughness, coating and heat treatment were investigated by applying repetitive impacts close to the cutting edge for detecting its fatigue strength. Complementary FEM simulations of the impact test, at various distances from the cutting edge, provided insights on the developed stress fields. The impact distance from the cutting edge was corroborated to have a dominant effect on the tool life, while a reduction of the roughness and the application of finer substrate grains led to an increase of the cutting edge fatigue strength. The proposed methodology facilitates an effective quality control of both coated and uncoated cutting inserts at loading conditions resembling those of interrupted cutting.
  • Publication
    Brittleness and fatigue effect of mono- and multi-layer PVD films on the cutting performance of coated cemented carbide inserts
    ( 2014)
    Skordaris, G.
    ;
    Bouzakis, K.D.
    ;
    Charalampous, P.
    ;
    Bouzakis, E.
    ;
    Paraskevopoulou, R.
    ;
    Lemmer, O.
    ;
    Bolz, S.
    The effect of brittleness and fatigue of mono- and multi-layer PVD films on coated tools cutting performance is introduced. Cemented carbide inserts were coated to the same overall film thickness with various numbers of layers. Nanoindentations were conducted to evaluate the hardness of the diverse coating structures. The film brittleness and fatigue were characterized by nano- and macro-impact tests respectively. The coated inserts' wear behaviour was investigated in milling hardened steel. The attained results revealed the coatings' brittleness and fatigue endurance enhancement by increasing the number of film's layers. This increase leads simultaneously to the coated tool life improvement.