Method of making grooving or parting insert

Abstract

A method of making a cutting tool, the cutting tool having a WC—Co based cemented carbide body and a multi-layer coating, the method including: applying a first innermost bonding layer TiN to the body; applying a second layer in the form of a mutlilayered structure having sublayers of (Ti x Al 1-x )N were x varies according to 0.45<x<0.55 and 0.70<x<0.80; applying a third layer of (Ti x Al 1-x )N where x is 0.45<x<0.55; and applying a forth outermost layer on TiN.

1. A method of making a cutting tool, the cutting tool comprising a WC—Co based cemented carbide body comprising WC with an average grain size of about 1.4 μm, 12-13 wt-% Co and 0.4-1.8 wt-% TaC+NbC, and a W-alloyed binder phase with a CW-ratio of 0.82-0.91, the method comprising:
 applying a first innermost 0.1-0.5 μm bonding layer of TiN to the body;  
 applying a second layer comprising a mutlilayered structure comprising a plurality of 0.05-0.2 μm thick sublayers of a composition (Ti x Al 1-x )N in which x varies repeatedly between the two ranges 0.45<x<0.55 and 0.70<x<0.80, a first sublayer of (Ti x Al 1-x )N adjacent to the TiN bonding layer having an x-value of 0.45<x<0.55, a second sublayer of (Ti x Al 1-x )N having an x-value of 0.70<x<0.80 and a third sublayer having x in the range 0.45<x<0.55, the sequence of sublayers alternating and repeating until 12-25 sublayers are built up;  
 applying a third 0.1-0.5 μm thick layer of (Ti x Al 1-x )N, where x is 0.45<x<0.55; and  
 applying a fourth outermost 0.1-0.2 μm layer of TiN;  
 wherein the total coating thickness close to a cutting edge of the tool is in the range of 1-8 μm and the thickness of the second layer constitutes 75-95% of the total coating thickness.  
 
     
     
       2. The method according to  claim 1 , wherein the cemented carbide body comprises a WC—Co composition of WC with an average grain size of about 1.4 μm, 12-13 wt-% Co and 0.4-1.8 wt-% TaC+NbC, and a W-alloyed binder phase with a CW-ratio of 0.82-0.91. 
     
     
       3. The method according to  claim 1 , wherein the coating is deposited by CVD techniques. 
     
     
       4. The method according to  claim 1 , the coating is deposited by PVD techniques. 
     
     
       5. A method according to  claim 1  wherein the CW-i ratio is    0 . 85 - 0 . 90 .