NKI17-20 bearing: complete specifications & equivalents
The NKI17-20 is a DIN 616 radial bearing sized 17 x 29 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 | 17 mm |
| Outer diameter D | 29 mm |
| Width B | 20 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 17.2 kN |
| Basic static load rating C0 | 27 kN |
| Fatigue load limit Pu | 3.35 kN |
| Reference speed (thermal) | 19000 rpm |
| Limiting speed (mechanical) | 22000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 53 g |
| Manufacturer designation | NKI 17/20 |
| 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 | 0.669 in |
|---|---|
| Outer diameter D | 1.142 in |
| Width B | 0.787 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 6 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) | 8 of 30 |
| Bore above smallest NKI-series size | 12 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NKI17-20 model number is decoded
For a 17 mm shaft that cannot be hardened on site, NKI 17/20 adds a hardened, ground inner ring to the machined needle roller design: envelope 17×29×20 mm per the machined-ring needle roller bearings with inner ring plan. The NKI 17/20 code gives bore 17 mm and width 20 mm explicitly; unlike the RNA/NK families the shaft only needs a standard k5/j5 seat because the hardened inner ring is the raceway. TN polymer cage executions run quieter and tolerate grease-lubricated pivot duty; steel cage executions remain the choice for higher temperature or oil-bath lubrication. Selection arithmetic: C 17.2 kN against C0 27 kN gives a C0/C ratio of 1.57, and the 3.35 kN fatigue load limit Pu sets the floor for the adjusted-life calculation at contaminated lubrication. Mounting: heat or press the inner ring onto the 17 mm k5 seat (max 120 °C), fit the flanged outer ring into the H7 housing bore, and check the 20 mm assembly for free rotation before applying load.
Typical equipment & failure modes
Common applications
- gearbox shafts where the journal cannot be hardened on site
- wheel and lever pivots needing a replaceable inner ring
- conveyor roller ends and return rollers
- agricultural implement pivots and cutter heads
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
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- rolling-contact fatigue spalling after the rated L10 life
- inner-ring raceway spalling after the narrow ring section runs hot with excessive interference
Selection pitfalls — read before you substitute
- On a 17 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 29 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.
- 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 17.2/27 kN ratings and 53 g mass are SKF catalogue values transcribed from ch. 7.4 of PUB BU/P1 17000 (PDF table page 638); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
Can the NKI 17/20 run on an unhardened shaft?
Yes — that is the point of this family. The NKI 17/20 carries its own hardened, ground inner ring on a 17 mm seat, so the shaft needs only a normal k5/j6 finish. The inner ring is separable and replaceable.
How should the NKI 17/20 be mounted?
Mount the inner ring on the 17 mm seat first (induction heat, max 120 °C, or press), then fit the flanged outer ring into the H7 housing bore. Verify free rotation and, for 2RS executions, check the wider outer ring against the housing depth.
What limits the service life of a NKI 17/20?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 17 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 6.0 mm radial section leaves no reserve once a raceway is dented or ribboned.
What are the dimensions and ratings of the NKI 17/20?
A NKI 17/20 measures 17 mm bore/Fw × 29 mm outside diameter × 20 mm width (0.669 × 1.142 × 0.787 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 17.2 kN, static C0 27 kN, fatigue limit Pu 3.35 kN, limiting speed 22,000 r/min, reference speed 19,000 r/min, mass about 53 g.
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.