6404-ZZ bearing: complete specifications & equivalents
The 6404-ZZ is a ISO 15 radial bearing sized 20 x 72 x 19 mm (bore x OD x width) with ZZ sealing. Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Bore diameter d | 20 mm |
| Outer diameter D | 72 mm |
| Width B | 19 mm |
| Seal / shield | ZZ |
| Internal clearance | CN / C3 available |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Operating temperature | -30 to +120 °C |
| Mass (geometry estimate) | 364 g |
| Standard | ISO 15 |
| Catalog version | iso15-ed4-geometry |
| Last verified | 2026-09-23 |
Source: ISO 15 boundary-dimensions standard · extracted 2026-09-23
Standard-interchange bearing: dimensions per ISO 15; CN clearance, P0 tolerance and a stamped-steel cage are catalogue defaults unless the supplier states otherwise, and mass is a geometry-derived estimate. Brand catalogue load ratings and limiting speeds for 6404 are being backfilled — use the inquiry form for certified values.
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 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×72×19 mm envelope per ISO 15; seal variant differs (ZZ vs OPEN) — 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-ZZ model number is decoded
In the 6400-series (ISO 15 diameter series 4) the last two digits encode the bore: 6404 carries bore code 04 = 20 mm. Outside diameter 72 mm and width 19 mm come from the ISO 15 boundary-dimensions general plan. Suffix -ZZ denotes two non-contact metallic shields; they retain grease and block coarse debris but are not liquid-tight. For normal-load mounting with a rotating inner ring on a 20 mm shaft, typical catalogue practice is a k5 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude.
Typical equipment & failure modes
Common applications
- agricultural equipment
- fans and blowers
- electric motors
- centrifugal pumps
Known failure patterns
- fine-particle abrasion when non-contact shields let dust past in dirty duty
- grease aging in the shield-for-life cavity with no relubrication path
- false brinelling from vibration while the shaft is stationary
- fretting corrosion on a loose shaft seat
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-ZZ; 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.
- ZZ shields are non-contact: 6404-ZZ blocks chips and coarse dust but is not waterproof — do not install it expecting a pressure-wash seal, step up to 6404-2RS for that.
- Shielded 6404-ZZ units are typically greased for life; prying the shields out for regreasing usually bends them and leaves a gap that throws grease in service.
- Do not quieten a noisy bearing by preloading it: the 6400-series is a deep-groove design, not angular-contact; axial preload raises temperature and shortens grease life.
Frequently asked questions
What are the dimensions of a 6404-ZZ bearing?
A 6404-ZZ 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 fitted with two non-contact metallic shields. Geometry-based estimated mass is about 364 g for a steel-cage unit; catalogue masses vary slightly with seal and cage design.
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 the ZZ suffix on 6404-ZZ mean?
ZZ means two non-contact sheet-metal shields, one each side. They retain factory grease and block coarse particles with little friction, but do not seal against liquids, fine dust or pressure washing.
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.
Are 6404 bearings from different brands interchangeable?
For boundary dimensions, yes: every brand's 6404 uses the same ISO 15 envelope (20×72×19 mm). Load ratings, limiting speeds, clearance, precision class and sealing design can differ, so verify those in the supplier catalogue when substituting. Seal suffixes also differ by brand (2RS, DDU, LLU and similar).
Reviewed & verified by the MPN Base engineering desk against source catalog iso15-ed4-geometry on 2026-09-23. Read our editorial & correction policy.