Serrated End Mill Teeth for Chatter Reduction
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Solution Overview
Problem
End mills face challenges in achieving effective roughing and semi-finishing operations due to issues like chatter, and existing designs often require trade-offs between reducing chatter and maintaining robustness and economic competitiveness, especially when machining difficult materials like titanium.
Innovation Solution
The design incorporates cutting teeth with repetitive and/or symmetric features, including serrated and non-serrated teeth, where serrations are spaced apart from the end relief, and rake cutting sub-surfaces have actual internal cutting angles greater than imaginary angles, with specific dimensions and arrangements to minimize chatter and heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If end mills use asymmetric elements to reduce chatter, then chatter is reduced, but device complexity increases and manufacturing cost increases
Solution Approach 1:
The patent applies asymmetry by providing asymmetric rake surfaces where the first rake surface has a different profile than the second rake surface. Specifically, the first rake surface includes a first relief portion and the second rake surface includes a second relief portion, creating asymmetric chip flow paths that reduce chatter vibrations during machining operations.
Solution Approach 2:
The rake surfaces are segmented into multiple portions including relief portions and cutting portions. Each rake surface is divided into a relief portion that relieves stress and a cutting portion that performs material removal. This segmentation allows independent optimization of each portion to reduce chatter while maintaining manufacturing feasibility.
2Object-affected harmful factors
If end mills use asymmetric elements to reduce chatter, then chatter is reduced, but manufacturing cost increases
Solution Approach 1:
The asymmetric rake surface design with differentiated relief portions creates effective chatter reduction while maintaining economic competitiveness. The asymmetry is achieved through controlled variations in relief portion geometry rather than complex asymmetric tooth arrangements, reducing manufacturing complexity and cost.
Solution Approach 2:
The relief portions are strategically positioned and dimensioned to provide local stress relief exactly where needed during the cutting cycle. This localized quality enhancement targets specific high-stress zones without requiring asymmetric modifications throughout the entire end mill structure, thereby controlling manufacturing costs.
3Productivity
If serrations are placed close to end relief, then roughing capability is enhanced, but tooth robustness decreases
Solution Approach 1:
Serrations are provided on specific rake surfaces at controlled distances from the end relief, creating local variations in chip engagement that enhance roughing capability. The selective placement of serrations on particular rake surfaces rather than uniformly across all teeth provides aggressive material removal where needed while preserving tooth robustness in critical areas.
Data Source
AI summary
An end mill having a plurality of teeth configured for both roughing and semi-finishing applications, the teeth being alternated with a plurality of flutes. At least one tooth of the plurality of cutting teeth is a serrated tooth formed with serrations along a relief surface thereof and at least one other tooth is free of serrations. Each tooth of the plurality of cutting teeth includes an actual internal cutting angle formed at an intersection of a rake cutting sub-surface and a relief surface. The actual internal cutting angle of each tooth has a greater value than an imaginary internal cutting angle formed at an intersection of imaginary extension lines of a rake recessed sub-surface and a relief surface of the same tooth.