Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
  • C23C30/005—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process on hard metal substrates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T407/00—Cutters, for shaping
  • Y10T407/27—Cutters, for shaping comprising tool of specific chemical composition
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24942—Structurally defined web or sheet [e.g., overall dimension, etc.] including components having same physical characteristic in differing degree
  • Y10T428/2495—Thickness [relative or absolute]
  • Y10T428/24967—Absolute thicknesses specified
  • Y10T428/24975—No layer or component greater than 5 mils thick
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
  • Y10T428/263—Coating layer not in excess of 5 mils thick or equivalent
  • Y10T428/264—Up to 3 mils
  • Y10T428/265—1 mil or less
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T82/00—Turning
  • Y10T82/10—Process of turning
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T83/00—Cutting
  • Y10T83/04—Processes

Definitions

• the present invention relates to a coated cemented carbide milling insert for wet or dry machining of cast iron such as nodular cast irons.
• the cutting edges are regarded as being worn according to different wear mechanisms. Wear types such as chemical wear, abrasive wear and adhesive wear, are rarely encountered in a pure state, and complex wear patterns are often the result.
• 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.
• the machmability of cast irons can vary considerably between the various groups but also within a certain group. Small variation in the chemical composition or the micro-structure, related to the casting technique, can have significant influence on the tool life.
• EP 1205569 discloses a coated milling insert particularly useful for milling of grey cast iron with or without cast skin under wet conditions at low and moderate cutting speeds and milling of nodular cast iron and compacted graphite iron with or without cast skin under wet conditions at moderate cutting speeds.
• the insert is characterised 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 TiC x N y with columnar grains followed by a layer of K-AI 2 O3 and a top layer of TiN.
• EP 1655391 discloses coated milling inserts particularly useful for milling of grey cast iron with or without cast skin under dry conditions at preferably rather high cutting speeds and milling of nodular cast iron and compacted graphite iron with or without cast skin under dry conditions at rather high cutting speeds.
• the inserts are characterised 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 TiC x N y with columnar grains followed by a wet blasted layer of ⁇ -Al 2 C>3.
• the cutting tool insert according to the present invention includes a cemented carbide substrate with a relatively low amount of cubic carbides, with a relatively low binder phase content, that is medium to highly alloyed with W and a fine to medium WC grain size.
• This substrate is provided with a wear resistant coating comprising a (Ti x Ali_ x )N layer.
• Fig 1 shows in 4000Ox a scanning electron microscopy image of a fracture cross section of a cemented carbide insert according to the present invention in which 1. Cemented carbide body and 2. (Ti x Al 1 -JN layer.
• a coated cutting tool insert consisting of a cemented carbide body and a coating.
• the cemented carbide body has a composition of 5-7, preferably 5.5-6.5, most preferably 5.8-6.2 wt% Co, 0.05-2.0 wt%, preferably 0.08-1.5 wt%, most preferably 0.1-1.2 wt% total amount of the metals Ti, Nb and Ta and balance WC.
• the content of Ti and Nb is on a level corresponding to a technical impurity.
• the coercivity (Hc) of the cemented carbide is 14-19 kA/m, preferably 14.8-18.3 kA/m.
• the cobalt binder phase is medium to highly alloyed with tungsten.
• the S-value depends on the content of tungsten in the binder phase and increases with a decreasing tungsten content.
• the cemented carbide body has an S-value of 0.81-0.96, preferably 0.84-0.95, most preferably 0.85-0.95.
• the coating comprises a layer of (Ti x Ali_ x ) N, where x is between 0.25 and 0.50, preferably between 0.30 and 0.40, most preferably between 0.33 and 0.35.
• the crystal structure of the (Ti, Al) N-layer is of NaCl type.
• the total thickness of the layer is between 1.0 and 5.0 ⁇ m, preferably between 1.5 and 4.0 ⁇ m. The thickness is measured on the middle of the flank face.
• the layer is strongly textured in the (200) -direction, with a texture coefficient TC (200) larger than 1.3, preferably between 1.5 and 2.5.
• the texture coefficient (TC) is defined as follows:
• I (hkl) intensity of the (hkl) reflection
• the layer is in compressive residual stress with a strain of 2.5*10 ⁇ 3 -5.0*10 ⁇ 3 , preferably 3.0*10 ⁇ 3 -4.0*10 "3 .
• a layer of TiN between 0.1 and 0.5 ⁇ m thick is deposited on the final (Ti x Ali_ x )N layer.
• the present invention also relates to a method of making a cutting insert by powder metallurgical technique, wet milling of powders forming hard constituents and binder phase, compacting the milled mixture to bodies of desired shape and size and sintering, comprising a cemented carbide substrate and a coating.
• a substrate is provided consisting of 5-7, preferably 5.5-6.5, most preferably 5.8-6.2 wt% Co, 0.05-2.0 wt%, preferably 0.08-1.5 wt%, most preferably 0.1-1.2 wt% total amount of the metals Ti, Nb and Ta and balance WC.
• the content of Ti and Nb is on a level corresponding to a technical impurity.
• the manufacturing conditions are chosen to obtain an as- sintered structure with a coercivity, Hc, within 14-19 kA/m, preferably 14.8-18.3 kA/m and with a S-value within 0.81-0.96, preferably 0.84-0.95, most preferably 0.85-0.95.
• a coating comprising a (Ti ⁇ Ali- ⁇ )N layer, where x is between 0.25 and 0.50, preferably between 0.30 and 0.40, most preferably between 0.33 and 0.35.
• the crystal structure of the (Ti, Al) N-layer is of NaCl type.
• the total thickness of the layer is between 1.0 and 5.0 ⁇ m, preferably between 1.5 and 4.0 ⁇ m. The thickness is measured on the middle of the flank face.
• the method used to grow the layer is based on arc evaporation of an alloyed, or composite cathode, under the following conditions:
• the Ti+Al cathode composition is 25 to 50 at.% Ti, preferably 30 to 40 at.% Ti, most preferably 33 to 35 at.% Ti.
• the surface is cleaned preferably by applying a soft ion etching.
• the ion etching is performed in an Ar atmosphere or in a mixture of Ar and H 2 .
• the evaporation current is between 50 A and 200 A depending on cathode size and cathode material. When using cathodes of 63 mm in diameter the evaporation current is preferably between 60 A and 100 A.
• the substrate bias is between -20 V and -35 V.
• the deposition temperature is between 400°C and 700 0 C, preferably between 500 0 C and 600 0 C.
• the (Ti, Al) N-layer is grown in an Ar+N2 atmosphere consisting of 0-50 vol.% Ar, preferably 0-20 vol.%, at a total pressure of 1.0 Pa to 7.0 Pa, preferably 3.0 Pa to 5.5 Pa.
• TiN-layer On top of the (Ti, Al) N-layer a TiN-layer of between 0.1 and 0.5 ⁇ m thickness may be deposited using Arc evaporation as known.
• the cutting tool insert as described above is treated after coating with a wet blasting or brushing operation, such that the surface quality of the coated tool is improved.
• the present invention also relates to the use of a cutting tool insert according to above in milling of nodular cast iron, in both wet and dry conditions with a cutting speed of 75-300 m/min and feed per tooth of 0.05-0.4 mm.
• Grade A A cemented carbide substrate in accordance with the invention with the composition 6 wt% Co, 0.2 Ta and balance WC, a binder phase alloyed with W corresponding to an S-value of 0.92 was produced by conventional milling of powders, pressing of green compacts and subsequent sintering at 1430 ° C.
• the Hc value for the cemented carbide was 16.5 kA/m, corresponding to a mean intercept length of about 0.65 ⁇ m.
• the substrate was coated in accordance with the invention with a (Ti, Al) N-layer, deposited by using cathodic arc evaporation.
• the layer was deposited using a Ti+Al cathode composition of 33 at.% Ti and the (Ti, Al) N layer was grown in an Ar+N 2 atmosphere.
• the thickness of the coating was 2.8 ⁇ m, when measured on the middle of the flank face.
• X-ray diffraction showed that the (Ti 7 Al)N layer had a TC (200) of 1.8.
• Fig 1 shows in 4000Ox a scanning electron microscopy image of a fracture cross section of the coated cemented carbide.
• Grade B A substrate with composition 6 wt% Co, 0.2 Ta and balance WC, a binder phase alloyed with W corresponding to an S- value of 0.92, and a Hc value of 16.4 kA/m was coated with a 0.3 ⁇ m thick layer of TiN layer, a 4.2 ⁇ m thick layer of columnar MTCVD TiC x N y , and a 3.5 ⁇ m thick layer of OJ-Al 2 O 3 deposited at about 1000°C.
• Grade C A substrate with composition 7.6 wt% Co, 0.9 Ta, 0.3 Nb and balance WC, a binder phase alloyed with W corresponding to an S-value of 0.90, and a Hc value of 14 kA/m was coated with a 0.1 ⁇ m thick layer of TiN, a 2.8 ⁇ m thick layer of columnar MTCVD TiC x N y , a 2.1 ⁇ m thick layer of ⁇ -Al 2 C> 3 and a 0.5 ⁇ m thick layer of TiN, deposited at about 1000 ° C.
• Grade D A substrate with composition 8.1 wt% Co, 1.1 Ta, 0.3 Nb and balance WC, a binder phase alloyed with W corresponding to an S-value of 0.89, and a Hc value of 15 kA/m was combined with a coating according to Grade A.
• the tool life of Grade A was limited by flank wear.
• the tool life of Grade B was limited by the combination of flank wear and delamination of the coating.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Cutting Tools, Boring Holders, And Turrets (AREA)

Applications Claiming Priority (3)

Publications (3)

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Cited By (1)

Citations (4)

• 2008
  • 2008-09-11 EP EP08830773.1A patent/EP2201153B1/de active Active

Patent Citations (4)

Non-Patent Citations (1)

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