618-9 bearing: complete specifications & equivalents
The 618-9 is a ISO 15 radial bearing sized 9 x 17 x 4 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 9 mm |
| Outer diameter D | 17 mm |
| Width B | 4 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 0.871 kN |
| Basic static load rating C0 | 0.34 kN |
| Fatigue load limit Pu | 0.014 kN |
| Reference speed (thermal) | 85000 rpm |
| Limiting speed (mechanical) | 53000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3.4 g |
| Manufacturer designation | 618/9 |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-27 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-27
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018)); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & 61800-series range
| Bore d | 0.354 in |
|---|---|
| Outer diameter D | 0.669 in |
| Width B | 0.157 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 4 mm |
| Smallest bore in 61800-series | 1 mm |
| Largest outer diameter in 61800-series | 1820 mm |
| Width range across 61800-series | 1–140 mm |
| Bore position in 61800-series (smallest first) | 10 of 74 |
| Bore above smallest 61800-series size | 8 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| W618-9 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 9×17×4 mm envelope, but the stainless and chrome-steel executions carry different catalogue ratings (0.871/0.34 kN vs 0.761/0.335 kN) — envelope match, not a load-rating equivalent; choose by corrosion versus load duty. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 618-9 model number is decoded
In the miniature 61800-series, the bore is written directly after the slash as 9 mm (bores below 10 mm use the slash spelling). The envelope is 9×17×4 mm (0.354×0.669×0.157 in) with a 4.0 mm radial section height, C 0.871 kN, C0 0.34 kN and Pu 0.014 kN. The open 618/9 carries no shields or seals and relies on application lubrication and external sealing. Limiting speed 53000 r/min, catalogue mass 3.4 g. A thin section saves space but leaves little margin for misalignment or shaft deflection.
Typical equipment & failure modes
Common applications
- clutch and transmission assemblies
- robotics and automation joints
- lay shafts and idler shafts
- textile and packaging machinery
Known failure patterns
- contamination wear when the open arrangement is used without external seals
- lubricant starvation where no regreasing interval is maintained
- cage damage from running beyond the limiting speed
- raceway smearing under marginal lubrication at start-up
Selection pitfalls — read before you substitute
- Assign interference to the rotating ring: on a conventional shaft-mounted 9 mm position the inner ring rotates, so use a k5/m6 shaft seat with an H7 housing — reverse the logic if the outer ring rotates.
- Catalogue ratings for 618-9 (C 0.871 kN, C0 0.34 kN) are SKF figures from PUB BU/P1 17000; geometry revisions can change ratings without changing the designation, so keep the catalogue edition with the specification.
- Open 618-9 needs external sealing at the arrangement level; in dusty housings its life depends entirely on those external seals and the regreasing schedule.
- Plan a relubrication interval for 618-9; run-to-failure on open deep-groove bearings is the dominant early-failure cause.
- Catalogue ratings for 618-9 (C 0.871 kN, C0 0.34 kN) are SKF figures from PUB BU/P1 17000; geometry revisions can change ratings without changing the designation, so keep the catalogue edition with the specification.
- Mount by heating the inner ring (max 120 °C) — driving 618-9 home through the outer ring or balls brinells the raceways.
Frequently asked questions
What are the dimensions of 618-9?
The SKF 618/9 measures 9 mm bore × 17 mm OD × 4 mm width (0.354 × 0.669 × 0.157 in), mass about 3.4 g. It is open, with no shields or seals.
Why is there a slash in the designation 618/9?
The slash writes a bore that falls outside the two-digit code table: 618/9 means 9 mm bore. The site slug 618-9 replaces the slash with a hyphen.
What load can 618-9 take?
Catalogue values for 618/9: dynamic C 0.871 kN, static C0 0.34 kN, fatigue limit Pu 0.014 kN. Use C in life calculation and C0 for static checks at 9 mm bore.
What is the speed rating of 618-9?
SKF lists a 85000 r/min thermal reference speed and a 53000 r/min mechanical limiting speed for 618/9; real limits also depend on lubrication and fits.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-27. Read our editorial & correction policy.