NbN Coated Carbide Insert for Titanium Milling

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Solution Overview

Problem

Machining of titanium-based alloys faces challenges with short tool life and low metal removal rates due to high temperatures and unfavorable temperature distribution, necessitating improved cutting tool inserts that can withstand mechanical and thermal shocks.

Innovation Solution

A cutting tool insert with a cemented carbide substrate comprising 11-12.5 wt% cobalt, 0.2-1.2 wt% chromium, and 86.3-88.4 wt% tungsten carbide, coated with a layer of NbN, which enhances cutting properties and tool life through improved thermal and mechanical shock resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If coated carbide substrates with high cobalt-content are used, then cutting performance is improved, but resistance to mechanical shocks and thermal shocks deteriorates

Engineering Contradiction:

Improvecutting performanceVSAvoidresistance to mechanical shocks and thermal shocks

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention applies parameter changes by precisely controlling the cobalt content within a narrow range of 10.4-12.7 wt% and chromium content of 0.2-1.2 wt%, rather than using high cobalt content indiscriminately. This optimized composition, combined with specific coercivity requirements (11-19 kA/m), resolves the contradiction by finding the optimal balance point that provides sufficient cutting performance while maintaining adequate shock resistance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention employs composite materials by combining cemented carbide substrate with specific coating layers. The substrate itself is a composite of tungsten carbide grains bound by a controlled cobalt-chromium binder phase, and this is further combined with coating layers that provide additional protection. This composite structure allows the tool to achieve both good cutting performance and improved resistance to mechanical and thermal shocks.

Inventive Principle:

Principle #40Composite materials

2Duration of action of stationary object

If wet machining is used to minimize heat generation, then tool life is increased, but metal removal rate decreases

Engineering Contradiction:

Improvetool lifeVSAvoidmetal removal rate

Core Design Contradiction:

Duration of action of stationary objectVSProductivity

Solution Approach 1:

The invention converts the harmful high temperatures generated during dry machining into beneficial effects by using heat-resistant coating materials and optimizing the substrate composition to withstand elevated temperatures. The coating layers and controlled cobalt-chromium content enable the tool to operate effectively at higher temperatures, allowing dry machining to achieve both acceptable tool life and high metal removal rates, thus converting the thermal challenge into an operational advantage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS9523145B2Coated cutting insert

Publication Date: 2016.12.20 SECO TOOLS AB

AI summary

A cutting tool insert having a cemented carbide substrate and a coating including a layer of NbN, wherein the cemented carbide substrate includes 11-12.5 wt % cobalt, 0.2-1.2 wt % chromium, and 86.3-88.4 wt % wolfram carbide.