HK0306-TN bearing: complete specifications & equivalents
The HK0306-TN is a ISO 3245 radial bearing sized 3 x 6.5 x 6 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 3 mm |
| Outer diameter D | 6.5 mm |
| Width B | 6 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 1.23 kN |
| Basic static load rating C0 | 0.88 kN |
| Fatigue load limit Pu | 0.088 kN |
| Reference speed (thermal) | 24000 rpm |
| Limiting speed (mechanical) | 26000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1 g |
| Manufacturer designation | HK 0306 TN |
| Standard | ISO 3245 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.2 drawn cup needle roller bearings |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.2 drawn cup needle roller bearings) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.2 drawn cup needle roller bearings); 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 & HK-series range
| Bore d | 0.118 in |
|---|---|
| Outer diameter D | 0.256 in |
| Width B | 0.236 in |
| ISO bore code | 06 |
| Radial section height (D−d)/2 | 1.8 mm |
| Smallest bore in HK-series | 3 mm |
| Largest outer diameter in HK-series | 68 mm |
| Width range across HK-series | 6–38 mm |
| Bore position in HK-series (smallest first) | 1 of 26 |
| Bore above smallest HK-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| HK0306FT2 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | NTN bearing on the same 3×6.5×6 mm envelope, but catalogue C/C0 differ (1.23/0.88 vs 0.925/0.565 kN) — envelope interchange only after a load check. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the HK0306-TN model number is decoded
SKF supplies HK 0306 TN for housings where machining an outer-ring pocket is uneconomical: the 6.5 mm shell broached from sheet steel press-fits into a plain bore and runs a 3 mm hardened shaft. In HK 0306, Fw = 3 mm names the shaft that becomes the inner raceway and B = 6 mm the cup width; the shell outside diameter 6.5 mm is fixed by the boundary plan, so the housing bore needs only a press-fit tolerance. Open caged execution: the standard HK drawn cup with steel cage, relubricable through the shaft where the housing allows. Caged HK bearings space the rollers for lower friction than full complement HK types; the cage is not a seal — 2RS executions are the sealed members of the family. For life calculation, the 1.23/0.88 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. The shell is intentionally thin: seat it square with a slow press stroke, support the housing wall behind the bore, and stop the moment the cup face meets the shoulder — hammer blows split drawn cups.
Typical equipment & failure modes
Common applications
- auto steering gear rack supports
- clutch release mechanisms and cable pulleys
- office equipment and power tool gear trains
- steering column and pedal-box pivots in passenger cars
Known failure patterns
- raceway spalling once the catalogue L10 life is exceeded or after overload events
- fretting corrosion of the cup outside diameter in a soft or oversized housing bore
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- brinelling of raceways from impact or pressing force transmitted through the rolling elements
Selection pitfalls — read before you substitute
- At Fw 3 mm the rolling elements are under two millimetres long — handle the HK 0306 TN like a watch part: one dropped assembly, one over-pressed cup or one coarse journal finish outweighs any catalogue rating difference.
- Do not interchange envelope-identical needle families blindly: HK 0306 TN shares its 3×6.5×6 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.
- Reference and limiting speeds are different limits: the 24,000 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.
- The 1.23/0.88 kN ratings and 1 g mass are SKF catalogue values transcribed from ch. 7.2 of PUB BU/P1 17000 (PDF table page 620); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
What limits the service life of a HK 0306 TN?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 3 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 1.8 mm radial section leaves no reserve once a raceway is dented or ribboned.
What are the dimensions and ratings of the HK 0306 TN?
A HK 0306 TN measures 3 mm bore/Fw × 6.5 mm outside diameter × 6 mm width (0.118 × 0.256 × 0.236 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 1.23 kN, static C0 0.88 kN, fatigue limit Pu 0.088 kN, limiting speed 26,000 r/min, reference speed 24,000 r/min, mass about 1 g.
How is the HK 0306 TN designation read?
HK = open-end drawn cup needle roller bearing (ISO 3245); the first two digits give Fw 3 mm, the last two the width 6 mm, the shell OD 6.5 mm follows the plan. 2RS adds both-side contact seals, TN the polymer cage.
Can the HK 0306 TN run on an unhardened shaft?
No. In this execution the 3 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.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.2 drawn cup needle roller bearings on 2026-09-26. Read our editorial & correction policy.