NKI28-30 bearing: complete specifications & equivalents
The NKI28-30 is a DIN 616 radial bearing sized 28 x 42 x 30 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 28 mm |
| Outer diameter D | 42 mm |
| Width B | 30 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 34.1 kN |
| Basic static load rating C0 | 65.5 kN |
| Fatigue load limit Pu | 8.3 kN |
| Reference speed (thermal) | 12000 rpm |
| Limiting speed (mechanical) | 14000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 140 g |
| Manufacturer designation | NKI 28/30 |
| 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 | 1.102 in |
|---|---|
| Outer diameter D | 1.654 in |
| Width B | 1.181 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 7 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) | 12 of 30 |
| Bore above smallest NKI-series size | 23 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NKI28-30 model number is decoded
For a 28 mm shaft that cannot be hardened on site, NKI 28/30 adds a hardened, ground inner ring to the machined needle roller design: envelope 28×42×30 mm per the machined-ring needle roller bearings with inner ring plan. In SKF nomenclature the leading letters mark a machined-ring needle bearing with inner ring: figures state 28 mm d and 30 mm B, the 42 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. For life calculation, the 34.1/65.5 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. For NA 49 2RS executions the wider outer ring changes the housing depth: verify the 30 mm width and s offset dimensions against the open execution before reusing an existing bore.
Typical equipment & failure modes
Common applications
- agricultural implement pivots and cutter heads
- electric motor armature shafts with ground seats
- printing and paper-handling rollers
- gearbox shafts where the journal cannot be hardened on site
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
- electrical erosion on VFD-driven shafts without brush or insulated mounting
- inner-ring raceway spalling after the narrow ring section runs hot with excessive interference
Selection pitfalls — read before you substitute
- At 28 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 28 mm seats can bend past the compensation range long before the load rating is exhausted.
- 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.
- Do not interchange envelope-identical needle families blindly: NKI 28/30 shares its 28×42×30 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.
- The 34.1/65.5 kN ratings and 140 g mass are SKF catalogue values transcribed from ch. 7.4 of PUB BU/P1 17000 (PDF table page 640); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
Which dimensions does the NKI 28/30 have?
A NKI 28/30 measures 28 mm bore/Fw × 42 mm outside diameter × 30 mm width (1.102 × 1.654 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 34.1 kN, static C0 65.5 kN, fatigue limit Pu 8.3 kN, limiting speed 14,000 r/min, reference speed 12,000 r/min, mass about 140 g.
What does NKI 28/30 mean in SKF part numbering?
The letters mark a machined-ring needle roller bearing with inner ring: 28 mm bore, 30 mm width, 42 mm OD per the series plan. The hardened inner ring is the raceway, so an ordinary k5 shaft seat suffices.
Does the NKI 28/30 need a hardened and ground shaft?
Yes — that is the point of this family. The NKI 28/30 carries its own hardened, ground inner ring on a 28 mm seat, so the shaft needs only a normal k5/j6 finish. The inner ring is separable and replaceable.
What mounting mistakes ruin a NKI 28/30?
Mount the inner ring on the 28 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.
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.