W61804-ZZ bearing: complete specifications & equivalents
The W61804-ZZ is a ISO 15 radial bearing sized 20 x 32 x 7 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 | 20 mm |
| Outer diameter D | 32 mm |
| Width B | 7 mm |
| Material | SS440C |
| Seal / shield | ZZ |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 3.12 kN |
| Basic static load rating C0 | 2.08 kN |
| Fatigue load limit Pu | 0.09 kN |
| Reference speed (thermal) | 48000 rpm |
| Limiting speed (mechanical) | 24000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 17 g |
| Manufacturer designation | W 61804-2Z |
| 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 & 61800-series range
| Bore d | 0.787 in |
|---|---|
| Outer diameter D | 1.26 in |
| Width B | 0.276 in |
| ISO bore code | 04 |
| Radial section height (D−d)/2 | 6 mm |
| Smallest bore in 61800-series | 1 mm |
| Largest outer diameter in 61800-series | 1820 mm |
| Width range across 61800-series | 1–140 mm |
| Bore position in 61800-series (smallest first) | 15 of 74 |
| Bore above smallest 61800-series size | 19 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 61804-ZZ | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | NSK NSK 6804ZZ shares the 20×32×7 mm envelope but carries different catalogue ratings (3.12/2.08 kN vs 4.4/2.47 kN) — the stainless execution is not a load-rating equivalent. |
| W61804-2RS | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 20×32×7 mm envelope and equivalent catalogue ratings; W 61804-2RS1 is the two contact elastomer seals execution of this size — boundary dimensions interchangeable, only the seal/shield/cage execution differs. |
| 61804 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF SKF 61804 shares the 20×32×7 mm envelope but carries different catalogue ratings (3.12/2.08 kN vs 4.03/2.32 kN) — the stainless execution is not a load-rating equivalent. |
| 61804-2RS | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF SKF 61804-2RS1 shares the 20×32×7 mm envelope but carries different catalogue ratings (3.12/2.08 kN vs 4.03/2.32 kN) — the stainless execution is not a load-rating equivalent. |
| 61804-RSR | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF SKF 61804-2RZ shares the 20×32×7 mm envelope but carries different catalogue ratings (3.12/2.08 kN vs 4.03/2.32 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 W61804-ZZ model number is decoded
The W prefix denotes SKF stainless steel deep-groove bearings (X108CrMo17 / AISI 440C class rings). In the 61800-series, the last two digits encode the bore: 61804 carries code 04 = 20 mm (code × 5). Envelope 20×32×7 mm (0.787×1.26×0.276 in), C 3.12 kN, C0 2.08 kN, Pu 0.09 kN; limiting speed 24000 r/min and mass 17 g. SKF spells the double shield W 61804-2Z (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
- small pumps handling corrosive media
- bicycle and outdoor equipment
- appliances exposed to moisture
- food and beverage conveyors
Known failure patterns
- surface staining and pitting when even the stainless steel is left unlubricated in salty or acidic duty
- seal and grease failure before the rings corrode in sustained washdown service
- 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
- Corrosion resistance depends on clean, undamaged surfaces: never weld near W61804-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 W61804-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 — W61804-ZZ is not marine-grade stainless.
- The stainless steel is martensitic and MAGNETIC; do not reject W61804-ZZ over magnetism — only austenitic grades are non-magnetic, and those are too soft for bearing raceways.
- Clearance suffixes follow the seal code in the designation stack (e.g. W 61804-2Z/C3 in SKF spelling); no suffix means normal CN internal clearance.
- Assign interference to the rotating ring: on a conventional shaft-mounted 20 mm position the inner ring rotates, so use a k5/m6 shaft seat with an H7 housing — reverse the logic if the outer ring rotates.
Frequently asked questions
What are the dimensions of the stainless W61804-ZZ?
SKF W 61804-2Z measures 20×32×7 mm (0.787×1.26×0.276 in), about 17 g, C 3.12 kN.
What does the W in W 61804-2Z 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.
What grease is supplied in W61804-ZZ?
Sealed units are pre-greased for life; for food or pharmaceutical duty order (or re-grease before service) with an NSF H1 registered food-grade grease.
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 W61804-ZZ; 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.