Seals
O-Ring Groove Design Calculator
Gland design for AS568B o-rings (dashes 004–028): squeeze, gland fill and clearance for radial static seals, with leak and over-compression warnings.
Parameters
Results
- Cross-section (actual)(CS)
- 1.778 mm
- Inner diameter (actual)(ID)
- 11.455 mm
- Actual gland depth(B − ID)
- 3.145 mm
- Squeeze(ε)
- 23.1
- Gland fill(fill)
- 33.3
- Max recommended clearance(c_max)
- 0.445 mm
Design checks
- [PASS] Squeeze 23.12% inside the 14–28% safety windowsqueeze_window
- [PASS] Squeeze 23.12% within the recommended 18–25% for radial static sealssqueeze_recommended
- [PASS] Gland fill 33.31% ≤ 90% (recommended ≤ 85%)fill_limit
Formulas
CS — cross-section from the AS568B table (custom value overrides)= 1.77800
Expression: AS568_CS(dashSize, customCS)
ID — inner diameter from the AS568B table (custom value overrides)= 11.4550
Expression: AS568_ID(dashSize, customID)
Actual gland depth measured across the section: bore − ID (groove root at the o-ring ID)= 3.14500
Expression: bore - effectiveID
Squeeze = (2·CS − depth)/CS × 100%= 23.1159
Expression: (2 * effectiveCS - grooveDepth) / effectiveCS * 100
Gland fill = (π·CS²/4)/(w × depth) × 100%= 33.3107
Expression: pi * effectiveCS^2 / 4 / (grooveWidth * grooveDepth) * 100
Extrusion-gap guideline: keep the mating clearance ≤ 0.25·CS (static, low-pressure practice)= 0.444500
Expression: 0.25 * effectiveCS
0.25 — Empirical anti-extrusion bound for static seals without pressure correction
Results are for preliminary design. Verify before manufacturing.
Export
STEP export runs entirely in your browser; the geometry kernel downloads once on first export.
How the o-ring groove calculator works
The geometry starts from the SAE AS568B size table (dashes 004–028, the 1.778 mm cross-section series): inner diameter ID and cross-section CS, three decimals. A custom ID/CS value greater than zero overrides the table for non-standard rings. The gland model is a radial static seal with the groove root at the o-ring inner diameter — the ring is mounted at its natural diameter, without stretch — so the actual gland depth measured across the section is bore − ID. The squeeze follows ε = (2·CS − depth)/CS × 100%: a radial static seal wants 18–25% (below 14% the ring cannot follow the surfaces and leaks; above 28% the elastomer suffers permanent set and the seal is destroyed). The gland fill is the ratio of the o-ring cross-section area π·CS²/4 to the groove cross-section w × depth; Parker practice keeps it at or below 85% (hard limit 90%) so thermal expansion and manufacturing tolerances always have somewhere to go.
The output also gives the maximum recommended clearance between the mating metal parts: keeping the extrusion gap at or below 0.25·CS is the usual static-seal practice before pressure-specific gap tables take over — at higher pressures the gap must shrink or a back-up ring is required. Three checks run on every change: the squeeze safety window (14–28%, red outside), the recommended 18–25% band (advisory), and the gland fill limit (red above 90%). Elastomer choice, pressure, temperature and fluid compatibility are outside this calculator — the geometry here assumes a standard rectangular gland in a radial static arrangement.
Sealing a bearing position? Pair this with the bearing L10 life calculator.