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6303 Deep Groove Ball Bearing 17x47x14mm
At 17mm bore, the 6303 bearing sits at the center of the 6300 medium-series range. It handles loads that push a 6203 bearing past its 9.55 kN limit, without requiring the 20mm shaft and 52mm housing bore of a 6304 bearing.
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: 16,000 RPM (open), 14,000 RPM (ZZ), 11,000 RPM (2RS). 13.5 kN dynamic load (Cr), 6.55 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 20% of Cr under light-to-moderate speeds with CN clearance.
- 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 | 6303 |
| Bearing Type | Deep Groove Ball Bearing, Single Row |
| Sealing | Open / ZZ (Metal Shield) / 2RS (Rubber Seal) |
| Bore Dia. (d) | 17 mm |
| Outside Dia. (D) | 47 mm |
| Width (B) | 14 mm |
| Precision | ABEC-3 (Standard), ABEC-5 Available |
| Dynamic Load (Cr) | 13.5 kN |
| Static Load (Cor) | 6.55 kN |
| Max Speed | 16,000 RPM (Open) / 14,000 (ZZ) / 11,000 (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
17 x 47 x 14 mm
Dynamic Load Cr
13.5 kN
Static Load Cor
6.55 kN
Max Speed
16,000 RPM
Sealing
Open / ZZ / 2RS
Precision
ABEC-3
Shielding and Lubrication
The 6303 bearing ships in three sealing configurations, each matched to a distinct operating environment. Open bearings reach 16,000 RPM without seal drag and are specified for oil-bath or circulating-oil systems where external lubrication is present and the housing provides contamination control.
ZZ metal-shielded 6303 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 14,000 RPM and handle moderate dust environments: electric motors, fans, and enclosed gearboxes. The 14 mm width of the 6303 bearing provides a grease reservoir that supports extended service intervals without re-greasing in horizontal-shaft motor applications.
2RS rubber-sealed 6303 bearings use nitrile contact seals on the inner ring land. At 11,000 RPM, the 2RS 6303 bearing handles agricultural machinery, conveyor rollers, and outdoor power transmission equipment where water, mud, and abrasive dust are routine. The contact seal lip adds measurable drag: expect 4 degrees C to 7 degrees C higher steady-state temperature than the equivalent ZZ bearing at the same speed. The 14 mm width holds approximately 27% more grease volume than the 12 mm-wide 6203-2RS, extending sealed-for-life operating hours in moderate-load applications.
Performance
The 6303 bearing delivers 13.5 kN dynamic load capacity (Cr) and 6.55 kN static load capacity (Cor). On the same 17 mm shaft, the 6203 bearing (17x40x12 mm) offers 9.55 kN Cr and 4.80 kN Cor. The 6303 bearing adds 7 mm OD and 2 mm width, accommodating larger-diameter balls and deeper raceway grooves. The result is a 41% increase in dynamic capacity and a 36% increase in static capacity.
Moving up one bore size, the 6304 bearing (20x52x15 mm) gains 19% more dynamic capacity (16.0 kN vs 13.5 kN) at the cost of a 3 mm larger shaft diameter and a 5 mm larger housing bore. This positions the 6303 bearing as the most commonly specified mid-range deep groove ball bearing: it covers the 10 kN to 13.5 kN radial load range that neither the 6203 bearing nor the 6304 bearing addresses efficiently. For a design running a 6203 bearing near its 9.55 kN fatigue limit, switching to a 6303 bearing extends calculated L10 life by a factor of approximately 2.8 at identical load and speed.
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. At C3 clearance and moderate axial load (less than or equal to 2.7 kN), the contact angle shifts approximately 8 degrees to 12 degrees, sufficient for combined radial-axial loading in gearbox and actuator applications.
OEM and Customization
Yuanhe supplies the 6303 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 16,000 RPM), glass-reinforced polyamide (reduced weight, lower noise, to 11,000 RPM), or machined brass (high-speed stability above 14,000 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 motors 5 kW to 15 kW, industrial pump shafts and impeller assemblies, HVAC air handler blowers and condenser fan motors, conveyor head and tail pulleys, agricultural PTO shafts and tiller spindle assemblies, compact gearbox input and output shafts, power tool armatures and gear trains, textile machinery rollers and tensioners, fitness equipment crank and pulley assemblies, centrifugal fan and blower shafts, compact actuator and linear drive lead screws, light-duty wheel hub assemblies, small compressor crankshafts. Any 17 mm shaft application with radial loads between 9.5 kN and 13.5 kN where the 6203 bearing reaches its operational limit.
Frequently Asked Questions
At what radial load should I switch from a 6203 bearing to a 6303 bearing on a 17 mm shaft? +
Switch when the application radial load exceeds approximately 70% of the 6203 bearing dynamic rating (above 6.7 kN sustained). The 6303 bearing delivers 13.5 kN Cr: a 41% increase over the 6203 bearing at 9.55 kN. The trade-off is a 7 mm larger housing bore (47 mm vs 40 mm) and a 2 mm wider bearing seat (14 mm vs 12 mm). If the housing can accept the 47 mm OD, the 6303 bearing extends calculated L10 life by approximately 2.8x and provides a 36% higher static safety margin (6.55 kN vs 4.80 kN). For loads above 10 kN radial, the 6303 bearing is the clear choice: the 6203 bearing operates at less than 50% of rated L10 life at that level.
What cage material is recommended for a 6303 bearing running continuously at 14,000 RPM? +
Machined brass is the recommended cage for 6303 bearings operating continuously above 14,000 RPM. At these speeds, stamped steel cages experience centrifugal stress that can initiate fatigue cracks at the rivet joints after 3,000 to 5,000 hours. Brass cages dissipate heat more effectively and maintain dimensional stability under thermal cycling. For intermittent high-speed operation (bursts to 14,000 RPM with steady-state cruise at 8,000 to 10,000 RPM), stamped steel is acceptable and more cost-effective. Glass-reinforced polyamide cages are limited to 11,000 RPM due to centrifugal softening at elevated temperature.
How does the 6303 bearing fit into a duplex pair for leadscrew support in CNC or 3D printer applications? +
Two 6303 bearings in a back-to-back (DB) duplex arrangement provide bidirectional axial stiffness for leadscrew support in light CNC routers and large-format 3D printers. With a 17 mm bore, the 6303 bearing pair fits common NEMA 23 and NEMA 34 stepper motor shaft diameters. At C3 clearance and light axial preload (50 to 80 N per bearing), the pair achieves approximately 50 N per micron axial stiffness: sufficient for positioning accuracy under 0.05 mm in non-contact machining. The 47 mm OD requires a housing bore that accommodates two bearings side by side with a spacer ring between outer rings for preload adjustment. For higher-stiffness leadscrew supports, consider an angular contact pair instead of deep groove.
How does the 47 mm OD of the 6303 bearing affect housing design compared to the 40 mm OD 6203 bearing? +
The 47 mm OD of the 6303 bearing adds 7 mm of diameter versus the 6203 bearing at 40 mm. In aluminum housings, this requires an additional 3.5 mm of wall thickness to maintain the same press-fit interference without housing deformation. The larger OD also increases the bearing surface area by approximately 38%, improving heat transfer to the housing: at 10,000 RPM under 8 kN radial load, the 6303 bearing runs 3 degrees C to 5 degrees C cooler in an aluminum housing than a 6203 bearing at equivalent load. The 14 mm width adds 2 mm of axial stack height; most motor end-bell housings designed for 6203 bearings can be machined to accept the 6303 bearing with a 7 mm bore enlargement and 2 mm deeper counterbore, provided the housing flange has sufficient radial thickness.
