We were given the opportunity to manufacture and develop a PTFE and elastomeric seal for a pharmaceutical powder processing application.

The seal it self was to be made from PTFE, which would then have a FDA compliant silicone rubber seal moulded onto it.

The PTFE needed to be chemically treated to allow the seal to have the silicone rubber moulded on to it, to ensure the two materials bonded together with enough strength that the silicone would not delaminate from the PTFE surface in the end application.

Adjusting for Chemical etching 

The seal was manufactured to drawing from AF001 Virgin PTFE, and then subjected to a chemical etching process which would adjust the surface profile of the PTFE and allow the normally low friction non-stick surface to have the silicone rubber vulcanized onto it. 

After the etching process was completed, a suitable high temperature bonding agent was also applied, and the seal was ready for loading into the mould.

By ensuring that the sodium ammonia etching, the bonding agent, and the physical seal design and the key that was machined into it, were all optimized, we were able to ensure the best possible bond strength. This ensured that the two seals would not suffer from bond failure and delamination in process.

Achieving a reduction in wear

Virgin PTFE offers a non-stick highly chemical resistant surface for sealing materials, the PTFE will also transfer a microscopic layer of material on to the mating sealing surface, so that the two surfaces run exceptionally smoothly together, which dramatically reduces wear.

As a sealing material PTFE offers other advantages, such as compressive strength, and high operating temperatures. AFT offer a full design and manufacturing service for spring energized lip seals, back up rings, and hydraulic piston rings. 

Need a non-standard seal?
Our team can design and manufacture custom seals to any specification, in a range of materials including VICTREX PEEK and PTFE.
Custom Seals