Surface-Coated Cutting Tool With Alternating Nitride Layers
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Solution Overview
Problem
Existing surface-coated cutting tools face issues with chipping and wear resistance, particularly when processing difficult-to-cut materials, leading to reduced tool life and increased costs due to high tool edge temperatures and inadequate adhesion between coating layers.
Innovation Solution
A surface-coated cutting tool with a multilayer structure comprising alternating layers of specific compositions and thicknesses, including a first alternating layer with Al and Cr nitride or carbonitride, and a second alternating layer with Al and Ti nitride or carbonitride, formed through physical vapor deposition, along with an adhesion layer to enhance bonding with the base material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single-layer hard coating is applied to improve wear resistance, then wear resistance is improved, but chipping resistance deteriorates due to brittleness
Solution Approach 1:
The coating is divided into multiple alternating layers with different compositions and properties. The first alternating layer contains hard phases for wear resistance, while the second alternating layer contains ductile phases for chipping resistance. This segmentation allows each layer to perform its specific function, resolving the contradiction between wear resistance and chipping resistance.
Solution Approach 2:
The invention uses composite coating structures where different material phases (hard and ductile) are combined in alternating layers. The first alternating layer comprises hard phases such as TiN, TiCN, or TiC, while the second alternating layer comprises ductile phases such as AlCrN or AlTiN. This composite structure enables simultaneous achievement of wear resistance and chipping resistance.
2Productivity
If cutting speed is increased to improve productivity, then productivity is improved, but tool edge temperature increases leading to reduced tool life
Solution Approach 1:
The invention changes the physical and chemical parameters of the coating layers to enable high-speed cutting. The specific composition ratios, layer thicknesses, and material phases are optimized to provide thermal stability and heat resistance, allowing the tool to maintain performance at elevated temperatures generated by high cutting speeds.
3Reliability
If alternating layers with different characteristics are formed to improve both wear resistance and toughness, then both properties are improved, but manufacturing complexity increases
Solution Approach 1:
The coating structure is segmented into two main alternating layer types that can be systematically repeated. This segmentation provides a manageable framework where each layer type has defined composition ranges and thickness specifications, making the complex multi-layer structure easier to design and manufacture through standardized parameter sets.
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 tool exhibits improved chipping resistance and wear resistance, extending tool life and maintaining cutting edge quality under severe conditions by optimizing layer thickness ratios, atomic ratios, and adhesion, thus addressing the limitations of previous technologies.
Implementation Method 1
forming the first alternating layer by alternately layering the one or plurality of the first layers and the one or plurality of the second layers through physical vapor deposition; and forming the second alternating layer on the first alternating layer by alternately layering the one or plurality of the third layers and the one or plurality of the fourth layers through the physical vapor deposition
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A surface-coated cutting tool includes a base material and a coating film formed on a surface of the base material. The coating film includes a first alternating layer and a second alternating layer formed on the first alternating layer. The first alternating layer includes first and second layers. The second alternating layer includes third and fourth layers. One or a plurality of the first layers and one or a plurality of the second layers are layered alternately, and one or a plurality of the third layers and one or a plurality of the fourth layers are layered alternately. Each of the one or plurality of the first layers is composed of a nitride or carbonitride of AlaCrbM11-a-b. Each of the one or plurality of the second layers is composed of a nitride or carbonitride of AlcTidM21-c-d. Each of the one or plurality of the third layers is composed of a nitride or carbonitride of AleTifM31-e-f. Each of the one or plurality of the fourth layers is composed of a nitride or carbonitride of AlgTihM41-g-h. Each of the M1, the M2, the M3, and the M4 is one or more elements selected from a group consisting of a group 4 element, a group 5 element, a group 6 element except Cr and Ti in a periodic table, Si, and B.