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6902 Thin-Section Deep Groove Ball Bearing 15x28x7mm
At 15mm bore and 28mm OD, the 6902 bearing is the thinnest deep groove ball bearing in its bore class. It saves 7mm of housing diameter versus the 6202 bearing while still delivering 4.35 kN dynamic load: enough for instrument drives, spindle motors, and compact actuator applications where every millimeter of radial space counts.
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: 28,000 RPM (open), 24,000 RPM (ZZ), 19,000 RPM (2RS). 4.35 kN dynamic load (Cr), 2.26 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 15% of Cr due to the 7mm cross-section limiting contact angle shift.
- 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 | 6902 |
| Bearing Type | Deep Groove Ball Bearing, Thin Section, Single Row |
| Sealing | Open / ZZ (Metal Shield) / 2RS (Rubber Seal) |
| Bore Dia. (d) | 15 mm |
| Outside Dia. (D) | 28 mm |
| Width (B) | 7 mm |
| Precision | ABEC-3 (Standard), ABEC-5 Available |
| Dynamic Load (Cr) | 4.35 kN |
| Static Load (Cor) | 2.26 kN |
| Max Speed | 28,000 RPM (Open) / 24,000 (ZZ) / 19,000 (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
15 x 28 x 7 mm
Dynamic Load Cr
4.35 kN
Static Load Cor
2.26 kN
Max Speed
28,000 RPM
Sealing
Open / ZZ / 2RS
Precision
ABEC-3
Shielding and Lubrication
The 6902 bearing ships in three sealing configurations, each matched to a distinct operating environment. Open bearings reach 28,000 RPM without seal drag and are specified for oil-bath or oil-mist systems where the housing provides contamination control. The 7 mm cross-section of the 6902 bearing reduces centrifugal force on the rolling elements, enabling higher speed limits than the 11 mm-wide 6202 bearing (28,000 vs 18,000 RPM open).
ZZ metal-shielded 6902 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 24,000 RPM and suit dental handpiece turbines, optical encoder spindles, and small servo motor drives where low torque and minimal heat generation are requirements. The non-contact design adds negligible drag: torque increase over an open 6902 bearing is under 2% at 12,000 RPM.
2RS rubber-sealed 6902 bearings use nitrile contact seals on the inner ring land. At 19,000 RPM, the 2RS 6902 bearing handles compact medical pumps, laboratory centrifuge rotors, and small spindle motors in semi-clean environments. The 7 mm width limits the grease reservoir: at 12,000 RPM and 60 degrees C, a 6902-2RS bearing with standard polyurea-mineral grease (NLGI 2) operates sealed-for-life for 1,200 to 2,500 hours under moderate radial load (less than or equal to 0.7 kN). The 28 mm OD provides a larger grease reservoir than the 24 mm OD 6901-2RS, extending service intervals by approximately 30% at equivalent load.
Performance
The 6902 bearing delivers 4.35 kN dynamic load capacity (Cr) and 2.26 kN static load capacity (Cor). On the same 15 mm shaft, the 6202 bearing (15x35x11 mm) offers 7.65 kN Cr and 3.75 kN Cor. The 6902 bearing does not compete with the 6202 bearing on load: it competes on radial envelope. When the housing bore cannot exceed 30 mm but the shaft is fixed at 15 mm, the 6902 bearing is the load-capacity leader among thin-section options at this bore diameter.
Within the 6900 thin-section series, the 6902 bearing sits between the 6901 bearing (12x24x6 mm, 2.89 kN Cr) and the 6903 bearing (17x30x7 mm, 4.65 kN Cr). For a 15 mm shaft, the 6902 bearing is the sole 6900-series option: the 6901 bearing is limited to a 12 mm bore, and the 6903 bearing starts at 17 mm. Compared to the 16002 bearing (15x32x8 mm, 5.60 kN Cr), the 6902 bearing saves 4 mm of OD while sacrificing 1.25 kN of dynamic capacity: a trade-off worth making when the housing bore is the binding constraint.
Radial internal clearance is CN as standard. C2 clearance is stocked for precision spindle and encoder applications where minimal radial play is critical. The thin 7 mm cross-section means running clearance is sensitive to housing material: in an aluminum housing at 80 degrees C, thermal expansion adds approximately 6 to 10 microns of radial clearance compared to a steel housing. Specify C2 clearance in aluminum housings to maintain preload at operating temperature.
OEM and Customization
Yuanhe supplies the 6902 bearing with full customization for volume OEM orders. Non-standard radial clearances (C2, CN, C3) 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 28,000 RPM), glass-reinforced polyamide (reduced weight, lower noise, to 19,000 RPM), or machined brass (high-speed stability above 24,000 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
Dental handpiece and surgical tool turbine spindles, optical encoder and resolver rotary stages, small servo motor rotor supports, laboratory centrifuge and microcentrifuge rotors, 3D printer hot-end and extruder drive shafts, medical infusion pump drives, textile spindle bearings for high-speed twisting frames, precision instrument and camera gimbal bearings, compact actuator and harmonic drive wave generator bearings, small cooling fan and blower motor shafts. Any 15 mm shaft application requiring a bearing OD under 30 mm with speeds above 18,000 RPM.
Frequently Asked Questions
How much radial space does a 6902 bearing save compared to a 6202 bearing on the same 15 mm shaft? +
The 6902 bearing saves 7 mm of housing diameter (28 mm OD vs 35 mm OD) and 4 mm of axial width (7 mm vs 11 mm) compared to a 6202 bearing on the same 15 mm shaft. Envelope volume: the 6902 bearing occupies approximately 58% less volume than the 6202 bearing. The trade-off is 43% lower dynamic load capacity (4.35 kN vs 7.65 kN) and 40% lower static capacity (2.26 kN vs 3.75 kN). The 6902 bearing is the correct choice when the housing OD is constrained to 30 mm or below. It is the wrong choice when load capacity governs and radial space is available for a 35 mm OD bearing.
What is the limiting speed of a 6902 bearing with a polyamide cage in an instrument drive? +
With a glass-reinforced polyamide cage, the 6902 open bearing reaches a limiting speed of approximately 34,000 RPM under light radial load (under 0.3 kN) in instrument drives with oil-mist lubrication. The polyamide cage reduces rotating mass by approximately 40% versus a stamped steel cage at the same envelope, lowering centrifugal stress at the cage pocket contacts. However, polyamide cages lose approximately 30% of their tensile strength at 100 degrees C, so the bearing temperature must stay under 80 degrees C for sustained operation above 28,000 RPM. For instrument drives running continuously above 30,000 RPM with oil-mist lubrication, a machined brass cage is the recommended upgrade.
Can a 6902 bearing replace a 6901 bearing in an existing design without housing modification? +
No direct drop-in replacement. The 6902 bearing has a 15 mm bore versus the 6901 bearing 12 mm bore. ODs differ (28 mm vs 24 mm) and widths differ (7 mm vs 6 mm). If the design can accept a 3 mm shaft diameter increase, a 4 mm housing bore increase, and a 1 mm width increase, the 6902 bearing delivers 51% more dynamic capacity (4.35 kN vs 2.89 kN) and a 28,000 RPM speed limit. In most cases, upgrading from a 6901 bearing to a 6902 bearing requires a complete shaft and housing redesign, not a simple swap.
How does the 7 mm width of the 6902 bearing affect its performance in a vertical-shaft orientation? +
In vertical-shaft applications, the 7 mm width of the 6902 bearing reduces the ball-to-raceway contact ellipse length compared to wider bearings, which affects axial load distribution. At 15% of Cr axial load (approximately 0.65 kN), the 6902 bearing operates within its design envelope with CN clearance. At axial loads above 0.8 kN sustained, the contact ellipse approaches the raceway shoulder, increasing edge stress and reducing fatigue life. For vertical-shaft applications with combined loading above 2.0 kN radial and 0.6 kN axial, consider pairing two 6902 bearings in a face-to-face (DF) duplex arrangement: this doubles axial stiffness and load capacity while maintaining the 28 mm OD envelope.
