1218-K bearing: complete specifications & equivalents
The 1218-K is a ISO 15 radial bearing sized 90 x 160 x 30 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 | 160 mm |
| Width B | 30 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 57.2 kN |
| Basic static load rating C0 | 23.6 kN |
| Fatigue load limit Pu | 1.08 kN |
| Reference speed (thermal) | 8500 rpm |
| Limiting speed (mechanical) | 5300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2500 g |
| Manufacturer designation | 1218 K |
| 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 & 1200-series range
| Bore d | 3.543 in |
|---|---|
| Outer diameter D | 6.299 in |
| Width B | 1.181 in |
| ISO bore code | 18 |
| Radial section height (D−d)/2 | 35 mm |
| Smallest bore in 1200-series | 6 mm |
| Largest outer diameter in 1200-series | 230 mm |
| Width range across 1200-series | 6–154 mm |
| Bore position in 1200-series (smallest first) | 25 of 32 |
| Bore above smallest 1200-series size | 84 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 1218 | NTN | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
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 1218-K model number is decoded
The 12xx series is the light/normal-section self-aligning ball bearing (ISO dimension series 02). the last two digits encode the bore: 1218 carries code 18 = 90 mm (code × 5). Envelope 90×160×30 mm (3.543×6.299×1.181 in) with a 35.0 mm radial section height, C 57.2 kN, C0 23.6 kN and Pu 1.08 kN. The open 1218 K carries no shields or seals and relies on application lubrication and external sealing. The suffix identifies the glass-fibre-reinforced polyamide 66 cage execution. The K suffix marks a 1:12 tapered bore for direct mounting on a tapered shaft or with an adapter sleeve. Reference (thermal) speed 8500 r/min, limiting speed 5300 r/min, catalogue mass 2500 g.
Typical equipment & failure modes
Common applications
- industrial electric motors
- conveyor drum and pulley shafts
- agricultural gearboxes
- textile machinery drives
Known failure patterns
- lubricant starvation where no regreasing interval is maintained
- contamination wear when the open arrangement is used without adequate external sealing
- incorrect sleeve tightening that leaves the tapered bore loose or over-expanded, changing internal clearance
- adapter-sleeve fretting when the sleeve is not locked against the shaft shoulder
- rolling-contact fatigue spalling once the catalogue L10 life is exceeded
- brinelling from static overload or hammer blows during mounting
Selection pitfalls — read before you substitute
- At 90 mm bore, C3 clearance is the safe choice when interference fits plus temperature rise consume the CN clearance; a hot tight bearing with no residual clearance fails fast.
- Mount 1218-K by heating the inner ring (max 120 °C) on a cylindrical bore — driving it home through the outer ring or balls brinells the raceways.
- The K suffix means a 1:12 tapered bore: 1218-K is not a drop-in for the straight-bore version — it needs a tapered shaft or an H-series adapter sleeve.
- The suffix on 1218-K denotes a glass-fibre-reinforced polyamide 66 cage: quiet and light at the 5300 r/min limiting speed, but it softens above roughly 120 °C — check the oil temperature in hot drives.
- Mount 1218-K by heating the inner ring (max 120 °C) on a cylindrical bore — driving it home through the outer ring or balls brinells the raceways.
- The fatigue load limit is 1.08 kN; it feeds the equivalent-mean-load check, not the basic life calculation — do not substitute one for the other.
Frequently asked questions
What are the dimensions of 1218-K?
SKF 1218 K measures 90 mm bore × 160 mm OD × 30 mm width (3.543 × 6.299 × 1.181 in), mass about 2500 g. It is open, with no shields or seals.
How does the bore code in 1218 work?
The final two digits of 1218 are bore code 18, multiplied by 5 to give 90 mm.
How much misalignment can 1218-K tolerate?
Self-aligning ball bearings tolerate roughly 2–3° of static misalignment for open executions; sealed 2RS1 variants like 1218-K allow less (about 1°) because the seal lip binds first.
Can 1218-K take axial load?
A self-aligning ball bearing can carry some axial load in addition to radial load, but its axial capacity is lower than an angular-contact bearing of the same envelope. Use it where misalignment, not thrust, is the main requirement.
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.