A coated milling insert particularly useful for milling in low and medium alloyed steels with or without raw surface zones during wet or dry conditions. The insert is characterized by a WC-Co cemented carbide with a low content of cubic carbides and a highly w alloyed binder phase and a coating including an inner layer of ticxNyOz with columnar grains, a layer of κ-Al2O3 and, preferably, a top layer of TiN. The layers are deposited by using CVD methods.
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5. A method of making a milling insert comprising a cemented carbide body and a coating comprising coating a WC-Co-based cemented carbide body with a highly w-alloyed binder phase with a CW-ratio of 0.78-0.93 with
a first (innermost) layer of ticxNyOz with x+y+z=1, with a thickness of 0.1-1.5 μm, with equiaxed grains with size <0.5 μm using known CVD-methods
a second layer of ticxNyOz with x+y+z=1, with a thickness of 1-6 μm with columnar grains with a diameter of about <5 μm deposited by MTCVD-technique, using acetonitrile as the carbon and nitrogen source for forming the layer in a preferred temperature range of 850-900° C. and
a layer of a smooth κ-Al2O3 with a thickness of 0.5-5 μm.
1. A cutting tool insert for milling low and medium alloyed steels with or without raw surfaces during wet or dry conditions comprising a cemented carbide body and a coating wherein said cemented carbide body comprises WC, 8.6-9.5 wt-% Co and 0.2-1.8 wt-% cubic carbides of Ta, Ti and Nb, with Ti present on a level corresponding to a technical impurity, and a highly w-alloyed binder phase with a CW-ratio of 0.78-0.93 and said coating comprises
a first (innermost) layer of ticxNyOz with x+y+z=1, with a thickness of 0.1-1.5 μm, and with equiaxed grains with size <0.5 μm
a second layer of ticxNyOz with x+y+z=1, with a thickness of 1-6 μm with columnar grains with diameter of <5 μm and
a layer of a smooth, fine-grained (0.5-2 μm) κ-Al2O3 with a thickness of 0.5-5 μm.
2. The milling insert of
4. The milling insert of
6. The method of
7. The method of
8. The method of
9. The cutting tool insert of
10. The cutting tool insert of
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0. 13. The cutting tool insert of
0. 14. The cutting tool insert of
0. 15. The cutting tool insert of
0. 16. The cutting tool insert of
0. 17. The method of
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It has now been found according to the present invention, that improved cutting performance is achieved if the cemented carbide body has a CW-ratio of 0.78-0.93, preferably 0.80-0.91, and most preferably 0.82-0.90. The cemented carbide may contain small amounts, <1 volume %, of η-phase (M6C), without any detrimental effect. From the CW-value, it follows that no free graphite is allowed in the cemented carbide body according to the present invention.
The cement carbide body may contain a thin (about 5-25 μm) surface zone depleted in cubic carbides and often enriched in binder phase according to prior art such as disclosed in U.S. Pat. No. 4,610,931. In this case, the cemented carbide may contain carbonitride or even nitride.
The coating comprises
According to the method of the invention, a WC-Co-based cemented carbide body is made with a highly W-alloyed binder phase with a CW-ratio according to above, and a content of cubic carbide according to above, and a WC grain size according to above, and preferably without a binder phase enriched surface zone, a first (innermost) layer of TiCxNyOz with x+y+z=1, preferably z<0.5, with a thickness of <1.5 μm, and with equiaxed grains with size <0.5 μm using known CVD-methods.
The invention is additionally illustrated in connection with the following Examples which are to be considered as illustrative of the present invention. It should be understood, however, that the invention is not limited to the specific details of the Examples.
A. A cemented carbide milling tool in accordance with the invention, inserts of style SEKN 1204 AZ with the composition 9.1 wt-% Co, 1.25 wt-% TaC, 0.30 wt-% NbC and balance WC, with a binder phase highly alloyed with W, corresponding to a CW-ratio of 0.86 were coated with a 0.5 μm equiaxed TiCN-layer (with a high nitrogen content corresponding to an estimated C/N-ratio of 0.05) followed by a 4 μm thick TiCN-layer with columnar grains by using MTCVD-technique (temperature 885-850° C. and CH3CN as the carbon/nitrogen source). In subsequent steps during the same coating cycle, a 1.0 μm thick layer of Al2O3 was deposited using a temperature 970° C. and a concentration of H2S dopant of 0.4% as disclosed in EP-A-523 021 which corresponds to U.S. Pat. No. 5,674,564. A thin (0.3 μm) layer of TiN was deposited on top, according to known CVD-technique. XRD-measurement showed that the Al2O3-layer consisted of 100% κ-phase. The cemented carbide body had a WC grain size in average of 1.65 μm. The coated inserts were brushed by a nylon straw brush containing SiC grains. Examination of the brushed inserts in a light microscope showed that the thin TiN-layer had been brushed away only along the cutting edge, leaving there a smooth Al2O3-layer surface. Coating thickness measurements on cross sectioned brushed samples showed no reduction of the coating along the edge line except for the outer TiN-layer that was removed.
B. A strongly competitive cemented carbide grade in style SEKN 1204 from an external leading carbide producer was selected for comparison in a wet milling test. The carbide had a composition of 9.0 wt-% Co, 0.2 wt-% TiC, 0.5 wt-% TaC, 0.1 wt % NbC balance WC and a CW-ratio of 0.95. The WC-grain size was 2.5 μm. The insert had a coating consisting of a 6 μm TiCN layer and a 0.3 μm TiN layer.
The insert from A was compared against the insert from B in a wet milling test in a medium alloyed steel (HB=310) with hot-rolled surfaces. Two parallel bars, each having a thickness of 35 mm, were centrally positioned relative to the cutter body (diameter 100 mm), and the bars were placed with an air gap of 10 mm between them.
The cutting data were:
A comparison was made after milling 1200 mm. Variant A, according to the invention, showed no comb cracks and variant B showed 14 comb cracks. After milling 1800 mm, variant B broke down due to a lot of chipping and fracture between the comb cracks. Variant A, according to the invention, lasted 4200 mm, corresponding to an effective tool life of 11 min compared with about 4 min for variant B.
A. A cemented carbide milling tool in accordance with the invention, inserts of style SEKN 1204 AZ with the composition 9.1 wt-% Co, 1.23 wt-% TaC, 0.30 wt-% NbC and balance WC, with a binder phase highly alloyed with W corresponding to a CW-ratio of 0.85 were coated with a 0.5 μm equiaxed TiCN-layer (with a high nitrogen content corresponding to an estimated C/N-ratio of 0.05) followed by a 3.7 μm thick TiCN-layer with columnar grains by using MTCVD-technique (temperature 885-850° C. and CH3CN as the carbon/nitrogen source). In subsequent steps during the same coating cycle, a 0.9 μm thick layer of Al2O3 was deposited using a temperature 970° C. and a concentration of H2S dopant of 0.4% as disclosed in EP-A-523 021 which corresponds to U.S. Pat. No. 5,674,564. (A thin (0.3 μm) layer of TiN was deposited on top according to known CVD-technique. XRD-measurement showed that the Al2O3-layer consisted of 100% κ-phase. The cemented carbide body had a WC grain size in average of 1.6 μm.
B. A strongly competitive cemented carbide grade in style SEKN 1204 from an external leading cemented carbide producer was selected for comparison in a wet milling test. The carbide had a composition of 11.0 wt-% Co, 0.2 wt-% TaC, 0.3 wt % NbC balance WC and a CW-ratio of 0.90. The insert had a coating consisting of a 0.5 μm equiaxed TiCN layer, 2.0 μm TiCN columnar layer, 2.0 μm κ-Al2O3-layer and a 0.3 μm TiN-layer.
C. A strongly competitive cemented carbide grade in style SEKN 1204 from an external leading carbide producer was used. The carbide had a composition of 7.5 wt-% Co, 0.4 wt-% TaC, 0.1 wt % NbC, 0.3 wt % TiC balance WC and a CW-ratio of 0.95. The insert had a coating consisting of a 0.5 μm equiaxed TiCN-layer, 2.1 μm columnar TiCN-layer, 2.2 μm κ-Al2O3-layer and a 0.3 μm TiN-layer.
Inserts from A were compared against inserts from B and C in a wet milling test in a low alloyed steel (HB=190) with hot rolled surfaces. The bars were, as very common extremely rusty due to outdoor stocking. Two parallel bars each of a thickness having 32 mm were centrally positioned relative to the cutter body (diameter 100 mm), and the bars were placed with an air gap of 10 mm between them.
The cutting data were:
The insert C broke after 1100 mm, the insert B broke after 2150 mm and the insert A, according to the invention, broke after 2400 mm.
In this test all coatings were of similar type, and the major difference was on the cemented carbide. The results show that the coated cemented carbide according to the invention, exhibited longer tool life than two important competitor grades containing less and more binder phase resp than the coated grade according to the invention.
A. A cemented carbide milling tool in accordance with the invention, inserts of style SEKN 1204 AZ with the composition 9.1 wt-% Co, 1.23 wt-% TaC, 0.30 wt-% NbC and balance WC, with a binder phase highly alloyed with W corresponding to a CW-ratio of 0.86 were coated with a 0.5 μm equiaxed TiCN-layer (with a high nitrogen content corresponding to an estimated C/N-ratio of 0.05) followed by a 3.7 μm thick TiCN-layer with columnar grains by using MTCVD-technique (temperature 885-850° C. and CH3CN as the carbon/nitrogen source). In subsequent steps during the same coating cycle, a 1.1 μm thick layer of Al2O3 was deposited using a temperature of 970° C. and a concentration of H2S dopant of 0.4% as disclosed in EP-A-523 021 which corresponds to U.S. Pat. No. 5,674,564. A thin (0.3 μm) layer of TiN was deposited on top according to known CVD-technique. XRD-measurement showed that the Al2O3-layer consisted of 100% κ-phase. The cemented carbide body had a WC grain size in average of 1.7 μm. The coated inserts were brushed by a nylon straw brush containing SiC grains. Examination of the brushed inserts in a light microscope showed that the thin TiN-layer had been brushed away only along the cutting edge leaving there a smooth Al2O3-layer surface. Coating thickness measurements on cross-sectioned brushed samples showed no reduction of the coating along the edge line except for the outer TiN-layer that was removed.
B. A strongly competitive cemented carbide grade in style SEKN 1204 from an external leading carbide producer was used. The carbide had a composition of 8.0 wt-% Co, 1.9 wt-% TaC, 0.2 wt % NbC, 0.2 wt % TiC balance WC and a CW-ratio of 0.85. The insert had a coating consisting of a 1.1 μm TiN layer and 3.3 μm TiC layer.
C. A strongly competitive cemented carbide grade in style SEKN 1204 from an external leading carbide producer was used. The carbide (had a composition of 10.0 wt-% Co, 2.0 wt-% TaC, 0.2 wt % TiC, balance WC and a CW-ratio of 0.90. The insert had a coating consisting of a 0.5 μm equiaxed TiCN layer, 3.3 μm TiCN columnar layer, 0.7 μm κ-Al2O3-layer and a 0.5 μm TiN layer.
Inserts from A were compared against inserts from B and C in a dry milling test in a low alloyed steel (HB=290) with pre machined surfaces. A bar with a thickness of 180 mm was centrally positioned relative to the cutter body (diameter 250 mm).
The cutting data were:
Insert B broke after 5000 mm after comb crack formation and chipping. Insert C broke after 5400 mm by similar wear pattern and insert A was stopped after 6000 mm without other visible wear than a few small comb cracks.
The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein, however, is not to be construed as limited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from the spirit of the invention.
Ljungberg, Björn, Persson, Jeanette, Östlund, {dot over (A)}ke
| Patent | Priority | Assignee | Title |
| 10837104, | Aug 29 2015 | Kyocera Corporation | Coated tool |
| 8080323, | Jun 28 2007 | KENNAMETAL INC | Cutting insert with a wear-resistant coating scheme exhibiting wear indication and method of making the same |
| Patent | Priority | Assignee | Title |
| 4610931, | Mar 27 1981 | Kennametal Inc. | Preferentially binder enriched cemented carbide bodies and method of manufacture |
| 4643620, | May 27 1983 | Sumitomo Electric Industries, Ltd. | Coated hard metal tool |
| 5137774, | Jul 13 1989 | SECO TOOLS AB | Multi-oxide coated carbide body and method of producing the same |
| 5162147, | Jul 13 1989 | SECO TOOLS AB, A CORP OF SWEDEN | Kappa-alumina oxide coated carbide body and method of producing the same |
| 5372873, | Oct 22 1992 | Mitsubishi Materials Corporation | Multilayer coated hard alloy cutting tool |
| 5451469, | Dec 18 1992 | Sandvik Intellectual Property Aktiebolag | Cemented carbide with binder phase enriched surface zone |
| 5545490, | Jun 21 1994 | Mitsubishi Materials Corporation | Surface coated cutting tool |
| 5549980, | Feb 21 1992 | Sandvik Intellectual Property Aktiebolag | Cemented carbide with binder phase enriched surface zone |
| 5576093, | Oct 22 1992 | Mitsubishi Materials Corporation | Multilayer coated hard alloy cutting tool |
| 5652045, | Oct 20 1994 | Mitsubishi Materials Corporation | Coated tungsten carbide-based cemented carbide blade member |
| 5674564, | Jun 25 1991 | Sandvik Intellectual Property Aktiebolag | Alumina-coated sintered body |
| 5786069, | Aug 28 1996 | Sandvik Intellectual Property Aktiebolag | Coated turning insert |
| 5915162, | May 31 1993 | Sumitomo Electric Industries, Ltd. | Coated cutting tool and a process for the production of the same |
| 5920760, | May 31 1994 | Mitsubishi Materials Corporation | Coated hard alloy blade member |
| EP653499, | |||
| EP685572, | |||
| EP686707, | |||
| EP693574, | |||
| EP709484, |
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