MIM Anvil Angular Alignment via Coining

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Solution Overview

Problem

Existing circular surgical staplers face challenges in efficiently manufacturing anvils with consistent angular alignment and precise staple formation, which affects the reliability and effectiveness of tissue sealing and cutting during surgical procedures.

Innovation Solution

The development of a method for manufacturing anvils using metal injection molding (MIM) followed by selective machining and coining or electrochemical machining of staple forming pockets, allowing for the creation of anvils with improved structural integrity and precise staple formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional manufacturing methods are used for anvil production, then manufacturing simplicity is maintained, but manufacturing precision and angular alignment consistency deteriorate

Engineering Contradiction:
Improveangular alignment consistencyVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent combines metal injection molding with subsequent coining or electrochemical machining operations to create an integrated manufacturing process. The injection molding provides the base geometry and angular alignment, while the coining or electrochemical machining refines the staple forming pockets. This merging of processes achieves high manufacturing precision for angular alignment while maintaining reasonable ease of manufacture through automated processing steps.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs parameter changes by transitioning from a rough injection molded state to a finished state through coining or electrochemical machining. The coining process applies controlled pressure and heat to deform the metal, while electrochemical machining removes material through controlled electrical reactions. These parameter changes enable precise control over the angular alignment and staple pocket geometry, resolving the contradiction between manufacturing precision and ease of manufacture.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If metal injection molding is used for anvil production, then productivity increases, but manufacturing precision of staple formation deteriorates

Engineering Contradiction:
Improveanvil production rateVSAvoidstaple formation precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by first forming the anvil body through metal injection molding, which creates the basic geometry and angular alignment features. This preliminary step establishes the foundation for subsequent precision operations. The injection molded anvil then undergoes coining or electrochemical machining to refine the staple forming pockets. This sequence allows high productivity in the initial forming while maintaining precision in the final staple formation through targeted secondary operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces traditional mechanical machining operations with coining or electrochemical machining processes. Coining uses controlled plastic deformation through pressure application, while electrochemical machining uses controlled material removal through electrical reactions. These substitution methods enable higher precision in staple pocket formation compared to conventional mechanical machining, while maintaining compatibility with the injection molded geometry. This allows the system to achieve both high productivity from injection molding and high precision from the refined finishing processes.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If separate manufacturing of anvil head and shank is used, then ease of manufacture improves, but device complexity and assembly precision worsen

Engineering Contradiction:
Improvecomponent manufacturing flexibilityVSAvoidangular alignment between components
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent merges the anvil head and shank into a single integrated component manufactured through metal injection molding. This integration eliminates the need for separate manufacturing and assembly operations, thereby ensuring consistent angular alignment between what would have been separate components. The single-piece construction guarantees precise geometric relationships throughout the anvil structure, resolving the contradiction between ease of manufacture (through modular separate parts) and assembly precision (through integrated construction).

Inventive Principle:
Principle #5Merging (Combining)

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

This approach enables the production of anvils that ensure consistent angular alignment with the stapling head, resulting in precise staple formation and improved tissue sealing and cutting efficiency during surgical procedures.

Implementation Method 1

forming the head and the shank of the surgical circular stapler using a metal injection molding process

Methodology Applied
Scientific EffectMetal injection molding:

Implementation Method 2

coining or electrochemical machining of staple forming pockets

Methodology Applied
Scientific EffectCoining:

Implementation Method 3

coining or electrochemical machining of staple forming pockets

Methodology Applied
Scientific EffectElectrochemical machining:

Data Source

PatentEP4255320B1Metal injection molded anvil for circular surgical stapler
Publication Date: 2025.04.09 CILAG GMBH INTERNATIONAL
  • EP4255320B1 patent drawingFigure 1
  • EP4255320B1 patent drawingFigure 2
  • EP4255320B1 patent drawingFigure 3~4

AI summary

A method is used to manufacture an anvil of a circular surgical stapler. The anvil includes a head and a coupling feature that extends proximally from the head. The method includes forming each of the head and the coupling feature using at least one metal injection molding process. The method also includes after forming the coupling feature, machining a through bore into the coupling feature that extends completely through the coupling feature along a longitudinal axis of the coupling feature.