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Increasing the Coating Adhesion on Cutting Tools by Nano Technology

  

    Huicong Surface Treatment: The nano-technology application and the acicular structure of TiCN coating have enhanced the adhesion between alumina and TiCN layer. TiCN layer is wear-resistant while the alumina layer is heat-resistant.

    The good adhesion between TiCN acicular structure and alumina layer would increase the heat-resistance and wear-resistance of the inserts. The acicular structure and the enhanced adhesion with alumina layer remind people of Nano-Velcro material. TiCN layer is wear-resistant while the alumina layer is heat-resistant.

    TiCN normally is used for coating of cutting tools. In fact, according to Mr. Reinhard Pitonak, engineer of research department in Boehlerit ( one of the six companies in LMT Group), 90% of the inserts are CVD coated and there is at least one layer of TiCN on the coating. Mr. Pitonak stated, TiCN layer is applied for wear-resistance. He also explained that the grain size of the TiCN layer, which is with C grains and N grains and good wear-resistance, is 50 to 300 nm. Therefore, Boehlerit has applied the TiCN with 25 nm grain size. It was also discovered by Boehlerit that applying the super high temperature CVD coating process with this grain size of TiCN, the structure formed is unusualandwith better performance.

    There is one layer of acicular structure on the formed nano crystal coating layer. As a result, this layer on the top of TiCN coating was namedby the company ‘Nano-lock’ layer, which ‘locks’ the alumina layer on top of it. The adhesion between two layers is so strong that it is slightly possible that the alumina layer is peeled out during the cutting process. At the same time the alumina is protect cutting tools from heat during machining. Good wear-resistant of TiCN along with heat-resistant of alumina could allow higher cutting speed or longer tool life, Mr. Pitonak explained.

    Currently Nano-lock technology has been applied to LC228E inserts for grinding rods, LC239Q inserts for crankshaft machining and Steeltec turning inserts in Boehlerit. Based on the comparison cutting tests between Steeltec LC215K turning inserts with Nanolock technology and normal turning inserts, continuous cutting speed for Steeltec inserts is over 300 m/min and the tool life has increased 50% when machining 4140 steel.