NX20 bearing: complete specifications & equivalents
The NX20 is a DIN 616 radial bearing sized 20 x 30 x 28 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 20 mm |
| Outer diameter D | 30 mm |
| Width B | 28 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 13.2 kN |
| Basic static load rating C0 | 19.3 kN |
| Fatigue load limit Pu | 2.28 kN |
| Reference speed (thermal) | 6300 rpm |
| Limiting speed (mechanical) | 7500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 68 g |
| Manufacturer designation | NX 20 |
| Standard | DIN 616 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.8 needle roller / thrust ball, full complement thrust part |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.8 needle roller / thrust ball, full complement thrust part) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.8 needle roller / thrust ball, full complement thrust part); 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 & NX-series range
| Bore d | 0.787 in |
|---|---|
| Outer diameter D | 1.181 in |
| Width B | 1.102 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 5 mm |
| Smallest bore in NX-series | 7 mm |
| Largest outer diameter in NX-series | 47 mm |
| Width range across NX-series | 18–30 mm |
| Bore position in NX-series (smallest first) | 6 of 9 |
| Bore above smallest NX-series size | 13 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NX20-Z | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 20×30×28 mm envelope and equivalent catalogue ratings; NX20-Z is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply. |
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 NX20 model number is decoded
In SKF catalogue PUB BU/P1 17000, NX 20 denotes a combined bearing whose thrust part is filled with the maximum number of balls: highest axial capacity of the NX/NKX family at low-to-moderate speed, radial part 13.2 kN C. The number in NX 20 is the shaft diameter in millimetres; NX types differ from NKX only in the thrust part — full complement balls here, caged balls there — which changes axial capacity and speed ceiling. Execution notes: the thrust part is filled with the maximum number of balls, giving the family's highest axial capacity, but the packed set needs a minimum axial load (factor A 0.0016) to keep every ball tracking its raceway. Speed ceilings differ by part: 6,300 r/min thermal reference and 7,500 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. Check after fitting that the radial needle cage and the thrust part rotate independently where the design allows; binding between the two indicates a bent washer or a stray ball.
Typical equipment & failure modes
Common applications
- screw jack and lifting screw spindles
- valve and dosing pump stems with slow axial push
- light rotary tables under axial load
- oscillating pivots with steady axial preload
Known failure patterns
- raceway spalling once the catalogue L10 life is exceeded or after overload events
- cage pocket wear and roller skew after sustained operation with too little radial preload
- grease starvation at the roller ends when relubrication intervals are stretched in dirty duty
- electrical erosion on VFD-driven shafts without brush or insulated mounting
- thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor
Selection pitfalls — read before you substitute
- On a 20 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 30 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.
- Hardness is load capacity: in families without an inner ring the 20 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.
- The quoted 13.2/19.3 kN ratings are SKF catalogue values for this exact execution (NX 20); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.
- Do not treat the axial rating 7.8 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.
- The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NX 20 facing the working thrust.
- The 13.2/19.3 kN ratings and 68 g mass are SKF catalogue values transcribed from ch. 7.8 of PUB BU/P1 17000 (PDF table page 656); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
Can the NX 20 run on an unhardened shaft?
The radial needle part of the NX 20 runs directly on the 20 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table.
How should the NX 20 be mounted?
Press on the ring faces only with a fitting sleeve, keep everything square to the 20 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.
What limits the service life of a NX 20?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 20 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 5.0 mm radial section leaves no reserve once a raceway is dented or ribboned.
What are the dimensions and ratings of the NX 20?
A NX 20 measures 20 mm bore/Fw × 30 mm outside diameter × 28 mm width (0.787 × 1.181 × 1.102 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 13.2 kN, static C0 19.3 kN, fatigue limit Pu 2.28 kN, limiting speed 7,500 r/min, reference speed 6,300 r/min, mass about 68 g. Axial ratings of the thrust part: dynamic Ca 7.8 kN (Ca), static C0a 17.3 kN (C0a), minimum load factor A 0.0016; the thrust set carries load in one direction only.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.8 needle roller / thrust ball, full complement thrust part on 2026-09-26. Read our editorial & correction policy.