Gland design to the Trelleborg O-Ring design guide — static and dynamic radial seals (rod and piston), axial face seals, and non-circular face grooves via neutral-axis length. ISO 286 fits or custom tolerances on every dimension, AS568 / ISO 3601-1 Class A/B size selection, and squeeze, stretch, gland-fill and extrusion-gap checks with worst-case tolerance stacks.
1Seal configurationOuter radial (piston): groove on the inner part, O-Ring seals against the bore — the ring is stretched onto its groove. Inner radial (rod): groove in the housing, O-Ring seals against the rod — the ring is held by slight circumferential compression. Axial face seals are compressed between two flat faces; the pressure direction decides which groove wall the ring should rest against.
2Gland geometryEnter your hardware dimensions. Every diameter can carry a standard ISO 286 fit (computed from the standard's formulas) or your own ± deviations. The "Use guide groove" button fills the groove from the Trelleborg Table XV recommendation for the selected cross-section.
H8: +0.039 / +0 mm
h9: +-0 / -0.0624 mmThe O-Ring is stretched over this diameter.
+−
g6: -0.0087 / -0.0243 mm
3O-Ring selectionPick a cross-section, then a standard AS568 / ISO 3601-1 size. Class A carries the tighter AS568 inside-diameter tolerances (aerospace/precision); Class B the wider general-industrial tolerances of DIN ISO 3601-1:2013. Cross-section tolerances are common to both classes.
mm · ±0.1 mm (ISO 3601-1)
General industrial (DIN ISO 3601-1:2013)
Geometry-ideal d1 ≈ 43.73 mm. Selected size is the nearest standard size.
4Material & serviceMaterial choice is driven by the medium first, then temperature. The ranges here are typical continuous-service limits for standard compounds — always confirm against the specific compound datasheet and the medium at temperature.
The general-purpose default. Special low-temperature compounds reach −60°C.
Drives the permissible extrusion gap (Table XII uses 70/90 Shore; 80 uses the 90-Shore table conservatively... see notes).
Every seal metric across the full tolerance stack — the min and max columns take every contributing dimension to its most and least favourable limit simultaneously (worst-case by construction). These worst-case bounds, not the nominal, are what govern the design.
Result
Min
Max
Compression (squeeze) %
18.9
25.6
Compression (squeeze) mm
0.64
0.928
Housing fill %
65.6
79.8
Installed stretch (d1 → groove root) %
0.13
2.3
Effective cross-section mm
3.391
3.628
Gland height mm
2.7
2.751
Groove width mm
4.8
5
Colour key: green within guide limits · orange outside the target but not a hard failure · red out of spec. Dimensional rows aren't pass/fail-scored. Squeeze guide band for this cross-section & application: 12–26%.Extrusion gap (worst-case): 0.082 mm · permissible 0.1 mm.
Method and limits follow the Trelleborg Sealing Solutions O-Rings design guide: initial-squeeze bands per cross-section and application (Figures 15/16 — chart-read values, so treat band edges as ±1%), installed stretch limited to 8% (d1 < 50 mm) / 6% (d1 > 50 mm), circumferential compression to 3%, cross-section reduction approximated as 0.5% per 1% of stretch, axial seals seated against the pressure-side groove wall (OD 1–2% over the outer wall for internal pressure, d1 1–3% under the inner wall for external), permissible extrusion clearances from Table XII (70/90 Shore A; 80 Shore uses the 90-Shore table, which is optimistic — interpolate towards the 70-Shore values for marginal cases), and suggested groove dimensions from Table XV. Sizes and Class A inside-diameter tolerances are the AS568 / ISO 3601-1 values transcribed from published manufacturer tables; Class B tolerances interpolate a published DIN ISO 3601-1:2013 Class B table. ISO 286 fits are computed from the standard's formulas (they can differ from the rounded table values by a micron or two). Gland fill is computed against a rectangular idealised groove (corner radii and the clearance-gap volume neglected — slightly conservative) with the ≤75% nominal / ≤85% worst-case limits used across industry gland calculators. Worst cases stack every tolerance at its unfavourable limit simultaneously. Material temperature ranges are typical compound values from the guide — the specific compound datasheet and medium compatibility (including swell, which eats gland-fill margin) govern. Non-circular grooves use the neutral-axis length method with common-practice corner-radius guidance (r ≥ 3×d2 recommended, ≥ 2×d2 minimum). This is an estimation tool — have the final gland reviewed by your seal supplier.
Total compression force is a parametric estimate, not a chart lookup. The published compression-force data (Parker O-Ring Handbook Figures A4-12–16, Apple Rubber design guide, the Trelleborg calculator) exists only as image bar-charts giving a range of force per unit length of seal vs squeeze %, per cross-section and durometer — it isn't available as digitised values. This tool models that data with a transparent functional form: force per length rises as squeeze^1.5, scales linearly with cross-section (a per-unit-length compression) and by a durometer modulus factor (≈1.0 at 70 Shore A, ≈1.4 at 80, ≈2.0 at 90), with the amplitude calibrated to the one Parker band that could be independently confirmed (0.070″ cord, 70 Shore A, 10% squeeze → 2–5 lb/in). Total force = force-per-length × the seal's centreline length. It is deliberately a wide min–max band — use it as an order-of-magnitude seating/closing-force figure (e.g. sizing a bolted cover), and read the value off the actual chart or the Trelleborg calculator for anything load-critical.
Validated: a hand-worked static outer-radial (piston) seal — 20 mm d1, 3 mm cross-section, 20.4 mm groove root (2.0% stretch), 25.8 mm bore, 4.4 mm groove width — should give 2.97 mm effective cross-section after stretch-thinning, 9.09% squeeze (0.27 mm), and 58.3% gland fill by hand; this calculator returns all four numbers exactly.
Engineering Calculators