Why Groove Design Matters
An O ring works by controlled deformation. The gland must squeeze the rubber enough to seal. It must also leave space for pressure, swell, heat, and tolerance. A groove that is too shallow creates drag and early wear. A groove that is too deep may leak before pressure assists the seal.
Key Dimensions
The cross section is the round thickness of the ring. Gland depth sets radial compression. Groove width sets available volume. The groove diameter controls stretch when the ring is installed over a piston or into a bore. Clearance controls extrusion risk at pressure. Each value should be checked together, not alone.
Squeeze and Fill
Squeeze is the percent reduction in cross section. Static radial seals often use more squeeze than dynamic seals. Dynamic seals need lower friction and better lubrication. Gland fill compares ring area with groove area. High fill can trap rubber with no expansion space. Low fill may reduce stability.
Stretch, Clearance, and Pressure
Inside diameter stretch keeps the ring seated. Too much stretch reduces cross section and changes squeeze. Clearance is the open gap where rubber can extrude under pressure. Harder materials and backup rings can tolerate higher pressure. Soft materials need smaller gaps and careful tolerances.
Using the Results
This calculator gives engineering guidance from simplified gland geometry. It helps compare squeeze, fill, stretch, side clearance, and extrusion risk. Use catalog data for final production dimensions. Material, compound, fluid, surface finish, temperature, motion, and assembly method can change the safe range. Always test critical seals before release.
Practical Design Notes
Measure parts with the same unit system before entering values. Keep tolerances realistic, because small seal sections are sensitive. Consider thermal growth when metal and elastomer expand differently. Add volume swell when the fluid is known to attack or absorb into the compound. Check that side clearance remains enough for assembly. Review surface finish for moving seals, because rough surfaces cut the ring. Review lubrication for dynamic motion. For high pressure, reduce clearance or add a backup ring. For vacuum, avoid excessive fill and select a compatible compound. Document every assumption, then compare the output with a trusted manufacturer table before machining. Use prototypes for final confidence and safety.