Cutting Tool Coating Masking for Adhesion Control

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Solution Overview

Problem

The existing methods for sharpening and recoating cutting tools, such as those made of tungsten carbide, lead to undesirable coating accumulation, causing adhesion issues and tool failure after multiple sharpening cycles, and previous solutions like chemical removal or machining are costly or interfere with tool geometry.

Innovation Solution

A method involving grinding a cutting tip to form a sharpened intermediate tool, masking specific portions to expose only the cutting edge, and depositing a wear-resistant material onto the exposed areas to form a sharpened cutting tool, ensuring controlled coating thickness and preventing excessive coating accumulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the entire cutting tool is exposed to the coating process after grinding, then the recently ground surfaces are coated, but excessive coating thickness accumulates on non-ground surfaces causing adhesion failure

Engineering Contradiction:

Improvecoating adhesionVSAvoidcoating thickness

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The cutting tool surface is divided into two distinct zones: a first surface that is ground and requires coating, and a second surface that is not ground and should not receive coating. This segmentation allows selective coating application only where needed, preventing excessive coating accumulation on non-ground surfaces while ensuring proper coating on ground surfaces, thereby maintaining coating adhesion reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different surfaces of the cutting tool are given different coating treatments based on their functional requirements. The ground surface receives a wear-resistant coating to enhance durability, while the non-ground surface is intentionally left uncoated or minimally coated to avoid adhesion failure. This local differentiation of coating quality resolves the contradiction between needing sufficient coating thickness for protection and avoiding excessive thickness that causes delamination

Inventive Principle:

Principle #3Local quality

2Reliability

If chemical processes are used to remove coating before recoating, then the coating can be reapplied, but the Cobalt is removed from the cutting tool surface altering the carbide microstructure

Engineering Contradiction:

Improvecoating adhesionVSAvoidcarbide microstructure

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

Instead of removing the existing coating before recoating, the method performs a preliminary action of selectively masking the non-ground surface before the coating process. This prevents the need for chemical removal processes that would damage the carbide microstructure and remove Cobalt from the tool surface, while still allowing proper coating adhesion on the ground surface

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The existing coating on non-ground surfaces, which previously caused adhesion failure when accumulated, is converted from a harmful element into a beneficial one by being selectively preserved through masking. The method transforms the problem of coating accumulation into an opportunity to maintain a durable coating on ground surfaces while preventing the adhesion failure that would occur with repeated full-surface recoating

Inventive Principle:

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

3Reliability

If machining processes are used to remove previous coatings, then the tool can be recoated, but additional machining processes are costly and may negatively interfere with tool geometry

Engineering Contradiction:

Improvecoating adhesionVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The masking step is performed as a preliminary action before the coating process, eliminating the need for subsequent machining operations to remove excess coating. This simple masking approach is far less costly and less intrusive than machining processes, while still achieving the goal of preventing excessive coating accumulation and ensuring proper adhesion

Inventive Principle:

Principle #10Preliminary 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

This method extends the interval between sharpening operations, increases the number of sharpening cycles, and maintains tool sharpness by controlling the wear-resistant coating thickness, thereby enhancing tool life and preventing premature failure.

Implementation Method 1

depositing a wear-resistant material onto the exposed portion of the planar face of the intermediate cutting tool

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

The coating is typically applied by immersing the tool in an environment containing a mixture of gas including titanium aluminum nitride or titanium nitride for six to eight hours. During exposure to the gas mixture, a coating is deposited on all surfaces exposed to this environment.

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Data Source

PatentUS9005706B2Method for masking and coating cutting tool and cutting tool having wear-resistant coating in selected locations

Publication Date: 2015.04.14 AMERICAN AXLE & MANUFACTURING INC

AI summary

A method in which a cutting tip of an intermediate cutting tool is masked and a wear-resistant material is deposited onto the exposed portion of the intermediate cutting tool to form a sharpened cutting tool. A finished cutting tool is also provided.