NK8-12-TN bearing: complete specifications & equivalents
The NK8-12-TN is a DIN 616 radial bearing sized 8 x 15 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 | 8 mm |
| Outer diameter D | 15 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 | 3.8 kN |
| Basic static load rating C0 | 4.25 kN |
| Fatigue load limit Pu | 0.465 kN |
| Reference speed (thermal) | 32000 rpm |
| Limiting speed (mechanical) | 36000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 8.7 g |
| Manufacturer designation | NK 8/12 TN |
| Standard | DIN 616 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without an inner ring |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without 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. 7.3 machined rings with flanges, without 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 & NK-series range
| Bore d | 0.315 in |
|---|---|
| Outer diameter D | 0.591 in |
| Width B | 0.472 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 3.5 mm |
| Smallest bore in NK-series | 5 mm |
| Largest outer diameter in NK-series | 130 mm |
| Width range across NK-series | 10–40 mm |
| Bore position in NK-series (smallest first) | 4 of 46 |
| Bore above smallest NK-series size | 3 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NK8-12-TN model number is decoded
NK 8/12 TN belongs to the machined-ring needle roller family: an outer ring turned and ground to 15 mm with two retaining flanges, a roller-and-cage set inside, and envelope 8×15×12 mm on a hardened 8 mm shaft. In SKF nomenclature NK families drop the inner ring: the numbers after the letters give the 8 mm under-roller diameter and the 12 mm width, with the 15 mm outside diameter set by the machined-ring needle roller bearings without inner ring plan. SKF offers this family open as standard; a matching IR inner ring can be added separately when the shaft cannot be hardened, which converts the envelope into the NKI/NA equivalent. The 8.7 g catalogue mass and 3.5 mm radial section ((15−8)/2) frame a rating of about 0.47 kN dynamic per millimetre of bore — the needle construction's density advantage over ball bearings of the same envelope. Grease through the housing groove before fitting the shaft; the integral flanges hold the grease film at the roller ends, which is where these bearings first starve.
Typical equipment & failure modes
Common applications
- piston-pin style pivots in hydraulic pumps
- guide rollers running on hardened tracks
- swing arms and lever pivots with oscillating duty
- cam followers built up from separate components
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
- smearing of rollers and journal during idle periods because the radial section holds too little lubricant
Selection pitfalls — read before you substitute
- At Fw 8 mm the rolling elements are under two millimetres long — handle the NK 8/12 TN like a watch part: one dropped assembly, one over-pressed cup or one coarse journal finish outweighs any catalogue rating difference.
- The quoted 3.8/4.25 kN ratings are SKF catalogue values for this exact execution (NK 8/12 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 3.8/4.25 kN ratings and 8.7 g mass are SKF catalogue values transcribed from ch. 7.3 of PUB BU/P1 17000 (PDF table page 626); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
Does the NK 8/12 TN need a hardened and ground shaft?
No. In this execution the 8 mm shaft journal is the inner raceway: it must be ground and hardened to 58–64 HRC (with matching housing bore quality on the outside). If the shaft cannot meet that, order the inner-ring sibling (NKI/NA execution) plus its ground inner ring instead.
What mounting mistakes ruin a NK 8/12 TN?
Press on the ring faces only with a fitting sleeve, keep everything square to the 8 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs.
Is the NK 8/12 TN sealed?
No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty.
Which dimensions does the NK 8/12 TN have?
A NK 8/12 TN measures 8 mm bore/Fw × 15 mm outside diameter × 12 mm width (0.315 × 0.591 × 0.472 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 3.8 kN, static C0 4.25 kN, fatigue limit Pu 0.465 kN, limiting speed 36,000 r/min, reference speed 32,000 r/min, mass about 8.7 g.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without an inner ring on 2026-09-26. Read our editorial & correction policy.