Conditioned End Mill Cutting Edge for Chatter Reduction
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Solution Overview
Problem
Milling of non-ferrous materials like aluminum often results in chatter due to sharp cutting edges and high spindle rotational speeds, leading to poor surface finish, reduced tool life, and potential spindle bearing damage.
Innovation Solution
A rotary cutting tool with an end mill design featuring an inner eccentric relief with a relief angle of less than 5 degrees and an outer eccentric relief with a relief angle between 5 and 15 degrees, which reduces chatter and improves cutting performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sharp cutting edges are used for machining non-ferrous materials, then cutting performance is improved, but chatter increases
Solution Approach 1:
The patent applies different relief angles to different zones of the cutting edge. The inner eccentric relief has a smaller relief angle (0-5 degrees) while the outer eccentric relief has a larger relief angle (5-15 degrees). This local differentiation allows the cutting edge to maintain sharpness where needed while providing stability where required, resolving the contradiction between cutting performance and chatter reduction.
Solution Approach 2:
The patent changes the relief angle parameter along the length of the cutting edge. By varying the relief angle from the inner region (smaller angle) to the outer region (larger angle), the cutting edge properties are optimized to reduce chatter while maintaining effective cutting performance. This parameter variation directly addresses the technical contradiction.
2Productivity
If high spindle rotational speeds are used, then productivity is improved, but chatter increases
Solution Approach 1:
The differentiated relief structure with inner and outer eccentric reliefs provides local stability characteristics that allow high spindle speeds to be used without excessive chatter. The inner region with smaller relief angle maintains cutting effectiveness while the outer region with larger relief angle provides damping, enabling high-speed operation.
3Shape
If inner eccentric relief with small relief angle is used, then cutting edge sharpness is improved, but sliding friction increases
Solution Approach 1:
The patent compensates for the increased sliding friction in the inner relief region by providing a larger relief angle in the outer relief region. This local quality differentiation balances the friction characteristics across the cutting edge while maintaining the sharpness needed for effective cutting.
4Force
If outer eccentric relief with larger relief angle is used, then sliding friction is reduced, but cutting edge sharpness decreases
Solution Approach 1:
The patent maintains cutting edge sharpness in the inner relief region by using a smaller relief angle (0-5 degrees), while applying the larger relief angle (5-15 degrees) to the outer relief region where it is needed for friction reduction. This spatial differentiation resolves the contradiction between sharpness and friction reduction.
Data Source
AI summary
A rotary cutting tool includes a shank portion and a cutting portion extending from the shank portion to a cutting tip. The cutting portion has a plurality of blades separated by flutes. Each of the blades includes a relief surface and a radial cutting edge formed at an intersection between a respective flute and the relief surface. The relief surface includes an inner eccentric relief immediately adjacent the radial cutting edge and an outer eccentric relief immediately adjacent the inner eccentric relief. The inner eccentric relief is formed with an inner eccentric relief angle, β, of less than about 5 degrees, and wherein the outer eccentric relief is formed with an outer eccentric relief angle, β, of between about 5 degrees and about 15 degrees. A method of making the rotary cutting tool is also described.