Cutting Insert and Method for Production Thereof

A cutting insert, comprising:

• a hard metal, cermet or ceramic substrate body;
• and
• a multi-layer coating which is applied thereto by means of CVD methods of a total thickness of 5 to 40 μm and which starting from a surface of the substrate body has one or more hard material layers, over the hard material layers an alpha aluminium oxide (α-Al2O3) layer of a layer thickness of 1 to 20 μm and optionally at least portion-wise over the α-Al2O3 layer one or more further hard material layers as decorative or wear recognition layers,
• wherein the α-Al2O3 layer has a crystallographic preferential orientation, characterised by a texture coefficient TC (0 0 12)≧5 for the (0 0 12) growth direction with
• TC
• 
• (
• 0
• 0
• 12
• )
• =
• I
• 
• (
• 0
• 0
• 12
• )
• I
• 0
• 
• (
• 0
• 0
• 12
• )
• 
• [
• 1
• n
• 
• ∑
• n
• -
• 1
• n
• 
• I
• 
• (
• hkl
• )
• I
• 0
• 
• (
• hkl
• )
• ]
• -
• 1
• ,
• wherein
• I(hkl) are the intensities of the diffraction reflections measured by X-ray diffraction,
• I0(hkl) are the standard intensities of the diffraction reflections in accordance with pdf card 42-1468,
• n is the number of reflections used for the calculation, and
• the following reflections are used for the calculation of TC(0 0 12):
• (0 1 2), (1 0 4), (1 1 0), (1 1 3), (1 1 6), (3 0 0) and (0 0 12),
• wherein the α-Al2O3 layer has an inherent stress in the region of 0 to +300 MPas, and
• wherein the substrate within a region of 0 to 10 μm from the surface of the substrate body has an inherent stress minimum in the region of −2000 to −400 MPas.