NK15-20 bearing: complete specifications & equivalents
The NK15-20 is a DIN 616 radial bearing sized 15 x 23 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 | 15 mm |
| Outer diameter D | 23 mm |
| Width B | 20 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 13.8 kN |
| Basic static load rating C0 | 18.3 kN |
| Fatigue load limit Pu | 2.2 kN |
| Reference speed (thermal) | 24000 rpm |
| Limiting speed (mechanical) | 26000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 27 g |
| Manufacturer designation | NK 15/20 |
| 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 | 0.591 in |
|---|---|
| Outer diameter D | 0.906 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) | 9 of 46 |
| Bore above smallest NK-series size | 10 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NK15-20 model number is decoded
Where the shaft can be hardened and ground, SKF offers NK 15/20 in the machined-ring needle roller bearings without inner ring: outer ring only, needle rollers caged between integral flanges, 15 mm bore seat and 23 mm OD. Reading the designation: NK gives the series and the numbers the boundary plan — 15 mm Fw for the shaft seat, 20 mm width; the 23 mm OD comes from the dimension series, and the absence of an inner ring is built into the family name. 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 13.8/18.3 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
- 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
- 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
- rapid raceway scoring when the shaft journal hardness drops below 58 HRC or the ground finish wears away
Selection pitfalls — read before you substitute
- On a 15 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 23 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.
- The quoted 13.8/18.3 kN ratings are SKF catalogue values for this exact execution (NK 15/20); 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 13.8/18.3 kN ratings and 27 g mass are SKF catalogue values transcribed from ch. 7.3 of PUB BU/P1 17000 (PDF table page 626); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
Is the NK 15/20 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 15/20 have?
A NK 15/20 measures 15 mm bore/Fw × 23 mm outside diameter × 20 mm width (0.591 × 0.906 × 0.787 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 13.8 kN, static C0 18.3 kN, fatigue limit Pu 2.2 kN, limiting speed 26,000 r/min, reference speed 24,000 r/min, mass about 27 g.
What does NK 15/20 mean in SKF part numbering?
NK names a machined-ring needle roller bearing without inner ring: the figures give Fw 15 mm and width 20 mm, OD 23 mm comes from the dimension series, and the flanged outer ring retains the caged rollers.
Does the NK 15/20 need a hardened and ground shaft?
No. In this execution the 15 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.