Biocompatible Wire Processing for Fatigue Life and Ductility
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Solution Overview
Problem
Conventional methods for manufacturing biocompatible wires do not adequately achieve improved fatigue life, mechanical properties, and ductility, which are essential for medical applications such as Cardiac Rhythmic Management and neurostimulation devices.
Innovation Solution
A method involving cold working of biocompatible metallic materials with a cold work percentage of 97 to 99% and annealing in the range of 850 to 1100°C, utilizing Full Die Drawing (FDD) or Half Die Drawing (HDD) techniques to achieve specific grain size distribution and dislocation control, resulting in wires with enhanced strength and ductility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional manufacturing methods are used, then production is simpler, but fatigue life is insufficient
Solution Approach 1:
The patent applies parameter changes by optimizing the annealing temperature range (850-1100°C) and cold work percentage (97-99%) to achieve the desired grain size distribution and mechanical properties. This resolves the contradiction by systematically adjusting process parameters to improve fatigue life while maintaining manufacturing feasibility.
Solution Approach 2:
The patent employs preliminary action through the cold working step performed before annealing. The cold working at 97-99% reduction ratio creates a specific microstructure that, when subsequently annealed, produces the optimal grain size distribution for enhanced fatigue life. This sequential approach allows control over the final microstructure to achieve superior reliability.
2Strength
If cold work percentage is increased to improve strength, then ultimate strength increases, but ductility may deteriorate
Solution Approach 1:
The patent resolves this contradiction by changing the annealing temperature parameter to a specific range (850-1100°C) that allows the material to achieve high strength from 97-99% cold working while recovering ductility. The annealing process restores ductility by reducing dislocation density while maintaining the fine grain structure that provides high strength.
Solution Approach 2:
The patent applies periodic action through the two-stage process: first cold working to increase strength, then annealing to restore ductility. This periodic alternation between deformation and recovery operations allows the material to accumulate strength while periodically recovering ductility, achieving both properties simultaneously in the final product.
3Reliability
If grain size is reduced to improve fatigue life, then fatigue life improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent resolves this contradiction by identifying and controlling critical parameters (annealing temperature: 850-1100°C, cold work percentage: 97-99%) that directly influence grain size. By establishing specific parameter ranges rather than requiring precise single-value control, the patent achieves consistent fine grain structures and improved fatigue life while maintaining manufacturing feasibility.
Solution Approach 2:
The patent employs feedback through the annealing process that responds to the microstructure created by cold working. The annealing parameters are selected based on the degree of cold working applied, creating a feedback loop where the process adjusts to achieve the desired grain size distribution. This systematic approach ensures consistent grain refinement without requiring excessive manufacturing precision.
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
The method produces wires with improved fatigue life, higher ductility, and ultimate strength, suitable for medical devices by optimizing the microstructure and mechanical properties through controlled cold working and annealing processes.
Implementation Method 1
annealing the wire. A cold work percentage is 97 to 99%. The cold working is a drawing with a die reduction per pass ratio in a range of 6 to 40%. The annealing is done in a range of 850 to 1100° C.
Implementation Method 2
The present manufacturing method for a biocompatible wire can be considered as an optimized thermo-mechanical process including drawing and annealing steps
Implementation Method 3
cold working the workpiece into a wire. A cold work percentage is 97 to 99%. The cold working is a drawing with a die reduction per pass ratio in a range of 6 to 40%.
Implementation Method 4
The wires manufactured by the present manufacturing method can have an improved fatigue life through smaller grain sizes and a specific grain size distribution of the wire material and/or a controlled number of dislocations and twins in the crystal structure of the wire.
Data Source
AI summary
The disclosure relates to a method for manufacturing a biocompatible wire, a biocompatible wire comprising a biocompatible metallic material and a medical device comprising such wire. The method for manufacturing a biocompatible wire comprises providing a workpiece of a biocompatible metallic material, cold working the workpiece into a wire, and annealing the wire, wherein a cold work percentage is 97 to 99%, wherein the cold working is a drawing with a die reduction per pass ratio in a range of 6 to 40%, and wherein the annealing is done in a range of 850 to 1100° C.