Method of high-speed turning

Abstract

A method of high-speed turning of metal using a cutting tool insert for turning of steel. The cutting tool insert includes a (006) textured α-Al 2 O 3 coated cemented carbide grade. The cemented carbide body has 4.5-6.5 wt-% Co and 3-10 wt-% cubic carbide forming metals and an S-value of 0.77-0.92 and a coercivity of 10-20 kA/m. The α-Al 2 O 3 layer has a thickness ranging from 7 to 12 μm and is composed of columnar grains having a length/width ratio from 2 to 12 and is deposited on an MTCVD Ti(C,N) layer having a thickness from 4 to 12 μm. The alumina layer is characterised by a pronounced (006) growth texture. The alumina layer is the uppermost layer and is wet-blasted having an Ra value of less than 1 μm, giving the tool a black and shiny appearance.

1 . A method for high-speed turning of a metal, comprising the step of:
 subjecting the metal to high-speed turning using a cutting tool insert comprising a cemented carbide body and a coating, wherein the cemented carbide body comprises:   WC,   about 4.5-6.5 wt-% Co; and   about 3-10 wt-% of at least one cubic carbide forming metal selected from the group consisting of groups IVb, Vb and VIb of the periodic table;   wherein the cemented carbide body has an S-value of about 0.77-0.92 and a coercivity of about 10-20 kA/m adjacent;   wherein the coating comprises an uppermost layer,   wherein the uppermost layer is about 7-12 μm thick;   wherein the uppermost layer comprises an α-Al 2 O 3  layer textured in the <006>-directions with a texture coefficient TC(006) greater than about 2, TC(012), TC(110), TC(113), TC(202), TC(024) and TC(116) are simultaneously all less than about 1, and TC(104) being the second highest texture coefficient, the texture coefficient TC(hkl) being defined by:   
       
         
           
             
               
                 TC 
                  
                 
                   ( 
                   hkl 
                   ) 
                 
               
               = 
               
                 
                   
                     
                       I 
                        
                       
                         ( 
                         hkl 
                         ) 
                       
                     
                     
                       
                         I 
                         0 
                       
                        
                       
                         ( 
                         hkl 
                         ) 
                       
                     
                   
                    
                   
                     [ 
                     
                       
                         1 
                         n 
                       
                        
                       
                         
                           ∑ 
                           
                             n 
                             = 
                             1 
                           
                           n 
                         
                          
                         
                           
                             I 
                              
                             
                               ( 
                               hkl 
                               ) 
                             
                           
                           
                             
                               I 
                               0 
                             
                              
                             
                               ( 
                               hkl 
                               ) 
                             
                           
                         
                       
                     
                     ] 
                   
                 
                 
                   - 
                   1 
                 
               
             
           
         
         where 
         I(hkl)=measured intensity of the (hkl) reflection. 
         Io(hkl)=standard intensity according to JCPDS card 
         no 46-1212. 
         n=number of reflections used in the calculation (8). 
         (hkl) reflections used are: (012), (104), (110), (006), (113), (202), (024) and (116). 
       
     
     
         2 . The method of  claim 1 , wherein the metal subjected to high-speed turning is an iron-based alloy. 
     
     
         3 . The method of  claim 1 , wherein the metal subjected to high-speed turning is steel.