NN3021K bearing: complete specifications & equivalents
The NN3021K is a ISO 15 radial bearing sized 105 x 160 x 41 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 105 mm |
| Outer diameter D | 160 mm |
| Width B | 41 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 220 kN |
| Basic static load rating C0 | 320 kN |
| Fatigue load limit Pu | 36 kN |
| Limiting speed (mechanical) | 3800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2800 g |
| Manufacturer designation | NTN NN3021K |
| Standard | ISO 15 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & NN3000-series range
| Bore d | 4.134 in |
|---|---|
| Outer diameter D | 6.299 in |
| Width B | 1.614 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 27.5 mm |
| Smallest bore in NN3000-series | 25 mm |
| Largest outer diameter in NN3000-series | 680 mm |
| Width range across NN3000-series | 16–163 mm |
| Bore position in NN3000-series (smallest first) | 17 of 40 |
| Bore above smallest NN3000-series size | 80 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NN3021K | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
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 NN3021K model number is decoded
NN3021K is an NTN NN cylindrical roller bearing: two integral ribs on the outer ring and a ribless, separable inner ring — a non-locating bearing that lets the shaft float axially, inside the 105×160×41 mm ISO 15 envelope. Reading the code: NN for the double-row precision type, then the ISO 15 diameter/width series and the bore code — ×5 = 105 mm (00–03 use the 10/12/15/17 exception table). At 4,500 r/min with oil versus 3,800 r/min with grease (a 700 r/min band), lubrication choice for NN3021K is a thermal decision, not just a sealing one. Mass 2800 g for the 105×160×41 mm NN3021K execution covers the pressed-steel cage and full roller complement; substitute on mass plus rating, not envelope alone. Housing and shaft fillets must clear the ring chamfers of NN3021K; an oversized radius locks the ring on its face and tilts the 41 mm-wide seat.
Typical equipment & failure modes
Common applications
- CNC lathe and machining-centre spindle radial sets
- precision rotary-table and dividing-head bearings
- high-speed turbine and turbo-blower rotor supports
- coordinate-measuring and semiconductor-equipment drives
Known failure patterns
- inner-ring raceway spalling from overload in the line-contact Hertzian zone
- cage wear accelerated when the EA high-capacity roller complement runs continuously above its thermal balance
- grease starvation and cage drag when relubrication intervals are extended past the grease life
- edge loading from shaft deflection beyond the 3–4 arc-minute alignment limit
- rolling-contact fatigue after the catalogue L10 life is exceeded
Selection pitfalls — read before you substitute
- Induction-heat the 105 mm inner ring (max 120 °C) and mount it before fitting the outer ring; the ring mass makes square guidance essential — driving through the rollers brinells the 160 mm raceway.
- The 27.5 mm section at 105 mm bore leaves a narrow oil path; with the standard cage the relubrication groove and oil-level design must keep grease from churning in the 41 mm-wide cavity.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NN3021K skids at 3,800 r/min and fails by smearing long before L10 fatigue.
- The EA high-capacity roller complement changes the load figure versus the basic execution of the same number; the 220/320 kN pair here belongs to NN3021K as printed, not to the bare size.
- Grease limiting speed 3,800 r/min and oil 4,500 r/min are different limits for NN3021K: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- The 220/320 kN ratings, 36 kN Pu and 2800 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NN3021K (standard execution); other makes sharing the ISO 15 envelope revise internal geometry without changing the order number, so keep the 2203E reference with the specification for critical drives.
Frequently asked questions
What are the dimensions and catalogue data of NN3021K?
NN3021K is an NTN NN double-row precision cylindrical roller bearing to ISO 15: 105 mm bore, 160 mm OD and 41 mm width (4.134 × 6.299 × 1.614 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 220 kN, C0 320 kN, Pu 36 kN, grease limiting speed 3,800 r/min, oil 4,500 r/min, mass about 2800 g. It is open, with a machined or stamped steel cage per the precision execution.
What is the difference between NU, NJ, NUP, N and NF cylindrical roller bearings?
NN and NNU are double-row precision designs rather than single-row rib variants: NN has a ribbed inner ring and separable outer ring, NNU the reverse; both give high radial stiffness for spindles and are commonly ordered with P5/P4 precision and a K 1:12 tapered bore for preload setting. NN3021K is the NN execution.
What do the EA, E and ＊ suffixes mean on NTN cylindrical roller bearings?
EA is NTN's high-capacity design with a pressed sheet-steel cage and optimised roller complement in the same ISO 15 envelope; E marks the high-capacity design at the larger bores; the ＊ symbol printed before the code in the NTN catalogue marks the ULTAGE new-generation specification and is not typed as part of the order number. NN3021K is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NN bearing like NN3021K?
The K suffix denotes a 1:12 tapered bore. NN3021K mounts on a tapered shaft seat or adapter sleeve and is driven up to a measured residual clearance or preload — this is how precision spindle bearings achieve stiffness without locknut guesswork; the cylindrical-bore NN3021 execution of the same envelope mounts on a plain seat.
What speeds and lubrication apply to NN3021K?
NTN rates NN3021K at 3,800 r/min with grease and 4,500 r/min with oil. The grease figure is the cage/film mechanical ceiling; the oil figure assumes circulating or carefully supplied oil that removes heat from the line-contact zone.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.