WO2007028178A1

WO2007028178A1 - Method for producing cutting tip with a colored surface

Info

Publication number: WO2007028178A1
Application number: PCT/AT2006/000355
Authority: WO
Inventors: Jürgen Markus LACKNER; Wolfgang Waldhauser; Reinhard Pitonak
Original assignee: Boehlerit Gmbh & Co. Kg.
Priority date: 2005-09-09
Filing date: 2006-08-30
Publication date: 2007-03-15
Also published as: AT502526A1; AT502526B1

Abstract

The invention relates to a method for producing a tool or tool part, particularly a cutting element such as a cutting tip (5) whose surface, at least in areas, has a color with which a suitability of the tool or tool part for machining a specific material or a specific material group can be seen, particularly a color corresponding to a differentiation color according to ISO 513. In order to be able to easily produce a tool or tool part of this type with a surface color, which can be set in broad ranges, the invention provides the following steps: a) preparing a base body (1) of the tool or tool part; b) optionally applying at least one wear-resistant wear layer (1a) to a portion or an entire surface of the base body (1); c) applying a covering layer (2), which is comprised of a metal or of a metal compound and which is at least superficially oxidizable, to at least areas of the surface of the base body (1) and/or wear layer (1a), and; d) setting a surface color by partially or completely oxidizing the covering layer (2) in an area (4) that adjoins an exposed surface (3) of the covering layer (2). The invention also relates to a cutting element, particularly a cutting tip (5), for cutting machining materials.

Description

Method for the production of inserts with a colored surface

The invention relates to a method for producing a tool or tool part, in particular a cutting element such as a cutting plate whose surface has a color at least in areas through which a suitability of the tool or tool part for processing a particular material or a particular group of materials is visible, in particular a color according to a distinctive color according to ISO 513.

Furthermore, the invention has a cutting element, in particular a cutting insert for machining materials, comprising a base body, optionally at least one applied to a part or an entire surface of the body wear-resistant wear layer and at least applied to areas of the surface of the body and / or the wear layer Covering the subject.

Cutting inserts such as indexable inserts are used to machine metallic workpieces, for example by turning, milling or drilling, and to give workpieces a desired final or at least near-net shape. For this purpose, a variety of inserts with different macro and micro geometries is available, which is determined by the nature of the cutting engagement on the workpiece, stability of the cutting tool and clamping the insert and the workpiece, which insert geometry is used.

In addition to the above-mentioned geometric criteria, when selecting a suitable insert, it should also be considered from which material a base body of an insert should be made and, if so, whether it should be coated with a wear layer in order to counteract wear of the insert. This selection depends primarily on what material consists of the workpiece, which is to be machined. It is common practice to classify metallic materials into groups, namely steels, stainless steels, cast irons, non-ferrous metals, superalloys and titanium alloys, and hard materials such as hardened steels. Depending on the processed material group, basic bodies come with different compositions, for example, from a hard metal or a cermet, for use. If necessary, these are provided with a suitable coating.

For a tool user, it is easy to distinguish between different insert geometries and thus a suitable one

Cutting tip geometry for machining of metallic workpieces to choose. The problem, however, is that an operator can not readily conclude on a cutting tip composition and thus on a suitability of the cutting plate for machining a particular group of materials. Therefore, there is a danger for a user to select an unsuitable insert, which not only can lead to the destruction of the insert itself, but also leads to the loss of working time and lowers productivity.

In order to allow a user a simple assignment of inserts to a machinable material group without much risk of misalignment, inserts are delivered in packages which are coded with a color. Each color of the color code corresponds to a material group. In total, according to ISO 513 (Classification and application of cutting materials for metal removal with defined cutting edges - Designations of the main groups and groups of application, 2004), Table 5 uses six different colors for metallic material groups, turning from blue to steel, yellow to steel stainless steels, red to cast iron, green to non-ferrous metals, brown to superalloys and titanium alloys, and gray to hard materials. Upon first removal of a cutting insert, a user can therefore read their suitability for processing a particular group of materials by the color coding of the packaging.

The methodology to apply a color code to the packaging of inserts is unsatisfactory that this fails as soon as the inserts are not put back in the associated packaging after use. There are therefore efforts to mark inserts directly in color, so that their suitability for use is easily detected at any time.

In the context, it is known procedurally that can be produced on inserts by depositing metals by CVD (chemical vapor deposition) or PVD (physical vapor deposition) layers, which are quite different Colors may have. However, only a limited spectrum of colors is available with the intrinsic colors of the layers and, in particular, not all colors can be achieved in accordance with ISO 513. Therefore, as an alternative to a color coding of a package, it is only possible to apply layers with replacement colors to cutting plates, with each replacement color corresponding in turn to a color in accordance with ISO 513. This results in a complicated assignment of inserts and represents a potential source of error.

Another disadvantage of the state of the art is that deposits of the processed metallic materials with high adhesion between the material and the coating often take place on known colored layers, which can consequently lead to a detachment of the coating and possibly to a breakout of the cutting plate ,

Starting from the prior art, it is an object of the invention to provide a method of the type mentioned above, with which in a simple manner a tool or tool part, in particular a cutting element such as a cutting plate, can be prepared with a wide range adjustable color of a surface.

Another object of the invention is to provide a cutting element of the type mentioned above, the cover layer permanently holds and indicates for a long time, for which material group the cutting element is designed and in which an adhesion of the machined materials is low.

The procedural object is achieved by a method according to claim 1.

Advantageous variants of the method according to the invention are the subject matter of claims 2 to 9.

The advantages of a method according to the invention can be seen in particular in that tools or tool parts such as inserts can be provided in a simple manner with a cover layer which holds permanently and is suitable for displaying over a long period of time, for example, a suitability of the cutting plate for machining a specific material group. It is possible with the aid of the method according to the invention in a simple manner, to choose a desired color of the cover layer in a wide range and in particular a in To set the essential distinguishing color (yellow, blue, red, green, brown, gray) according to ISO 513. It is assumed that interference phenomena of the incident and reflected light occur on the free surface of the cover layer, which lead to a characteristic surface color of the cover layer. This could be due to various compositions of the free surface adjacent oxidized zone and a cutting plate inwardly of that zone. In this case, according to the invention, the applied layer of a metal or a metal compound can be completely oxidized, that is, to the exclusive presence of metal oxides, or only partially oxidized.

In addition, the intended oxidizing treatment of the covering layer makes it possible to make its surface less susceptible to deposits, which can be caused by contact with the machined workpiece or hot chips. This benefits the durability of the topcoat.

In order to achieve a good color effect, oxidation up to a depth of the cover layer of about 500 nanometers has proven to be expedient. In the range of about 100 to 300 nanometers, particularly intense colors can be achieved.

Although any type of application of a cover layer is possible, it is preferred if the cover layer is formed by deposition from the gas phase, for example via chemical vapor deposition or physical vapor deposition. An application of the cover layer by means of deposition from the gas phase proves to be favorable in terms of good adhesion of the cover layer on

Base body and / or the wear layer, whereby a durability of the cover layer is further increased.

It is also advantageous if the oxidizing treatment with oxygen or an oxygen-containing gas mixture takes place at a temperature of at least 300 ^° C. A reaction of the cover layer with an oxidizing gas allows a controllable, oxidizing treatment of the cover layer, without this being subsequently cleaned, as it may be necessary for liquid oxidants, for example a H ₂ O ₂ solution. Moreover, a reaction time when using oxygen or oxygen-containing gases even at pressures of one bar or be kept short, which is advantageous for mass production.

Also, in order to keep a reaction time and thus a production time short, a minimum temperature of 300 ° C is provided when using oxygen or oxygen-containing gases. It is also possible to use oxygen-releasing gases, for example CO ₂ , if sufficiently high reaction temperatures are present.

For the adjustment of a desired color by reaction with oxygen or an oxygen-containing gas at a temperature of more than 300 ⁰ C, it is expedient and sufficient if the tool or tool part for 5 to 300 minutes is brought into contact with oxygen or an oxygen-containing gas. Shorter contact times than five minutes can result in insufficient, only partial color adjustment. With longer contact times than 300 minutes, there is the possibility of complete oxidation of the cover layer, which can possibly lead to the disappearance of an interference phenomenon.

If an oxidation is carried out with oxygen or an oxygen-containing gas, then a temperature range of 300 to 600 ^° C. is recommended for this purpose. In this temperature range, an optimum oxidation rate is given. On the one hand, oxidation takes place sufficiently fast to set a desired color within an acceptable time. On the other hand, oxidation proceeds so slowly that it is easy to control and a color can be set exactly and reproducibly.

Alternatively to an oxidation by means of a gas, an applied conductive

Topcoat can be treated by anodic oxidation by electrochemical route. This allows a gentle oxidation at ambient temperatures.

In a particularly preferred variant of the invention, the cover layer is applied in a non-oxidizing atmosphere by chemical vapor deposition at a temperature of the main body of more than 650 ⁰ C, in particular more than 800 ⁰ C, after which the tool or tool part to a temperature of 300 Allow to cool to 600 ⁰ C and at this temperature, the cover layer with oxygen or an oxygen-containing gas is brought into contact to adjust a surface color. In this process variant is exploited that the tool or tool part after a CVD coating at a temperature of several hundred degrees and oxidation can be easily, quickly and easily controlled by a natural cooling of the tool or tool part in a temperature range of 300 to 600 ⁰ C delayed or interrupted and the Cover layer is oxidized in this temperature range. Then that can

Tool or tool part, of course, to cool to ambient temperature. Since oxidation, depending on the temperature and the desired color, can take place in a relatively short time, for example, a process duration for the production of cutting plates with a color indicator layer is in the range of the usual process time for producing a coated cutting plate.

It is preferred if the cover layer is applied with a thickness of 0.05 to 1.5 μm, in particular 0.05 to 0.5 μm. Although the cover layer should be adherent and resistant to wear when tools are used, it functions primarily as an indicator layer and anti-adhesive layer. It is therefore favorable, in particular to

Not too strongly influence the cutting properties of the base body or a wear layer, a cover layer with a thickness of not more than 1.5 .mu.m, preferably not more than 0.5 .mu.m, apply.

If the top layer has a thickness of less than 0.5 μm after application, this can be completely converted into an oxide layer or partially oxidized over its entire thickness in the context of the invention. On the other hand, if thicker layers, e.g. applied with a thickness of 1 micron, it is preferred that only a near-surface zone partially or completely oxidized up to a maximum of about 500 nm below the top layer surface. The remaining zone of the topcoat remains essentially unchanged.

In a production of cutting inserts by the process according to the invention, it has proven particularly useful if a cover layer of a transition metal of group IV, V, VI of the Periodic Table of the Elements or their alloys, in particular of titanium, applied and then oxidized. In particular, a cover layer of titanium can be converted by almost complete oxidation into a transparent oxide layer with a high refractive index, which can make a surface appear as yellow, red, blue, green, brown or gray, thus in any color that is necessary for a cutting plate marking , Alternatively, it is also possible for a cover layer of a metal carbide, metal nitride or metal carbonitride to be applied to one of the elements titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten and then oxidized. Layers of these metals, like the aforementioned metals, can appear by partial oxidation with almost any color.

In particular, in a cover layer of titanium nitride, the colors yellow, red, blue, green, brown and gray can be adjusted by partial oxidation and thus all the colors used for suitability marking of inserts are achieved. Moreover, these layers are also very resistant to wear and can thus increase the service life of inserts.

The further object of the invention is achieved by a cutting element according to claim 10. Advantageous embodiments of a cutting insert according to the invention are the subject matter of claims 11 to 13.

Advantages of a cutting element according to the invention, such as a cutting plate, can be seen in particular in that it has a well-adhering covering layer, by means of which it is indicated for a long time for which material group the cutting element is designed. At the same time an adhesion of chips or particles of a machined metallic workpiece is reduced due to an at least partial oxidation of the cover layer. The cover layer of a cutting insert according to the invention is thus multifunctional: on the one hand, a suitability for use of the cutting plate is signaled by the color of the cover layer. On the other hand, the near-surface oxidized zone causes beading of hot metal chips or metal particles and can thus contribute to an extended service life of the cutting plate. Both effects are achieved despite a small thickness of the oxidized zone of a maximum of about 500 nanometers.

It is expedient if the cover layer has a thickness of 0.05 μm to 1.5 μm, in particular 0.05 to 0.5 μm. Although the cover layer should be resistant to wear, it serves primarily as an indicator layer or non-adhesive layer. It is therefore advantageous, in order not to obscure the cutting properties of the base body or a wear layer, to apply a cover layer with a thickness of not more than 1.5 μm, preferably not more than 0.5 μm. An advantageous embodiment of the cover layer is given by a partially oxidized layer of a metal, wherein the metal consists of a transition metal of group IV, V, VI of the Periodic Table of the Elements or their alloys. These metals form metal oxides, which are stable even at high temperatures, such as occur in a cutting process. Titanium is particularly preferred among these metals, since titanium, upon oxidation, forms titanium oxides of the general formula Ti _x O y where 0 <x <1 and 0 <y≤2, which provide a good sliding action of the insert against the machined workpiece at high temperatures, and consequently wear is minimized.

If particularly high wear resistance of the cover layer is required, it can also consist of an at least partially partially oxidized layer of a metal carbide, metal nitride or metal carbonitride of one of the elements titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten.

Further advantages and effects of the invention will become apparent from the context of the description and the embodiments.

In the following, the invention will be described in more detail with reference to figures and example series, which represent possible embodiments of the invention.

Show it

Figure 1: Partial cross section of an insert with a cover layer which is oxidized over the entire thickness with oxygen; Figure 2: Partial cross section of an insert with a wear layer and a

Topcoat oxidized with oxygen throughout its thickness;

FIG. 3: Partial cross section of an insert with a wear layer and a

Topcoat oxidized with oxygen over part of its thickness;

Figure 4: Partial cross-section of an insert with a cover layer which is oxidized over a part of its thickness with oxygen.

In Figure 1, a cross section of a cutting plate S is partially shown. The cutting plate S has a main body 1, for example of a hard metal or a cermet. On the main body 1 is directly applied a 100 to 450 nanometers thick cover layer 2 made of titanium, which by anodic oxidation or with Oxygen over the entire layer thickness D is oxidized. Such a coating can therefore also be applied in areas near the cutting edge S ₁ in areas near the cutting edge. This can be used to advantage in indexable inserts, which have a plurality of equivalent cutting edges. Despite its non-stick properties, an oxidised cover layer 2 has a finite service life in the area of the cutting edges, where the highest loads and temperatures occur during use. If the cover layer 2 now closes in the region of a cutting edge, the user is informed that this cutting edge has already been used. At the same time, a cover layer 2 is present at the unused cutting edges or the corresponding areas, so that a suitability for use of the indexable insert is still directly apparent.

In addition to the variant shown in FIG. 1, it is also possible, as shown in FIG. 2, for a cover layer 2 to be applied to a highly wear-resistant wear layer 1a, for example of Al ₂ O ₃ . In this case, a thickness of the wear layer 1a is greater than that of the cover layer 2, which acts primarily as an anti-adhesion layer or friction-reducing layer and was oxidized over its entire thickness.

Alternatively, as shown in FIG. 3, the cover layer 2 may also be applied to a wear layer 1a and oxidized with respect to its thickness only in a zone 4 near the free surface 3. For example, the cover layer 2 may have a thickness of about 1 μm and be oxidized in a near-surface zone 4 to a depth of 450 nanometers. This alternative proves to be advantageous if the cover layer 2 would not adhere sufficiently firmly to the wear layer 1a during oxidation over its entire thickness. For analogous reasons, it is also possible to apply a relatively thick cover layer 2 directly to a base body 1 and then to oxidize a near-surface zone 4 of the cover layer 2 (FIG. 4).

Example Series I 66 inserts with a base made of a hard metal were each coated in a coating system at a temperature of the body of about 1000 ⁰ C with titanium nitride (TiN), wherein the reaction gas of TiCl ₄ and N _{2 was} composed. After coating, the inserts were allowed to cool in the reaction chamber in an inert atmosphere to a treatment temperature between 425 and 550 ^° C and after reaching the treatment temperature for a holding time of 5 to 240 minutes kept at this temperature. During the holding time, the TiN cover layers of the inserts were oxidized with oxygen by introducing oxygen at a pressure of one bar into the constant-flow reaction chamber. Subsequently, the inserts were allowed to cool and removed from the reaction chamber.

After removal of the cutting inserts, the resulting surface colors of the oxidized TiN cover layers of the inserts were compared with shades of a RAL color chart and assigned accordingly. The colors of the cover layers are summarized in Table 1 for 36 inserts. As can be seen from the table, an almost arbitrary color adjustment can be carried out by an oxidizing treatment by varying the temperature and the holding time under otherwise constant conditions. In particular, with a single type of coating, colors are available which suitably reflect those according to ISO 513.

Table 1: Surface colors of oxidized titanium nitride coated inserts

Example series H

In a further series of experiments, 66 inserts analogously to Example Series I with Ti ₂ C (reaction gas: TiCl ₄ ZN ₂ ZCH ₄ ) coated and the thus applied Ti ₂ C coatings (layer thickness 5 microns) also analogous to Example Series I at different holding temperatures with oxygen oxidized. The oxidized Ti ₂ C- cover layers resulted, inter alia, the following colors: blue (holding temperature: 425 ⁰ C, hold time: 20 minutes), Rosy (holding temperature: 425 ⁰ C, hold time: .40 minutes); Green (holding temperature: 550 ⁰ C, holding time: 100 minutes), Violet (holding temperature: 550 ⁰ C, holding time: 80 minutes).

Example series III

In a third test series 66 inserts through chemical vapor deposition were at 1025 ⁰ C, first with an approximately 5 micron thick layer of Al ₂ O ₃ coated (reaction gas AlCl _3, H ₂ O) and a 0.5 micron thick layer on this layer by means of PVD from Titan applied. Subsequently, the cover layers of titanium were oxidized analogously to Example Series I at different holding temperatures and with oxygen.

The colors of the oxidized Ti cladding layers are summarized in Table 2 for 36 inserts. As can be seen, a wide range of different colors can be adjusted depending on the holding temperature and holding time.

Table 2: Surface colors of oxidized titanium coated inserts

.Image IV

In a fourth series of experiments, 66 inserts were coated by chemical vapor deposition at 1025 ^° C. with TiN and then with titanium. Subsequently, the cover layers of titanium were oxidized analogously to Example Series I at different holding temperatures and with oxygen.

The oxidized Ti cladding layers resulted in the same colors as Example Series III at the same holding temperatures and holding times.

Claims

claims

1. A method for producing a tool or tool part, in particular a cutting element such as a cutting plate whose surface has a color at least in areas through which a suitability of the tool or tool part for processing a particular material or a particular group of materials is visible, in particular a color according to a distinguishing color according to ISO 513, comprising the following steps: a) providing a base body of the tool or tool part, b) optionally applying at least one wear-resistant wear layer on a part or an entire surface of the base body, c) applying one consisting of a metal or a metal compound Cover layer, which is at least superficially oxidizable, on at least areas of the surface of the base body and / or the wear layer, d) setting a surface color by partial or complete oxidation of the cover layer in one Zone, which adjoins a free surface of the cover layer.

2. The method of claim 1, wherein the oxidation of the cover layer in step d) to a maximum of about 500 nanometers below the free surface thereof is performed.

3. The method of claim 1 or 2, wherein the cover layer is formed by deposition from the gas phase.

4. The method according to any one of claims 1 to 3, wherein the oxidizing treatment in step d) with oxygen or an oxygen-containing gas mixture at a temperature of at least 300 ⁰ C.

5. The method of claim 4, wherein the tool or tool part is brought at a temperature of 300 to 600 ⁰ C for 5 to 300 minutes in contact with oxygen or an oxygen-containing gas.

6. The method according to any one of claims 1 to 5, wherein the cover layer in a non-oxidizing atmosphere by chemical vapor deposition (CVD) at a temperature of the body of more than 650 ⁰ C, in particular more than 800 ⁰ C, is applied, after which Tool or the tool part to a temperature of 300 to 600 ⁰ C. allowed to cool and at this temperature, the cover layer with oxygen or an oxygen-containing gas is brought into contact to adjust a surface color.

7. The method according to any one of claims 1 to 6, wherein the cover layer with a thickness of 0.5 to 2.5 .mu.m, in particular 0.5 to 0.5 microns, is applied.

8. The method according to any one of claims 1 to 7, wherein in step c) a cover layer of a transition metal of Group IV, V, VI of the Periodic Table of the Elements or their alloys, in particular titanium, is applied.

9. The method according to any one of claims 1 to 7, wherein in step c) a cover layer of a metal carbide, metal nitride or metal carbonitride of one of the elements titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten is applied.

10. cutting element, in particular cutting plate for machining of

Materials comprising a base body, optionally at least one on a part or an entire surface of the body applied wear-resistant wear layer and at least on areas of the surface of the base body and / or the wear layer applied cover layer, wherein the cover layer of a metal, a metal nitride, a metal carbide or a metal carbonitride and is partially or completely oxidized in a zone which adjoins a free surface of the cover layer and extends to a maximum of about 500 nanometers below the same.

11. Cutting element according to claim 10, wherein the cover layer has a thickness of 0.05 .mu.m to 1.5 .mu.m, in particular 0.05 to 0.5 .mu.m.

12. Cutting element according to claim 10 or 11, wherein the metal is a transition metal of group IV, V, VI of the Periodic Table of the Elements or their alloys, in particular titanium.

13. The cutting element according to claim 10, wherein the cover layer consists of an at least partially partially oxidized layer of a metal carbide, metal nitride or metal carbonitride of one of the elements titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten.