W604-ZZ bearing: complete specifications & equivalents
The W604-ZZ is a ISO 15 radial bearing sized 4 x 12 x 4 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 | 4 mm |
| Outer diameter D | 12 mm |
| Width B | 4 mm |
| Material | SS440C |
| Seal / shield | ZZ |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 0.54 kN |
| Basic static load rating C0 | 0.176 kN |
| Fatigue load limit Pu | 0.008 kN |
| Reference speed (thermal) | 130000 rpm |
| Limiting speed (mechanical) | 63000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2.15 g |
| Manufacturer designation | W 604-2Z |
| 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 & 6000-series range
| Bore d | 0.157 in |
|---|---|
| Outer diameter D | 0.472 in |
| Width B | 0.157 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 4 mm |
| Smallest bore in 6000-series | 4 mm |
| Largest outer diameter in 6000-series | 1150 mm |
| Width range across 6000-series | 4–155 mm |
| Bore position in 6000-series (smallest first) | 1 of 61 |
| Bore above smallest 6000-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| W604-2RS | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 4×12×4 mm envelope and equivalent catalogue ratings; W 604-2RS1 is the two contact elastomer seals execution of this size — boundary dimensions interchangeable, only the seal/shield/cage execution differs. |
| W604 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 4×12×4 mm envelope and equivalent catalogue ratings; W 604 is the open arrangement execution of this size — boundary dimensions interchangeable, only the seal/shield/cage execution differs. |
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 W604-ZZ model number is decoded
The W prefix denotes SKF stainless steel deep-groove bearings (X108CrMo17 / AISI 440C class rings). In the 6000-series, the final digit is the bore in millimetres: 604 fits a 4 mm shaft (direct-number miniature spelling). Envelope 4×12×4 mm (0.157×0.472×0.157 in), C 0.54 kN, C0 0.176 kN, Pu 0.008 kN; limiting speed 63000 r/min and mass 2.15 g. SKF spells the double shield W 604-2Z (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
- bicycle and outdoor equipment
- appliances exposed to moisture
- food and beverage conveyors
- pharmaceutical and packaging machines
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
- The stainless steel is martensitic and MAGNETIC; do not reject W604-ZZ over magnetism — only austenitic grades are non-magnetic, and those are too soft for bearing raceways.
- Stainless bearings carry lower load ratings than chrome steel of the same envelope: W604-ZZ is quoted at C 0.54 kN versus the 4 mm-wide 52100 version — do not swap on dimensions alone.
- Food, pharmaceutical and washdown positions need food-grade grease (e.g. NSF H1 registered) inside W604-ZZ; standard fill is industrial grease unless specified otherwise.
- Corrosion resistance depends on clean, undamaged surfaces: never weld near W604-ZZ or scratch the raceways during mounting, since the damaged spot starts corrosion.
- Clearance suffixes follow the seal code in the designation stack (e.g. W 604-2Z/C3 in SKF spelling); no suffix means normal CN internal clearance.
- Fillet radii must clear the W604-ZZ chamfer so the 4 mm-wide ring seats square; an oversized shaft radius creates point contact on the ring face.
Frequently asked questions
What are the dimensions of the stainless W604-ZZ?
SKF W 604-2Z measures 4×12×4 mm (0.157×0.472×0.157 in), about 2.15 g, C 0.54 kN.
What does the W in W 604-2Z 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 W604-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.