KR101444457B1 - Coated cutting tool insert - Google Patents

Abstract

A coated cutting tool insert is provided to improve the cutting performance of the insert by forming a coating including a number of wear resistance layers which have been subject to a post surface treatment. A coated cutting tool insert comprises a body having generally polygonal or round shape with at least one rake face and at least one clearance face. The insert is partially coated with a coating. The coating includes alpha Al2O3 layer serving as an outer layer of the rake face. The alpha Al2O3 layer has a texture in the 104-direction with a texture coefficient TC(104)>1.5. The alpha Al2O3 layer has a texture in the 104-direction with a texture coefficient TC(104)>2. The alpha Al2O3 layer has a texture in the 104-direction with a texture coefficient TC(104)>2.5. The alpha Al2O3 layer has a texture in the 012-direction with a texture coefficient TC(012)>1.3, preferably TC(012)>1.5. The alpha Al2O3 layer has a texture in the 110-direction with a texture coefficient TC(110)>1.5.

Description

[0001] COATED CUTTING TOOL INSERT [0002]

1 is a diagram showing a goniometer apparatus for evaluating residual stress by X-ray measurement, wherein

E = Euler 1/4-cradle,

S = sample,

I = incident X-ray beam,

D = dispersed X-ray beam,

θ = dispersion angle,

ω = θ,

ψ = inclination angle along the Euler 1/4-cradle,

φ = rotation angle around the sample axis.

The present invention relates to coated high performance cutting tool inserts useful for turning of steels, such as low alloy steels, carbon steels and toughness steels, especially at high cutting speeds. The insert is based on a Co-binder having tungsten carbide (WC), cubic carbide and cobalt (Co) rich surface areas and providing the cutting insert with excellent resistance to plastic deformation and high toughness behavior. The coating also includes a plurality of abrasion resistant layers that have undergone surface treatment to provide surprisingly improved cutting performance to the tool inserts.

Today, most of the cutting tool is based on a cemented carbide insert coated with several hard layers like TiC, TiC _x N _y, TiN, TiC _x N _y O _z and Al ₂ O _3. The arrangement and thickness of the individual layers are carefully selected so that the different cutting application surfaces and the workpiece material to be cut meet. The most frequently used coating methods are chemical vapor deposition (CVD) and physical vapor deposition (PVD). In particular, CVD coating inserts have a great advantage over flank wear resistance and crater wear resistance over uncoated inserts.

Chemical vapor deposition is performed at a higher temperature range, i.e., 950 to 1050 ° C. Because of this high deposition temperature and mismatches in the coefficient of thermal expansion between the deposited coating material and the cemented carbide tool insert, chemical vapor deposition processes can lead to coatings having a cooling crack and high tensile stress (sometimes up to 1000 MPa). Under certain cutting conditions, the high tensile stress can be a disadvantage because it can further promote the cooling crack to propagate to the cemented carbide to cause breakage of the cutting edge.

In the metal cutting industry, there is a continuing effort to increase the ability to withstand higher cutting speeds without consuming the ability to resist breakage or chipping during cutting areas, e.g., low speed cuts.

A significant improvement in the application area has been achieved by combining the insert with the binder phase rich surface zone and the coating with the optimum thickness.

However, as the coating thickness is increased, a positive effect on the wear resistance may be due to an increase in the risk of coating delamination and an increase in negative effects in the form of a reduction in toughness which makes the cutting tool less reliable. . This applies especially to softer workpiece materials such as low carbon steel and stainless steel, and is applied when the coating thickness is about 5 to 10 [mu] m. Also, thicker coatings generally have negative characteristics when they cause more uneven surfaces and cuts to damage materials such as low carbon steels and stainless steels. As an enhancement, a post-smoothing operation is applied by brushing or wet blasting as disclosed in various patent publications such as EP 0 298 729, EP 1 306 150 and EP 0 736 615 . In US 5,861, 210, the purpose was to expose Al ₂ O ₃ as an upper layer on the slope, for example, to form a smooth cutting edge and leave TiN on the flank to be used as a wear detection layer. A coating having high resistance to flaking can be obtained.

For example, any post-treatment that exposes surfaces, e.g., coating surfaces, to mechanical effects such as wet or dry blasting will have some effect on the surface finish and the stress state (?) Of the coating.

A strong intense blasting impact may lower the tensile stress at the time of CVD-coating, but occasionally it is possible to deplete the coating surface finish or to peel off the coating by creating ditches along the cooling cracks .

Very strong treatments may cause large changes in stress conditions, such as from high tensile to high compression, as disclosed in EP-A-1 311 712 where dry blasting techniques are used.

It has been found that a cutting tool insert having a constant cemented carbide base composition combination and a constant coating structure and thickness and post-treated by wet blasting under controlled conditions achieves excellent cutting characteristics over a wider range than conventional cutting tool inserts Amazingly, I just found it.

The cobalt binder phase is alloyed with a large amount of W. The content of W on the binder can be expressed as CW-ratio:

CW- ratio _{= M s / (% Co *} 0.0161 parts by weight)

Where M _s is the measured saturation magnetization (hAm 2 / kg), and wt% Co is the Co content of the cemented carbide. The low CW-ratio corresponds to a high W-content on the Co-binder. The post-treatment used would give a suitable tensile strength level for the coating, and Al ₂ O ₃ Will impart certain significant crystallization properties to the layer, and will give superior surface finish to the top surface.

The mentioned combination with blasting technology effectively expands the coating thickness limitations that can be applied without adverse performance conditions. As a result of the invention, an excellent width of application area is now possible. Significant improvements in toughness behavior and coating adhesion have been achieved.

In order to significantly change the stress state of the coating by blasting, a blasting medium such as an Al ₂ O ₃ grit must strike the coating surface with a high impulse. The impact force can be controlled, for example, by blasting pulp pressure (wet blasting), the distance between the blasting nozzle and the coating surface, the particle size of the blasting medium, the concentration of the blasting medium and the impact angle of the blasting jet .

It is an object of the present invention to provide a CVD-coated tool insert having improved toughness properties with high temperature resistance without sacrificing edge security or toughness of the cutting edge.

The present invention therefore relates to a coated cutting tool insert consisting of a generally polygonal or round shaped body consisting of a coating and a cemented carbide base, with at least one bevelled surface and at least one clearance surface. The main body comprises 4.4 to 6.6, preferably 5.0 to 6.0, most preferably 5.0 to 5.8 weight percent Co, 4 to 8.5 weight percent cubic carbide, balance WC, preferably 85 to 91 weight percent WC, 87 to 90 wt.% WC, preferably a composition having an average particle size of 1 to 4 mu m, a CW-ratio in the range of 0.78 to 0.92, and a surface area depleted from cubic carbides TiC, TaC and / or NbC.

The thickness of the surface zone depleted from the cubic carbide can range from 10 占 퐉, alternatively from 15 占 퐉, or alternatively from 20 占 퐉 to 40 占 퐉, alternatively up to 35 占 퐉, alternatively 30 占 퐉, Or alternatively up to 25 [mu] m.

The coating comprises at least one TiC _x N _y layer and one well-crystalline layer of 100% alpha-Al ₂ O ₃ . The α-Al ₂ O ₃ layer is therefore an outermost visible layer on the inclined surface, the layer is hard to sufficiently high energy wet blasting be tensile stress relaxation in both the Al ₂ O ₃ layer and the TiC _x N _y layer cutting nalseon . The Al ₂ O ₃ outermost layer has a very smooth surface at least on the chip contact area on the slope.

Surprisingly, it has been found that a significantly improved toughness performance can be achieved if a generally polygonal or round shaped and at least partially coated cutting tool insert with at least one bevel and at least one relief face is formed with the following characteristics:

- the second layer of TiC _x N _y is from 3 탆, preferably from 4 탆, more preferably from 5 탆, most preferably from 6 탆 to 15 탆, preferably up to 13 탆, Y = 0, x + y = 1, preferably made by MTCVD, with a tensile stress of 50 to 500 MPa, preferably 50 to 450 MPa, Most preferably 50 to 400 MPa.

The outer? -Al ₂ O ₃ layer has a thickness from 3 μm, preferably from 3.5 μm, most preferably from 4 μm to 12 μm, preferably up to 11 μm, most preferably up to 10 μm Is an outermost layer on an inclined surface along a cutting edge having an average roughness (Ra) <0.12 mu m, preferably, Ra &amp;le; 0.10 mu m at least in a chip contact area of an inclined surface, and an average roughness is measured by an atomic force microscope (AFM) The intensity (peak height-background) ratio was measured over an area of 10 탆 x 10 탆 by I (012) / I (024) ≥ 1.3, preferably ≥ 1.5.

Preferably, between the TiC _x N _y layer and the? -Al ₂ O ₃ layer there is a thin adhesion layer of TiC _x N _y O _z of 0.2 to 2 μm wherein x≥0, y≥0, z≥0 . The total thickness of the two layers is 25 占 퐉 or less.

Further, according to the present invention, additional layers may be included in the coating structure between the substrate and the layers, which are composed of metal nitrides and / or carbides and / or oxides, and the metal elements are Ti, Nb, Hf, V , Ta, Mo, Zr, Cr, W and Al, and the total coating thickness is less than 5 占 퐉.

The induced compressive stress is preferably unstable to the temperature rise that occurs during the cutting operation, as compared to the case where some tensile stress is still present in the coating, so that a slight tensile stress remains in the TiC _x N _y layer . In addition, when compressive stress is induced by blasting, a very high blasting impact force is required, and in such a state, peeling of the coating often occurs along the cutting edge.

The residual stress (σ) of the internal TiC _x N _y layer is determined by the well known sin ² ψ method (1987 New York, Springer-Verlag, IC Noyan, JB Cohen, Quot;) described above) is determined by X-ray diffraction measurement. The measurement is carried out using CuK _alpha -radiation as a TiC _x N _y (422) reflection in a goniometer setting as shown in Fig. The measurement is carried out in the plane as much as possible. It is recommended to use the side slope technique (ψ-dimensional method) with an angle of 6 to 11 ψ, at equidistance in the range of sin ² ψ from 0 to 0.5 (ψ = 45 °). Also, equidistant distribution of phi-angles in the [phi] -sector of 90 [deg.] Is preferred. In order to clarify the biaxial stress state, the sample is tilted at ψ and rotated at φ = 0 °, 90 °. It is recommended to confirm the presence of shear stresses, and therefore both the negative and positive ψ angles are measured. In the case of an Euler 1/4 cradle, this is done by measuring the sample at φ = 180 °, 270 ° for different ψ angles. The sin ² Ψ method uses the Pseudo Voigt Fit function to calculate the Bruker AXS (n = 0,20) ratio for Young's modulus, E = 480 GPa and Poisson's ratio for the MTCVD Ti (C, DIFFRAC ^Plus Stress 32 v. 0.0 &gt; 1.04 &lt; / RTI &gt; is preferably used to calculate the residual stress. In this case, a parameter of E-modulus = 480 Gpa and Poisson's ratio v = 0.20 is used. In the case of a biaxial stress state, the tensile stress is calculated as the average of the obtained biaxial stresses.

Since the required high angle 2 angle X-ray diffraction reflection is too weak, the sin ² Ψ method can not generally be used for α-Al ₂ O ₃ . However, there is a tendency for α-Al ₂ O ₃ Other useful measurements related to the state of the disease have been found.

alpha -Al ₂ O ₃ The diffraction intensity ratio I (012) / I (024) for the powder is near 1.5. The powder diffraction file JCPDS 431484 shows the intensities I ₀ (012) = 72 and I ₀ (024) = 48. The intensity ratio I (012) / I (024) was surprisingly much lower than the expected value of 1.5 for the chemical vapor deposition (CVD) a-Al ₂ O ₃ layer which received a tensile stress of the cemented carbide (approximately σ greater than 350 MPa) , Often less than one. This may be due to some irregularities in the crystal lattice caused by the tensile stress. The ratio I (012) / I (024) is close to or greater than 1.5 when the layer is removed, e.g., by stress, by a strong blasting operation, or when the layer is completely removed from the substrate or powder . The higher the blasting force applied, the higher the ratio. Thus, this intensity ratio can be used as an important state feature of α-Al ₂ O ₃ layer.

According to the invention, the cutting tool insert has, the penultimate TiC _x N _y Layer and an external a-Al ₂ O ₃ layer. The Al ₂ O ₃ is EP 603 144, which imparts a crystallographic texture to the Al ₂ O ₃ layer in the 012 direction with a texture index TC (012) of greater than 1.3, preferably greater than 1.5, US 5,851, 687 and US 5,702, 808, which provide a texture 110 in a direction 110 that is greater than 1.5. Very smooth surface and to obtain a lower tensile stress, said coating is a slurry consisting of F150 grit (grit) (FEPA- standard) of Al ₂ O ₃ in water by the air pressure 2.2 ~ 2.6bar for about 10 to 20 seconds per insert Lt; RTI ID = 0.0 &gt; blasting &lt; / RTI &gt; The spray gun is placed at about 10 mm from the insert at a 90 ° spray angle. The insert has a different color on the clearance surface than on the black slanted surface. TiN (yellow), TiC _x N _y (gray or bronze), ZrC _x N _y (red or bronze), where x≥0, y≥0 and x + y = 1, or Tic ) Of 0.1 to 2 mu m in thickness is preferably laminated. Thereafter, the insert is blasted and the upper layer is removed to reveal the black Al ₂ O ₃ layer. The coating on the slope has a desired low tensile stress of 50 to 500 MPa and a margin of about 500 to 700 MPa. The CTE of the used carbide insert and the choice of coating result in a tensile stress on the slope Is lower than the tensile stress of the margin surface. In another embodiment of the present invention, the coated insert is blasted on both the slope and the clearance side, the possibility that the colored heat resistant paint is applied to the clearance side, or the colored PVD layer is deposited thereon to identify the used cutting edge .

Example  One

The following samples were prepared.

A) a cobalt carbide composition having a composition of 5.5 wt% Co, 2.9 wt% TaC, 0.5 wt% NbC, 1.4 wt% TiC, 0.9 wt% TiN, balance WC with an average particle size of about 2 μm, And a surface area depleted from the cemented carbide insert.

B) a cobalt carbide having a composition of 5.5 wt.% Co, 2.9 wt.% TaC, 0.5 wt.% NbC, 1.9 wt.% TiC, 0.4 wt.% TiN, balance WC with an average particle size of about 2 μm, And a surface area depleted from the cemented carbide insert.

C) Cubic carbide having a composition of 5.5 wt% Co, 2.9 wt% TaC, 0.5 wt% NbC, 1.6 wt% TiC, 0.7 wt% TiN, balance WC with an average particle size of about 2 μm, And a surface area depleted from the cemented carbide insert.

The saturation magnetization (M _s ) for A) to C) was 0.077 hAm ² / kg and the CW ratio was 0.87. For inserts according to A) to C), a TiN layer with a thickness of 0.5 μm was formed by a general CVD method at 930 ° C., followed by TiCl ₄ , H ₂ , N ₂ and CH ₃ CN as reaction gases at 885 ° C., Method, a TiC _x N _y Coat the layer. In a continuous reaction step for the same coating period, a layer of TiC _x O _z of about 0.5 탆 thickness is deposited using TiCl ₄ , CO, and H ₂ at 1000 캜, followed by a 7 탆 thick layer of? -Al ₂ O ₃ Before the layer is deposited, the Al ₂ O ₃ reaction is initiated by pouring the mixture of 2% CO ₂ , 3.2% HCl and 94.8% H ₂ into the reactor for 2 minutes. At the top, a thin, about 0.5 탆 TiN layer is deposited. The reaction conditions during the deposition step are as follows.

step TiN
1, 6 TiC _x N _y
2 TiC _x O _z
3 Al ₂ O ₃ - start
4 Al ₂ O ₃
5 TiCl ₄ 1.5% 1.4% 2 % N ₂ 38% 38% CO ₂ 2 % 4 % CO 6% AlCl ₃ 3.2% H ₂ S - 0.3% HCl 3.2% 3.2% H ₂ Remainder Remainder Remainder Remainder Remainder CH ₃ CN - 0.6% pressure 160 mbar 60 mbar 60 mbar 60 mbar 70 mbar Temperature 930 ° C 885 ° C 1000 ℃ 1000 ℃ 1000 ℃ time 30 minutes 4.5 hours 20 minutes 2 minutes 7 hours

Additional inserts include:

D) A cemented carbide cutting insert of the same type as A) except that the thickness of the TiC _x N _y layer is 6 μm and the thickness of the α-Al ₂ O ₃ layer is 10 μm is TiC _x N _y And the deposition time of Al ₂ O ₃ were 4 hours and 10 hours, respectively.

E) TiC _x N _y layer with a thickness of 6 ㎛ and α-Al ₂ O to a thickness of 10 ㎛ of _three layers other than B) and the same type of cemented carbide cutting inserts are TiC _x N _y And the deposition time of Al ₂ O ₃ were 4 hours and 10 hours, respectively.

F) A cemented carbide cutting insert of the same type as in C) except that the thickness of the TiC _x N _y layer is 6 μm and the thickness of the α-Al ₂ O ₃ layer is 10 μm is TiC _x N _y And the deposition time of Al ₂ O ₃ were 4 hours and 10 hours, respectively.

According to the X-ray diffraction analysis of the deposited Al ₂ O ₃ layer of the insert according to the above A) to F), it was composed only of the α-phase having the texture coefficient (TC) (012) of 1.6 defined by the following formula Proved.

here,

I (hkl) = measured (hkl) reflection intensity,

I ₀ (hkl) = powder diffraction file Standard intensity of JCPDS No. 43-1484,

n = number of reflections used in the calculation, hkl reflections used are: (012), (104), (110), (113), (024), (116).

The coated inserts according to A) to F) are post-treated by the blasting method described above to blast the slopes of the insert with a blasting pressure of 2.4 bar and an exposure time of 20 seconds.

The smoothness of the coated surface expressed as known roughness value (Ra) is measured on an apparatus of surface imaging system AG (SIS) by atomic force microscope (AFM). The roughness is measured at 10 randomly selected planar areas (10 mu m x 10 mu m) in the chip contact area on the slope. The average value (MRa) of the ten Ra values measured was 0.11 탆.

X-ray diffraction analysis using a Bragg-Brentano diffractometer (D5000 from Simens) was used to determine the I (012) / I (024) ratio with copper Kα-radiation.

The I (012) / I (024) ratio obtained on the free surface is about 1.4. The I (012) / I (024) ratio obtained on the slope is about 2.2.

Residual stresses use the ψ-geometric property on X-ray diffractor-GADDS with X-ray diffractometer Bruker equipped with laser video positioning, Euler 1/4 cradle, rotating anode as X-ray source (CuKα) and area detector . A 0.5 mm collimator is used to focus the beam. Using a goniometer set at 2θ = 126 °, ω = 63 ° and Φ = 0 °, 90 °, 180 ° and 270 °, TiC _x N _y Analysis is carried out in reflection, and eight Ψ slopes are made at each Φ at 0 ° to 70 °. By using the software DIFFRAC ^plus Stress v.1.04 of the Bruker AXS with a Young's modulus constant E = 480 Gpa and Poisson's ratio γ = 0.20 and using a pseudo-Voigt-fit function to obtain reflections, The above sin ² Ψ method is used for the evaluation. The biaxial stress state is confirmed, and the average value is used as the residual stress value. Both the inclined plane and the clearance plane are measured. The tensile stress obtained on the clearance side was about 630 MPa in the insert according to the above A) to F). The tensile stress on the slope was about 370 MPa for inserts according to A) to C) and about 390 MPa for inserts according to D) to F).

Example  2

Insert A) of Example 1 was measured and compared to a commercial, non-blasted insert (high performance insert in P15 region) for toughness in a longitudinal swivel with disconnected cuts.

Material: Carbon steel SS1312

Cutting data:

Cutting speed = 120 m / min

Cutting depth = 1.5 mm

Start at a feed rate of 0.15 mm and progressively increase by 0.08 mm / min until the blade breaks

Each 10 blades were tested.

Insert style: CNMG120408-PM

result :

Average breakage transfer Commercial insert 0.244 mm / rev The insert A of Example 1) 0.275 mm / rev

Example  3

Insert D) of Example 1 was tested and compared to the same commercial insert as Example 2 for toughness in a longitudinal pivoting operation with disconnected cuts.

Material: Carbon steel SS1312

Cutting data:

Cutting speed = 140 m / min

Cutting depth = 1.5 mm

Start at a feed rate of 0.15 mm and progressively increase by 0.08 mm / min until the blade breaks

Each 10 blades were tested.

Insert style: CNMG120408-PM

result :

Average breakage transfer Commercial insert 0.232 mm / rev The insert D of Example 1) 0.315 mm / rev

Example  4

Insert A) of Example 1 was tested and compared to the same commercial insert as in Example 2 for resistance to total plastic deformation in the operation of SS2541.

Cutting data:

Cutting speed = 220 m / min

Feed amount = 0.35 mm / rev

Cutting depth = 2 mm

Tool life criterion = Flank wear ≥ 0.5 mm

result :

Number of machining cycles required to reach tool life Commercial insert 65 The insert A of Example 1) 85

Example  5

Inserts A) of Example 1 were tested and compared to the same commercial inserts as in Example 2 for resistance to plastic deformation near the edges at the turn of SS2244-05.

Cutting data

Cutting speed: 200 m / min

Feed rate: 0.35 mm / rev

Cutting thickness: 2.5 mm

Tool life criterion: Flank wear ≥ 0.4 mm

result :

To reach tool life
Number of machining cycles required Commercial insert 19 The insert A of Example 1) 27 ^*

* Insert A) was terminated early after 27 cycles before reaching the specified tool life criteria.

In Examples 3 to 5, the inserts A) and inserts D) of Example 1 and the inventive inserts exhibited excellent strength characteristics and good elastic deformation resistance as compared with the conventional inserts.

Example  6

The inserts B), C), E) and F) of Example 1 were tested and compared to the commercial inserts described in Example 2 for strength in longitudinal rotary motion using discontinuous cutting.

Material: Carbon steel SS1312

Cutting data:

Cutting speed = 150 m / min

Cutting depth = 1.5 mm

Start at a feed rate of 0.15 mm and progressively increase by 0.08 mm / min until the blade breaks

Each 10 blades were tested.

Insert style: CNMG120408-PM

result :

Breakage average feed (mm / rev) Commercial insert 0.206 B) 0.270 C) 0.259 E) 0.230 F) 0.216

Example  7

The inserts B) and C) of Example 1 were tested and the resistance to total elastic deformation in the face-to-face operation of SS2541 was compared to the commercial insert of Example 2. [

Cutting data:

Cutting speed = 200 m / min

Feed amount = 0.35 mm / rev

Cutting depth = 2 mm

Tool life criterion: Flank wear ≥ 0.5 mm

Insert style: CNMG120408-PM

result :

To reach tool life
Number of machining cycles required Commercial insert 59.5 B) 61 C) 63

Example  8

Inserts B), C), E) and F) from Example 1 were tested to compare commonly available inserts as in Example 2 against resistance to total plastic deformation in the operation of SS2541. This test included two different insert sizes, represented by two different insert styles: CNMG160612-PR (cutting edge length = 16 mm) and CNMG190612-PR (cutting edge length = 19 mm).

Cutting data:

Cutting speed = 220 m / min

Feed amount = 0.35 mm / rev

Cutting depth = 3 mm

Tool life criterion: Flank wear ≥ 0.5 mm

result :

To reach tool life
Number of machining cycles required CNMG160612-PR CNMG190612-PR Commercial insert 36 50 B) 52 70 C) 45 52 E) 51 77 F) 51 58

INDUSTRIAL APPLICABILITY As described above, according to the present invention, there is provided a CVD-coated tool insert having improved toughness properties with high temperature resistance without sacrificing the safety or toughness of the cutting edge.

Claims (6)

A cemented carbide-coated cutting tool insert comprising a body of polygonal or rounded shape having at least one inclined surface and at least one clearance surface, Wherein the insert has a composition in the range of 5.0 to 6.0 wt% Co, 4 to 8.5 wt% cubic carbide, balance WC and CW-ratio of 0.78 to 0.92, wherein CW-ratio = M _s / (wt% Co * 0.0161) M _s : measured saturation magnetization (hAm 2 / kg), wt% Co: Co content of cemented carbide), the thickness of the surface area depleted of cubic carbide TiC, TaC and / or NbC is 10 to 40 μm, Comprises a layer of at least one TiC _x N _y layer (where x? 0, y? 0 and x + y = 1) and at least an outer layer of the sloped? -Al ₂ O ₃ layer At least partially, In the at least one inclined surface, The TiC _x N _y layer has a thickness of 3 탆 to 15 탆, a tensile stress level of 50 to 500 MPa, Wherein the α-Al ₂ O ₃ layer is an outermost layer having an X-ray diffraction intensity ratio of I (012) / I (024) ≥1.3 and a thickness of not less than 3 μm and not more than 12 μm, The average Ra value (MRa) is &lt; 0.12 mu m, In the at least one marginal plane, The TiC _x N _y layer has a tensile stress in the range of 500 to 700 MPa, The? -Al ₂ O ₃ layer has an X-ray diffraction intensity ratio of I (012) / I (024) <1.5, At least one inclined surface and the at least one clearance surface, The TiC _x N _y layer has a thickness of 3 탆 to 15 탆, a tensile stress level of 50 to 500 MPa, Wherein the α-Al ₂ O ₃ layer has an X-ray diffraction intensity ratio of I (012) / I (024) ≥1.3 and a thickness of not less than 3 μm and not more than 12 μm, (MRa) is an outermost layer of an oblique surface of &lt; 0.12 占 퐉, and the outermost layer in the clearance surface is a colored heat-resistant paint or a colored PVD layer. The method of claim 1, wherein the TiC _x N _y layer and said α-Al ₂ O ₃ layer between the thin TiC of _{0.2 ~ 2 ㎛ x N y O} z bonding layer (here, x≥0, z> 0 and y 0.0 &gt; = 0). &Lt; / RTI &gt; The cutting tool insert according to claim 1 or 2, wherein the α-Al ₂ O ₃ layer has a texture coefficient of the 012 directional texture of TC (012)> 1.3. The cutting insert according to claim 1 or 2, wherein the α-Al ₂ O ₃ layer has a texture coefficient of the 110 directional texture of TC (110)> 1.5. The method of claim 1 or 2, wherein the coating is a metal nitride and / or a carbide and / or oxide having a metal element selected from Ti, Nb, Hf, V, Ta, Mo, Zr, Cr, &Lt; / RTI &gt; characterized in that the additional layers constituted have a total layer thickness of less than 5 mu m. The insert of claim 1 or 2, wherein the thickness of the surface area depleted of cubic carbide is greater than or equal to 15 urn and less than or equal to 35 urn.

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