The balloon formation is achieved by a process called expansion blow molding, in which the polymer-based tube is stretched biaxially in both the longitudinal and radial directions under pressure and at high temperatures.
The temperature and pressure will vary depending on the material and the diameter of the balloon. For example, a nylon 12 balloon would form at 170° to 200°F and a 12 3 mm nylon balloon could form at 35 bar whereas a 10 mm balloon would form at 15 bar. Continue reading to know more about balloon design & manufacturing.
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The goal is to mechanically stretch the polymer chains to ensure maximum balloon strength and resist further growth. The result is a well-defined diameter.
The orientation of the polymer in the tube should be arbitrary. During the stretching process, the stress is relatively constant. After the polymer yarn is maximally stretched, the tension increases drastically. At this point, the material has the greatest strength and will resist further growth.
There is usually an expected strain ratio for a given axis and material (e.g. about 6 × radial strain and 4.7 × axial for nylon 12).
When forming the balloon, the tube is placed in a mold. A hose is that part of a hose in which the two ends are clamped in a controlled process to perform three functions:
- Check where bubbles form on the tube.
- Improves the formation of conical sections.
- Allows for the smaller outside neck diameter (OD) required for low-profile catheters.
