U.S. patent application number 13/165289 was filed with the patent office on 2011-10-13 for oxide coated cutting insert.
This patent application is currently assigned to SECO TOOLS AB. Invention is credited to Mats JOHANSSON, Tommy LARSSON.
Application Number | 20110250362 13/165289 |
Document ID | / |
Family ID | 41053915 |
Filed Date | 2011-10-13 |
United States Patent
Application |
20110250362 |
Kind Code |
A1 |
LARSSON; Tommy ; et
al. |
October 13, 2011 |
OXIDE COATED CUTTING INSERT
Abstract
A cutting tool insert, particularly useful for machining of
steel and stainless steel, comprising a body of a hard alloy of
cemented carbide, cermet, ceramics, cubic boron nitride based
material or high speed steel a hard and wear resistant coating; and
at least (Al,Cr).sub.2O.sub.3 layer applied to said body is
disclosed. Methods of making a cutting tool insert are also
disclosed. In addition, methods for machining of cast iron using
the cutting tool inserts are disclosed.
Inventors: |
LARSSON; Tommy; (ANGELSBERG,
SE) ; JOHANSSON; Mats; (LINKOPING, SE) |
Assignee: |
SECO TOOLS AB
Fagersta
SE
|
Family ID: |
41053915 |
Appl. No.: |
13/165289 |
Filed: |
June 21, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12399466 |
Mar 6, 2009 |
7989060 |
|
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13165289 |
|
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Current U.S.
Class: |
427/453 ;
409/131 |
Current CPC
Class: |
B23B 2228/105 20130101;
Y10T 407/27 20150115; B23C 2228/08 20130101; C22C 2204/00 20130101;
B23B 2222/80 20130101; B23B 27/14 20130101; C23C 14/081 20130101;
Y10T 409/303752 20150115; C23C 14/083 20130101; B23B 2224/04
20130101; B23B 2270/54 20130101; B23B 2228/10 20130101; C23C 14/325
20130101; Y10T 428/265 20150115; B23C 2228/04 20130101 |
Class at
Publication: |
427/453 ;
409/131 |
International
Class: |
C23C 4/10 20060101
C23C004/10; B23C 3/00 20060101 B23C003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 7, 2008 |
SE |
0800541-5 |
Claims
1. A method of making a cutting tool insert comprising: a body
comprising a hard alloy selected from the group consisting of
cemented carbide, cermet, ceramics, cubic boron nitride based
material, and high speed steel; and a hard and wear resistant
coating applied on said body; wherein said coating comprises at
least one (Al,Cr).sub.2O.sub.3 layer; wherein said
(Al,Cr).sub.2O.sub.3 layer has a corundum phase crystalline
structure and a structure and a composition
(Al.sub.1-yCr.sub.y).sub.2O.sub.3 with about
0.5.ltoreq.y.ltoreq.about 0.7 with a thickness of about 0.5 .mu.m
to about 10 .mu.m and a fiber texture, rotational symmetry, in the
direction of the coated surface normal with an inclination angle,
.phi., of the basal planes relative to the coated surface normal is
about 0.degree.<y<about 20.degree. or the inclination angle,
.phi., for the highest peak in the pole plot is about
0.degree.<.phi.<about 20.degree. said method comprising the
step of: depositing on said body said (Al,Cr).sub.2O.sub.3 layer by
cathodic arc evaporation using Al+Cr-cathodes with a composition of
about (20 at % Al+80 at % Cr) and about (60 at % Al+40 at % Cr), an
evaporation current between about 50 A and about 200 A depending on
the cathode size in an atmosphere comprising a gas selected from
the group consisting of Ar, O.sub.2, and combinations thereof, at a
total pressure of about 2.0 Pa to about 7.0 Pa, a bias of about -50
V to about -200 V, and a deposition temperature of about
500.degree. C. and about 700.degree. C.
2. The method according to claim 1, depositing said
(Al,Cr).sub.2O.sub.3 layer by cathodic arc evaporation using
Al+Cr-cathodes with a composition of about (30 at % Al+70 at % Cr)
and about (50 at % Al+50 at % Cr), an evaporation current between
about 60 A and about 90 A depending on the cathode size in an
atmosphere that is O.sub.2 at a total pressure of about 4.0 Pa to
about 7.0 Pa, a bias of about -50 V to about -100 V and a
deposition temperature of about 600.degree. C. and about
700.degree. C.
3. A method for machining of steel or stainless steel, comprising:
machining with a cutting tool insert according to claim 1 at a
cutting speed of about 75-600 m/min, with an average feed, per
tooth in the case of milling, of about 0.08-0.5 mm.
4. A method for machining of steel or stainless steel, comprising:
machining with a cutting tool insert according to claim 1 at a
cutting speed of about 150-500 m/min, with an average feed, per
tooth in the case of milling, of about 0.1-0.4 mm.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 12/399,466, filed Mar. 6, 2009, which claims priority to
Swedish Application No. 0800541-5 filed Mar. 7, 2008. The entire
contents of each of the above-identified applications are hereby
incorporated by reference.
FIELD OF THE INVENTION
[0002] This invention relates to tools for machining by chip
removal. More specifically, the invention relates to cutting tool
inserts comprising a body of a hard alloy of cemented carbide,
cermet, ceramics, cubic boron nitride based material or high speed
steel and a hard and wear resistant oxide designed to be used in
machining of steels, preferably at high cutting speeds. The said
coating is composed of one or more layers of which at least one
layer is a textured physical vapor deposited (PVD) corundum phase
alumina containing chromium (Al,Cr).sub.2O.sub.3.
BACKGROUND OF THE INVENTION
[0003] Textured .alpha.-Al.sub.2O.sub.3 layers, produced with
chemical vapor deposition (CVD) is disclosed in, e.g., EP 603144,
EP 1528125, EP 1477581, EP 659153, EP 1655387, EP 659903, EP
738336, EP 1655388, EP 1655392, US 2007/104945, US 2004/202877.
[0004] EP 1479791 discloses a cutting tool composed of cemented
carbide or cermet, and a hard coating; wherein the hard coating
includes an .alpha.-Al.sub.2O.sub.3 layer formed by CVD, with the
highest peak, measuring the inclination of the
.alpha.-Al.sub.2O.sub.3 basal planes relative to the normal of the
surface within a range of 0-10 degrees as determined by electron
back scattering diffraction (EBSD).
[0005] EP 744473 discloses textured .gamma.-Al.sub.2O.sub.3 layers
produced by PVD.
[0006] U.S. Pat. No. 5,310,607 discloses a hard coating including
(Al,Cr).sub.2O.sub.3 crystals and a chromium content higher than 5
at % wherein the (Al,Cr).sub.2O.sub.3 is a single crystal. The
coating is deposited at a temperature lower than 900.degree. C. The
hard coating is deposited by a CVD or PVD process.
[0007] When machining steels with an alumina coated cemented
carbide tool, the cutting edge is worn according to different wear
mechanisms, such as chemical wear, abrasive wear, adhesive wear and
by edge chipping caused by cracks formed along the cutting edge.
The domination of any of the wear mechanisms is determined by the
application, and is dependent on properties of the machined
material, applied cutting parameters and the properties of the tool
material. In general, it is very difficult to improve all tool
properties simultaneously, and commercial cemented carbide grades
have usually been optimised with respect to one or few of the above
mentioned wear types, and have consequently been optimised for
specific application areas. This can, for instance, be achieved by
controlling the texture of the alumina layer.
[0008] What is needed is a wear resistant and hard oxide coated
cutting tool with enhanced performance for machining of steels and
stainless steels. The invention is directed to these, as well as
other, important needs.
SUMMARY OF THE INVENTION
[0009] Accordingly, the invention is directed to cutting tool
inserts comprising a body of a hard alloy of cemented carbide,
cermet, ceramics, cubic boron nitride based material or high speed
steel comprising a textured oxide layer of corundum phase
(Al,Cr).sub.2O.sub.3 with excellent metal machining properties.
[0010] In one embodiment, the invention is directed to cutting tool
inserts, comprising:
[0011] a body comprising a hard alloy selected from the group
consisting of cemented carbide, cermet, ceramics, cubic boron
nitride based material, and high speed steel; and
[0012] a hard and wear resistant coating applied on said body;
[0013] wherein said coating comprises at least one
(Al,Cr).sub.2O.sub.3 layer;
[0014] wherein said (Al,Cr).sub.2O.sub.3 layer has a corundum phase
crystalline structure and a structure and a composition
(Al.sub.1-yCr.sub.y).sub.2O.sub.3 with about
0.5.ltoreq.y.ltoreq.about 0.7 with a thickness of about 0.5 .mu.m
to about 10 .mu.m and a fiber texture, rotational symmetry, in the
direction of the coated surface normal with an inclination angle,
.phi., of the basal planes relative to the coated surface normal is
about 0.degree.<.phi.<about 20.degree. or the inclination
angle, .phi., for the highest peak in the pole plot is about
0.degree.<.phi.<about 20.degree..
[0015] In other embodiments, the invention is directed to methods
of making a cutting tool insert comprising:
[0016] a body comprising a hard alloy selected from the group
consisting of cemented carbide, cermet, ceramics, cubic boron
nitride based material, and high speed steel; and
[0017] a hard and wear resistant coating applied on said body;
[0018] wherein said coating comprises at least one
(Al,Cr).sub.2O.sub.3 layer;
[0019] wherein said (Al,Cr).sub.2O.sub.3 layer has a corundum phase
crystalline structure and a structure and a composition
(Al.sub.1-yCr.sub.y).sub.2O.sub.3 with about
0.5.ltoreq.y.ltoreq.about 0.7 with a thickness of about 0.5 .mu.m
to about 10 .mu.m and a fiber texture, rotational symmetry, in the
direction of the coated surface normal with an inclination angle,
.phi., of the basal planes relative to the coated surface normal is
about 0.degree.<.phi.<about 20.degree. or the inclination
angle, .phi., for the highest peak in the pole plot is about
0.degree.<y<about 20.degree.
[0020] said method comprising the step of:
[0021] depositing on said body said (Al,Cr).sub.2O.sub.3 layer by
cathodic arc evaporation using Al+Cr-cathodes with a composition of
about (20 at % Al+80 at % Cr) and about (60 at % Al+40 at % Cr), an
evaporation current between about 50 A and about 200 A depending on
the cathode size in an atmosphere comprising a gas selected from
the group consisting of Ar, O.sub.2, and combinations thereof, at a
total pressure of about 2.0 Pa to about 7.0 Pa, a bias of about -50
V to about -200 V, and a deposition temperature of about
500.degree. C. and about 700.degree. C.
[0022] In yet other embodiments, the invention is directed to
methods for machining of steel and stainless steel, comprising the
step of:
[0023] using a cutting tool insert described herein at a cutting
speed of about 75-600 m/min, with an average feed, per tooth in the
case of milling, of about 0.08-0.5 mm.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
the principles of the invention. In the drawings:
[0025] FIG. 1A shows a schematic view of the hexagonal crystal
structure with the a-axis (100), b-axis (010) and c-axis (001)
marked.
[0026] FIG. 1B shows a schematic view of the fibre texture with (S)
coated surface, (.phi.) the inclination angle of the c-axis (001)
of the hexagonal structure (FIG. 1A) and the normal (n) to the
coating surface.
[0027] FIG. 2 shows a schematic side view of the deposition chamber
showing (1) vacuum chamber, (2a) cathode material A, (2b) cathode
material B, (3) fixture, (4) power supply for biasing, (5a)
cathodic arc power supply (5b) cathodic arc power supply, (6) inlet
for process gas and (7) outlet for vacuum pump.
[0028] FIG. 3 shows a scanning electron micrograph in secondary
mode of a fractured cross section of a coating according to the
invention. (A) body, (B) bonding layer, (C) (Al,Cr)O layer, (D)
(Al,Cr)N layer and (E) TiN layer.
[0029] FIG. 4 shows an x-ray diffraction pattern of a textured
(Al,Cr).sub.2O.sub.3 layer. The peaks of cemented carbide are
marked with solid lines whereas the peaks originating from
(Al,Cr).sub.2O.sub.3 with dashed lines.
[0030] FIG. 5A shows (001) pole figure and FIG. 5B shows (001) pole
plot graph of a (Al,Cr).sub.2O.sub.3 layer according to the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0031] The invention is directed, in one aspect, to a cutting tool
for machining by chip removal, particularly useful in metal cutting
of steel and stainless steel, comprising a body of a hard alloy of
cemented carbide, cermet, ceramics, cubic boron nitride based
material or high speed steel onto which a coating is deposited
comprising:
[0032] preferably a first (innermost) bonding layer (FIG. 3, layer
B) of, e.g., TiN or (Al,Cr)N preferably less than about 0.5 .mu.m
according to prior art;
[0033] a layer of (Al.sub.1-yCr.sub.y).sub.2O.sub.3 with about
0.5.ltoreq.y.ltoreq.about 0.7, preferably y is about 0.6, with a
thickness of about 0.5-10 .mu.m, preferably about 1-5 .mu.m, most
preferably about 2-4 .mu.m, with textured columnar grains. The
(Al,Cr).sub.2O.sub.3 layer has a corundum structure formed by PVD
and a fiber texture with rotational symmetry in the direction of
the coated surface normal with an inclination angle, .phi., (FIG.
1B) of the basal planes relative to the coated surface normal (FIG.
5A) or the inclination angle, .phi., for the highest peak in the
pole plot (FIG. 5B) with about 0.degree.<.phi.<about
20.degree., preferably about 0.degree.<.phi.<about 10.degree.
as determined by, e.g., electron back scattering diffraction (EBSD)
or x-ray diffraction (XRD).
[0034] The (Al,Cr)O layer has a compressive stress level of about
-4.5<.sigma.<-about 0.5 GPa, preferably of about
-3.0<.sigma.<about -1.0 GPa.
[0035] The composition, y, of (Al.sub.1-yCr.sub.y).sub.2O.sub.3 is
determined by, e.g., energy dispersive spectroscopy (EDS) or
wavelength dispersive X-ray spectroscopy (WDS).
[0036] The body may further be coated with an inner single- and/or
multilayer coating of, e.g. TiN, TiC, Ti(C,N), (Al,Cr)N or
(Ti,Al)N, preferably (Ti,Al)N, (Al,Cr)N, and/or an outer single-
and/or multilayer coating of, e.g. TiN, TiC, Ti(C,N), (Al,Cr)N or
(Ti,Al)N, preferably (Ti,Al)N, (Al,Cr)N, to a total thickness,
including the thickness of the (Al,Cr).sub.2O.sub.3 layer, of about
1 to 20 .mu.m, preferably about 1 to 10 .mu.m and most preferably
about 2 to 7 .mu.m according to prior art.
[0037] The deposition method for the layer of the present invention
is based on cathodic arc evaporation of an alloy or composite
cathode under the following conditions; (Al,Cr).sub.2O.sub.3 layers
are grown using Al+Cr-cathodes with a composition between about (20
at % Al+80 at % Cr) and about (60 at % Al+40 at % Cr) and
preferably between about (30 at % Al+70 at % Cr) and about (50 at %
Al+50 at % Cr). The evaporation current is between about 50 A and
about 200 A depending on the cathode size and preferably between
about 60 A and about 90 A using cathodes of 63 mm in diameter. The
layers are grown in an Ar+O.sub.2 atmosphere, preferably in a pure
O.sub.2 atmosphere at a total pressure of about 2.0 Pa to about 7.0
Pa, preferably about 4.0 Pa to about 7.0 Pa. The bias is about -50
V to about -200 V, preferably about -50 V to about -100 V. The
deposition temperature is between about 500.degree. C. and about
700.degree. C., preferably between about 600.degree. C. and about
700.degree. C.
[0038] The invention also relates to the use of cutting tool
inserts according to the above for machining of steel and stainless
steel at cutting speeds of about 75-600 m/min, preferably about
150-500 m/min, with an average feed, per tooth in the case of
milling, of about 0.08-0.5 mm, preferably about 0.1-0.4 mm
depending on cutting speed and insert geometry.
[0039] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
any methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, the preferred methods and materials are now described.
All publications mentioned hereunder are incorporated herein by
reference. Unless mentioned otherwise, the techniques employed or
contemplated herein are standard methodologies well known to one of
ordinary skill in the art. The materials, methods, and examples are
illustrative only and not limiting.
[0040] The present invention is further defined in the following
Examples, in which all parts and percentages are by weight and
degrees are Celsius, unless otherwise stated. It should be
understood that these examples, while indicating preferred
embodiments of the invention, are given by way of illustration
only. From the above discussion and these examples, one skilled in
the art can ascertain the essential characteristics of this
invention, and without departing from the spirit and scope thereof,
can make various changes and modifications of the invention to
adapt it to various usages and conditions.
EXAMPLES
Example 1
[0041] Grade A: Cemented carbide inserts with the composition 10.3
wt % Co and balance WC, were used.
[0042] Before deposition, the inserts were cleaned in ultrasonic
baths of an alkali solution and alcohol. The system was evacuated
to a pressure of less than 2.0.times.10.sup.-3 Pa, after which the
body were sputter cleaned with Ar ions. At first, a bonding layer
of TiN with a thickness of 0.2 .mu.m followed by a textured
(Al,Cr).sub.2O.sub.3 layer of thickness 2.5 .mu.m, were grown by
cathodic arc evaporation of an alloyed (40 at % Al+60 at % Cr)
cathode, 63 mm in diameter (position (2a) and (2b) in FIG. 2A) in
99.995% pure O.sub.2 atmosphere at a total pressure of 5.5 Pa and a
deposition temperature of about 650.degree. C. to a total coating
thickness of 3 .mu.m. The evaporation current was 75 A and the bias
was held at -75 V during depositions. Finally, a top coating
consisting of 0.3 .mu.m (Al,Cr)N and 0.2 .mu.m TiN was applied.
[0043] A fractured cross-section SEM micrograph of the coating is
shown in FIG. 3 with (A) body, (B) bonding layer, (C) (Al,Cr)O
layer, (D) (Al,Cr)N layer and (E) TiN layer.
[0044] The XRD patterns of the as-deposited layers were obtained
using CuK.alpha.-radiation and a .theta.-2.theta. configuration.
FIG. 4 shows the XRD pattern of a coating according to the
invention with a textured corundum phase alumina
(Al,Cr).sub.2O.sub.3 layer. The peaks originating from the
(Al,Cr).sub.2O.sub.3 layer are marked with dashed lines whereas the
peaks of cemented carbide are marked with solid lines.
[0045] The EBSD pole figure (FIG. 5A) and pole plot graph (FIG. 5B)
of the as-deposited corundum phase (Al,Cr).sub.2O.sub.3 layers in
the c-axis (001) direction (FIG. 1A), respectively, showing a fiber
texture (rotational symmetry) in the direction of the coated
surface normal (FIG. 1B) with an inclination angle, .phi. (FIG.
1B), of the basal planes relative to the coated surface normal
between 0 and 20.degree.. The highest peak in the pole plot is
close to 0.degree.. The EBSD data were obtained using a LEO Ultra
55 scanning electron microscope operated at 20 kV equipped with a
HKL Nordlys II EBSD detector and evaluated with the Channel 5
software.
[0046] The residual stress, .sigma., of the (Al,Cr).sub.2O.sub.3
coating was evaluated by XRD measurements using the sin.sup.2 .psi.
method. The measurements were performed using CrK.alpha.-radiation
on the (Al,Cr).sub.2O.sub.3 (116)-reflection. The residual stress
value was 2.1.+-.0.2 GPa as evaluated using a Poisson's ratio of
.nu.=0.26 and Young's modulus of E=420 GPa.
[0047] The composition, y=0.49, of
(Al.sub.1-yCr.sub.y).sub.2O.sub.3 was estimated by energy
dispersive spectroscopy (EDS) analysis using a LEO Ultra 55
scanning electron microscope with a Thermo Noran EDS detector
operating at 10 kV. The data were evaluated using a Noran System
Six (NSS ver 2) software.
Example 2
[0048] Grade B: A layer of 3.0 .mu.m Ti.sub.0.34Al.sub.0.66N was
deposited by PVD on cemented carbide inserts with the composition
10.3 wt % Co and balance WC, according to prior art.
Example 3
[0049] Grade C: A coating consisting of 3.0 .mu.m Ti(C,N)+3 .mu.m
.alpha.-Al.sub.2O.sub.3 was deposited by CVD on cemented carbide
inserts with the composition 10.3 wt % Co and balance WC, according
to prior art.
Example 4
[0050] Grade D: Example 1 was repeated using cemented carbide
inserts with the composition 5.3 wt % Co and balance WC.
Example 5
[0051] Grade E: A layer of 3.0 .mu.m Ti.sub.0.34Al.sub.0.66N was
deposited by PVD on cemented carbide inserts with the composition
5.3 wt % Co and balance WC, according to prior art.
Example 6
[0052] Grade F: A coating consisting of 3.0 .mu.m Ti(C,N)+3 .mu.m
.alpha.-Al.sub.2O.sub.3 was deposited by CVD on cemented carbide
inserts with the composition 5.3 wt % Co and balance WC, according
to prior art.
Example 7
[0053] Grades A, B and C were tested in machining in steel.
TABLE-US-00001 Operation Face milling Cutter diameter 125 mm
Material SS1672 Insert type SEEX1204AFTN-M15 Cutting speed 300
m/min Feed 0.2 mm/tooth Depth of cut 2.5 mm Width of cut 120 mm
Results Tool life (min) Grade A (grade according to invention) 7.4
Grade B 6.2 Grade C 3.3
[0054] The test was stopped at the same maximum flank wear. The
wear resistance was much improved with the grade according to the
invention.
Example 8
[0055] Grades A, B and C were tested in machining in stainless
steel.
TABLE-US-00002 Operation Shoulder milling Cutter diameter 32 mm
Material SS1672 Insert type XOEX120408-M07 Cutting speed 275 m/min
Feed 0.25 mm/tooth Depth of cut 3 mm Width of cut 8.8 mm Results
Tool life (min) Grade A (grade according to invention) 6.2 Grade B
4.1 Grade C failed
The test was stopped at the same maximum flank wear. The wear
resistance was much improved with the grade according to the
invention.
Example 9
[0056] Grades D, E and F were tested in machining in stainless
steel.
TABLE-US-00003 Operation Interrupted turning Material SS2348 Insert
type CNMG120408-MR3 Cutting speed 80 m/min Feed 0.3 mm Depth of cut
2 mm Results Tool life (cycles) Grade D (grade according to
invention) 7 Grade E 2 Grade F 5
The test was stopped at the same maximum flank wear. The wear
resistance was much improved with the grade according to the
invention.
Example 10
[0057] Grades D, E and F were tested in machining in stainless
steel.
TABLE-US-00004 Operation Interrupted turning Material SS1672 Insert
type CNMG120408-MR3 Cutting speed 350 m/min Feed 0.3 mm Depth of
cut 2 mm Results Tool life (min) Grade D (grade according to
invention) 11.1 Grade E 4.5 Grade F 9.2
The test was stopped at the same maximum flank wear. The wear
resistance was much improved with the grade according to the
invention.
[0058] When ranges are used herein for physical properties, such as
molecular weight, or chemical properties, such as chemical
formulae, all combinations and subcombinations of ranges specific
embodiments therein are intended to be included.
[0059] The disclosures of each patent, patent application, and
publication cited or described in this document are hereby
incorporated herein by reference, in their entirety.
[0060] Those skilled in the art will appreciate that numerous
changes and modifications can be made to the preferred embodiments
of the invention and that such changes and modifications can be
made without departing from the spirit of the invention. It is,
therefore, intended that the appended claims cover all such
equivalent variations as fall within the true spirit and scope of
the invention.
* * * * *