Sandvik Ab

Sandvik Intellectual Property Ab

Sanvik Intellectual Property Aktiebolag

Michael Thysell

Anders Lenander

Mikael Lindholm

Lisa Palmqvist

Bjorn Ljungberg

Bj&ouml;rn Ljungberg

Bj&ouml;rn Lungberg

A method of making a cutting insert includes forming a powder mixture containing WC, 2-10 wt % Co, 4-12 wt % cubic carbides, adding N in an amount of 0.9-1.7% of the weight of the cubic carbides, mixing the powder with a pressing agent, milling and spray drying the mixture, compacting and sintering the material at 1300-1500 in an atmosphere of sintering gas 40-60 mbar, applying post-sintering treatment, and applying a coating by CVD or MTCVD.

Method of making cemented carbide insert

The present invention relates to a coated cemented carbide insert for turning of steel, like low alloyed steels, carbon steels and tough hardened steels at high cutting speeds. The cemented carbide consists of WC, 2-10 wt. % Co and 4-12 wt. % of cubic carbides of metals from groups 4, 5 or 6 of the periodic table, preferably Ti, Ta and Nb. The Co-binder phase is highly alloyed with W with a CW-ratio of 0.75-0.90. The insert has a binder phase enriched and essentially cubic carbide free surface zone A of a thickness of &#x3c;20 &#x3bc;m and along a line C essentially bisecting the edge, in the direction from the edge to the centre of the insert, a binder phase content increases essentially monotonously until it reaches the bulk composition. The binder phase content at the edge is 0.65-0.75 times the binder phase content by volume of the bulk and the depth of the binder phase depletion is 100-300 &#x3bc;m, preferably 150-250 &#x3bc;m. The insert is coated with 3-12 &#x3bc;m columnar TiCN-layer followed by a 2-12 &#x3bc;m thick AlO-layer.

Cemented carbide insert

A method of making a cutting insert includes forming a powder mixture containing WC, 2-10 wt % Co, 4-12 wt % cubic carbides, adding N in an amount of 0.9-1.7 % of the weight of the cubic carbides, mixing the powder with a pressing agent, milling and spray drying the mixture, compacting and sintering the material at 1300-1500 in an atmosphere of sintering gas 40-60 mbar, applying post-sintering treatment, and applying a coating by CVD or MTCVD.

The present invention relates to a coated cemented carbide insert for turning of steel, like low alloyed steels, carbon steels and tough hardened steels at high cutting speeds. The cemented carbide consists of WC, 2-10 wt. % Co and 4-12 wt. % of cubic carbides of metals from groups 4, 5 or 6 of the periodic table, preferably Ti, Ta and Nb. The Co-binder phase is highly alloyed with W with a CW-ratio of 0.75-0.90. The insert has a binder phase enriched and essentially cubic carbide free surface zone A of a thickness of <20 &mgr;m and along a line C essentially bisecting the edge, in the direction from the edge to the centre of the insert, a binder phase content increases essentially monotonously until it reaches the bulk composition. The binder phase content at the edge is 0.65-0.75 times the binder phase content by volume of the bulk and the depth of the binder phase depletion is 100-300 &mgr;m, preferably 150-250 &mgr;m. The insert is coated with 3-12 &mgr;m columnar TiCN-layer followed by a 2-12 &mgr;m thick Al,O,-layer.

A multilayer coated cutting tool comprising a cemented carbide body with at least one sintered-on inlay containing polycrystalline cubic boron nitride forming at least one cutting edge. Reduced crater wear of the rake face of the tool is achieved by reducing chemical interaction between tool and workpiece/chip material, and used edges of indexable inserts can be readily identified. The tool is provided with a multilayer coating by thermal CVD, the coating including (1) a first, innermost, layer of TiC.sub.x N.sub.y O.sub.z with x+y+z=1, with y&gt;x and z&lt;0.2, with equiaxed grains with size &lt;0.5 .mu.m and a total thickness &lt;1.5 .mu.m, (2) a second layer of TiC.sub.x N.sub.y O.sub.z with x+y+z=1, preferably with z=0, x&gt;0.3, most preferably x&gt;0.5, having a thickness of 1-8 .mu.m, with columnar grains, and (3) a third layer of a smooth, fine-grained (grain size about 1 .mu.m) layer of (.alpha.-Al.sub.2 O.sub.3 or .kappa.-Al.sub.2 O.sub.3 or mixtures thereof, with a thickness of 2-10 .mu.m.

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Stockholm, Sweden

Michael Thysell