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6306 Deep Groove Ball Bearing 30x72x19mm
At 30mm bore and 72mm OD, the 6306 bearing carries the highest dynamic load rating in the standard single-row 30mm-bore class. The 19mm width and deep-groove raceway geometry deliver 28.1 kN Cr without stepping up to a double-row or cylindrical roller design.
Key Specifications
- Sealing: Open, ZZ (metal shields), 2RS (NBR rubber contact seals). ZZ retains full rated speed.
- Speed and Load: 28.1 kN dynamic (Cr), 16.0 kN static (Cor). 8,000 RPM open/ZZ; 4,800 RPM with 2RS seals.
- Axial Load: Supports 15-20% of radial rating in CN clearance. Approximately 4.2-5.6 kN sustained.
- Temperature: -40 to 120 C with standard grease. Fluorinated grease options extend to 180 C.
- Material and Precision: GCr15 bearing steel (AISI 52100 equivalent). ABEC-3 standard; ABEC-5 available.
For any inquiries, please contact with our Supporting Team at sales@yuanhecd.com.
| Model | 6306 |
| Bore (d) | 30 mm |
| OD (D) | 72 mm |
| Width (B) | 19 mm |
| Type | Open / Shielded / Sealed |
| ABEC | ABEC-3 |
| Material | GCr15 bearing steel (AISI 52100) |
| Dynamic Load Cr | 28.1 kN |
| Static Load Cor | 16.0 kN |
| Max Speed | 8,000 RPM (open/ZZ) 4,800 RPM (2RS) |
| Temperature | -40 to 120 C |
Bore x OD x Width
30 x 72 x 19 mm
Dynamic Load Cr
28.1 kN
Static Load Cor
16.0 kN
Max Speed
8,000 RPM
Sealing
Open / ZZ / 2RS
Precision
ABEC-3
Shielding and Lubrication
The 6306 ZZ bearing uses non-contact SPCC steel shields pressed into the outer ring. At 72mm OD, the shield-to-inner-ring clearance forms a narrow labyrinth that excludes coarse dust while preserving the 8,000 RPM speed rating. Each bearing ships pre-packed with lithium soap grease at 25-35% fill. For horizontal-shaft applications above 5 hp, grease distribution at startup establishes a stable lubricant film before the rolling elements reach full speed.
The 6306 2RS bearing variant uses nitrile rubber contact seals on the inner ring shoulder. At this bearing size, seal drag reduces the speed limit to approximately 4,800 RPM. The 19mm width provides a large grease reservoir: roughly 40% more volume than a 6206 bearing, extending relubrication intervals in continuous-duty pumps, fans, and conveyor drives where downtime for bearing service must be minimized.
Performance
At 28.1 kN dynamic and 16.0 kN static, the 6306 bearing delivers 49% more capacity than the 6206 bearing (30x62x16mm, 19.5 kN Cr). The series-3 cross-section gains 10mm OD and 3mm width over the 62-series, increasing both ball diameter and raceway conformity. A 6006 bearing (30x55x13mm, 13.8 kN) saves 17mm OD for lightweight designs but surrenders more than half the dynamic capacity. Select the 6306 bearing when radial load governs the design. If housing OD is constrained to 62mm or below, specify a 6206 or 6006 bearing instead.
C3 radial clearance is the most common OEM specification for deep groove ball bearing applications in electric motors from 5 to 15 hp, where the shaft heats faster than the housing and closes the running clearance. ABEC-3 tolerance is standard. For high-speed spindles and machine tool applications, ABEC-5 and paired mounting arrangements are available.
OEM and Customization
Yuanhe manufactures the 6306 bearing to customer specifications. Common OEM customizations include C3 and C4 internal clearance for motor and pump applications with thermal gradients, stainless steel (AISI 440C) for food-grade and washdown duty, and fluorinated grease rated to 180 C for kiln car wheel bearings and continuous oven rollers. Cage options include stamped steel, glass-reinforced PA66, and machined brass for applications above 6,000 RPM. Standard lead time is 7 to 15 days. Submit drawings or existing part numbers for a quote, or contact Yuanhe directly.
Applications
Electric motors (5 to 20 hp)
Industrial gearboxes and transmission shafts
Centrifugal and positive-displacement pumps
Conveyor head and tail pulleys
HVAC fan shafts and air-handling units
Agricultural machinery and PTO drivelines
Mining conveyor idlers
Textile carding and spinning frames
Compact construction equipment
Frequently Asked Questions
How much more load can a 6306 bearing handle compared to a 6206 bearing? +
The 6306 bearing delivers 28.1 kN dynamic load, approximately 49% more than the 6206 bearing (19.5 kN). Static load increases from 11.3 kN to 16.0 kN. The gain comes from the series-3 cross-section: 10mm larger OD and 3mm extra width allow larger-diameter balls and a deeper raceway groove. The tradeoff is a 10mm larger housing bore. Verify housing dimensions before upgrading from 6206 to 6306.
What internal clearance should a 6306 bearing have for an electric motor? +
C3 radial clearance is standard for motors in the 5-15 hp range. When the motor shaft reaches operating temperature faster than the housing, the inner ring expands and consumes the initial clearance. C3 provides 15-33 microns of radial play, ensuring the bearing does not preload itself at temperature. For belt-drive radial loads, C3 also accommodates slight housing distortion under belt tension. CN clearance suits assemblies where both shaft and housing run at similar temperatures.
Can the 6306 bearing run continuously at 8,000 RPM with grease lubrication? +
In open or ZZ configuration with standard lithium soap grease, 8,000 RPM is the reference speed for light to moderate loads. For sustained operation near this speed, polyurea grease with synthetic base oil (ISO VG 32-46) resists channeling and thermal breakdown. Beyond 8,000 RPM or with combined radial-axial loads above 30% of Cr, oil-mist or circulating oil lubrication is recommended. The 2RS sealed variant should not exceed 4,800 RPM due to seal lip friction.
Is the 6306 bearing available with a snap ring groove? +
The 6306 N variant includes a snap ring groove on the outer ring for axial location without shouldering the housing bore. The 6306 NR adds the snap ring. These variants simplify housing design by eliminating the need for a housing shoulder or end cover to retain the bearing axially. The groove is machined to ISO 464 dimensions. Yuanhe supplies 6306, 6306 N, and 6306 NR configurations. Specify the exact variant when requesting a quote.
