NF304EA bearing: complete specifications & equivalents
The NF304EA is a ISO 15 radial bearing sized 20 x 52 x 15 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 20 mm |
| Outer diameter D | 52 mm |
| Width B | 15 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 37.5 kN |
| Basic static load rating C0 | 26.9 kN |
| Fatigue load limit Pu | 3.25 kN |
| Limiting speed (mechanical) | 13000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 147 g |
| Manufacturer designation | NTN NF304EA |
| 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 | 0.787 in |
|---|---|
| Outer diameter D | 2.047 in |
| Width B | 0.591 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 16 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) | 1 of 32 |
| Bore above smallest NF300-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NF304EA | 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 NF304EA model number is decoded
For pure radial duty on a 20 mm shaft NTN supplies NF304EA: one integral rib on each ring; the open execution is rated 13,000 r/min on grease and 18,000 r/min on oil. The leading NF defines the rib arrangement (one rib on each ring); the dimension-series digits and the two-digit bore code resolve to 20 mm, with 52 mm OD and 15 mm width from the ISO 15 general plan. Minimum radial load matters: an unloaded NF304EA at high speed skids its rollers and smears the raceway; spring preload or the rotor weight typically covers the requirement in motors and pumps. The 20 mm (0.787 in) bore and 52 mm (2.047 in) OD are ISO 15 boundary values; fillet and shoulder dimensions must still come from the NTN mounting table for the 15 mm-wide ring. After mounting verify the outer ring slides axially by hand at ambient temperature; a stuck float ring in a NF304EA non-locating position preloads the bearing when the shaft grows.
Typical equipment & failure modes
Common applications
- appliance and office-machine drives
- agricultural PTO and implement gear shafts
- small conveyor and fan rotor positions
- small electric-motor armature shafts
Known failure patterns
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- pressed-steel cage pocket wear when rollers skid at light load or too-thin lubricant
- grease starvation and cage drag when relubrication intervals are extended past the grease life
- hard-particle indentation of raceways in unfiltered oil or open arrangements
- electrical pitting on VFD-driven motor shafts without grounding protection
Selection pitfalls — read before you substitute
- Small 20 mm-bore cylindrical rollers are skid-sensitive: ensure the radial load exceeds the minimum-load floor at operating speed, or the NF304EA rollers smear even with correct grease.
- Grease limiting speed 13,000 r/min and oil 18,000 r/min are different limits for NF304EA: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 52 mm race brinells and releases as vibration within hours.
- Open NF304EA 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 20 mm contact.
- Do not replace NF304EA with a deep-groove ball bearing on rating alone: line contact gives 37.5 kN radial capacity but the bearing cannot carry the thrust duty a ball bearing can and misalignment tolerance is only 3–4 arc-minutes.
- The 37.5/26.9 kN ratings, 3.25 kN Pu and 147 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NF304EA (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 NF304EA?
NF304EA is an NTN NF single-row cylindrical roller bearing to ISO 15: 20 mm bore, 52 mm OD and 15 mm width (0.787 × 2.047 × 0.591 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 37.5 kN, C0 26.9 kN, Pu 3.25 kN, grease limiting speed 13,000 r/min, oil 18,000 r/min, mass about 147 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. NF304EA 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 NF304EA 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 NF304EA?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 27.5 mm, Ew 45.5 mm. The nominal bore/OD remain 20/52 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 13,000 r/min grease / 18,000 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.