W618-1 bearing: complete specifications & equivalents
The W618-1 is a ISO 15 radial bearing sized 1 x 3 x 1 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 1 mm |
| Outer diameter D | 3 mm |
| Width B | 1 mm |
| Material | SS440C |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 0.052 kN |
| Basic static load rating C0 | 0.012 kN |
| Fatigue load limit Pu | 0.001 kN |
| Reference speed (thermal) | 240000 rpm |
| Limiting speed (mechanical) | 150000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 0.03 g |
| Manufacturer designation | W 618/1 |
| 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 | 0.039 in |
|---|---|
| Outer diameter D | 0.118 in |
| Width B | 0.039 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 1 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) | 1 of 74 |
| Bore above smallest 61800-series size | 0 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the W618-1 model number is decoded
The W prefix denotes SKF stainless steel deep-groove bearings (X108CrMo17 / AISI 440C class rings). In the 61800-series, the bore is written directly after the slash as 1 mm (bores below 10 mm use the slash spelling). Envelope 1×3×1 mm (0.039×0.118×0.039 in), C 0.052 kN, C0 0.012 kN, Pu 0.001 kN; limiting speed 150000 r/min and mass 0.03 g. The open W 618/1 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
- Food, pharmaceutical and washdown positions need food-grade grease (e.g. NSF H1 registered) inside W618-1; standard fill is industrial grease unless specified otherwise.
- Corrosion resistance depends on clean, undamaged surfaces: never weld near W618-1 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 W618-1 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 — W618-1 is not marine-grade stainless.
- At 1 mm bore, C3 clearance is the safe choice when interference fits plus temperature rise consume the CN clearance; a hot tight bearing with no residual clearance fails fast.
- The fatigue load limit is 0.001 kN; it feeds the equivalent-mean-load check, not the basic life calculation — do not substitute one for the other.
Frequently asked questions
What are the dimensions of the stainless W618-1?
SKF W 618/1 measures 1×3×1 mm (0.039×0.118×0.039 in), about 0.03 g, C 0.052 kN.
What does the W in W 618/1 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.
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 W618-1; add seals and food-grade grease for wet positions.
Can I replace a chrome-steel bearing with stainless W618-1?
The envelope matches, but stainless rates lower (C 0.052 kN for W 618/1); for corrosive environments that trade-off is intended, for high loads it shortens life.
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.