3 mm bore bearings
11 models with a 3 mm (0.118 in) bore across 2 bearing types, outside diameters from 5 to 10 mm. Tables are grouped by type; open a model for full specs and equivalents.
11 models 5–10 mm OD range 2 brands
| Model | Series | d (mm) | D (mm) | B (mm) | Brand | Seal | Clearance | C (kN) |
|---|---|---|---|---|---|---|---|---|
| W637-3-ZZ | 6300 | 3 | 6 | 3 | SKF | ZZ | CN | 0.117 |
| W618-3 | 61800 | 3 | 7 | 2 | SKF | open | CN | 0.178 |
| W638-3-ZZ | 63800 | 3 | 7 | 3 | SKF | ZZ | CN | 0.178 |
| W619-3-ZZ | 61900 | 3 | 8 | 3 | SKF | ZZ | CN | 0.225 |
| W639-3-ZZ | 6300 | 3 | 8 | 4 | SKF | ZZ | CN | 0.319 |
| W623-2RS | 6200 | 3 | 10 | 4 | SKF | 2RS | CN | 0.358 |
| W623-ZZ | 6200 | 3 | 10 | 4 | SKF | ZZ | CN | 0.358 |
Selecting a 3 mm bore bearing
The bore fixes the shaft, not the bearing capacity. At 3 mm the catalog spans 5–10 mm outside diameter: the light sections suit compact housings and moderate duty, while the larger ODs use bigger rolling elements and carry substantially more load. Select first by the required dynamic load rating C for the calculated L10 life, then by available radial space.
For a rotating inner ring a j5 shaft seat with an H7 housing is the usual starting point; an interference fit plus thermal growth consumes internal clearance, so C3 is the common industrial default rather than CN. Sealed variants (-2RS, -ZZ) trade a small amount of speed for contamination protection and maintenance-free operation — compare the sealed and open versions of the same envelope before substituting one for the other.
Frequently asked questions
What bearings have a 3 mm bore?
This index lists 11 verified bearing models with a 3 mm (0.118 in) bore across 2 bearing types, from 5 to 10 mm outside diameter. Open any model for the full specification table, seal/clearance options and graded cross references.
How do I choose between the 5–10 mm OD options for a 3 mm shaft?
On a fixed 3 mm bore, a smaller outside diameter means a lighter section for limited housing space and moderate load; a larger OD with a wider ring carries more radial and axial load and lasts longer at the same duty. Compare the C dynamic load rating in each model table, then match seal type, internal clearance (CN/C3/C4) and precision class to the actual mounting and operating temperature.
What shaft fit and bore code apply to 3 mm bearings?
A 3 mm bore on a rotating inner ring normally uses a j5 shaft seat with an H7 housing bore (verify against the catalogue for heavy or stationary-ring duty). Bore diameters below 20 mm follow the 10/12/15/17 mm exception table rather than code × 5.