Cemented carbide insert for turning, milling and drilling

Abstract

There is disclosed a cemented carbide insert with excellent properties for machining of steels and stainless steels. The cemented carbide comprises WC and 4-25% Co. The WC-grains have an average grain size in the range 0.2-3.5 μm and a narrow grain size distribution in the range 0-4.5 μm. According to the method of the invention a cemented carbide cutting tool insert is made by mixing powders of WC, TiC, TaC and/or NbC, binder metal and pressing agent, drying preferably by spray drying, pressing to inserts and sintering. The method characterised in that a deagglomerated WC-powder with a narrow grain size distribution is used, that the powders of TiC, TaC and/or NbC are deagglomerated and that the mixing is wet mixing with no change in grain size or grain size distribution.

1. A cemented carbide insert provided with a thin wear resistant coating with excellent properties for machining of steels and stainless steels comprising WC, 5-12.5 wt-% Co and 0-10 wt-% cubic carbides such as TiC, TaC, NbC or mixtures thereof wherein the WC-grains have an average grain size in the range 1.0-3.0 μm the WC grains have a narrow grain size distribution in the range 0.5-4.5 μm the W-content in the binder phase expressed as the “CW-ratio” defined as
   CW-ratio=M s /wt%Co*0.0161         CW   ⁢     -     ⁢   ratio     =       M   s       (       wt   .           ⁢   %     ⁢           ⁢   Co   ×   0.0161     )             
 
       where M s  is the measured saturation magnetization of the sintered cemented carbide insert in kA/m  hAm 2   /kg  and wt % Co is the weight percentage of Co in the cemented carbide, is 0.86-0.96. 
     
     
       2. The cemented carbide insert of  claim 1  wherein said coating comprises TiC x N x O z  with columnar grains followed by a layer of α-Al 2 O 3 , κ-Al 2 O 3  or a mixture of α-and κ-Al 2 O 3 . 
     
     
       3. The cemented carbide insert of  claim 2  wherein said coating includes an outer TiN- layer.   
     
     
       4. The cemented carbide insert of  claim 3  wherein said TiN- layer is brushed.   
     
     
       5. The cemented carbide insert of  claim 2  wherein said layer is of α- Al   2   O   3   .   
     
     
       6. The cemented carbide insert of  claim 2  wherein said layer is of κ- Al   2   O   3   .   
     
     
       7. The cemented carbide insert of  claim 2  wherein said layer is of a mixture of α- Al   2   O   3    and κ - Al   2   O   3   .   
     
     
       8. The cemented carbide insert of  claim 2  wherein said layer is of κ- Al   2   O   3    and said coating includes an outer TiN - layer.   
     
     
       9. The cemented carbide insert of  claim 2  wherein said layer is of α- Al   2   O   3    and said coating includes an outer TiN - layer.   
     
     
       10. The cemented carbide insert of  claim 2  wherein said layer is of a mixture of α- Al   2   O   3    and κ - Al   2   O   3    and said coating includes an outer TiN - layer.