Laser Power Adjustment for Polymer Stent Machining
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Solution Overview
Problem
Laser machining of stents often results in unwanted heat transfer, creating a heat affected zone that can adversely affect the properties of the material and lead to inconsistent strut widths and poor quality cuts, particularly in polymer tubing where slight variations in processing conditions significantly impact the machining power requirements.
Innovation Solution
Determine a specific laser power level for each polymer tubing section to achieve repeatable strut widths and reduce the heat affected zone, using ultrashort-pulse lasers like femtosecond lasers to precision-machine stent patterns with controlled power settings that account for variations in morphology and processing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser machining is used to fabricate stents from polymer tubing, then material removal and stent pattern formation are achieved, but heat transfer to the substrate creates a heat affected zone that adversely affects material properties and causes inconsistent strut widths
Solution Approach 1:
The patent applies parameter changes by adjusting laser power settings based on the specific morphology and processing conditions of each polymer tubing lot. By varying the laser power parameter to match the actual properties of the tubing being processed, the method achieves consistent strut widths while minimizing the heat affected zone, thereby resolving the contradiction between manufacturing precision and heat-induced material degradation
Solution Approach 2:
The patent implements feedback by measuring the actual morphology parameters of each tubing section and using this information to determine the appropriate laser power level. This closed-loop approach ensures that the laser machining parameters are optimized for each specific batch of tubing, preventing heat affected zone issues while maintaining precise strut width control
2Manufacturing precision
If standard laser power settings are used for all polymer tubing sections, then processing simplicity is maintained, but variations in tubing morphology and processing conditions lead to poor quality cuts and inconsistent stent dimensions
Solution Approach 1:
The patent applies preliminary action by determining the appropriate laser power level for each tubing section before actual stent fabrication begins. This pre-characterization step involves measuring tubing morphology and calculating the optimal power setting, which is then stored and used during production. This approach maintains manufacturing precision while limiting complexity to a one-time setup procedure rather than continuous adjustment
Solution Approach 2:
The patent changes the laser power parameter based on measured tubing properties such as wall thickness, density, and crystallinity. By establishing a relationship between these morphology parameters and the required laser power, the method achieves consistent stent dimensions without requiring complex real-time control systems, as the appropriate power level is predetermined for each tubing batch
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 method ensures consistent stent dimensions and quality by adjusting laser power for each tubing section, minimizing heat input and reducing defects like flash, glitter, and islands, thereby enhancing the mechanical properties and biocompatibility of the stents.
Implementation Method 1
Laser machining processes transport photon energy into a target material in the form of thermal energy or photochemical energy. Material is removed by melting and blow away, or by direct vaporization/ablation.
Implementation Method 2
Laser machining processes transport photon energy into a target material in the form of thermal energy or photochemical energy.
Implementation Method 3
Material is removed by melting and blow away, or by direct vaporization/ablation.
Implementation Method 4
Material is removed by melting and blow away, or by direct vaporization/ablation.
Data Source
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AI summary
Laser machining polymer tubing sections to form stents such that the power of the laser machining is adjusted for each tubing section to obtain repeatable strut widths for stents formed from different tubing sections is disclosed. A threshold power for laser machining each section is determined and the power used for machining each section is based on the threshold power.