NKIS20 bearing: complete specifications & equivalents
The NKIS20 is a DIN 616 radial bearing sized 20 x 42 x 20 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 | 42 mm |
| Width B | 20 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 28.6 kN |
| Basic static load rating C0 | 39 kN |
| Fatigue load limit Pu | 4.75 kN |
| Reference speed (thermal) | 13000 rpm |
| Limiting speed (mechanical) | 15000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 130 g |
| Manufacturer designation | NKIS 20 |
| 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 & NKIS-series range
| Bore d | 0.787 in |
|---|---|
| Outer diameter D | 1.654 in |
| Width B | 0.787 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 11 mm |
| Smallest bore in NKIS-series | 15 mm |
| Largest outer diameter in NKIS-series | 95 mm |
| Width range across NKIS-series | 20–28 mm |
| Bore position in NKIS-series (smallest first) | 3 of 12 |
| Bore above smallest NKIS-series size | 5 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| PNA20-42 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×42×20 mm envelope, but catalogue C/C0 differ between the executions (28.6/39 vs 19/32.5 kN) — boundary dimensions match, not a load-rating equivalent. |
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 NKIS20 model number is decoded
The wide-section machined-ring needle roller bearings with inner ring execution NKIS 20 measures 20×42×20 mm: needle rollers caged between a flanged outer ring and a ground inner ring, used wherever the journal cannot serve as a raceway. In SKF nomenclature the leading letters mark a machined-ring needle bearing with inner ring: figures state 20 mm d and 20 mm B, the 42 mm outside diameter from the wide-section machined-ring needle roller bearings with inner ring, and the 2RS suffix would add contact seals. TN polymer cage executions run quieter and tolerate grease-lubricated pivot duty; steel cage executions remain the choice for higher temperature or oil-bath lubrication. Speed planning separates the two ceilings: 13,000 r/min thermal reference and 15,000 r/min mechanical limiting — needle bearings tolerate high rpm only with adequate lubricant film at the 20 mm seat. For NA 49 2RS executions the wider outer ring changes the housing depth: verify the 20 mm width and s offset dimensions against the open execution before reusing an existing bore.
Typical equipment & failure modes
Common applications
- wheel and lever pivots needing a replaceable inner ring
- conveyor roller ends and return rollers
- agricultural implement pivots and cutter heads
- electric motor armature shafts with ground seats
Known failure patterns
- needle edge loading and raceway denting when the shaft deflects beyond the compensation range
- cage pocket wear and roller skew after sustained operation with too little radial preload
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- electrical erosion on VFD-driven shafts without brush or insulated mounting
- inner-ring raceway spalling after the narrow ring section runs hot with excessive interference
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 42 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.
- Reference and limiting speeds are different limits: the 13,000 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.
- 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 28.6/39 kN ratings and 130 g mass are SKF catalogue values transcribed from ch. 7.4 of PUB BU/P1 17000 (PDF table page 640); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
Which dimensions does the NKIS 20 have?
A NKIS 20 measures 20 mm bore/Fw × 42 mm outside diameter × 20 mm width (0.787 × 1.654 × 0.787 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 28.6 kN, static C0 39 kN, fatigue limit Pu 4.75 kN, limiting speed 15,000 r/min, reference speed 13,000 r/min, mass about 130 g.
What does NKIS 20 mean in SKF part numbering?
The letters mark a machined-ring needle roller bearing with inner ring: 20 mm bore, 20 mm width, 42 mm OD per the series plan. The hardened inner ring is the raceway, so an ordinary k5 shaft seat suffices.
Does the NKIS 20 need a hardened and ground shaft?
Yes — that is the point of this family. The NKIS 20 carries its own hardened, ground inner ring on a 20 mm seat, so the shaft needs only a normal k5/j6 finish. The inner ring is separable and replaceable.
What mounting mistakes ruin a NKIS 20?
Mount the inner ring on the 20 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.
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.