NKI7-12-TN bearing: complete specifications & equivalents
The NKI7-12-TN is a DIN 616 radial bearing sized 7 x 17 x 12 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 7 mm |
| Outer diameter D | 17 mm |
| Width B | 12 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 4.57 kN |
| Basic static load rating C0 | 5.7 kN |
| Fatigue load limit Pu | 0.63 kN |
| Reference speed (thermal) | 28000 rpm |
| Limiting speed (mechanical) | 32000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 14 g |
| Manufacturer designation | NKI 7/12 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 | 0.276 in |
|---|---|
| Outer diameter D | 0.669 in |
| Width B | 0.472 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 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) | 3 of 30 |
| Bore above smallest NKI-series size | 2 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NKI7-12-TN model number is decoded
The machined-ring needle roller bearings with inner ring execution NKI 7/12 TN measures 7×17×12 mm: needle rollers caged between a flanged outer ring and a ground inner ring, used wherever the journal cannot serve as a raceway. Reading the designation: the letters name the series with inner ring, the numbers the boundary plan — 7 mm bore (d), 12 mm width; the 17 mm OD follows the dimension series, and the inner ring is a separate ground component. 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. Selection arithmetic: C 4.57 kN against C0 5.7 kN gives a C0/C ratio of 1.25, and the 0.63 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 12 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
- grease starvation at the roller ends when relubrication intervals are stretched in dirty duty
- hard-particle indentation in unfiltered lubricant
- inner-ring raceway spalling after the narrow ring section runs hot with excessive interference
Selection pitfalls — read before you substitute
- At Fw 7 mm the rolling elements are under two millimetres long — handle the NKI 7/12 TN like a watch part: one dropped assembly, one over-pressed cup or one coarse journal finish outweighs any catalogue rating difference.
- The quoted 4.57/5.7 kN ratings are SKF catalogue values for this exact execution (NKI 7/12 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 4.57/5.7 kN ratings and 14 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
What does NKI 7/12 TN mean in SKF part numbering?
The letters mark a machined-ring needle roller bearing with inner ring: 7 mm bore, 12 mm width, 17 mm OD per the series plan. The hardened inner ring is the raceway, so an ordinary k5 shaft seat suffices.
Does the NKI 7/12 TN need a hardened and ground shaft?
Yes — that is the point of this family. The NKI 7/12 TN carries its own hardened, ground inner ring on a 7 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 7/12 TN?
Mount the inner ring on the 7 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 7/12 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.
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.