Surgical Bur Anti-Chatter Flute Geometry
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Solution Overview
Problem
Surgical burs experience chatter due to regeneration of waviness, resonant frequency, and clogging of inter-flute gaps, leading to vibrations and reduced effectiveness during tissue excision.
Innovation Solution
The surgical bur design features multiple sets of flutes with cutting edges positioned at different locations along the bur head, including chamfered edges that reduce the number of cutting edges at the distal end, minimizing chatter by reducing tooth passing frequency and preventing tissue entrapment in inter-flute gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a bur head is pressed against tissue to make a deep cut, then tissue excision effectiveness is improved, but chatter vibrations increase due to clogging of inter-flute gaps
Solution Approach 1:
The bur head is divided into multiple sets of flutes (first set, second set, third set) positioned at different locations along the bur head. This segmentation allows different flute sets to engage tissue at different depths and positions, preventing simultaneous clogging of all flutes and reducing chatter vibrations while maintaining effective tissue excision.
Solution Approach 2:
Different sets of flutes are positioned at different locations along the bur head with varying numbers and configurations. The first set has a different number of flutes than the second set, and the third set has yet another configuration. This local variation in flute quality and distribution optimizes cutting performance at different zones while preventing uniform clogging patterns that cause chatter.
2Productivity
If multiple cutting edges are positioned at the distal end to increase tissue removal rate, then productivity is improved, but chatter frequency increases due to higher tooth passing frequency
Solution Approach 1:
The cutting edges are segmented into multiple sets positioned at different locations along the bur head rather than concentrating all cutting edges at the distal end. This distribution reduces the tooth passing frequency at any single location while maintaining overall tissue removal effectiveness through the combined action of multiple flute sets.
Solution Approach 2:
Instead of increasing the number of cutting edges in one dimension (at the distal end), the invention distributes cutting edges along the longitudinal dimension of the bur head. This dimensional redistribution reduces the concentration of tooth passing events at any single point, thereby reducing chatter frequency while maintaining total cutting capability.
3Ease of manufacture
If flutes are configured to cut in phase to simplify geometry, then manufacturing is simplified, but regeneration of waviness causes chatter vibrations
Solution Approach 1:
The different sets of flutes are configured with asymmetric characteristics - the first set has a different number of flutes than the second set, and the third set has yet another configuration. This asymmetric flute arrangement disrupts the phase relationships that would otherwise cause waviness regeneration and chatter, while still allowing for practical manufacturing through standardized flute formation processes.
Data Source
AI summary
A surgical bur including a shaft with a bur head. A number of flutes are formed on the bur head. Each flute has a cutting edge. Chamfer surfaces form the front, distally directed faces of some of the burs. The flutes without chamfer surfaces having cutting edges emerge from the bur head at locations relatively close to the distal end tip of the head. The flutes over which the chamfer surfaces extend have cutting edges that start, extend proximally rearward, from locations that are, spaced proximal from the distal end tip.