NKI100-40 bearing: complete specifications & equivalents
The NKI100-40 is a DIN 616 radial bearing sized 100 x 130 x 40 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 100 mm |
| Outer diameter D | 130 mm |
| Width B | 40 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 123 kN |
| Basic static load rating C0 | 305 kN |
| Fatigue load limit Pu | 37.5 kN |
| Reference speed (thermal) | 3600 rpm |
| Limiting speed (mechanical) | 4000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1350 g |
| Manufacturer designation | NKI 100/40 |
| 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 | 3.937 in |
|---|---|
| Outer diameter D | 5.118 in |
| Width B | 1.575 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 15 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) | 30 of 30 |
| Bore above smallest NKI-series size | 95 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NKI100-40 model number is decoded
For a 100 mm shaft that cannot be hardened on site, NKI 100/40 adds a hardened, ground inner ring to the machined needle roller design: envelope 100×130×40 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 100 mm d and 40 mm B, the 130 mm outside diameter from the machined-ring needle roller bearings with inner ring, and the 2RS suffix would add contact seals. Execution notes: the inner ring is ground on bore and raceway, so the shaft seat is a normal k5/j6; the flanged outer ring needs no housing shoulder, and NA 49 2RS executions add seals with a wider outer ring. The 1350 g catalogue mass and 15.0 mm radial section ((130−100)/2) frame a rating of about 1.23 kN dynamic per millimetre of bore — the needle construction's density advantage over ball bearings of the same envelope. Mounting: heat or press the inner ring onto the 100 mm k5 seat (max 120 °C), fit the flanged outer ring into the H7 housing bore, and check the 40 mm assembly for free rotation before applying load.
Typical equipment & failure modes
Common applications
- conveyor roller ends and return rollers
- agricultural implement pivots and cutter heads
- electric motor armature shafts with ground seats
- printing and paper-handling rollers
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
- grease starvation at the roller ends when relubrication intervals are stretched in dirty duty
- corrosion pitting from condensation in intermittently operated machinery
- inner-ring raceway spalling after the narrow ring section runs hot with excessive interference
Selection pitfalls — read before you substitute
- Above 50 mm bore, thermal growth matters: the 100 mm inner ring or journal grows with temperature faster than the housing, and the small clearance of a needle roller contact leaves little reserve — check running clearance hot, not just at assembly.
- The quoted 123/305 kN ratings are SKF catalogue values for this exact execution (NKI 100/40); 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 123/305 kN ratings and 1350 g mass are SKF catalogue values transcribed from ch. 7.4 of PUB BU/P1 17000 (PDF table page 646); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
Does the NKI 100/40 need a hardened and ground shaft?
Yes — that is the point of this family. The NKI 100/40 carries its own hardened, ground inner ring on a 100 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 100/40?
Mount the inner ring on the 100 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 100/40 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 100/40 have?
A NKI 100/40 measures 100 mm bore/Fw × 130 mm outside diameter × 40 mm width (3.937 × 5.118 × 1.575 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 123 kN, static C0 305 kN, fatigue limit Pu 37.5 kN, limiting speed 4,000 r/min, reference speed 3,600 r/min, mass about 1350 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.