NK6-12-TN bearing: complete specifications & equivalents
The NK6-12-TN is a DIN 616 radial bearing sized 6 x 12 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 | 6 mm |
| Outer diameter D | 12 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 | 3.3 kN |
| Basic static load rating C0 | 3.2 kN |
| Fatigue load limit Pu | 0.345 kN |
| Reference speed (thermal) | 34000 rpm |
| Limiting speed (mechanical) | 38000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 5.7 g |
| Manufacturer designation | NK 6/12 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 | 0.236 in |
|---|---|
| Outer diameter D | 0.472 in |
| Width B | 0.472 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 3 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) | 2 of 46 |
| Bore above smallest NK-series size | 1 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NK6-12-TN model number is decoded
NK 6/12 TN is a machined-ring needle roller bearing without an inner ring: a solid outer ring with integral flanges guiding the caged rollers, riding directly on a 6 mm hardened shaft journal, as listed in SKF catalogue PUB BU/P1 17000. Reading the designation: NK gives the series and the numbers the boundary plan — 6 mm Fw for the shaft seat, 12 mm width; the 12 mm OD comes from the dimension series, and the absence of an inner ring is built into the family name. The wide NKS/NKIS siblings share the Fw and OD but add width for higher ratings — check both when the radial space allows a wider seat. The 5.7 g catalogue mass and 3.0 mm radial section ((12−6)/2) frame a rating of about 0.55 kN dynamic per millimetre of bore — the needle construction's density advantage over ball bearings of the same envelope. Mounting: the flanged outer ring presses into the H7 housing bore against its flange face; the shaft (hardened to 58–64 HRC, ground) enters afterwards, and axial retention is by the housing wall plus a cover washer.
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
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- corrosion pitting from condensation in intermittently operated machinery
- rapid raceway scoring when the shaft journal hardness drops below 58 HRC or the ground finish wears away
Selection pitfalls — read before you substitute
- At Fw 6 mm the rolling elements are under two millimetres long — handle the NK 6/12 TN like a watch part: one dropped assembly, one over-pressed cup or one coarse journal finish outweighs any catalogue rating difference.
- 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: NK 6/12 TN shares its 6×12×12 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.
- The 3.3/3.2 kN ratings and 5.7 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 6/12 TN need a hardened and ground shaft?
No. In this execution the 6 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 6/12 TN?
Press on the ring faces only with a fitting sleeve, keep everything square to the 6 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 6/12 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 6/12 TN have?
A NK 6/12 TN measures 6 mm bore/Fw × 12 mm outside diameter × 12 mm width (0.236 × 0.472 × 0.472 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 3.3 kN, static C0 3.2 kN, fatigue limit Pu 0.345 kN, limiting speed 38,000 r/min, reference speed 34,000 r/min, mass about 5.7 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.