NF306EA bearing: complete specifications & equivalents
The NF306EA is a ISO 15 radial bearing sized 30 x 72 x 19 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 30 mm |
| Outer diameter D | 72 mm |
| Width B | 19 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 63 kN |
| Basic static load rating C0 | 50 kN |
| Fatigue load limit Pu | 6.15 kN |
| Limiting speed (mechanical) | 9300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 353 g |
| Manufacturer designation | NTN NF306EA |
| 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 & NF300-series range
| Bore d | 1.181 in |
|---|---|
| Outer diameter D | 2.835 in |
| Width B | 0.748 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 21 mm |
| Smallest bore in NF300-series | 20 mm |
| Largest outer diameter in NF300-series | 580 mm |
| Width range across NF300-series | 15–108 mm |
| Bore position in NF300-series (smallest first) | 3 of 32 |
| Bore above smallest NF300-series size | 10 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NF306EA | 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 NF306EA model number is decoded
NF306EA is the standard section of the NTN NF300 dimension series for a 30 mm shaft — 63 kN of basic dynamic capacity in a 353 g, open bearing. Numbering ties NF306EA to its envelope: type code NF, series NF300, 30 mm bore; the 72×19 mm outline therefore swaps dimensionally with other ISO 15 bearings of the same code, though rib arrangements differ by prefix. NTN prints two speed ceilings: 9,300 r/min grease and 13,200 r/min oil — the pressed-steel cage and lubricant film set the real limit at the 30 mm bore. Speed ratio check: limiting 9,300 r/min is .70 of the 13,200 r/min oil value for NF306EA; grease-churn heating closes that gap as fill quantity rises. Heat the inner ring to max 120 °C for the 30 mm interference fit and support the ring face square during fitting; cocking over a keyway brinells the raceway before first rotation.
Typical equipment & failure modes
Common applications
- medium electric-motor and generator shafts
- pump and compressor crankshafts and rotors
- machine-tool gearbox and spindle radial sets
- material-handling drum and wheel shafts
Known failure patterns
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- cage distortion after a mounting blow carried through the roller set
- grease starvation and cage drag when relubrication intervals are extended past the grease life
- rolling-contact fatigue after the catalogue L10 life is exceeded
- fretting corrosion on a loose rotating shaft seat
Selection pitfalls — read before you substitute
- On this 30 mm bore, shaft thermal growth can preload the inner ring if the fit is too tight; verify residual interference at temperature and confirm the float ring still slides after mounting NF306EA.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 72 mm race brinells and releases as vibration within hours.
- Open NF306EA units need application-supplied sealing and a defined lubricant schedule; film thickness is the first failure mode for line contact when viscosity drops at the 30 mm contact.
- Wide (22/23) and light (10/49) executions at 30 mm bore share bore but not OD/width; check the full NF300 series code before substituting, because housing and shoulder geometry will not interchange.
- If the shaft must be located both ways, do not use NF306EA alone: pair it with a locating bearing or specify the NUP execution with the matching loose rib ring from the 2203E table.
- The 63/50 kN ratings, 6.15 kN Pu and 353 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NF306EA (EA pressed-steel-cage 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 NF306EA?
NF306EA is an NTN NF single-row cylindrical roller bearing to ISO 15: 30 mm bore, 72 mm OD and 19 mm width (1.181 × 2.835 × 0.748 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 63 kN, C0 50 kN, Pu 6.15 kN, grease limiting speed 9,300 r/min, oil 13,200 r/min, mass about 353 g. It is open, with the EA high-capacity pressed sheet-steel cage.
What is the difference between NU, NJ, NUP, N and NF cylindrical roller bearings?
The prefix states the rib arrangement: NU has two outer-ring ribs and a ribless inner ring (float, no axial load); NJ adds ribs for one-direction location; NUP adds a loose L-ring to locate both directions; N has two inner-ring ribs and a separable outer ring; NF has one rib per ring for one-direction guidance. NF306EA is one integral rib on each ring — separable inner ring with single-direction axial guidance and a defined shaft position.
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. This page's bearing carries the EA pressed-steel-cage execution.
Can NF306EA take axial load and locate a shaft?
the NF design gives one-direction axial guidance via its single outer-ring rib. The loose rib ring still only suits light/short-duration axial guidance; heavy thrust belongs to a dedicated thrust bearing.
What do Fw and Ew mean for NF306EA?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 40.5 mm, Ew 62.5 mm. The nominal bore/OD remain 30/72 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 9,300 r/min grease / 13,200 r/min oil.
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.