Thin-Walled ePTFE Tube Extrusion via Short Land Die
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ram extrusion techniques struggle to produce vascular grafts with uniformly thin walls, as existing methods often result in wall thicknesses greater than 0.100 mm, which is undesirable for minimal profile intraluminal prostheses like stent grafts.
Innovation Solution
The use of an inventive die and mandrel with a short land length and a polyamide-imide mandrel in a conventional ram extruder allows for the extrusion of polymeric tubular members with wall thicknesses as low as 0.020 mm to 0.080 mm, utilizing a die with a land length of 0.020 inch to 0.100 inch and a mandrel made from a slightly compressible hard plastic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ram extrusion techniques are used, then the extrusion process is simple and reliable, but the wall thickness cannot be reduced below 0.100 mm
Solution Approach 1:
The patent changes critical parameters of the extrusion system: reducing die land length from conventional values to 0.020-0.100 inch, selecting specific PTFE resin characteristics (gel fraction, viscosity), and optimizing extrusion conditions (temperature, pressure, ram speed) to achieve uniform wall thicknesses of 0.020-0.100 mm that cannot be obtained with conventional parameters
Solution Approach 2:
The patent introduces an intermediary substance (specific lubricant composition) between the PTFE material and the die/mandrel surfaces to enable smooth extrusion of extremely thin-walled tubes without sticking or deformation, facilitating the production of walls thinner than 0.100 mm
2Manufacturing precision
If air injection is used to prevent collapse during extrusion, then thin-walled tubes can be produced, but the process complexity increases
Solution Approach 1:
The patent extracts and eliminates the need for air injection support by optimizing the die design (short land length, specific geometry) and material formulation, allowing the PTFE to be extruded as extremely thin-walled tubes (0.020-0.100 mm) without requiring internal air pressure to prevent collapse during extrusion
3Manufacturing precision
If the die land length is reduced to enable thin wall extrusion, then wall thickness can be reduced, but the die becomes more difficult to manufacture
Solution Approach 1:
The patent specifies precise die parameters (land length 0.020-0.100 inch, specific angles, tolerances) that balance the need for thin wall production with manufacturability, creating a die design that achieves 0.020-0.100 mm wall thickness while remaining feasible to fabricate using conventional precision machining techniques
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
Enables the production of strong coherent tubular members with extremely thin walls, suitable for vascular grafts, using conventional extrusion equipment at low processing pressures, with wall thicknesses consistently maintained within the desired range of 0.020 mm to 0.080 mm, demonstrating excellent physical properties for use in intraluminal prostheses.
Implementation Method 1
a mandrel made from a slightly compressible hard plastic
Implementation Method 2
The use of an inventive die and mandrel with a short land length and a polyamide-imide mandrel in a conventional ram extruder allows for the extrusion of polymeric tubular members
Data Source
AI summary
An extrusion device is described herein, including an inventive die and mandrel that enable the production, using a conventional ram extruder, of strong coherent extremely thin-walled tubes having a wall thickness in the range of about 0.020 mm and about 0.080 mm.