NKI45-25-TN bearing: complete specifications & equivalents
The NKI45-25-TN is a DIN 616 radial bearing sized 45 x 62 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 | 45 mm |
| Outer diameter D | 62 mm |
| Width B | 25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 42.9 kN |
| Basic static load rating C0 | 91.5 kN |
| Fatigue load limit Pu | 11.2 kN |
| Reference speed (thermal) | 8000 rpm |
| Limiting speed (mechanical) | 9000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 220 g |
| Manufacturer designation | NKI 45/25 TN |
| 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 | 1.772 in |
|---|---|
| Outer diameter D | 2.441 in |
| Width B | 0.984 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 8.5 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) | 19 of 30 |
| Bore above smallest NKI-series size | 40 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NKI45-25-TN model number is decoded
SKF lists NKI 45/25 TN in the machined-ring needle roller bearings with inner ring with boundary dimensions 45×62×25 mm: an inner ring turns on the shaft while the flanged outer ring carries the needle roller complement in the housing. In SKF nomenclature the leading letters mark a machined-ring needle bearing with inner ring: figures state 45 mm d and 25 mm B, the 62 mm outside diameter from the machined-ring needle roller bearings with inner ring, and the 2RS suffix would add contact seals. The 2RS executions of the 49 series carry contact seals on both faces and a wider outer ring — their B and s dimensions differ from the open execution, so housings must be re-checked before substituting. Selection arithmetic: C 42.9 kN against C0 91.5 kN gives a C0/C ratio of 2.13, and the 11.2 kN fatigue load limit Pu sets the floor for the adjusted-life calculation at contaminated lubrication. For NA 49 2RS executions the wider outer ring changes the housing depth: verify the 25 mm width and s offset dimensions against the open execution before reusing an existing bore.
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
- needle edge loading and raceway denting when the shaft deflects beyond the compensation range
- polymer cage deformation when the local temperature exceeds the 120 °C sustained limit
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- hard-particle indentation in unfiltered lubricant
- inner-ring bore fretting on a loose shaft seat, migrating hard particles into the rolling contact
Selection pitfalls — read before you substitute
- At 45 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 45 mm seats can bend past the compensation range long before the load rating is exhausted.
- The quoted 42.9/91.5 kN ratings are SKF catalogue values for this exact execution (NKI 45/25 TN); 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 42.9/91.5 kN ratings and 220 g mass are SKF catalogue values transcribed from ch. 7.4 of PUB BU/P1 17000 (PDF table page 642); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
What mounting mistakes ruin a NKI 45/25 TN?
Mount the inner ring on the 45 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.
Is the NKI 45/25 TN sealed?
No — the open execution relies on housing seals; 2RS executions of the 49 series add contact seals with a wider outer ring as a separate order number.
Which dimensions does the NKI 45/25 TN have?
A NKI 45/25 TN measures 45 mm bore/Fw × 62 mm outside diameter × 25 mm width (1.772 × 2.441 × 0.984 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 42.9 kN, static C0 91.5 kN, fatigue limit Pu 11.2 kN, limiting speed 9,000 r/min, reference speed 8,000 r/min, mass about 220 g.
What does NKI 45/25 TN mean in SKF part numbering?
The letters mark a machined-ring needle roller bearing with inner ring: 45 mm bore, 25 mm width, 62 mm OD per the series plan. The hardened inner ring is the raceway, so an ordinary k5 shaft seat suffices.
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.