W628-ZZ bearing: complete specifications & equivalents
The W628-ZZ is a ISO 15 radial bearing sized 8 x 24 x 8 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 | 8 mm |
| Outer diameter D | 24 mm |
| Width B | 8 mm |
| Material | SS440C |
| Seal / shield | ZZ |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 2.47 kN |
| Basic static load rating C0 | 1.12 kN |
| Fatigue load limit Pu | 0.048 kN |
| Reference speed (thermal) | 70000 rpm |
| Limiting speed (mechanical) | 36000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 18 g |
| Manufacturer designation | W 628-2Z |
| 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 & 62800-series range
| Bore d | 0.315 in |
|---|---|
| Outer diameter D | 0.945 in |
| Width B | 0.315 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 8 mm |
| Smallest bore in 62800-series | 5 mm |
| Largest outer diameter in 62800-series | 24 mm |
| Width range across 62800-series | 4–8 mm |
| Bore position in 62800-series (smallest first) | 4 of 5 |
| Bore above smallest 62800-series size | 3 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 628 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 8×24×8 mm envelope, but the stainless and chrome-steel executions carry different catalogue ratings (2.47/1.12 kN vs 3.9/1.66 kN) — envelope match, not a load-rating equivalent; choose by corrosion versus load duty. |
| 628-2RS | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 8×24×8 mm envelope, but the stainless and chrome-steel executions carry different catalogue ratings (2.47/1.12 kN vs 3.9/1.66 kN) — envelope match, not a load-rating equivalent; choose by corrosion versus load duty. |
| 628-RSR | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 8×24×8 mm envelope, but the stainless and chrome-steel executions carry different catalogue ratings (2.47/1.12 kN vs 3.9/1.66 kN) — envelope match, not a load-rating equivalent; choose by corrosion versus load duty. |
| 628-ZZ | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 8×24×8 mm envelope, but the stainless and chrome-steel executions carry different catalogue ratings (2.47/1.12 kN vs 3.9/1.66 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 W628-ZZ model number is decoded
The W prefix denotes SKF stainless steel deep-groove bearings (X108CrMo17 / AISI 440C class rings). In the 62800-series, the final digit is the bore in millimetres: 628 fits a 8 mm shaft (direct-number miniature spelling). Envelope 8×24×8 mm (0.315×0.945×0.315 in), C 2.47 kN, C0 1.12 kN, Pu 0.048 kN; limiting speed 36000 r/min and mass 18 g. SKF spells the double shield W 628-2Z (suffix 2Z); the shields are non-contact, retain grease and block coarse debris but are not liquid-tight. Stainless is chosen for corrosion and washdown duty, not for extra load — the same-envelope chrome-steel bearing rates higher.
Typical equipment & failure modes
Common applications
- medical and laboratory devices
- small pumps handling corrosive media
- bicycle and outdoor equipment
- appliances exposed to moisture
Known failure patterns
- seal and grease failure before the rings corrode in sustained washdown service
- surface staining and pitting when even the stainless steel is left unlubricated in salty or acidic duty
- fine-particle abrasion when non-contact shields let dust through in a dirty environment
- grease aging inside the shielded cavity with no relubrication path
Selection pitfalls — read before you substitute
- Food, pharmaceutical and washdown positions need food-grade grease (e.g. NSF H1 registered) inside W628-ZZ; standard fill is industrial grease unless specified otherwise.
- Corrosion resistance depends on clean, undamaged surfaces: never weld near W628-ZZ or scratch the raceways during mounting, since the damaged spot starts corrosion.
- Temperatures above roughly 300 °C temper the stainless races; even standard greases fail far earlier — keep W628-ZZ inside the quoted grease temperature range.
- W-prefix stainless rings (X108CrMo17 / AISI 440C class) resist moisture and weak chemicals but will still rust in chloride-rich or salt-spray duty without protection — W628-ZZ is not marine-grade stainless.
- Do not preload W628-ZZ to silence it: a deep-groove ball bearing is not angular-contact, and axial preload only raises temperature and shortens grease life.
- Clearance suffixes follow the seal code in the designation stack (e.g. W 628-2Z/C3 in SKF spelling); no suffix means normal CN internal clearance.
Frequently asked questions
What are the dimensions of the stainless W628-ZZ?
SKF W 628-2Z measures 8×24×8 mm (0.315×0.945×0.315 in), about 18 g, C 2.47 kN.
What does the W in W 628-2Z mean?
W is the SKF prefix for stainless steel deep-groove bearings (rings in X108CrMo17 / AISI 440C class); the rest of the designation follows the normal series and bore rules.
Is the stainless bearing magnetic?
Yes. Bearing stainless steels are martensitic (hardened) and magnetic; non-magnetic austenitic grades cannot be hardened enough for raceways and balls.
Where is W628-ZZ typically used?
Food and packaging machines, pharmaceutical equipment, washdown conveyors, chemical and marine-atmosphere drives and appliances exposed to moisture.
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.