Coated Cutting Tool Insert
AssigneeSandvik Intellectual Property AB
InventorsRickard Sundström, Marie Pettersson, Susanne Norgren, Bernt Larsson
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Abstract
The present invention discloses a coated cutting tool insert particularly useful for dry and wet machining, preferably milling, in low and medium alloyed steels, stainless steels, with or without raw surface zones. The insert is characterized by a WC-TaC-NbC-Co cemented carbide with a W alloyed Co-binder phase and a coating including an innermost layer of TiCxNyOz with columnar grains and a top layer at least on the rake face of a smooth α-Al2O3.
Claims29
A cutting tool milling insert for machining of low and medium alloyed steels, stainless steels, with or without raw surfaces during wet or dry conditions comprising a cemented carbide body and a coating,
- wherein said cemented carbide body has a composition of 8.5-9.7 wt % Co, 1.00-1.45 wt % TaC, 0.10-0.50 wt % NbC, and balance WC, a coercivity in a range 11.7-13.3 kA/m, and a CW-ratio of 0.85-<1.00, and
- wherein said insert is at least partly coated with a 4.1-6.9 μm thick coating including at least three layers of TiCxNyOz of which one layer is adjacent to the cemented carbide and a blasted α-Al2O3-layer is an outer layer at least on a rake face, the TiCxNyOz layers having a total thickness of 1.9-3.6 μm, the coating comprising:
- a first TiCxNyOz layer adjacent to the cemented carbide having a composition of x+y=1, x>=0,
- a second TiCxNyOz layer having a composition of x>0.4, y>0.4 and 0=<z<0.1,
- a third TiCxNyOz layer adjacent to the α-Al2O3-layer having a composition of x+y+z >=1 and z>0, and
- the α-Al2O3-layer having a thickness of 1.8-3.6 μm with flattened grains on surfaces that have been subjected to a blasting treatment.
Method of making a cutting insert comprising a cemented carbide body and a coating by powder metallurgical technique, the method comprising:
- wet milling of powders forming hard constituents and binder phase;
- compacting the milled mixture to bodies of desired shape and sizes and
- wherein said cemented carbide body has a composition of 8.5-9.7 wt % Co, 1.00-1.45 wt % TaC, 0.10-0.50 wt % NbC, and balance WC, a coercivity in a range 11.7-13.3 kA/m, and a CW-ratio of 0.85-<1.00, and
- wherein said body is at least partly coated with a 4.1-6.9 μm thick coating including at least three layers of TiCxNyOz forming an inner coating with an α-Al2O3-layer as the outer layer at least on a rake face, the TiCxNyOz-layers have a total thickness of 1.9-3.6 μm, the coating comprising:
- a first TiCxNyOz layer adjacent to the cemented carbide having a composition of x+y=1, x>=0, using a CVD method using a reaction mixture consisting of TiCl4, H2 and N2,
- a second TiCxNyOz layer having a composition of x>0.4, y>0.4 and 0=<z<0.1, by using a MTCVD-technique, temperature 885-850° C. and CH3CN as the carbon/nitrogen source,
- a third TiCxNyOz layer adjacent to the α-Al2O3-layer having a composition of x+y+z>=1 and z>0, using a CVD method using a reaction mixture consisting of TiCl4, H2 and N2,
- wherein the α-Al2O3-layer with a thickness of 1.8-3.6 μm is deposited by using a CVD-technique, and
- wherein the method includes subjecting the insert to a blasting treatment at least on the rake face.
28 Method according to claim 8, wherein the cutting speed for face milling is 150-300 m/min.
Dependencies are inferred from the claim text.