W6304 bearing: complete specifications & equivalents
The W6304 is a ISO 15 radial bearing sized 20 x 52 x 15 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 20 mm |
| Outer diameter D | 52 mm |
| Width B | 15 mm |
| Material | SS440C |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 13.8 kN |
| Basic static load rating C0 | 7.8 kN |
| Fatigue load limit Pu | 0.335 kN |
| Reference speed (thermal) | 34000 rpm |
| Limiting speed (mechanical) | 20000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 136 g |
| Manufacturer designation | W 6304 |
| 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 | 0.787 in |
|---|---|
| Outer diameter D | 2.047 in |
| Width B | 0.591 in |
| ISO bore code | 04 |
| Radial section height (D−d)/2 | 16 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) | 9 of 40 |
| Bore above smallest 6300-series size | 18 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| W6304-2RS | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 20×52×15 mm envelope and equivalent catalogue ratings; W 6304-2RS1 is the two contact elastomer seals execution of this size — boundary dimensions interchangeable, only the seal/shield/cage execution differs. |
| W6304-ZZ | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 20×52×15 mm envelope and equivalent catalogue ratings; W 6304-2Z is the two non-contact shields execution of this size — boundary dimensions interchangeable, only the seal/shield/cage execution differs. |
| 6304 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF SKF 6304 shares the 20×52×15 mm envelope but carries different catalogue ratings (13.8/7.8 kN vs 16.8/7.8 kN) — the stainless execution is not a load-rating equivalent. |
| 6304-ZZ | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF SKF 6304-2Z shares the 20×52×15 mm envelope but carries different catalogue ratings (13.8/7.8 kN vs 16.8/7.8 kN) — the stainless execution is not a load-rating equivalent. |
| 6304-2RS | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF SKF 6304-2RSH shares the 20×52×15 mm envelope but carries different catalogue ratings (13.8/7.8 kN vs 16.8/7.8 kN) — the stainless execution is not a load-rating equivalent. |
| 6304-RSR | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF SKF 6304-2RSL shares the 20×52×15 mm envelope but carries different catalogue ratings (13.8/7.8 kN vs 15.9/7.8 kN) — the stainless execution is not a load-rating equivalent. |
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 W6304 model number is decoded
The W prefix denotes SKF stainless steel deep-groove bearings (X108CrMo17 / AISI 440C class rings). In the 6300-series, the last two digits encode the bore: 6304 carries code 04 = 20 mm (code × 5). Envelope 20×52×15 mm (0.787×2.047×0.591 in), C 13.8 kN, C0 7.8 kN, Pu 0.335 kN; limiting speed 20000 r/min and mass 136 g. The open W 6304 carries no shields or seals and relies on application lubrication and external sealing. 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
- food and beverage conveyors
- pharmaceutical and packaging machines
- washdown-duty equipment
- chemical and marine atmospheres
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
- contamination wear when the open arrangement is used without external seals
- lubricant starvation where no regreasing interval is maintained
Selection pitfalls — read before you substitute
- The stainless steel is martensitic and MAGNETIC; do not reject W6304 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: W6304 is quoted at C 13.8 kN versus the 15 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 W6304; standard fill is industrial grease unless specified otherwise.
- Corrosion resistance depends on clean, undamaged surfaces: never weld near W6304 or scratch the raceways during mounting, since the damaged spot starts corrosion.
- Deep-groove geometry tolerates only minutes of misalignment; if the 52 mm housing bore cannot be aligned, move to a self-aligning bearing rather than shimming W6304.
- Fillet radii must clear the W6304 chamfer so the 15 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 W6304?
SKF W 6304 measures 20×52×15 mm (0.787×2.047×0.591 in), about 136 g, C 13.8 kN.
What does the W in W 6304 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.
What grease is supplied in W6304?
The open bearing may ship with a rust-preventive film only; specify a food-grade grease for HACCP areas and plan relubrication.
Are W stainless bearings waterproof?
No — the stainless rings resist moisture and weak chemicals far better than 52100 chrome steel, but salt spray, strong chlorides and unlubricated washdown duty can still corrode W6304; add seals and food-grade grease for wet positions.
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.