6307-ZZ bearing: complete specifications & equivalents
The 6307-ZZ is a ISO 15 radial bearing sized 35 x 80 x 21 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 | 35 mm |
| Outer diameter D | 80 mm |
| Width B | 21 mm |
| Material | GCr15 |
| Seal / shield | ZZ |
| Internal clearance | CN / C3 available |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 35.1 kN |
| Basic static load rating C0 | 19 kN |
| Fatigue load limit Pu | 0.815 kN |
| Reference speed (thermal) | 19000 rpm |
| Limiting speed (mechanical) | 9500 rpm |
| Operating temperature | -30 to +120 °C |
| Mass | 480 g |
| Manufacturer designation | SKF 6307-2Z |
| 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 & 6300-series range
| Bore d | 1.378 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 0.827 in |
| ISO bore code | 07 |
| Radial section height (D−d)/2 | 22.5 mm |
| Smallest bore in 6300-series | 2 mm |
| Largest outer diameter in 6300-series | 500 mm |
| Width range across 6300-series | 3–95 mm |
| Bore position in 6300-series (smallest first) | 14 of 40 |
| Bore above smallest 6300-series size | 33 mm |
Mounting, lubrication & life for 6307-ZZ
Recommended fits & mounting
- Rotating inner ring on a 35 mm shaft: k5; housing bore H7 for normal stationary-load outer rings. Reverse the logic if the outer ring rotates.
- Fit by induction heating (max 120 °C) where practical — never drive the ring home through the rolling elements.
- Keep shaft and housing fillet radii below the bearing chamfer so the 21 mm-wide ring seats square on its shoulder.
Lubrication strategy
Non-contact metal shields block coarse debris while running nearly as cool as open. No relubrication path on the standard execution; the shield cavity grease ages even though the steel is still serviceable.
Worked L10 life example (illustrative duty)
For ball bearings, L10h = (C/P)3 · 106 / (60·n). Taking an example radial equivalent load P = 3 kN at n = 1,500 r/min (a small belted motor duty — substitute the real equivalent load from the application calculation):
C = 35.1 kN → L10h ≈ 17,796 hours
Choosing a section at the same 35 mm bore
| Series | Open execution | OD × width | C (kN) | Limiting speed (r/min) |
|---|---|---|---|---|
| 60xx | 6007-FAG | 62 × 14 | 17.5 | 17,700 |
| 62xx | 6207-FAG | 72 × 17 | 28.0 | 15,000 |
| 63xx | 6307-FAG | 80 × 21 | 37.0 | 13,600 |
| 64xx | 6407-FAG | 100 × 25 | 56.0 | 9,500 |
| 618xx | 61807-FAG | 47 × 7 | 4.7 | 21,600 |
| 619xx | 61907-FAG | 55 × 10 | 10.9 | 17,800 |
| 160xx | 16007 | 62 × 9 | 12.3 | 16,700 |
A larger section is not a drop-in swap — OD and width change — and same-envelope seal variants are compared on the 35×80×21 envelope page. Match meaning, not the size chart alone: see what the cross-reference levels mean.
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 6307-2RS-FAG | FAG | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 35×80×21 mm envelope per ISO 15; seal variant differs (ZZ vs 2RS) — confirm sealing suits the duty. |
| 6307-FAG | FAG | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 35×80×21 mm envelope per ISO 15; seal variant differs (ZZ vs OPEN) — confirm sealing suits the duty. |
| 6307-ZZ-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. |
| 6307 | ISO 15 | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | ISO 15 boundary-dimension envelope; seal suffix convention varies by brand (2RS / DDU / LLU / 2RSR) — verify seal design and temperature range before substituting. |
| 6307-2RS-NSK | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 35×80×21 mm envelope per ISO 15; seal variant differs (ZZ vs 2RS) — confirm sealing suits the duty. |
| 6307-NSK | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 35×80×21 mm envelope per ISO 15; seal variant differs (ZZ vs OPEN) — confirm sealing suits the duty. |
| 6307-RSR | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 35×80×21 mm envelope per ISO 15; seal variant differs (ZZ vs RSR) — confirm sealing suits the duty. |
| 6307-ZZ-NSK | NSK | 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. |
| 6307-2RS-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 35×80×21 mm envelope per ISO 15; seal variant differs (ZZ vs 2RS) — confirm sealing suits the duty. |
| 6307-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 35×80×21 mm envelope per ISO 15; seal variant differs (ZZ vs OPEN) — confirm sealing suits the duty. |
| 6307-RSR-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 35×80×21 mm envelope per ISO 15; seal variant differs (ZZ vs RSR) — confirm sealing suits the duty. |
| 6307-ZZ-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. |
| 7307 | SKF | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | — |
| NU307 | SKF | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | — |
| 6307-M | SKF | full Dimensions and internal design equivalent — standard interchange. | SKF 6307 M (machined brass cage, open arrangement) is the same-size execution on the 35×80×21 mm envelope with ratings within 10 % — boundary dimensions interchangeable. |
| W6307-2RS | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF stainless execution W 6307-2RS1 shares the 35×80×21 mm envelope but rates differently (35.1/19 kN vs 28.6/19 kN) — not a load-rating equivalent. |
| 307 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF 307 shares the 35×80×21 mm envelope but catalogue C/C0 differ — envelope match only after a load check. |
| 307-ZZ | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF 307-2Z shares the 35×80×21 mm envelope but catalogue C/C0 differ — envelope match only after a load check. |
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 6307-ZZ model number is decoded
6307-ZZ carries two non-contact sheet-steel shields that hold the factory grease in and keep coarse debris out; they do not seal against liquids. Within the medium 63xx section (diameter series 3 of ISO 15), multiplying bore code 07 by five gives the 35 mm bore; the 80 mm outside diameter and 21 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 35 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. SKF's own suffix is 2Z (this page's industry-neutral spelling is -ZZ); catalogue number 6307-2Z.
Typical equipment & failure modes
Common applications
- fans and blowers
- electric motors
- centrifugal pumps
- small gearboxes
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
- raceway smearing under marginal lubrication at start-up
- edge loading from shaft deflection or housing misalignment
Selection pitfalls — read before you substitute
- At a 35 mm bore, a shaft-seat burr or an overtight setscrew can score the thin inner ring of 6307-ZZ; check shaft finish and runout (target Ra ≤ 1.6 µm) before pressing it home.
- The 63xx medium series gains rating at 35 mm bore through a 80 mm OD and 21 mm width; the heavier rolling elements also trade away some speed versus a 6207.
- ZZ shields are non-contact: 6307-ZZ blocks chips and coarse dust but is not waterproof — do not install it expecting a pressure-wash seal, step up to 6307-2RS for that.
- Shielded 6307-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.
- Never mix components between two 6307-ZZ units: rings, cage and balls are factory-matched and are not field-interchangeable, even between identical designations.
- Measure the shaft, do not trust the drawing: a 35 mm nominal journal worn by even 0.02 mm turns an interference seat into a creeping fit that frets the bore of 6307-ZZ.
- SKF spells the shielded version 6307-2Z (one shield: 6307-Z), not "-ZZ": the suffix language differs by brand even though the ISO envelope is identical, so quote the brand designation when ordering.
- The single-shield execution 6307-Z is a distinct order number in catalogue 17000: it suits open gears or oil-bath arrangements where the unshielded face faces the lubricant, and it is not interchangeable with the double-shield 6307-2Z for high-contamination positions.
- The 35.1/19 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 6307-ZZ bearing?
A 6307-ZZ deep-groove ball bearing has a 35 mm bore, 80 mm outer diameter and 21 mm width (1.378 × 3.15 × 0.827 in), per ISO 15 boundary dimensions. It is fitted with two non-contact metallic shields.
How does the 6300 compare with other series at the same 35 mm bore?
The '3' is the medium diameter series: 80×21 mm, 22.5 mm radial section at 35 mm bore, carrying more load than a 6207 but needing a larger housing bore and giving up some speed.
Are 6307 bearings from different brands interchangeable?
For boundary dimensions, yes: every brand's 6307 uses the same ISO 15 envelope (35×80×21 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, 2RSL and similar).
What internal clearance does 6307-ZZ have?
Unless a clearance suffix says otherwise, 6307-ZZ is manufactured to normal (CN) radial internal clearance. Tight fits and hot shafts consume clearance in service — for those conditions order the C3 execution of 6307 and verify the residual clearance after mounting.
What is the SKF designation and catalogue data for 6307-ZZ?
In the SKF Rolling Bearings catalogue this size is listed as 6307-2Z — two non-contact sheet-metal shields, 35×80×21 mm per ISO 15. Quoted values: C 35.1 kN, C0 19 kN, Pu 0.815 kN, limiting speed 9500 r/min, mass 480 g. Brand suffixes (2Z, 2RSH, 2RSL) differ from the industry-neutral spelling 6307-ZZ.
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.