NK70-25 bearing: complete specifications & equivalents
The NK70-25 is a DIN 616 radial bearing sized 70 x 85 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 | 85 mm |
| Width B | 25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 44.6 kN |
| Basic static load rating C0 | 98 kN |
| Fatigue load limit Pu | 12.2 kN |
| Reference speed (thermal) | 6000 rpm |
| Limiting speed (mechanical) | 6700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 260 g |
| Manufacturer designation | NK 70/25 |
| Standard | DIN 616 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without an inner ring |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without 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. 7.3 machined rings with flanges, without 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 & NK-series range
| Bore d | 2.756 in |
|---|---|
| Outer diameter D | 3.346 in |
| Width B | 0.984 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 7.5 mm |
| Smallest bore in NK-series | 5 mm |
| Largest outer diameter in NK-series | 130 mm |
| Width range across NK-series | 10–40 mm |
| Bore position in NK-series (smallest first) | 37 of 46 |
| Bore above smallest NK-series size | 65 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NK70-25 model number is decoded
SKF's machined-ring needle roller bearings without inner ring include NK 70/25: 70 mm Fw, 85 mm outside diameter, 25 mm width — a machined and ground outer ring whose rolled flanges retain the needle rollers, running on the shaft as the inner raceway. The letters identify a flanged machined outer ring without inner ring; the figures give 70 mm Fw and 25 mm B — dimensionally identical envelopes exist with an inner ring under the NA/NKI names, which changes the shaft seat entirely. Execution notes: the outer ring flanges are rolled from the ring material (no loose ribs to dislodge), the roller set is caged for low friction, and the TN option swaps in a polymer cage for quieter running. For life calculation, the 44.6/98 kN ratings assume raceway geometry supplied by the shaft and housing in families without an inner ring — journal hardness, roundness and finish are part of the bearing, not of the application. Grease through the housing groove before fitting the shaft; the integral flanges hold the grease film at the roller ends, which is where these bearings first starve.
Typical equipment & failure modes
Common applications
- guide rollers running on hardened tracks
- swing arms and lever pivots with oscillating duty
- cam followers built up from separate components
- crank pins and eccentrics where the hardened journal is the raceway
Known failure patterns
- raceway spalling once the catalogue L10 life is exceeded or after overload events
- polymer cage deformation when the local temperature exceeds the 120 °C sustained limit
- grease starvation at the roller ends when relubrication intervals are stretched in dirty duty
- hard-particle indentation in unfiltered lubricant
- smearing of rollers and journal during idle periods because the radial section holds too little lubricant
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.
- Do not interchange envelope-identical needle families blindly: NK 70/25 shares its 70×85×25 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.
- Reference and limiting speeds are different limits: the 6,000 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.
- The 44.6/98 kN ratings and 260 g mass are SKF catalogue values transcribed from ch. 7.3 of PUB BU/P1 17000 (PDF table page 632); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
What are the dimensions and ratings of the NK 70/25?
A NK 70/25 measures 70 mm bore/Fw × 85 mm outside diameter × 25 mm width (2.756 × 3.346 × 0.984 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 44.6 kN, static C0 98 kN, fatigue limit Pu 12.2 kN, limiting speed 6,700 r/min, reference speed 6,000 r/min, mass about 260 g.
How is the NK 70/25 designation read?
NK names a machined-ring needle roller bearing without inner ring: the figures give Fw 70 mm and width 25 mm, OD 85 mm comes from the dimension series, and the flanged outer ring retains the caged rollers.
Can the NK 70/25 run on an unhardened shaft?
No. In this execution the 70 mm shaft journal is the inner raceway: it must be ground and hardened to 58–64 HRC (with matching housing bore quality on the outside). If the shaft cannot meet that, order the inner-ring sibling (NKI/NA execution) plus its ground inner ring instead.
How should the NK 70/25 be mounted?
Press on the ring faces only with a fitting sleeve, keep everything square to the 70 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without an inner ring on 2026-09-26. Read our editorial & correction policy.