cBN Cutting Tool Coating for Hardened Steel Edge Notching
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Solution Overview
Problem
Conventional surface-coated cBN-based sintered tools experience edge notching and reduced tool life when used in high-speed cutting operations on hardened steels due to insufficient high-temperature strength and heat resistance of their hard coating layers.
Innovation Solution
A cutting tool with a hard coating layer comprising a lower layer of Ti—Al composite nitride ([Ti1-XAlX]N) and an upper layer with an alternately layered structure of Ti—Al composite nitride and Ti nitride (TiN) thin layers, providing enhanced heat resistance, high-temperature hardness, and shock-resistant strength, which prevents edge notching and extends tool life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single-layer Ti-Al composite nitride coating is used, then heat resistance and high-temperature hardness are improved, but high-temperature strength and shock-resistant strength are insufficient
Solution Approach 1:
The coating is divided into multiple functional layers: a lower layer of Ti-Al composite nitride for heat resistance and high-temperature hardness, and an upper layer with alternating Ti-Al nitride and TiN thin layers for enhanced high-temperature strength and shock resistance. This segmentation allows each layer to specialize in specific performance requirements.
Solution Approach 2:
The invention uses composite coating structures combining different nitride materials (Ti-Al composite nitride and TiN) with complementary properties. The Ti-Al nitride provides heat resistance and hardness, while TiN layers contribute high-temperature strength and shock resistance, creating a synergistic composite coating system.
2Productivity
If cutting speed is increased for labor saving and productivity, then productivity is improved, but edge notching occurs due to high heat and mechanical load
Solution Approach 1:
The multi-layer coating structure is designed in advance to cushion and absorb the extreme thermal and mechanical loads generated during high-speed cutting. The TiN layers act as shock-absorbing elements that prevent edge notching before it occurs, enabling sustained high-speed operation.
Solution Approach 2:
The invention changes the coating structure parameters from a single-layer configuration to a multi-layer configuration with specific thickness ratios. The upper layer thin layers (0.05-0.5 μm) alternate between Ti-Al nitride and TiN, creating a structure that optimizes both heat resistance and shock resistance for high-speed cutting conditions.
3Duration of action of moving object
If a thicker coating layer is used to improve wear resistance, then wear resistance is improved, but edge notching resistance deteriorates
Solution Approach 1:
Different regions of the coating have different thicknesses and compositions optimized for their specific functions. The lower layer is thicker (1.0-3.0 μm) for overall wear resistance, while the upper layer consists of thin alternating layers (0.05-0.5 μm each) that provide shock resistance without adding excessive thickness that would cause notching.
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 maintains excellent surface finish and wear resistance over an extended period during high-speed cutting operations on hardened steels, ensuring labor savings, energy savings, and cost reduction in metal cutting operations.
Implementation Method 1
a hard coating layer vapor-deposited on the surface of the main body
Data Source
AI summary
A cutting tool made of surface-coated cubic boron nitride-based ultrahigh pressure sintered material, comprising a cutting insert main body formed by ultrahigh pressure sintering of compact composed of titanium nitride, aluminum and/or aluminum oxide, and boron nitride, and a hard coating layer vapor deposited on the main body. The main body has a texture containing cubic boron nitride, titanium nitride and reaction product. The hard coating layer has a lower layer of composite nitride having a composition of [Ti1-XAlX]N, where X is in a range from 0.40 to 0.60 in an atomic ratio, and the upper layer comprises a thin layer A having the composition of [Ti1-XAlX]N, where X is in a range from 0.40 to 0.60 in an atomic ratio, and a thin layer B consisting of a Ti nitride (TiN). The upper layer has a consisting of the thin layer A and a thin layer B layered alternately.