Snap Ring
Retaining Rings & Clips · circlip · retaining ring · C-clip
Definition: A snap ring is a spring-steel ring that seats in a machined groove to retain parts on a shaft (external) or in a bore (internal).
Anatomy
■ Ring body■ Opening
Governing standards: ASME B18.27 · DIN 471 / DIN 472
Common Sizes
| Inch | Metric | Head width | Head height |
|---|---|---|---|
| external for 1/4 shaft | M6 shaft | — | groove 0.022 deep |
| external for 1/2 shaft | M12 shaft | — | groove 0.039 deep |
| internal for 1 bore | M25 bore | — | groove 0.039 deep |
Representative sizes. Full dimensional data lives in the standards listed below.
Grades & Strength
| Grade | Material | Tensile (psi) | Marking |
|---|---|---|---|
| Carbon steel | spring steel | — | None |
| Stainless | stainless spring steel | — | None |
Materials
- Spring steel
- Stainless spring steel
Pros & Cons
Pros
- Compact, low-profile retention
- Cheap and standardized
- High axial retention when seated
Cons
- Needs a machined groove
- Requires snap-ring pliers
- Can fly off — wear eye protection
Typical Uses
- Retaining bearings and gears
- Holding pins and shafts
- Bore-retained components
Alternatives & Related
- Spring Pin — Retention through a hole instead of a groove
- Dowel Pin — Solid locating pin
Where to Buy
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FAQ
Internal vs external snap ring?
An internal ring seats in a groove inside a bore (lugs squeeze inward); an external ring seats in a groove on a shaft (lugs spread outward).
What pliers do I need for snap rings?
Interchangeable-head snap-ring pliers, with tips matched to the lug holes and the ring type (internal vs external).