Our customer required a silicone seal over moulded onto a metal carrier ring to allow for easy assembly; however the seal would also need to have a continuous hollow section around the top perimeter of the carrier. This was to ensure that there would be no areas where contamination could enter.
A hollow section in a seal would normally be produced by extrusion methods, and then each end of the extrusion could be joined to form the seal. In this case, the customer wanted a moulded solution that would allow for the seal to be moulded onto the metal carrier ring.
We were able to solve the problem for the customer by using a three stage process.
First, we prepare the steel rings by applying bonding agents – this along with specific design of the ring offers both mechanical and chemical bond once moulded.
The silicone seal section is designed with an inside and outside wall. These two walls form a loop feature where they meet at the top. We placed the metal ring into the specially designed mould tool ensuring minimal movement, and moulded the inside face of the outer seal wall to the outside face of the steel ring.
The final process was to manually bond the inner wall to the inside face of the carrier ring – this closes the seal and forms the sealed loop feature that runs around the top of the carrier.