Catheter Tip Insert Molding for Multi-Layer Integrity
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Solution Overview
Problem
The existing method of forming a catheter tip by pushing a cut end into a heated die distorts multi-layer tubing structures, leading to incomplete hydrophilic coating adhesion and increased cycle time due to die heating and cooling requirements.
Innovation Solution
A catheter tip is formed using an insert molding process where a pre-heated plug is press-fitted into the tubing lumen, allowing injection molding of a tip with controlled geometry and maintaining the integrity of multi-layer structures for hydrophilic coating compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a heated die is used to form the catheter tip, then the tube material softens and forms the desired tip shape, but the die must be repeatedly heated and cooled which increases cycle time
Solution Approach 1:
The tube end is pre-heated by a heating element integrated into the die assembly before the forming operation. This allows the material to be softened only when needed, eliminating the need to repeatedly heat and cool the entire die for each cycle, thus reducing cycle time while maintaining forming capability
2Manufacturing precision
If a heated die is used to form the catheter tip, then the tube material softens for forming, but the heating process distorts the multi-layer structure and compromises coating adhesion
Solution Approach 1:
The heating is applied locally only to the tube end region that needs to be formed, rather than heating the entire tube or die. The heating element is positioned to affect only the immediate area around the die opening, preserving the integrity of the multi-layer structure in the tube body while still enabling tip formation
Solution Approach 2:
A forming mandrel or die with a controlled temperature profile acts as an intermediary tool. The die is heated to a temperature that softens the tube material sufficiently for forming but is maintained at a controlled level to prevent excessive heat transfer that would distort the multi-layer structure or compromise the hydrophilic coating integrity
3Length of moving object
If the tube is cut to length and then formed, then the tube can be precisely sized, but the cut end requires secondary forming operation adding process steps
Solution Approach 1:
The cutting operation and tip forming operation are combined into a single integrated process. The tube is cut to length and then immediately formed in the same fixture or tooling setup without requiring separate handling or additional equipment, reducing the number of process steps while maintaining dimensional 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
This method reduces cycle time, ensures proper bonding, and maintains the outer layer material for effective hydrophilic coating adhesion, improving catheter tip formation efficiency and reducing costs.
Implementation Method 1
The injection molding steps are further characterized in that a plug is press fit into the lumen at one end of the tubing just prior to inserting that end into the injection mold
Implementation Method 2
During the injection molding step that forms the tip on the end of the tube the plug acts as a molding shut-off to ensure proper filling of the mold
Data Source
AI summary
A catheter has extruded length of tubing and an injection molded tip that facilitates insertion of the catheter into the body. The catheter is fabricated by the steps of providing the tubing, for example, by extruding the tubing from a thermoplastic resin cutting the tubing to the desired length, inserting a plug into the tubing, inserting one end of the tubing into an injection mold cavity, creating and forming a tip in an injection molding step, and demolding the tubing with the formed tip.