6304 Bearing
20×52×15 mm
Specifications
Bore (d)
20 mm
OD (D)
52 mm
Width (B)
15 mm
Fillet radius
1.1 mm
Dynamic C
15.9 kN
Static C₀
7.8 kN
Fatigue limit Pᵤ
0.335 kN
Speed (grease)
14,000 rpm
Speed (oil)
18,000 rpm
Weight (open)
0.155 kg
Standard
ISO 15:2017
DIN
DIN 625
Variants (SKF suffix convention)
| Variant | SKF model | Weight (kg) | Description |
|---|---|---|---|
| Open | 6304 | 0.155 | No seals — for clean environments, re-greaseable |
| Rubber sealed (both) | 6304 2RS1 | 0.16 | Maintenance-free, best dust/moisture protection |
| Metal shielded (both) | 6304 Z | 0.157 | Lower torque than 2RS, good dust protection |
Brand Interchange
All brands below manufacture the 6304 to ISO 15:2017 — fully interchangeable on bore, OD, and width.
| Brand | Open | 2RS sealed | ZZ shielded |
|---|---|---|---|
| SKF | 6304 | 6304 2RS1 | 6304 Z |
| FAG | 6304 | 6304 2RS | 6304 Z |
| NSK | 6304 | 6304 2RS | 6304 ZZ |
| NTN | 6304 | 6304 2RS | 6304 ZZ |
| KOYO | 6304 | 6304 2RS | 6304 ZZ |
| NACHI | 6304 | 6304 2NSE9 | 6304 ZZE |
| Timken | 6304 | 6304 2RS | 6304 ZZ |
Chinese Manufacturer Alternatives
Dimensionally interchangeable with SKF/NSK per ISO 15:2017. Indicative FOB price: $0.8–$1.8 USD (MOQ 100 pcs, P0 open).
| Manufacturer | Model | Grade | Tier |
|---|---|---|---|
| ZWZ | 6304 | P0 | Mid-range |
| LYC | 6304 | P0 | Mid-range |
| C&U | 6304 | P0 | Budget |
| HRB | 6304 | P0 | Budget |
Old Chinese GB numbers: 304, 80304
Request Quote from Chinese FactoriesRecommended Fit
Normal load: k6 · Heavy: m6
Stationary: H7 · Rotating: M7
Frequently Asked Questions — 6304 Bearing
What are the dimensions of the 6304 bearing?
The 6304 bearing measures 20mm bore × 52mm outer diameter × 15mm width, with a fillet radius of 1.1mm. This conforms to ISO 15:2017.
What is the load rating of the 6304?
The 6304 has a dynamic load rating (C) of 15.9 kN and a static load rating (C₀) of 7.8 kN. These values are used in ISO 281 L10 life calculations.
What speed can the 6304 run at?
With grease lubrication, the 6304 has a reference speed of 14,000 rpm. With oil lubrication, the limit is 18,000 rpm.
Are SKF, NSK, FAG, and Timken 6304 interchangeable?
Yes. All major bearing brands (SKF, FAG, NSK, NTN, KOYO, NACHI, Timken) produce the 6304 to ISO 15:2017 dimensional standards. They are fully interchangeable on bore, OD, and width dimensions.
What Chinese brands make a 6304 equivalent?
ZWZ, LYC (Luoyang), C&U (Changzhou), and HRB (Harbin) all manufacture 6304 equivalents to ISO 15:2017. Old Chinese GB numbers: 304, 80304. All are dimensionally interchangeable with SKF/NSK.
What is the difference between 6304 open, 6304 2RS, and 6304 ZZ?
Open: no seals, suitable for clean environments with re-lubrication access. 2RS (rubber sealed both sides): maintenance-free, best for dusty or wet environments. ZZ (metal shielded): lower torque than 2RS, good dust protection but not waterproof. For most applications, 2RS is recommended.
What shaft tolerance fits the 6304 bearing?
For a rotating inner ring (most common), use shaft tolerance k6 for normal loads or m6 for heavy loads. For a non-rotating shaft, h6 or js6 is appropriate. Housing bore should be H7 for a stationary outer ring. Use our Bearing Fit Calculator for exact tolerance values.
How do I calculate 6304 bearing life?
L10 = (C/P)³ where C = 15.9 kN (dynamic rating) and P is your applied equivalent load (kN). L10h = L10 × 10⁶ / (60 × n), where n is speed in RPM. Use our Bearing Life Calculator to compute this automatically.