Tap drill with enhanced performance

Abstract

The present invention relates to a tap drill comprising a substrate and a coating, wherein the coating is deposited on at least a portion of the substrate comprising the head of the drill, the coating comprising a first layer deposited directly on the substrate and a second layer deposited atop the first layer, wherein the first layer is a wear resistant layer of (Al, Cr)N deposited by Hi PIMS and the second layer is a friction reduction layer, wherein the second layer is a metal carbide layer or a metal-carbide comprising layer deposited by using a physical vapor deposition (PVD) process of the type magnetron sputtering, preferably of the type HiPIMS.

Claims

1. A tap drill comprising: a substrate and a coating, wherein the coating is deposited on at least a portion of the substrate comprising a head of the drill, the coating comprising a first layer deposited directly on the substrate and a second layer deposited atop the first layer, wherein the first layer is a wear resistant layer of (Al, Cr)N deposited by HiPIMS and the second layer is a friction reduction layer, wherein the second layer is a metal carbide layer deposited by using a physical vapor deposition (PVD) process of the type magnetron sputtering.

2. The tap drill according to claim 1, wherein the second layer is deposited by using HiPIMS.

3. The tap drill according to claim 1, wherein the metal carbide layer is a titanium carbide layer or a tungsten carbide layer.

4. A method for producing a tap drill comprising a substrate and a coating, the method comprising: depositing the coating on at least a portion of the substrate comprising a head of the drill, the coating comprising a first layer and a second layer; using a HiPIMS process to deposit the first layer directly on the substrate; and depositing the second layer atop the first layer; wherein the first layer is a wear resistant layer of (AlCr)N, and wherein the second layer is a friction reduction layer, and the second layer is a metal carbide layer.

5. The method for producing a tap drill according to claim 4, wherein the second layer is a titanium carbide layer and is deposited by sputtering of Ti or TiC targets in an atmosphere comprising argon and a carbon-containing gas.

6. The method for producing a tap drill according to claim 5, comprising using HiPIMS techniques for sputtering of the Ti or TiC targets.

Description

(1) FIG. 1 shows a coating for tap drill according to the present invention.

(2) FIG. 2 shows the benefits of the present invention in comparison with the state of the art.

(3) FIG. 1 shows in the upper part a picture of a tap drill 1 according to the present invention. The tap drill 1 comprises a substrate 2 and a coating 3. The coating 3 is deposited on at least a portion of the substrate 2 comprising the head of the drill 1.

(4) The coating 3 comprises a first layer 4. The first layer 4 is deposited directly on the substrate 2. The coating 3 comprises a second layer 5. The second layer 5 is deposited atop the first layer 4.

(5) The first layer 4 is a wear resistant layer of (Al, Cr)N. The first layer 4 is deposited by HiPIMS. The second layer 5 is a friction reducing layer. The second layer 5 is a metal carbide layer or a metal-carbide comprising layer. It can also be preferably of carbon-containing titanium nitride or titan carbonitride or diamond like carbon doped with tungsten or a tungsten carbide layer. The second layer 5 is deposited using physical a vapor deposition (PVD) process, preferably of the type magnetron sputtering, preferably of the type HiPIMS.

(6) This can be seen in FIG. 2, which shows n a diagram the relative tool life of different coatings and/or depositing methods. The tool life of the Benchmark tool is defined to 100%. In FIG. 2 the Benchmark tool has been deposited with TiN. An AlCrN coating shows the same tool life of 100% compared to the Benchmark. An AlCrN+TiN coating, which has been deposited by Arc deposition and post-treated in order to reduce roughness shows a tool life of 160% compared to the Benchmark. A significant tool life increase can be seen. An AlCrN+WC/C coating that has been deposited by Arc deposition shows a tool life of 3% compared to the Benchmark. An AlCrN+WC/C coating deposited by HiPIMS deposition shows a tool life of 710% compared to the Benchmark.

(7) AlCrN+TiN coating (deposited by arc plus post-treatment in order to reduce roughness) show significant tool life increase vs. Benchmark.

(8) Smooth coating surface has advantage.

(9) Coatings produced by sputtering, in particular by HiPIMS show much better performance compared to coatings produced by arc, in particular if arc-deposited coating is without post-treatment.

(10) HiPIMS provides the possibility to produce dense and smooth coatings. Coating like the AlCrN+WC/C coating shown in FIG. 1 can be produced in one deposition run. AlCrN+Ti(CN) coating shows increase in the tool life. This is actually the main topic for application.

(11) Preferably the first layer 4 is deposited by sputtering of Cr targets in a nitrogen reactive atmosphere (comprising argon and nitrogen or only nitrogen) by using HiPIMS techniques.

(12) According to a preferred embodiment of the present invention, the second layer 5 is a tungsten carbide comprising layer of the type WC/C (WC+C) which can deposited by sputtering of WC targets in an atmosphere comprising argon and a carbon-containing gas, preferably acetylene gas (i.e. preferably in an atmosphere comprising argon and acetylene gas). According to a variant of this preferred embodiment instead of conventional sputtering techniques HiPIMS techniques are used for sputtering of the WC targets.

(13) According to a further preferred embodiment of the present invention, the second layer 5 is a titanium carbide comprising layer which can be deposited by sputtering of Ti or TiC targets in an atmosphere comprising argon and a carbon-containing gas, preferably acetylene gas (i.e. preferably in an atmosphere comprising argon and acetylene gas). According to a variant of this preferred embodiment instead of conventional sputtering techniques HiPIMS techniques are used for sputtering of the Ti or TiC targets.