NK65-25 bearing: complete specifications & equivalents
The NK65-25 is a DIN 616 radial bearing sized 65 x 78 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 | 65 mm |
| Outer diameter D | 78 mm |
| Width B | 25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 44 kN |
| Basic static load rating C0 | 104 kN |
| Fatigue load limit Pu | 12.7 kN |
| Reference speed (thermal) | 6300 rpm |
| Limiting speed (mechanical) | 7000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 220 g |
| Manufacturer designation | NK 65/25 |
| 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 | 2.559 in |
|---|---|
| Outer diameter D | 3.071 in |
| Width B | 0.984 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 6.5 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) | 35 of 46 |
| Bore above smallest NK-series size | 60 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NK65-25 model number is decoded
NK 65/25 is a ribbed machined-ring needle roller bearing (no inner ring) sized 65×78×25 mm: the ground outside diameter seats in the housing, the integral flanges hold the rollers, and the 65 mm shaft journal completes the bearing. In SKF nomenclature NK families drop the inner ring: the numbers after the letters give the 65 mm under-roller diameter and the 25 mm width, with the 78 mm outside diameter set by the machined-ring needle roller bearings without inner ring plan. The machined ring is through-hardened and ground on OD, bore-side raceway and faces; the flanged lip design means the housing shoulder can be omitted — the ring clamps axially between housing wall and cover washer. For life calculation, the 44/104 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. Fit the outer ring with a press and a fitting sleeve, not by hammering the flanges — rolled flanges chip; the 78 mm ground OD takes the press fit that prevents outer-ring creep in oscillating duty.
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
- needle edge loading and raceway denting when the shaft deflects beyond the compensation range
- cage pocket wear and roller skew after sustained operation with too little radial preload
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- false brinelling of standby equipment under external vibration
- 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 65 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.
- The quoted 44/104 kN ratings are SKF catalogue values for this exact execution (NK 65/25); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.
- 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.
- The 44/104 kN ratings and 220 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
Is the NK 65/25 sealed?
No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty.
Which dimensions does the NK 65/25 have?
A NK 65/25 measures 65 mm bore/Fw × 78 mm outside diameter × 25 mm width (2.559 × 3.071 × 0.984 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 44 kN, static C0 104 kN, fatigue limit Pu 12.7 kN, limiting speed 7,000 r/min, reference speed 6,300 r/min, mass about 220 g.
What does NK 65/25 mean in SKF part numbering?
NK names a machined-ring needle roller bearing without inner ring: the figures give Fw 65 mm and width 25 mm, OD 78 mm comes from the dimension series, and the flanged outer ring retains the caged rollers.
Does the NK 65/25 need a hardened and ground shaft?
No. In this execution the 65 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.
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.