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6304 Deep Groove Ball Bearing 20x52x15mm
When radial load is the binding constraint and the shaft is 20mm, the 6304 bearing delivers 16.0 kN dynamic capacity in a 52mm OD envelope. It is the highest-load 20mm-bore deep groove ball bearing in the ISO metric series.
Key Specifications
- Sealing: Open, ZZ (metal shields), or 2RS (rubber seals) in three configurations covering clean housing, dust-protected, and moisture-sealed environments.
- Speed and Load: 11,000 RPM (open) with 16.0 kN dynamic and 7.88 kN static load rating; ZZ configuration rated to 11，000RPM.
- Dimensions: 20mm bore x 52mm OD x 15mm width. Series 3 medium cross-section, the widest and highest-capacity 20mm-bore deep groove ball bearing.
- Temperature Range: -20C to 120C with standard polyurea grease; 150C peak on request with high-temperature lubricant.
- Precision: Standard ABEC-1. ABEC-3 available for tighter runout control in motor and spindle applications.
For any inquiries, please contact with our Supporting Team at sales@yuanhecd.com.
| Model | 6304 |
| Bore (d) | 20 mm |
| OD (D) | 52 mm |
| Width (B) | 15 mm |
| Type | Open / Shielded / Sealed |
| ABEC | ABEC-3 |
| Material | GCr15 bearing steel (AISI 52100) |
| Dynamic Load Cr | 16.0 kN |
| Static Load Cor | 7.88 kN |
| Max Speed | 11,000 RPM |
Bore x OD x Width
20 x 52 x 15 mm
Dynamic Load Cr
16.0 kN
Static Load Cor
7.88 kN
Max Speed
11,000 RPM
Sealing
Open / ZZ / 2RS
Precision
ABEC-3
Shielding and Lubrication
The 6304 ZZ bearing uses two SPCC steel shields pressed into the outer ring. These non-contact covers form a narrow labyrinth gap that retains factory grease while adding zero rotational drag, preserving the full 11,000 RPM speed ceiling. Each bearing ships pre-packed with polyurea-thickened mineral grease at 25 to 35 percent fill, sufficient for the service life under normal enclosed operating conditions without field relubrication.
At 15mm width, the 6304 bearing carries a larger grease reservoir than any other 20mm-bore deep groove design. This additional volume extends relubrication intervals in continuous-duty applications. For environments with moisture, coolant spray, or fine dust, the 6304 2RS bearing variant replaces metal shields with nitrile rubber contact seals at the cost of a reduced speed limit around 7,000 RPM.
Performance
The 6304 bearing carries 16.0 kN dynamic and 7.88 kN static load, the highest ratings among standard 20mm-bore deep groove ball bearings. The load advantage comes from the series 3 cross-section: at 15mm wide with a 52mm OD, the 6304 bearing packs 25 percent more roller path length than a 6204 bearing (20x47x14mm, 12.8 kN) and 71 percent more than a 6004 bearing (20x42x12mm, 9.38 kN).
The tradeoff is envelope size. A 6004 bearing saves 10mm in housing diameter and 3mm in width. A 6204 bearing saves 5mm OD and 1mm width. Specify the 6304 bearing when load capacity governs the design. If the housing bore already accommodates 52mm, there is no weight or cost penalty for using the higher-rated bearing. ABEC-3 tolerance reduces raceway runout and quiets bearing tone in electric motor applications under 3 hp.
OEM and Customization
Yuanhe manufactures the 6304 bearing to customer specifications. Common OEM customizations include C3 internal clearance for electric motors where the shaft runs hotter than the housing, high-temperature grease for kiln fans and oven conveyors operating continuously above 120C, and stainless steel (440C) rings and balls for food processing washdown environments. Custom cage materials and non-standard bore diameters are available against drawing. Standard lead time is 7 to 15 days for OEM orders. Submit bearing dimensions or existing part numbers for a quote, or contact Yuanhe directly.
Applications
Electric motors (0.5 to 3 hp)
Industrial gearboxes and speed reducers
Centrifugal pumps
Conveyor head pulleys
HVAC blowers and fan assemblies
Agricultural PTO shafts
Textile spinning frames
Bench grinders
Compact hydraulic power packs
Food processing mixers
Frequently Asked Questions
What axial load can a 6304 deep groove ball bearing support? +
A 6304 bearing in standard CN clearance handles axial loads up to approximately 15-20% of its dynamic radial rating. With Cr = 16.0 kN, this translates to roughly 2.4-3.2 kN sustained axial load. C3 clearance increases axial capacity to about 25% of Cr. For pure thrust applications, a thrust ball bearing or angular contact bearing is recommended.
What is the maximum speed for a 6304 bearing? +
The 6304 bearing reaches 11,000 RPM in open configuration and approximately 7,000 RPM with 2RS seals. Actual maximum speed depends on load, lubrication method, and operating temperature. For sustained operation above 8,000 RPM with grease lubrication, a polyurea or synthetic ester grease with appropriate viscosity is recommended.
What are the sealing options for the 6304 bearing? +
The 6304 bearing is available in three sealing configurations: Open for oil-bath or oil-mist systems, ZZ with non-contact metal shields for clean environments at full speed, and 2RS with NBR rubber contact seals for dust and moisture protection at reduced speed. Select based on contamination level and RPM requirements.
How does the 6304 bearing compare to the 6204 bearing? +
The 6304 bearing (20x52x15mm, 16.0 kN) provides 25% more dynamic capacity than the 6204 bearing (20x47x14mm, 12.8 kN) through a wider cross-section. The tradeoff is 5mm larger OD and 1mm wider envelope. Choose the 6304 bearing when load governs the design. Choose the 6204 bearing when housing OD is constrained below 52mm. Yuanhe supplies both series in standard and custom configurations.
