What are the differences between uniaxial and transverse gasket tape

Update:06-12-2021
Summary:

The challenges thrown by PTFE Tape OEM as a material ar […]

The challenges thrown by PTFE Tape OEM as a material are myriad. As we have already illustrated in various articles, the processing techniques needed for PTFE differ from those of other polymers so dramatically, that nearly every end-product requires a special-purpose machine that can be used for no other plastic. The main reason for this is that PTFE is not melt-processable. As a result, heating the polymer into a liquid state to then either mould or extrude it is not possible. Hence, we end up with processes such as paste extrusion (PTFE Tubes), skiving PTFE tapes and isostatic moulding moulded PTFE parts.Even within the space of PTFE, expanded PTFE  remains an anomaly in terms of processing complexity.

We have covered in earlier articles that ePTFE depends on a minimum of nine different parameters, including the grade of material, the nature of the lubricant, the extrusion process, and the stretching process – to name only a few. Each of these parameters needs to be kept in range, with any deviations only revealed once the final product is out  at which point it is too late to make any changes.While we have mastered the process of making mono-axial ePTFE gasket tapes  the standard ePTFE tape used in industrial applications  cross-directional tapes are another issue altogether. In this article, we look at the development of the same and what advantages it affords.

The main issue with mono-axial ePTFE gasket tapes is that due to the orientation of the fibrils being in only one direction, the material is susceptible to tearing when tension is applied in the transverse direction. On the other hand, the material exhibits immense compressibility, allowing it to form a perfect seal with minimal pressure and retain its form over a range oftemperatures. As such, the tape works brilliantly in applications such as flange-to-flange connections, where the assembly is not intended to be dismantled frequently, once installed.

However, in applications where the frequent opening of the system occurs, the mono-axial tapes fail over the medium-long term. For example, using mono-axial tape along the rim of a vessel that is opened multiple times a day would not work, since the constant application and relaxation of pressure would cause the fibrils to come loose and the tape to slowly disintegrate. Furthermore, with very poor recovery mono-axial tape is soft but lacks elasticity seal becomes less effective each time the lid is closed and opened again.