6021-ZZ bearing: complete specifications & equivalents
The 6021-ZZ is a ISO 15 radial bearing sized 105 x 160 x 26 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 | 105 mm |
| Outer diameter D | 160 mm |
| Width B | 26 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 | 76.1 kN |
| Basic static load rating C0 | 65.5 kN |
| Fatigue load limit Pu | 2.4 kN |
| Reference speed (thermal) | 8500 rpm |
| Limiting speed (mechanical) | 4300 rpm |
| Operating temperature | -30 to +120 °C |
| Mass | 1650 g |
| Manufacturer designation | SKF 6021-2Z |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-24 |
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 & 6000-series range
| Bore d | 4.134 in |
|---|---|
| Outer diameter D | 6.299 in |
| Width B | 1.024 in |
| ISO bore code | 21 |
| Radial section height (D−d)/2 | 27.5 mm |
| Smallest bore in 6000-series | 4 mm |
| Largest outer diameter in 6000-series | 1150 mm |
| Width range across 6000-series | 4–155 mm |
| Bore position in 6000-series (smallest first) | 28 of 61 |
| Bore above smallest 6000-series size | 101 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 6021 | 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. |
| 6021-2RS-NSK | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×160×26 mm envelope per ISO 15; seal variant differs (ZZ vs 2RS) — confirm sealing suits the duty. |
| 6021-NSK | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×160×26 mm envelope per ISO 15; seal variant differs (ZZ vs OPEN) — confirm sealing suits the duty. |
| 6021-RSR | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×160×26 mm envelope per ISO 15; seal variant differs (ZZ vs RSR) — confirm sealing suits the duty. |
| 6021-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. |
| 6021-M | SKF | full Dimensions and internal design equivalent — standard interchange. | SKF 6021 M (machined brass cage, open arrangement) is the same-size execution on the 105×160×26 mm envelope with ratings within 10 % — boundary dimensions interchangeable. |
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 6021-ZZ model number is decoded
In the 6000-series (diameter series 0 of ISO 15) the last two digits encode the bore: 6021 carries bore code 21 = 105 mm. Outside diameter 160 mm and width 26 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 105 mm shaft, typical catalogue practice is a m6 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. SKF's own suffix is 2Z (this page's industry-neutral spelling is -ZZ); catalogue number 6021-2Z.
Typical equipment & failure modes
Common applications
- hoists and winches
- heavy conveyors
- pulp and paper machinery
- medium and heavy industrial drives
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
- brinelling from static overload or hammering during mounting
- false brinelling from vibration while the shaft is stationary
Selection pitfalls — read before you substitute
- Large bores like the 105 mm of 6021-ZZ demand clean, burr-free seats; one raised burr under a ring this size cocks the bearing and concentrates load at the raceway edge, cutting life drastically.
- Choosing the 60xx extra-light section saves radial space at 105 mm bore, but the trade-off is rating: if the drive sees shock or frequent start-stop cycles, re-check the L10 life against a 6221 before committing to the smaller envelope.
- ZZ shields are non-contact: 6021-ZZ blocks chips and coarse dust but is not waterproof — do not install it expecting a pressure-wash seal, step up to 6021-2RS for that.
- Shielded 6021-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.
- A 105 mm bore listing showing the right d/D/B but no standard or precision-class reference may be a loose-tolerance import; measure bore/OD spread before fitting it to a machined shaft.
- Suffixes stack in a defined order — clearance follows the seal code, e.g. 6021-C3. No clearance suffix means normal CN clearance.
- SKF spells the shielded version 6021-2Z (one shield: 6021-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 6021-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 6021-2Z for high-contamination positions.
- The 76.1/65.5 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 6021-ZZ bearing?
A 6021-ZZ deep-groove ball bearing has a 105 mm bore, 160 mm outer diameter and 26 mm width (4.134 × 6.299 × 1.024 in), per ISO 15 boundary dimensions. It is fitted with two non-contact metallic shields.
What internal clearance does 6021-ZZ have?
Unless a clearance suffix says otherwise, 6021-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 6021 and verify the residual clearance after mounting.
How should 6021-ZZ be mounted?
Apply the mounting force to the ring being fitted: on a 105 mm shaft seat the press load must pass through the inner-ring face only. Induction heating of the inner ring (max 120 °C) is the clean method at this size. Never strike the outer ring, the cage or the seals.
What lubrication does 6021-ZZ need?
6021-ZZ is greased at the factory and the shields hold the fill for the bearing's service life; relubrication is not intended, and adding grease through the shield gap usually forces dirt in with it.
What is the SKF designation and catalogue data for 6021-ZZ?
In the SKF Rolling Bearings catalogue this size is listed as 6021-2Z — two non-contact sheet-metal shields, 105×160×26 mm per ISO 15. Quoted values: C 76.1 kN, C0 65.5 kN, Pu 2.4 kN, limiting speed 4300 r/min, mass 1650 g. Brand suffixes (2Z, 2RSH, 2RSL) differ from the industry-neutral spelling 6021-ZZ.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-24. Read our editorial & correction policy.