Multilayer Braze Joint for cBN/PCD Cutting Tool Bond Strength
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Solution Overview
Problem
Existing cutting tools with cBN or PCD cutting edge tips face challenges in achieving strong bonding strength with cemented carbide supporting bodies, leading to inadequate tool life and performance in metal cutting applications.
Innovation Solution
A braze joint comprising a first layer of TiC, a second layer of metallic Ni, Cu, and Ti, and a third layer of metallic Ag and Cu is used to bond the cBN or PCD cutting edge tip to a cemented carbide supporting body, with specific thicknesses and compositions to enhance bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a simple braze material is used to bond the cutting edge tip to the supporting body, then the manufacturing process is simple, but the bonding strength is insufficient leading to inadequate tool life
Solution Approach 1:
The braze joint is segmented into three distinct layers with different compositions and functions: a first layer (10-400 nm) adjacent to the supporting body, a second layer (0.5-8 μm) in the middle, and a third layer (4-145 μm) adjacent to the cutting edge tip. Each layer is optimized for specific bonding requirements, allowing the complex multi-layer structure to achieve superior bonding strength while managing the complexity through functional specialization.
Solution Approach 2:
The braze joint employs composite material structure with three layers having different compositions. The first layer contains reactive metals for strong bonding to the supporting body, the second layer provides intermediate bonding properties, and the third layer offers compatibility with the cutting edge tip material. This composite approach enables the braze joint to achieve bonding strength exceeding that of the cutting edge tip itself.
2Strength
If a thick braze joint is used to ensure strong bonding, then the bonding strength is improved, but the tool life is reduced due to increased heat accumulation and stress concentration
Solution Approach 1:
The invention precisely controls the thickness parameters of each braze layer: the first layer is 10-400 nm, the second layer is 0.5-8 μm, and the third layer is 4-145 μm. The total braze joint thickness is controlled at 5-150 μm. These parameter optimizations ensure sufficient bonding strength while minimizing heat accumulation and stress concentration, thereby extending tool life.
Solution Approach 2:
Different regions of the braze joint have different thicknesses and compositions optimized for their specific functions. The first layer near the supporting body is thin (10-400 nm) for strong bonding, the middle second layer (0.5-8 μm) provides transition, and the third layer near the cutting tip (4-145 μm) ensures compatibility. This local quality differentiation achieves optimal bonding strength while minimizing negative effects on tool life.
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 new braze joint provides excellent bonding strength, resulting in extended tool life and improved performance in metal cutting operations such as turning and milling.
Implementation Method 1
a first layer of TiC situated next to the supporting body
Implementation Method 2
provides excellent bonding strength
Implementation Method 3
a second layer comprising in average at least 5 wt % metallic Ni, in average 25-60 wt % metallic Cu and in average 15-45 wt % metallic Ti
Implementation Method 4
a third layer, with an average thickness of 4-145 μm, comprising metallic Ag and metallic Cu
Data Source
AI summary
A cutting tool includes a supporting body and a cBN or PCD cutting edge tip attached to the supporting body via a 5-150 μm braze joint. The supporting body is cemented carbide having 3-25 wt % of a metallic binder, optionally up to 25 wt % of carbides or carbonitrides of one or more elements of group 4, 5, or 6, and the rest WC. The metallic binder includes at least 40 wt % Ni, and the braze joint has, in the order from the supporting body, a first layer of TiC situated next thereto, with an average thickness of 10-400 nm, a second layer, with an average thickness of 0.5-8 μm, having in average at least 5 wt % metallic Ni, in average 25-60 wt % metallic Cu and in average 15-45 wt % metallic Ti, and a third layer, with an average thickness of 4-145 μm, having metallic Ag and metallic Cu.