CBN Turning Insert Geometry for Smooth Finish and Low Wear
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Solution Overview
Problem
Existing turning inserts with cubic boron nitride (CBN) cutting edges face limitations in achieving smooth surface finishes and low wear during longitudinal turning of hardened steels, particularly those above 55 HRc, and are not versatile for turning in opposite directions.
Innovation Solution
A turning insert design featuring a head portion connected to a stem portion with a cutting edge that includes a surface generating cutting edge, major cutting edge portions, and corner cutting edges, optimized for improved surface finish and reduced wear, allowing for efficient turning in both directions by adjusting the angle and curvature of the cutting edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional turning inserts with CBN cutting edges are used for longitudinal turning of hardened steel, then the inserts can machine the material, but the surface finish is rough and insert wear is high
Solution Approach 1:
The cutting edge is designed with different zones having distinct geometric properties: a surface-generating portion with specific curvature radius (0.2-2.0 mm) for achieving smooth surface finish, and major cutting edge portions with specific angles (5-20°) for efficient material removal and reduced wear. This local differentiation of cutting edge quality allows simultaneous optimization of surface finish and tool life
Solution Approach 2:
The patent optimizes specific geometric parameters of the cutting edge including the radius of curvature of the surface-generating portion (0.2-2.0 mm), the angles of major cutting edge portions (5-20°), and the relative positions of different cutting edge zones. These parameter changes transform the cutting edge geometry to achieve both smooth surface finish and reduced insert wear during longitudinal turning of hardened steel
2Adaptability or versatility
If conventional turning inserts are designed for longitudinal turning, then they can machine in one direction, but they are not versatile for turning in opposite directions
Solution Approach 1:
The cutting edge is designed with asymmetric geometry relative to the longitudinal centerline of the insert. The surface-generating portion and major cutting edge portions are positioned and angled asymmetrically, allowing the insert to be used for longitudinal turning in both forward and reverse directions while maintaining optimal cutting performance. This asymmetric design provides versatility without requiring complex additional components
Solution Approach 2:
The insert geometry is designed to perform multiple functions: the same cutting edge configuration enables effective longitudinal turning in both directions, and the corner portions can also perform radial grooving operations. This multi-functionality increases adaptability while avoiding the need for multiple specialized inserts
Data Source
AI summary
A turning insert includes a head portion connected to a stem portion. A CBN cutting edge includes a surface generating cutting edge and two major cutting edge portions, such that each major cutting edge portion forms an angle of 5-20° in relation to a tangent line of the cutting edge at a forward point of the cutting edge.