HIPIMS Coated Cutting Tool for Built-Up Edge and Wear Reduction

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Solution Overview

Problem

Cutting tools used for machining ISO-S materials, such as titanium and heat-resistant super alloys, face challenges with high temperature generation due to poor heat conductivity and work hardening, leading to increased wear and built-up edge issues, which affect tool life and surface finish quality.

Innovation Solution

A coated cutting tool with a substrate of cemented carbide, cermet, or ceramics, featuring a High Power Impulse Magnetron Sputtering (HIPIMS)-deposited nitride layer of Ti, Zr, Hf, V, Ta, Nb, Cr, or Al, combined with a HIPIMS-deposited (AlaMe1−a)2O3 oxide layer, where the oxide layer is situated above the nitride layer, enhancing adhesion and wear resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional CVD or PVD coatings are used on cutting tools for machining ISO-S materials, then the tool can perform basic cutting operations, but the tool experiences high wear and built-up edge formation due to high temperatures and poor heat conductivity of the workpiece material

Engineering Contradiction:
Improvetool lifeVSAvoidbuilt-up edge and wear
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies a multi-layer composite coating structure consisting of alternating nitride layers (e.g., (Ti,Al)N) and oxide layers (e.g., Al2O3) deposited by HIPIMS. This composite structure combines the advantages of nitride layers (hardness, thermal stability) and oxide layers (oxidation resistance, low adhesion to workpiece material), thereby reducing built-up edge formation and wear while extending tool life when machining ISO-S materials like titanium and heat-resistant super alloys.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent utilizes HIPIMS (High Power Impulse Magnetron Sputtering) deposition process which changes the physical and chemical parameters of the coating during deposition. By controlling pulse duration, power density, and gas pressure parameters, the process creates coatings with enhanced density, reduced porosity, and improved adhesion, which directly reduces wear and prevents built-up edge formation under high-temperature machining conditions.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If higher cutting speeds are used to increase productivity, then machining efficiency improves, but temperature generation increases due to poor heat conductivity of ISO-S materials, leading to accelerated wear and tool failure

Engineering Contradiction:
Improvecutting speedVSAvoidtemperature at cutting zone
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The alternating nitride and oxide layers in the composite coating create a thermally stable structure that resists thermal degradation at high cutting speeds. The oxide layers provide thermal barrier properties while the nitride layers maintain structural integrity, allowing the tool to sustain higher cutting speeds without thermal failure or accelerated wear.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The coating structure provides different local properties at different layers: nitride layers offer high hardness and thermal stability at the wear surface, while oxide layers provide oxidation resistance and reduced workpiece material adhesion in the intermediate zones. This localized functional distribution enables the tool to withstand high-temperature conditions during high-speed machining of ISO-S materials.

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If standard PVD coatings are used, then the coating process is relatively simple, but the coating structure and properties are insufficient to prevent built-up edge and provide adequate wear resistance for demanding ISO-S material machining

Engineering Contradiction:
Improvecoating deposition processVSAvoidwear resistance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

While maintaining a single HIPIMS deposition process (ease of manufacture), the patent creates a composite multi-layer coating structure through automated alternating deposition of nitride and oxide materials. This approach combines the simplicity of a single deposition technology with the enhanced performance of composite materials, achieving superior wear resistance and built-up edge prevention compared to standard single-layer or multi-step PVD coatings.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The HIPIMS deposition process employs periodic pulsing of power to the magnetron targets, creating alternating layers of nitride and oxide materials in a systematic sequence. This periodic deposition action, controlled by timing parameters, automatically generates the composite layered structure that provides enhanced wear resistance and prevents built-up edge formation while maintaining process simplicity.

Inventive Principle:
Principle #19Periodic action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution significantly reduces built-up edge formation and allows for higher cutting speeds and extended tool life by improving wear resistance and surface finish quality during machining of ISO-S materials.

Implementation Method 1

a coating comprising a nitride layer which is a High Power Impulse Magnetron Sputtering (HIPIMS)-deposited layer

Methodology Applied
Scientific EffectMagnetron sputtering: Sputtering

Data Source

PatentUS11104987B2Coated cutting tool and a method for its production
Publication Date: 2021.08.31 WALTER AG

AI summary

A coated cutting tool includes a substrate of cemented carbide, cermet, cBN, ceramics or HSS and a coating of a nitride layer, which is a High Power Impulse Magnetron Sputtering (HIPIMS) deposited layer of a nitride of one or more of Ti, Zr, Hf, V, Ta, Nb, Cr, Si and Al, and a HIPIMS-deposited oxide layer being an (AlaMe1−a)2O3 layer, 0.05≤a≤1, wherein Me is one or more of Ti, Mg, Ag, Zr, Si, V, Fe, Hf, B and Cr. The oxide layer is situated above the nitride layer. Also, a method is disclosed for producing a coated cutting tool having the nitride layer and oxide layer, the nitride layer and the oxide layer being deposited by a HIPIMS process.