CBN Cutting Tool Coating Structure for Peeling and Flank Wear
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Solution Overview
Problem
Existing cutting tools with cubic boron nitride sintered materials and conventional hard heat-resistant coatings suffer from peeling and wear issues during high-efficiency cutting processes due to droplets in the coating, leading to reduced wear resistance and peeling resistance.
Innovation Solution
A cutting tool with a substrate made of cubic boron nitride sintered material and a coating featuring a MAIN layer with titanium or chromium-based crystal grains in the cubic crystal system, where the number of voids on the flank face is less than on the rake face, enhancing wear and peeling resistance by absorbing impact and reducing abrasive wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-feed rate cutting is performed to improve productivity, then cutting efficiency increases, but coating peeling and wear occur more severely
Solution Approach 1:
The patent enables high-feed rate cutting by changing the coating parameters - specifically controlling Ti atomic ratio to 0.3-0.7 and voids to 30 or less per 100μm. These parameter changes create a coating that can withstand the increased mechanical stresses of high-feed rate cutting without peeling or excessive wear, thus maintaining tool life while improving productivity.
2Reliability
If the number of voids in the coating is increased to absorb impact, then peeling resistance improves, but manufacturing precision may be affected
Solution Approach 1:
The patent optimizes the void count parameter to be 30 or less per 100μm, finding the optimal balance between impact absorption and coating quality. This parameter setting provides sufficient voids to absorb cutting impacts and improve peeling resistance while maintaining manufacturing precision and coating integrity.
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 cutting tool exhibits improved wear resistance and peeling resistance, with specific configurations of voids and droplets in the coating layer effectively suppressing peeling and flank wear, maintaining tool performance during high-feed rate cutting.
Implementation Method 1
the number of voids per 100 μm in length of the MAIN layer on the flank face in a cross section of the MAIN layer obtained when the MAIN layer is cut along a plane including a normal to the flank face, is 30 or less
Implementation Method 2
the MAIN layer including crystal grains of M x Al 1-x N in the cubic crystal system, in the M x Al 1-x N, the metal element M having an atomic ratio x of 0.3 or more and 0.7 or less
Data Source
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AI summary
A cutting tool comprises a rake face and a flank face, the cutting tool being composed of a substrate made of a cubic boron nitride sintered material and a coating provided on the substrate, the cubic boron nitride sintered material including cubic boron nitride, the coating including a MAIN layer, in the MAIN layer, M representing a metal element including titanium, chromium, or both, the MAIN layer including crystal grains of MxAl1-xN in the cubic crystal system, in the MxAl1-xN, the metal element M having an atomic ratio x of 0.3 or more and 0.7 or less, the cubic boron nitride being contained at a ratio of 20% by volume or more with respect to the cubic boron nitride sintered material, nF < nR being satisfied, where nF represents a number of voids per 100 µm in length of the MAIN layer on the flank face in a cross section of the MAIN layer obtained when the MAIN layer is cut along a plane including a normal to the flank face, and nR represents a number of voids per 100 µm in length of the MAIN layer on the rake face in a cross section of the MAIN layer obtained when the MAIN layer is cut along a plane including a normal to the rake face, nD being 3 or less, where nD represents a number of droplets per 100 µm in length of the MAIN layer on the flank face in a cross section of the MAIN layer obtained when the MAIN layer is cut along a plane including a normal to the flank face.