6218-ZZ bearing: complete specifications & equivalents
The 6218-ZZ is a ISO 15 radial bearing sized 90 x 160 x 30 mm (bore x OD x width) with ZZ sealing. 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 | ZZ |
| Internal clearance | CN / C3 available |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 101 kN |
| Basic static load rating C0 | 73.5 kN |
| Fatigue load limit Pu | 2.8 kN |
| Reference speed (thermal) | 8500 rpm |
| Limiting speed (mechanical) | 4300 rpm |
| Operating temperature | -30 to +120 °C |
| Mass | 2300 g |
| Manufacturer designation | SKF 6218-2Z |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-25 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-24
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 & 6200-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 6200-series | 3 mm |
| Largest outer diameter in 6200-series | 540 mm |
| Width range across 6200-series | 2.5–85 mm |
| Bore position in 6200-series (smallest first) | 27 of 45 |
| Bore above smallest 6200-series size | 87 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 6218 | ISO 15 | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | ISO 15 boundary-dimension envelope; seal suffix convention varies by brand (2RS / DDU / LLU / 2RSR) — verify seal design and temperature range before substituting. |
| 6218-2RS-NSK | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×160×30 mm envelope per ISO 15; seal variant differs (ZZ vs 2RS) — confirm sealing suits the duty. |
| 6218-NSK | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×160×30 mm envelope per ISO 15; seal variant differs (ZZ vs OPEN) — confirm sealing suits the duty. |
| 6218-RSR | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×160×30 mm envelope per ISO 15; seal variant differs (ZZ vs RSR) — confirm sealing suits the duty. |
| 6218-ZZ-NSK | NSK | 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. |
| 6218-2RS-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×160×30 mm envelope per ISO 15; seal variant differs (ZZ vs 2RS) — confirm sealing suits the duty. |
| 6218-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×160×30 mm envelope per ISO 15; seal variant differs (ZZ vs OPEN) — confirm sealing suits the duty. |
| 6218-RSR-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×160×30 mm envelope per ISO 15; seal variant differs (ZZ vs RSR) — confirm sealing suits the duty. |
| 6218-ZZ-NTN | 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. |
| 7218 | SKF | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | — |
| NU218 | SKF | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | — |
| 6218-M | SKF | full Dimensions and internal design equivalent — standard interchange. | SKF 6218 M (machined brass cage, open arrangement) is the same-size execution on the 90×160×30 mm envelope with ratings within 10 % — boundary dimensions interchangeable. |
| 218 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF 218 shares the 90×160×30 mm envelope but catalogue C/C0 differ — envelope match only after a load check. |
| 218-ZZ | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF 218-2Z shares the 90×160×30 mm envelope but catalogue C/C0 differ — envelope match only after a load check. |
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 6218-ZZ model number is decoded
6218-ZZ carries two non-contact sheet-steel shields that hold the factory grease in and keep coarse debris out; they do not seal against liquids. Within the light 62xx section (diameter series 2 of ISO 15), multiplying bore code 18 by five gives the 90 mm bore; the 160 mm outside diameter and 30 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 90 mm shaft under normal load, catalogue practice seats it on a k5 shaft fit with an H7 housing bore — confirm against the actual load direction and magnitude before committing. SKF's own suffix is 2Z (this page's industry-neutral spelling is -ZZ); catalogue number 6218-2Z.
Typical equipment & failure modes
Common applications
- hoists and winches
- heavy conveyors
- pulp and paper machinery
- medium and heavy industrial drives
Known failure patterns
- fine-particle abrasion when non-contact shields let dust past in dirty duty
- grease aging in the shield-for-life cavity with no relubrication path
- brinelling from static overload or hammering during mounting
- false brinelling from vibration while the shaft is stationary
Selection pitfalls — read before you substitute
- At 90 mm bore the ring mass is significant: heat 6218 on an induction heater (max 120 °C), never over an open flame, and plan puller access or a withdrawal sleeve now for the day it has to come off again.
- At 90 mm bore the 62xx light series is the workhorse section; its 160×30 mm envelope is what most motor and gearbox seats are machined for, so any alternative section must be checked against both this OD and this width, not the bore alone.
- ZZ shields are non-contact: 6218-ZZ blocks chips and coarse dust but is not waterproof — do not install it expecting a pressure-wash seal, step up to 6218-2RS for that.
- Do not wash 6218-ZZ in solvent before mounting: the grease inside the shielded cavity is the service fill, and solvent creeping past the shield gap strips it out.
- Measure the shaft, do not trust the drawing: a 90 mm nominal journal worn by even 0.02 mm turns an interference seat into a creeping fit that frets the bore of 6218-ZZ.
- Do not quieten a noisy bearing by preloading it: the 6200-series is a deep-groove design, not angular-contact; axial preload raises temperature and shortens grease life.
- SKF spells the shielded version 6218-2Z (one shield: 6218-Z), not "-ZZ": the suffix language differs by brand even though the ISO envelope is identical, so quote the brand designation when ordering.
- The single-shield execution 6218-Z is a distinct order number in catalogue 17000: it suits open gears or oil-bath arrangements where the unshielded face faces the lubricant, and it is not interchangeable with the double-shield 6218-2Z for high-contamination positions.
- The 101/73.5 kN ratings here are SKF Explorer-class figures from catalogue PUB BU/P1 17000/1 EN (Oct 2018); SKF can revise internal geometry and ratings without changing the designation, so treat the catalogue version and date as part of the specification and re-verify for critical drives.
Frequently asked questions
What are the dimensions of a 6218-ZZ bearing?
A 6218-ZZ deep-groove ball bearing has a 90 mm bore, 160 mm outer diameter and 30 mm width (3.543 × 6.299 × 1.181 in), per ISO 15 boundary dimensions. It is fitted with two non-contact metallic shields.
What lubrication does 6218-ZZ need?
6218-ZZ is greased at the factory and the shields hold the fill for the bearing's service life; relubrication is not intended, and adding grease through the shield gap usually forces dirt in with it.
How does the 6218 bore code work?
The last two digits of 6218 are bore code 18, giving 18 × 5 = 90 mm bore. The 160 mm outside diameter and 30 mm width follow the ISO 15 diameter series, not the bore code alone.
What does the ZZ suffix on 6218-ZZ mean?
ZZ means two non-contact sheet-metal shields, one each side. They retain factory grease and block coarse particles with little friction, but do not seal against liquids, fine dust or pressure washing.
What is the SKF designation and catalogue data for 6218-ZZ?
In the SKF Rolling Bearings catalogue this size is listed as 6218-2Z — two non-contact sheet-metal shields, 90×160×30 mm per ISO 15. Quoted values: C 101 kN, C0 73.5 kN, Pu 2.8 kN, limiting speed 4300 r/min, mass 2300 g. Brand suffixes (2Z, 2RSH, 2RSL) differ from the industry-neutral spelling 6218-ZZ.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-25. Read our editorial & correction policy.