NK24-20 bearing: complete specifications & equivalents
The NK24-20 is a DIN 616 radial bearing sized 24 x 32 x 20 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 24 mm |
| Outer diameter D | 32 mm |
| Width B | 20 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 19 kN |
| Basic static load rating C0 | 32.5 kN |
| Fatigue load limit Pu | 4 kN |
| Reference speed (thermal) | 16000 rpm |
| Limiting speed (mechanical) | 19000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 40 g |
| Manufacturer designation | NK 24/20 |
| 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 | 0.945 in |
|---|---|
| Outer diameter D | 1.26 in |
| Width B | 0.787 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 4 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) | 17 of 46 |
| Bore above smallest NK-series size | 19 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NK24-20 model number is decoded
NK 24/20 belongs to the machined-ring needle roller family: an outer ring turned and ground to 32 mm with two retaining flanges, a roller-and-cage set inside, and envelope 24×32×20 mm on a hardened 24 mm shaft. The letters identify a flanged machined outer ring without inner ring; the figures give 24 mm Fw and 20 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. Speed planning separates the two ceilings: 16,000 r/min thermal reference and 19,000 r/min mechanical limiting — needle bearings tolerate high rpm only with adequate lubricant film at the 24 mm seat. Fit the outer ring with a press and a fitting sleeve, not by hammering the flanges — rolled flanges chip; the 32 mm ground OD takes the press fit that prevents outer-ring creep in oscillating duty.
Typical equipment & failure modes
Common applications
- gearbox planetary and idler gears on hardened pins
- piston-pin style pivots in hydraulic pumps
- guide rollers running on hardened tracks
- swing arms and lever pivots with oscillating duty
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
- brinelling of raceways from impact or pressing force transmitted through the rolling elements
- smearing of rollers and journal during idle periods because the radial section holds too little lubricant
Selection pitfalls — read before you substitute
- On a 24 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 32 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.
- Do not interchange envelope-identical needle families blindly: NK 24/20 shares its 24×32×20 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 16,000 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 19/32.5 kN ratings and 40 g mass are SKF catalogue values transcribed from ch. 7.3 of PUB BU/P1 17000 (PDF table page 628); 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 24/20?
A NK 24/20 measures 24 mm bore/Fw × 32 mm outside diameter × 20 mm width (0.945 × 1.26 × 0.787 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 19 kN, static C0 32.5 kN, fatigue limit Pu 4 kN, limiting speed 19,000 r/min, reference speed 16,000 r/min, mass about 40 g.
How is the NK 24/20 designation read?
NK names a machined-ring needle roller bearing without inner ring: the figures give Fw 24 mm and width 20 mm, OD 32 mm comes from the dimension series, and the flanged outer ring retains the caged rollers.
Can the NK 24/20 run on an unhardened shaft?
No. In this execution the 24 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 24/20 be mounted?
Press on the ring faces only with a fitting sleeve, keep everything square to the 24 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.