Rings start as extruded cord
Large and non-standard rings are not moulded - they are cut from extruded cord and joined. That route is what makes unusual diameters and low-volume custom sizes economical, since no mould has to be built.
The joint decides the part
A ring is only as good as its join. Failure modes are a visible step at the bond, misalignment that leaves a leak path, and a joint weaker than the cord itself. All three are joint problems, not material problems.
What automatic bonding changes
Bonding on a dedicated machine gives repeatable alignment and a consistent joint, rather than results that depend on who was on the bench. Consistency is the whole argument - a hand-bonded ring can be perfect and the next one can be a reject.
Inspection of the joint
The joint is checked for alignment and for strength under load - a bonded ring should hold together under significant force rather than opening at the join. If a supplier cannot tell you how the joint is tested, assume it is not.
Specifying a ring
Give us the groove dimensions, the cord diameter, how much force the assembly delivers, and the operating temperature. If the groove is not final, send the housing and we will measure it.
Profiles for this application
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Working on something like this?
Send the drawing, cross-section, operating temperature and what the seal has to resist. We will tell you whether a stock profile fits or the part needs extruding, and quote both.