O-Ring Groove Dimensions for AS568-105

AS568-105 O-Ring Specifications

• Dash Number: AS568-105 (100 Series)
• Inside Diameter (ID): 0.143″ (3.63mm)
• Cross-Section (CS): 0.103″ (2.62mm) — 3/32″ nominal
• Outside Diameter (OD): 0.349″ (8.86mm)

Groove Dimensions for AS568-105

The groove dimensions below are based on Parker O-Ring Handbook recommendations for standard 3/32″ (2.62mm) cross-section o-rings. These provide the proper squeeze ratio for reliable sealing.

Face Seal (Static Application)

Face seals are the most common type — used when the o-ring sits in a groove on a flat surface with no relative motion between parts.

• Groove Depth: 0.081″ (2.06mm)
• Groove Width: 0.143″ (3.63mm)
• O-Ring Squeeze: 0.012″ to 0.022″ (11.7% to 21.4%)
• Gland Fill: ~75% maximum (allows for thermal expansion)

Piston Seal (Dynamic Application)

Piston seals sit in a groove on a piston that moves inside a bore. The o-ring seals against the bore wall.

• Groove Depth: 0.081″ (2.06mm)
• Groove Width: 0.143″ (3.63mm)
• O-Ring Squeeze: 0.01″ to 0.022″ (9.7% to 21.4%)
• Bore Diameter: O-ring OD (0.349″) + diametral clearance (typically 0.002″-0.005″)

Rod Seal (Dynamic Application)

Rod seals sit in a groove in a bore, sealing against a rod that passes through. The o-ring compresses radially against the rod.

• Groove Depth: 0.081″ (2.06mm)
• Groove Width: 0.143″ (3.63mm)
• O-Ring Squeeze: 0.01″ to 0.022″ (9.7% to 21.4%)
• Rod Diameter: O-ring ID (0.143″) minus diametral clearance

Why These Groove Dimensions?

O-ring groove design is a balance of three factors:

• Squeeze (compression): The groove must compress the o-ring enough to create a seal. For the AS568-105 (3/32″ CS), the target squeeze is 16% of the cross-section. Too little squeeze = leaks. Too much = excessive friction and premature wear.
• Gland fill: The o-ring should fill no more than ~75% of the groove volume. The remaining 25% is free space that allows for thermal expansion of the rubber compound.
• Width clearance: The groove width (0.143″) is wider than the o-ring cross-section (0.103″) to prevent pinching and allow the o-ring to move slightly under pressure.

Material Considerations

The groove dimensions above work for standard o-ring materials (Buna-N/Nitrile, Viton/FKM, EPDM, Silicone). For harder materials (90+ Shore A durometer), you may need to adjust squeeze slightly. Softer materials (below 60 Shore A) may require tighter grooves to prevent extrusion at high pressure.

Surface Finish Requirements

• Static seals: 32 microinch Ra (0.8 μm) maximum on sealing surfaces
• Dynamic seals: 16 microinch Ra (0.4 μm) maximum on sliding surfaces
• Groove bottom: 63 microinch Ra (1.6 μm) maximum
• Break all sharp edges — use 0.005″-0.015″ radius or 15° chamfer at groove corners

Related AS568 Sizes

• AS568-102 Groove Dimensions — ID: 0.049″ (3/32″ CS)
• AS568-103 Groove Dimensions — ID: 0.081″ (3/32″ CS)
• AS568-104 Groove Dimensions — ID: 0.112″ (3/32″ CS)
• AS568-106 Groove Dimensions — ID: 0.174″ (3/32″ CS)
• AS568-107 Groove Dimensions — ID: 0.206″ (3/32″ CS)
• AS568-108 Groove Dimensions — ID: 0.237″ (3/32″ CS)