O-Ring Groove / Gland Design
Also known as: gland design · O-ring groove · groove geometry · groove depth
O-ring groove (gland) design specifies groove depth, width, and surface finish to achieve 15–25% diametral squeeze and 6–15% free volume — ensuring seal without extrusion or over-stress.
Technical Detail
A properly designed O-ring groove controls three parameters: (1) Diametral squeeze (compression): groove depth D = cross-section W × (1 – squeeze%). Target 15–25% for static face seals, 10–20% for dynamic radial seals. Example: AS568-214 (W = 2.62 mm), 20% squeeze → groove depth = 2.10 mm. (2) Free volume: groove width must leave 6–15% of the groove volume empty for thermal expansion. Width ≥ 1.5× cross-section W. At high temperature leave 12–15% free volume. (3) Surface finish: groove Ra 0.8–1.6 µm for dynamic; 1.6–3.2 µm for static. Mating face Ra ≤ 0.8 µm for face seals. Add 15° lead-in chamfer minimum 1× W depth at groove entry. Extrusion gap: ≤0.13 mm at 70 Shore A / 7 MPa (per AS568B Table 3); use harder compound or PTFE back-up rings for larger gaps or higher pressures. Full groove tables in AS568B Appendix A, ISO 3601-2, JIS B2406.
Reference Standards
- SAE AS568B Appendix A
- ISO 3601-2:2016
- JIS B2406
Related Terms
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- JIS B2401 (Japanese O-Ring Standard) — JIS B2401 is the Japanese Industrial Standard for O-rings, defining P-series (piston/bore), G-series…
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- Dynamic vs Static Seal — A static seal prevents leakage between non-moving surfaces (flange faces, port plugs); a dynamic sea…