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Surface Finish
The ideal surface finish for dynamic surfaces against which the O-Ring will rub is 5 to 16 µ inch RMS. Rougher and
smoother surfaces may result in increased friction and reduced seal life. Rougher finishes up to 64 µ inch RMS can be
tolerated in static applications.
Final Specification
End use plays a key role in O-Ring design. Dynamic seals, whether reciprocating, oscillating or rotating motion (or any
combination of these) call for the highest degree of precision in O-Ring design because of the dimensional variations
involved. Static applications on the other hand, permit wider tolerances, rougher surface finishes and greater applied
pressure limits without danger of failure.
1. Improper mechanical design - may cause excessive pressure on O-Ring, abrasion from friction (particularly
with dynamic seals), compression set.
2. Fluid attack - chemicals or oils may degrade O-Ring material; high fluid pressure may work O-Ring
beyond its limits, cause extrusion flow.
3. O-Ring design - dimension or cross-section may not be properly matched to the application; material may
not be sufficient to withstand fluids, pressures, dynamic friction abrasion.
4. Temperatures - excessive heat (either from ambient or fluid conditions) can cause degradation; excessive
cold can cause embrittlement.