Reference chart for internal and external retaining ring sizes with groove dimensions, ring thickness, and gap specifications. Covers 3/8" through 3" for both external (shaft) and internal (bore) rings per ANSI B27.7.
| Shaft / Bore Size ▲ | Ring Thickness ▲ | Free Diameter ▲ | Groove Diameter ▲ | Groove Width ▲ | Groove Depth ▲ | Max RPM ▲ |
|---|---|---|---|---|---|---|
| 3/8" shaft | 0.025" | 0.360" | 0.348" | 0.028" | 0.021" | 32,000 |
| 7/16" shaft | 0.025" | 0.422" | 0.409" | 0.028" | 0.021" | 28,000 |
| 1/2" shaft | 0.035" | 0.484" | 0.468" | 0.038" | 0.023" | 24,000 |
| 9/16" shaft | 0.035" | 0.547" | 0.530" | 0.038" | 0.023" | 21,000 |
| 5/8" shaft | 0.042" | 0.609" | 0.590" | 0.046" | 0.027" | 19,000 |
| 3/4" shaft | 0.042" | 0.734" | 0.712" | 0.046" | 0.027" | 15,000 |
| 7/8" shaft | 0.050" | 0.859" | 0.833" | 0.054" | 0.031" | 12,000 |
| 1" shaft | 0.050" | 0.984" | 0.955" | 0.054" | 0.031" | 10,000 |
| 1-1/8" shaft | 0.050" | 1.109" | 1.078" | 0.054" | 0.031" | 9,000 |
| 1-1/4" shaft | 0.062" | 1.234" | 1.198" | 0.068" | 0.035" | 8,000 |
| 1-1/2" shaft | 0.062" | 1.484" | 1.443" | 0.068" | 0.035" | 6,500 |
| 1-3/4" shaft | 0.078" | 1.734" | 1.688" | 0.086" | 0.042" | 5,500 |
| 2" shaft | 0.078" | 1.984" | 1.933" | 0.086" | 0.042" | 4,500 |
| 2-1/2" shaft | 0.093" | 2.484" | 2.423" | 0.102" | 0.050" | 3,500 |
| 3" shaft | 0.109" | 2.984" | 2.913" | 0.120" | 0.058" | 2,800 |
| 3/8" bore | 0.015" | 0.403" | 0.400" | 0.018" | 0.015" | — |
| 1/2" bore | 0.025" | 0.522" | 0.528" | 0.028" | 0.020" | — |
| 5/8" bore | 0.035" | 0.649" | 0.656" | 0.038" | 0.024" | — |
| 3/4" bore | 0.042" | 0.774" | 0.782" | 0.046" | 0.027" | — |
| 7/8" bore | 0.042" | 0.899" | 0.908" | 0.046" | 0.027" | — |
| 1" bore | 0.042" | 1.024" | 1.035" | 0.046" | 0.027" | — |
| 1-1/4" bore | 0.050" | 1.275" | 1.290" | 0.054" | 0.031" | — |
| 1-1/2" bore | 0.062" | 1.524" | 1.543" | 0.068" | 0.035" | — |
| 2" bore | 0.062" | 2.024" | 2.050" | 0.068" | 0.035" | — |
| 2-1/2" bore | 0.078" | 2.524" | 2.558" | 0.086" | 0.042" | — |
| 3" bore | 0.093" | 3.024" | 3.065" | 0.102" | 0.050" | — |
Need retaining ring grooves machined?
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Upload CAD for Instant QuoteAn external retaining ring (also called a shaft ring) fits into a groove on the outside of a shaft to prevent axial movement of components. An internal retaining ring (also called a bore or housing ring) fits into a groove inside a bore or housing. External rings expand to snap onto the shaft; internal rings compress to fit inside the bore.
Groove dimensions are specified by the retaining ring standard (ANSI B27.7 or DIN 471/472). Key dimensions include groove diameter, groove width, and groove depth. The groove diameter must match the specific ring size. Groove width is typically slightly wider than the ring thickness to allow installation. Always use the manufacturer's specifications for your specific ring.
Standard retaining rings are made from carbon spring steel (SAE 1060-1090) with a phosphate and oil finish for corrosion protection. Stainless steel (15-7 PH or 302) rings are available for corrosion-resistant applications. Beryllium copper rings are used in non-magnetic or non-sparking environments.
Maximum RPM depends on the ring size, material, and whether it is an internal or external ring. External rings on rotating shafts are subject to centrifugal force which can unseat them at high speeds. As a general rule, standard carbon steel rings on shafts under 1 inch can handle 10,000 to 15,000 RPM. Larger rings have lower limits. Always check the manufacturer's RPM rating for your specific application.
Retaining rings can generally be reused if they were removed carefully without permanent deformation. However, if the ring shows signs of fatigue, loss of spring force, distortion, or corrosion, it should be replaced. In critical applications (aerospace, medical), always use new rings during reassembly.
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