6021-M (brass cage) bearing: complete specifications & equivalents
The 6021-M is a ISO 15 radial bearing sized 105 x 160 x 26 mm (bore x OD x width). 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 | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| 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) | 7500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1850 g |
| Manufacturer designation | 6021 M |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-27 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-27
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 |
|---|---|---|---|
| 6021-2RS-NSK | NSK | full Dimensions and internal design equivalent — standard interchange. | NSK counterpart NSK 6021DDU on the same 105×160×26 mm envelope with ratings within 10 % — interchange after checking seal, cage and precision details on both pages. |
| 6021-RSR | NSK | full Dimensions and internal design equivalent — standard interchange. | NSK counterpart NSK 6021VV on the same 105×160×26 mm envelope with ratings within 10 % — interchange after checking seal, cage and precision details on both pages. |
| 6021-ZZ-NSK | NSK | full Dimensions and internal design equivalent — standard interchange. | NSK counterpart NSK 6021ZZ on the same 105×160×26 mm envelope with ratings within 10 % — interchange after checking seal, cage and precision details on both pages. |
| 6021-NSK | NSK | full Dimensions and internal design equivalent — standard interchange. | NSK counterpart NSK 6021 on the same 105×160×26 mm envelope with ratings within 10 % — interchange after checking seal, cage and precision details on both pages. |
| 6021 | SKF | full Dimensions and internal design equivalent — standard interchange. | SKF SKF 6021 (open arrangement) shares the 105×160×26 mm envelope with ratings within 10 % — execution variant of the same size; boundary dimensions interchangeable. |
| 6021-2RS | SKF | full Dimensions and internal design equivalent — standard interchange. | SKF SKF 6021-2RS1 (two contact elastomer seals) shares the 105×160×26 mm envelope with ratings within 10 % — execution variant of the same size; boundary dimensions interchangeable. |
| 6021-ZZ | SKF | full Dimensions and internal design equivalent — standard interchange. | SKF SKF 6021-2Z (two non-contact shields) shares the 105×160×26 mm envelope with ratings within 10 % — execution variant of the same size; 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-M model number is decoded
In the 6000-series, the last two digits encode the bore: 6021 carries code 21 = 105 mm (code × 5). The envelope is 105×160×26 mm (4.134×6.299×1.024 in) with a 27.5 mm radial section height, C 76.1 kN, C0 65.5 kN and Pu 2.4 kN. The open 6021 M carries no shields or seals and relies on application lubrication and external sealing. The M suffix identifies the machined brass cage execution, a separate order number from the pressed-steel version. Limiting speed 7500 r/min, catalogue mass 1850 g.
Typical equipment & failure modes
Common applications
- agricultural gearboxes
- industrial electric motors
- gearboxes and speed reducers
- centrifugal and positive-displacement pumps
Known failure patterns
- contamination wear when the open arrangement is used without external seals
- lubricant starvation where no regreasing interval is maintained
- electrical pitting in VFD-driven motors without shaft grounding
- edge loading from shaft deflection or housing misalignment
Selection pitfalls — read before you substitute
- Catalogue ratings for 6021-M (C 76.1 kN, C0 65.5 kN) are SKF figures from PUB BU/P1 17000; geometry revisions can change ratings without changing the designation, so keep the catalogue edition with the specification.
- Catalogue ratings for 6021-M (C 76.1 kN, C0 65.5 kN) are SKF figures from PUB BU/P1 17000; geometry revisions can change ratings without changing the designation, so keep the catalogue edition with the specification.
- The M suffix on 6021-M denotes a machined brass cage: it is the choice for high speeds, marginal lubrication and shock/vibration duty, and it is temperature-tolerant where polymer cages are not — the 1850 g quoted mass includes the heavier cage.
- Open 6021-M needs external sealing at the arrangement level; in dusty housings its life depends entirely on those external seals and the regreasing schedule.
- Plan a relubrication interval for 6021-M; run-to-failure on open deep-groove bearings is the dominant early-failure cause.
- The fatigue load limit is 2.4 kN; it feeds the equivalent-mean-load check, not the basic life calculation — do not substitute one for the other.
- Where two 6021 bearings share one shaft in a preloaded or matched arrangement, order both from the same production lot; catalogue figures describe a single bearing, not a matched set.
- For positions that need relubrication, choose the open execution of 6021 and design the housing with a grease path; shielded and sealed versions are intended as fit-and-forget units.
Frequently asked questions
What are the dimensions of 6021-M?
The SKF 6021 M measures 105 mm bore × 160 mm OD × 26 mm width (4.134 × 6.299 × 1.024 in), mass about 1850 g. It is open, with no shields or seals.
How does the bore code in 6021 work?
The final two digits of 6021 are bore code 21, multiplied by 5 to give 105 mm.
What internal clearance does 6021-M have?
Standard supply is normal CN radial clearance unless a suffix states otherwise; for tight fits or hot shafts SKF lists the C3 execution of the same size — the residual clearance left after mounting is what governs running life.
How long can a greased 6021-M be stored?
Sealed and shielded SKF units carry a finite grease shelf life: SKF recommends first-in-first-out stock rotation and dry, cool, vibration-free storage. Open units ship with rust preventive only and are greased at assembly.
What load can 6021-M take?
Catalogue values for 6021 M: dynamic C 76.1 kN, static C0 65.5 kN, fatigue limit Pu 2.4 kN. Use C in life calculation and C0 for static checks at 105 mm bore.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-27. Read our editorial & correction policy.