6404 bearing: complete specifications & equivalents
The 6404 is a ISO 15 radial bearing sized 20 x 72 x 19 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 | 72 mm |
| Width B | 19 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN / C3 available |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 30.7 kN |
| Basic static load rating C0 | 15 kN |
| Fatigue load limit Pu | 0.64 kN |
| Reference speed (thermal) | 24000 rpm |
| Limiting speed (mechanical) | 15000 rpm |
| Operating temperature | -40 to +150 °C |
| Mass | 410 g |
| Manufacturer designation | SKF 6404 |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-25 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-24
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 & 6400-series range
| Bore d | 0.787 in |
|---|---|
| Outer diameter D | 2.835 in |
| Width B | 0.748 in |
| ISO bore code | 04 |
| Radial section height (D−d)/2 | 26 mm |
| Smallest bore in 6400-series | 10 mm |
| Largest outer diameter in 6400-series | 250 mm |
| Width range across 6400-series | 12–58 mm |
| Bore position in 6400-series (smallest first) | 5 of 21 |
| Bore above smallest 6400-series size | 10 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 6404-FAG | FAG | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
| 6404-2RS | GENERIC-ISO | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×72×19 mm envelope per ISO 15; seal variant differs (OPEN vs 2RS) — confirm sealing suits the duty. |
| 6404-NTN | NTN | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
| 6404-ZZ | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×72×19 mm envelope per ISO 15; seal variant differs (OPEN vs ZZ) — confirm sealing suits the duty. |
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 6404 model number is decoded
6404 is supplied open, without shields or seals, so the arrangement around it must supply and retain the lubricant. Within the heavy 64xx section (diameter series 4 of ISO 15), multiplying bore code 04 by five gives the 20 mm bore; the 72 mm outside diameter and 19 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 20 mm shaft under normal load, catalogue practice seats it on a k5 shaft fit with an H7 housing bore — confirm against the actual load direction and magnitude before committing. In the SKF catalogue this open execution carries the bare designation; protected variants are ordered separately as -2Z and -2RSH.
Typical equipment & failure modes
Common applications
- electric motors
- centrifugal pumps
- small gearboxes
- conveyors and drives
Known failure patterns
- contamination wear from dust and dirt ingress through the open arrangement
- lubricant starvation when no regreasing interval is maintained
- edge loading from shaft deflection or housing misalignment
- rolling-contact fatigue spalling after the rated L10 life is exceeded
Selection pitfalls — read before you substitute
- At a 20 mm bore, a shaft-seat burr or an overtight setscrew can score the thin inner ring of 6404; check shaft finish and runout (target Ra ≤ 1.6 µm) before pressing it home.
- The 64xx heavy section at 20 mm bore (72 mm OD) is built for high-load, lower-speed duty; specifying it in a high-rpm motor gives excess heat and short grease life — use 62/63 there.
- Storage matters for open bearings: 6404 leaves the factory with rust preventive only, so clean it and apply the service grease at assembly even if the rings look oily from the wrapper.
- Open bearings tolerate the highest speeds in the 6400-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 6404 units.
- The housing bore for the 72 mm OD should be round within IT7; an oval bore pinches the outer ring of 6404 and shows up later as two-point loaded raceway wear.
- Grease compatibility is not guaranteed between fills: mixing lithium and polyurea thickeners in a 6400-series position can soften the mixture and leak — clean out the old fill before switching grease types.
- The open 6404 needs external sealing and application-supplied lubrication; in the SKF catalogue the protected variants are separate order numbers 6404-2Z (shields) and 6404-2RSH (contact seals), not suffix-free 6404.
- The 30.7/15 kN ratings here are SKF Explorer-class figures from catalogue PUB BU/P1 17000/1 EN (Oct 2018); SKF can revise internal geometry and ratings without changing the designation, so treat the catalogue version and date as part of the specification and re-verify for critical drives.
Frequently asked questions
What are the dimensions of a 6404 bearing?
A 6404 deep-groove ball bearing has a 20 mm bore, 72 mm outer diameter and 19 mm width (0.787 × 2.835 × 0.748 in), per ISO 15 boundary dimensions. It is an open bearing with no seals or shields.
How does the 6404 bore code work?
The last two digits of 6404 are bore code 04, giving 04 × 5 = 20 mm bore. The 72 mm outside diameter and 19 mm width follow the ISO 15 diameter series, not the bore code alone.
What does no suffix on 6404 mean?
A bare 6404 designation means open: no shields or seals, normal CN radial clearance and P0 normal tolerance unless further suffixes are ordered. The application must supply and retain the lubrication.
How does the 6400 compare with other series at the same 20 mm bore?
The '4' is the heavy diameter series: 72×19 mm, 26.0 mm radial section at 20 mm bore — the highest-capacity single-row 6xx option here, aimed at lower-speed, high-load shafts.
What is the SKF designation and catalogue data for 6404?
In the SKF Rolling Bearings catalogue this size is listed as 6404 — the open (unsealed) execution, 20×72×19 mm per ISO 15. Quoted values: C 30.7 kN, C0 15 kN, Pu 0.64 kN, limiting speed 15000 r/min, mass 410 g. Brand suffixes (2Z, 2RSH, 2RSL) differ from the industry-neutral spelling 6404.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-25. Read our editorial & correction policy.