NKI70-25 bearing: complete specifications & equivalents
The NKI70-25 is a DIN 616 radial bearing sized 70 x 95 x 25 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 70 mm |
| Outer diameter D | 95 mm |
| Width B | 25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 56.1 kN |
| Basic static load rating C0 | 127 kN |
| Fatigue load limit Pu | 15.6 kN |
| Reference speed (thermal) | 5000 rpm |
| Limiting speed (mechanical) | 5600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 510 g |
| Manufacturer designation | NKI 70/25 |
| Standard | DIN 616 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.4 machined rings with flanges, with an inner ring |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.4 machined rings with flanges, with an inner ring) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.4 machined rings with flanges, with an inner ring); 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 & NKI-series range
| Bore d | 2.756 in |
|---|---|
| Outer diameter D | 3.74 in |
| Width B | 0.984 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 12.5 mm |
| Smallest bore in NKI-series | 5 mm |
| Largest outer diameter in NKI-series | 130 mm |
| Width range across NKI-series | 12–40 mm |
| Bore position in NKI-series (smallest first) | 24 of 30 |
| Bore above smallest NKI-series size | 65 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NKI70-25 model number is decoded
In SKF catalogue PUB BU/P1 17000, NKI 70/25 denotes a complete needle roller bearing for a 70 mm shaft — machined inner and outer rings, integral flanges on the outer ring retaining the roller set, 95 mm OD and 25 mm width. The designation NKI 70/25 tells you the envelope — 70×95×25 mm — and the family tells you the construction: complete bearing, replaceable inner ring, flanged outer ring retaining the needle rollers. Execution notes: the inner ring is ground on bore and raceway, so the shaft seat is a normal k5/j6; the flanged outer ring needs no housing shoulder, and NA 49 2RS executions add seals with a wider outer ring. The 510 g catalogue mass and 12.5 mm radial section ((95−70)/2) frame a rating of about 0.80 kN dynamic per millimetre of bore — the needle construction's density advantage over ball bearings of the same envelope. For NA 49 2RS executions the wider outer ring changes the housing depth: verify the 25 mm width and s offset dimensions against the open execution before reusing an existing bore.
Typical equipment & failure modes
Common applications
- conveyor roller ends and return rollers
- agricultural implement pivots and cutter heads
- electric motor armature shafts with ground seats
- printing and paper-handling rollers
Known failure patterns
- raceway spalling once the catalogue L10 life is exceeded or after overload events
- cage pocket wear and roller skew after sustained operation with too little radial preload
- grease starvation at the roller ends when relubrication intervals are stretched in dirty duty
- electrical erosion on VFD-driven shafts without brush or insulated mounting
- inner-ring bore fretting on a loose shaft seat, migrating hard particles into the rolling contact
Selection pitfalls — read before you substitute
- Above 50 mm bore, thermal growth matters: the 70 mm inner ring or journal grows with temperature faster than the housing, and the small clearance of a needle roller contact leaves little reserve — check running clearance hot, not just at assembly.
- Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.
- Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.
- The 56.1/127 kN ratings and 510 g mass are SKF catalogue values transcribed from ch. 7.4 of PUB BU/P1 17000 (PDF table page 644); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
What limits the service life of a NKI 70/25?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 70 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 12.5 mm radial section leaves no reserve once a raceway is dented or ribboned.
What are the dimensions and ratings of the NKI 70/25?
A NKI 70/25 measures 70 mm bore/Fw × 95 mm outside diameter × 25 mm width (2.756 × 3.74 × 0.984 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 56.1 kN, static C0 127 kN, fatigue limit Pu 15.6 kN, limiting speed 5,600 r/min, reference speed 5,000 r/min, mass about 510 g.
How is the NKI 70/25 designation read?
The letters mark a machined-ring needle roller bearing with inner ring: 70 mm bore, 25 mm width, 95 mm OD per the series plan. The hardened inner ring is the raceway, so an ordinary k5 shaft seat suffices.
Can the NKI 70/25 run on an unhardened shaft?
Yes — that is the point of this family. The NKI 70/25 carries its own hardened, ground inner ring on a 70 mm seat, so the shaft needs only a normal k5/j6 finish. The inner ring is separable and replaceable.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.4 machined rings with flanges, with an inner ring on 2026-09-26. Read our editorial & correction policy.