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info@polyflon.co.ukHeat Shrink Guidelines
Guidelines for the application of fluoropolymer heat shrink tubing
Production range
Fluoroplastic heat shrink tubing is manufactured from premium quality materials. The expansion process is undertaken close to the specific material’s melt temperature with no negative effects on mechanical, electrical of chemical properties.
When subjected to the required expansion temperature the tubing will shrink back to its original extruded size. PTFE has shrink ratios of 2:1 and 4:1. As a general rule FEP and MFA have a lower ratio i.e. 1.3:1 with PFA slightly lower at 1.2:1.
Choice of material for end use
Due to PTFE having a high shrink ratio the encapsulating of components with wide variations in diameter is possible. FEP, PFA and MFA have smaller ratios and therefore, should be used on objects with more consistent dimensions. For applications where a smooth surface is required MFA is an effective material.
Processing information
The table below sets out the shrinking temperatures required for all materials. PTFE needs approximately 330-340C. The tube is ready to shrink once it begins to turn transparent – its gel temperature has been reached.
FEP has a lower shrink temperature at 160-220C. Overheating will result in cracks or “dripping” and the tube loses its shrinking potential.
| Shrinking temperatures – C | ||||
|---|---|---|---|---|
| Material | PTFE | PFA | FEP | Dual Wall |
| Shrinking Temperature | 330 | 220 | 190 | 330 |
| Melt Temperature | - | 310 | 275 | 275 |
| Working Temperature | 265 | 265 | 205 | 205 |
To achieve a tight shrink fit with PTFE you may have to heat the object itself prior to shrinking. The object should be heated uniformally on the periphery as irregular heating and cooling can cause wrinkles and cracks. Ovens, Shrink Tunnels, Infrared Radiators, Fan Heaters or even a clean gas flame can be used as the heat source.
Please note that the shrinking process can result in a longitudinal shrinkage or elongation and the change in length may be +/-10%.
For more technical data or application solution please contact your Polyflon Team
Click here for printable version – Heat Shrink Guidelines
The data listed falls within the normal range of product properties but they should not be used to establish specification limits nor used alone as the basis of design. Polyflon Technology Limited assumes no responsibility for any advice furnished by it or for results obtained with respect to these products. All such advice is provided gratis and the buyer assumes sole responsibility for the results obtained in reliance thereon.
