The seal itself was to be made from PTFE, which would then have an 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 onto 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, 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 the 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 onto 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 offers a full design and manufacturing service for spring energised lip seals, backup rings, and hydraulic piston rings.