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6906 Thin-Section Deep Groove Ball Bearing 30x47x9mm
At 30mm bore and 47mm OD, the 6906 bearing saves 8mm of housing diameter versus the 6006 bearing while delivering 7.28 kN dynamic load. It is the highest-capacity thin-section deep groove ball bearing in the 6900 series, specified for spindle motors, robotic joints, and compact gearbox applications where radial space is the binding constraint.
Key Specifications
- Sealing: Open, ZZ non-contact metal shields, or 2RS double nitrile rubber contact seals. Three configurations for oil-bath, grease-packed, and contamination-resistant installations.
- Speed and Load: 15,000 RPM (open), 13,000 RPM (ZZ), 9,500 RPM (2RS). 7.28 kN dynamic load (Cr), 5.00 kN static load (Cor) at CN clearance.
- Material and Precision: GCr15 bearing steel (AISI 52100 equivalent), through-hardened to HRC 60-64. Standard ABEC-3. ABEC-5 available on request.
- Operating Direction: Deep groove raceway for bidirectional radial loads. Axial capacity approximately 18% of Cr at CN clearance, limited by the 9mm cross-section.
- Temperature Range: -20C to 120C with NBR seals and standard polyurea-mineral grease. High-temperature grease variants extend to 150C continuous.
For any inquiries, please contact with our Supporting Team at sales@yuanhecd.com.
| Model | 6906 |
| Bearing Type | Deep Groove Ball Bearing, Thin Section, Single Row |
| Sealing | Open / ZZ (Metal Shield) / 2RS (Rubber Seal) |
| Bore Dia. (d) | 30 mm |
| Outside Dia. (D) | 47 mm |
| Width (B) | 9 mm |
| Precision | ABEC-3 (Standard), ABEC-5 Available |
| Dynamic Load (Cr) | 7.28 kN |
| Static Load (Cor) | 5.00 kN |
| Max Speed | 15,000 RPM (Open) / 13,000 (ZZ) / 9,500 (2RS) |
| Temp. Range | -20°C to 120°C (NBR) / Up to 150°C (HT Grease) |
| Ring & Ball Material | GCr15 (AISI 52100), HRC 60-64 |
| Seal Material (2RS) | Nitrile Rubber (NBR) + Steel Insert |
| Lubrication | Polyurea-Mineral Grease, NLGI 2 |
Bore x OD x Width
30 x 47 x 9 mm
Dynamic Load Cr
7.28 kN
Static Load Cor
5.00 kN
Max Speed
15,000 RPM
Sealing
Open / ZZ / 2RS
Precision
ABEC-3
Shielding and Lubrication
The 6906 bearing ships in three sealing configurations, each matched to a distinct operating environment. Open bearings reach 15,000 RPM without seal drag and are specified for oil-bath or circulating-oil systems where the housing provides contamination control. The 9 mm cross-section balances thin-section space savings with enough radial depth for a full-complement grease charge: a design advantage over the narrower 7 mm-wide 6800-series bearings when relubrication access is limited.
ZZ metal-shielded 6906 bearings use non-contact steel shields with a 0.2 mm to 0.4 mm gap between the shield and inner ring land. They run to 13,000 RPM and suit electric motor rotor supports, industrial fan shafts, and compact gearbox input bearings where moderate dust protection is sufficient and low torque is required. The non-contact shields add under 2% drag compared to an open 6906 bearing at 8,000 RPM.
2RS rubber-sealed 6906 bearings use nitrile contact seals on the inner ring land. At 9,500 RPM, the 2RS 6906 bearing handles agricultural PTO shaft bearings, conveyor head pulleys, and outdoor HVAC condenser fan motors where water spray, mud, and abrasive dust are routine. The 9 mm width holds approximately 29% more grease volume than the 7 mm-wide 6806 bearing at the same bore, extending sealed-for-life service intervals. A 6906-2RS bearing with standard polyurea-mineral grease (NLGI 2) operates sealed-for-life at 7,000 RPM and 70 degrees C for 3,000 to 5,000 hours under moderate radial load (less than or equal to 1.5 kN).
Performance
The 6906 bearing delivers 7.28 kN dynamic load capacity (Cr) and 5.00 kN static load capacity (Cor). On the same 30 mm shaft, the 6006 bearing (30x55x13 mm) offers 13.2 kN Cr and 8.30 kN Cor. The 6906 bearing saves 8 mm of housing diameter (47 mm vs 55 mm) and 4 mm of axial width (9 mm vs 13 mm) at the cost of 45% lower dynamic capacity. It is not a replacement for the 6006 bearing: it is the correct choice when housing diameter is the primary design constraint and the radial load stays below 7.0 kN.
Within the 6900 thin-section series, the 6906 bearing is the largest-bore option before the series transitions to the 6907 bearing (35x55x10 mm, 10.8 kN Cr). The 6905 bearing (25x42x9 mm, 4.30 kN Cr) is the next step down. Moving from a 6905 bearing to a 6906 bearing gains 69% more dynamic capacity (7.28 kN vs 4.30 kN) while adding 5 mm of bore and 5 mm of OD: a significant capacity jump within the same 9 mm section width. For a 30 mm shaft, the 6906 bearing is the only 6900-series option available.
Radial internal clearance is CN as standard. C3 clearance is stocked for electric motor and pump applications where thermal expansion of the inner ring reduces running clearance. The 9 mm cross-section provides better dimensional stability under radial load than the 7 mm 6800-series bearings: radial deflection at 5.0 kN radial load is approximately 30% less than an equivalent 6806 bearing, which matters in robot joint applications where bearing stiffness directly affects positional accuracy.
OEM and Customization
Yuanhe supplies the 6906 bearing with full customization for volume OEM orders. Non-standard radial clearances (C2, C3, C4) are stocked or produced to order. Lubrication options include low-torque synthetic grease for instrument applications, food-grade grease (NSF H1 registered) for processing equipment, and high-temperature polyurea grease rated to 150 degrees C continuous. Stainless steel 440C rings and balls are available for corrosive or washdown environments: note that 440C derates dynamic load capacity by approximately 15% compared to GCr15. Cage options include stamped steel (standard, to 15,000 RPM), glass-reinforced polyamide (reduced weight, lower noise, to 9,500 RPM), or machined brass (high-speed stability above 13,000 RPM). Standard MOQ is 100 pieces per configuration. Sample orders of 10 to 50 pieces ship within 7 days. Every order includes a dimensional inspection report covering bore, OD, width, radial runout, and radial clearance. ISO 9001:2015 certified. Submit your drawing or specification for a same-day quote.
Applications
Electric motor rotor supports 3 kW to 10 kW, industrial fan and blower shafts, compact gearbox input and output shafts, agricultural PTO shaft bearings, conveyor head and tail pulleys, HVAC condenser fan motors, robotic joint harmonic drive input bearings, textile machinery roller and tensioner bearings, fitness equipment crank and pulley assemblies, small compressor crankshaft bearings, centrifugal pump shaft supports. Any 30 mm shaft application with radial loads between 4.5 kN and 7.3 kN where a 6006 bearing OD of 55 mm exceeds the housing envelope.
Frequently Asked Questions
How much radial space does a 6906 bearing save compared to a 6006 bearing on the same 30 mm shaft? +
The 6906 bearing saves 8 mm of housing diameter (47 mm OD vs 55 mm OD) and 4 mm of axial width (9 mm vs 13 mm) compared to a 6006 bearing on the same 30 mm shaft. Housing wall thickness at the bearing seat reduces by 4 mm radially. Envelope volume: the 6906 bearing occupies approximately 46% less volume than the 6006 bearing. The trade-off is 45% lower dynamic load capacity (7.28 kN vs 13.2 kN). The 6906 bearing is the correct choice when the housing OD is constrained to 50 mm or below on a 30 mm shaft.
What is the fatigue life improvement when upgrading from a 6905 bearing to a 6906 bearing? +
Upgrading from a 6905 bearing (25x42x9 mm, 4.30 kN Cr) to a 6906 bearing (30x47x9 mm, 7.28 kN Cr) provides a 69% increase in dynamic load capacity at the same 9 mm section width. At identical radial load and speed, calculated L10 life improves by a factor of approximately 4.8. Static safety margin increases from 2.88 kN to 5.00 kN (a 74% increase). The trade-off is a 5 mm larger shaft diameter and a 5 mm larger housing bore. This upgrade is practical when the shaft diameter must increase from 25 mm to 30 mm for structural reasons.
Can a 6906 bearing handle the combined radial and axial loads in a robot joint harmonic drive? +
A 6906 bearing with C3 clearance handles combined loads up to 4.0 kN radial and 0.9 kN axial in harmonic drive input bearing applications at speeds under 3,000 RPM. The 47 mm OD fits inside the flexspline bore of size 20 to 25 harmonic drive units. However, the 6906 bearing is not a cross-roller bearing replacement: its axial stiffness at 0.9 kN is approximately 25 N per micron, versus 80 to 120 N per micron for an equivalent-size crossed roller bearing. For robot joints requiring angular rigidity under 30 arc-seconds, consider pairing two 6906 bearings in a back-to-back duplex arrangement with light preload.
What grease fill specification is recommended for a 6906-2RS bearing in a spindle motor at 9,000 RPM? +
For a 6906-2RS bearing running continuously at 9,000 RPM in a spindle motor, specify a 25% to 30% grease fill with a low-viscosity synthetic diester grease (ISO VG 15 to 22 base oil). Full grease fill at this speed causes churning losses that raise steady-state temperature by 8 degrees C to 12 degrees C and reduce grease life by approximately 40%. The 9 mm width of the 6906 bearing provides enough cavity volume for a 25% fill to lubricate effectively for 2,000 to 3,000 hours at 70 degrees C. For spindle motors above 10,000 RPM, switch to the open 6906 bearing with oil-mist lubrication.
