6318-M bearing: complete specifications & equivalents
The 6318-M is a ISO 15 radial bearing sized 90 x 190 x 43 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 90 mm |
| Outer diameter D | 190 mm |
| Width B | 43 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 151 kN |
| Basic static load rating C0 | 108 kN |
| Fatigue load limit Pu | 3.8 kN |
| Reference speed (thermal) | 7500 rpm |
| Limiting speed (mechanical) | 7000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 6100 g |
| Manufacturer designation | 6318 M |
| 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 & 6300-series range
| Bore d | 3.543 in |
|---|---|
| Outer diameter D | 7.48 in |
| Width B | 1.693 in |
| ISO bore code | 18 |
| Radial section height (D−d)/2 | 50 mm |
| Smallest bore in 6300-series | 2 mm |
| Largest outer diameter in 6300-series | 500 mm |
| Width range across 6300-series | 3–95 mm |
| Bore position in 6300-series (smallest first) | 25 of 40 |
| Bore above smallest 6300-series size | 88 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 6318-RSR | NSK | full Dimensions and internal design equivalent — standard interchange. | NSK counterpart NSK 6318VV on the same 90×190×43 mm envelope with ratings within 10 % — interchange after checking seal, cage and precision details on both pages. |
| 318 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×190×43 mm envelope as SKF 318, but catalogue C/C0 differ (151/108 kN vs 157/160 kN) — envelope match only after a load check. |
| 318-ZZ | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×190×43 mm envelope as SKF 318-2Z, but catalogue C/C0 differ (151/108 kN vs 157/160 kN) — envelope match only after a load check. |
| 6318 | SKF | full Dimensions and internal design equivalent — standard interchange. | SKF SKF 6318 (open arrangement) shares the 90×190×43 mm envelope with ratings within 10 % — execution variant of the same size; boundary dimensions interchangeable. |
| 6318-ZZ | SKF | full Dimensions and internal design equivalent — standard interchange. | SKF SKF 6318-2Z (two non-contact shields) shares the 90×190×43 mm envelope with ratings within 10 % — execution variant of the same size; boundary dimensions interchangeable. |
| 6318-2RS | SKF | full Dimensions and internal design equivalent — standard interchange. | SKF SKF 6318-2RS1 (two contact elastomer seals) shares the 90×190×43 mm envelope with ratings within 10 % — execution variant of the same size; boundary dimensions interchangeable. |
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 6318-M model number is decoded
In the 6300-series, the last two digits encode the bore: 6318 carries code 18 = 90 mm (code × 5). The envelope is 90×190×43 mm (3.543×7.48×1.693 in) with a 50.0 mm radial section height, C 151 kN, C0 108 kN and Pu 3.8 kN. The open 6318 M carries no shields or seals and relies on application lubrication and external sealing. The M suffix identifies the machined brass cage execution, a separate order number from the pressed-steel version. Limiting speed 7000 r/min, catalogue mass 6100 g.
Typical equipment & failure modes
Common applications
- machine tool auxiliaries
- agricultural gearboxes
- industrial electric motors
- gearboxes and speed reducers
Known failure patterns
- contamination wear when the open arrangement is used without external seals
- lubricant starvation where no regreasing interval is maintained
- fretting corrosion on a creeping shaft or housing seat
- cage damage from running beyond the limiting speed
Selection pitfalls — read before you substitute
- Catalogue ratings for 6318-M (C 151 kN, C0 108 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.
- Catalogue ratings for 6318-M (C 151 kN, C0 108 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.
- The M suffix on 6318-M denotes a machined brass cage: it is the choice for high speeds, marginal lubrication and shock/vibration duty, and it is temperature-tolerant where polymer cages are not — the 6100 g quoted mass includes the heavier cage.
- Open 6318-M 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 6318-M; run-to-failure on open deep-groove bearings is the dominant early-failure cause.
- Deep-groove geometry tolerates only minutes of misalignment; if the 190 mm housing bore cannot be aligned, move to a self-aligning bearing rather than shimming 6318-M.
Frequently asked questions
What are the dimensions of 6318-M?
The SKF 6318 M measures 90 mm bore × 190 mm OD × 43 mm width (3.543 × 7.48 × 1.693 in), mass about 6100 g. It is open, with no shields or seals.
How does the bore code in 6318 work?
The final two digits of 6318 are bore code 18, multiplied by 5 to give 90 mm.
How heavy is 6318-M?
Catalogue mass is 6100 g for 6318 M; seal and cage executions of the same envelope differ by a few grams.
What load can 6318-M take?
Catalogue values for 6318 M: dynamic C 151 kN, static C0 108 kN, fatigue limit Pu 3.8 kN. Use C in life calculation and C0 for static checks at 90 mm bore.
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.