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68 Series
Home Deep Groove Ball Bearings 68 Series

6808 Open Thin-Section Deep Groove Ball Bearing For Oil-Lubricated & Enclosed Systems | 40×52×7 mm

6808 Open Thin-Section Deep Groove Ball Bearing For Oil-Lubricated & Enclosed Systems | 40×52×7 mm

The 6808 is a single-row, thin-section miniature deep groove ball bearing from the 6800 series, manufactured in an open configuration without shields or seals. Featuring a 40 mm bore and a highly compact 52 mm outer diameter, it delivers an extremely slim 7 mm cross-section. This open-type design is specifically engineered for internal machinery applications where the bearing operates within an already sealed housing, such as an oil bath or centralized lubrication system. By omitting the sealing components, the 6808 Open achieves the lowest possible starting and running torque, making it the premier choice for ultra-high-speed, space-constrained assemblies where frictional losses must be completely minimized.

6808 Deep Groove Ball Bearing 40×52×7 mm | 68 Series | Open Design

A high-efficiency, thin-wall bearing built for precision mechanisms that provide their own environmental protection and continuous lubrication. The open architecture of the 6808 exposes the rolling elements and raceways, an intentional design choice that allows for the unrestricted flow of lubricating oil or grease directly through the bearing. It covers the same 40 × 52 × 7 mm footprint as its shielded (6808-ZZ) and sealed (6808-2RS) counterparts, making it a direct fit for identical housing dimensions. Where sealed bearings restrict speed to prevent heat buildup, the 6808 Open thrives in high-RPM applications, leveraging continuous oil circulation to dissipate heat and flush away microscopic wear particles.

6808 Open Thin-Section Deep Groove Ball Bearing For Oil-Lubricated & Enclosed Systems | 40×52×7 mm

Comprehensive Applications

The 6808 Open is selected whenever a 40 mm shaft requires minimal friction and relies on external system lubrication within a tight outer envelope:

Industrial Gearboxes & Transmissions
  • Internal shaft supports in enclosed, oil-bathed gear reducers
  • High-speed transmission assemblies
  • Power take-off (PTO) internal mechanisms
Precision Optical & Measurement Equipment
  • Gimbal rings and camera stabilization systems in cleanroom environments
  • Rotary encoder shafts
  • Laser scanning and tracking pivots
Robotics & Motion Control
  • Internal robotic joint supports housed within sealed protective casings
  • Servo motor internal bearings
  • Automated assembly line actuator mechanisms
Performance Automotive & Aerospace
  • Lightweight internal engine or turbine components
  • Racing telemetry sensor pivots
  • Aerospace auxiliary control mechanisms in sealed housings

Key Performance Features

01. Unrestricted Lubrication Flow for Maximum Cooling

The absence of side shields or rubber seals means the 6808 Open can be seamlessly integrated into systems utilizing circulating oil, oil mist, or heavy grease packs. In high-speed gearboxes, the open design allows the system's oil to freely wash through the bearing cage and balls, constantly cooling the components and naturally flushing away any micro-contaminants generated by internal mechanical wear.

02. Ultra-Low Friction for High-Speed Efficiency

Without the physical drag of contact rubber seals or the aerodynamic resistance of tight-clearance metal shields, the 6808 Open operates with absolute minimal frictional torque. This allows the bearing to reach exceptional rotational speeds—up to 15,000 r/min when supported by proper oil lubrication—making it highly energy efficient for battery-operated or high-velocity precision machinery.

03. Exceptional Space and Weight Savings

As part of the 6800 thin-section family, the 40 mm to 52 mm bore-to-OD ratio provides engineers with the ability to utilize large, rigid drive shafts without demanding heavy, bulky housings. The open design further reduces the overall weight of the bearing by eliminating the extra mass of steel shields or rubber seals, critical for aerospace and portable device engineering.

Technical Specifications

Bearing Type Single Row Deep Groove Ball Bearing
ISO Dimension Series 6800 Series
Basic Designation 6808
Suffix None (Open Design)
Bore Diameter (d) 40 mm
Outer Diameter (D) 52 mm
Width (B) 7 mm
Material (Races & Balls) High-Carbon Chrome Steel (GCr15 / SAE 52100)
Precision Class ISO Class 6 (ABEC-3) / Class 5 (ABEC-5) Available
Cage Design Pressed Steel
Dynamic Load Rating (Cʳ) 4.95 kN
Static Load Rating (C₀ʳ) 4.20 kN
Limiting Speed (Grease) ~13,000 r/min
Limiting Speed (Oil) ~15,000 r/min
Weight (approx.) 0.032 kg

Interchange Part Numbers

The 6808 Open is cross-referenced under the base numerical conventions across major manufacturers, without the suffixes used for sealed variants:

  • SKF: 61808
  • NSK: 6808
  • FAG (Schaeffler): 6808
  • NTN: 6808
  • KOYO: 6808
  • NACHI: 6808
  • Generic: 6808, 61808, 6808 Open

Design & Configuration

The 6808 is a Conrad-type, single-row radial ball bearing optimized for thin-section, low-clearance applications. Because it lacks integral sealing components, it relies entirely on the cleanliness of the internal system housing to prevent contamination. The internal geometry supports a 4.95 kN dynamic load rating and a 4.20 kN static load rating. The defining advantage of this open configuration is its thermal and speed capability; the bearing can achieve roughly 13,000 r/min with standard grease and an impressive 15,000 r/min when supplied with continuous oil lubrication. For external applications exposed to dust or moisture, a 6808-ZZ or 6808-2RS must be used. However, for fully enclosed environments like gearboxes or cleanrooms—where maximum speed and uninhibited lubrication access are required—the 6808 Open is the definitive engineering choice.

"When the shaft requires a 40 mm bore but housing space is severely limited, the 6808 Open thin-section bearing delivers the ultimate low-friction solution. Its unshielded design allows for maximum oil flow and heat dissipation, making it the perfect internal component for high-speed enclosed systems like gear reducers, optical instruments, and precision robotics."

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The 6808 is a single-row, thin-section miniature deep groove ball bearing from the 6800 series, manufactured in an open configuration without shields or seals. Featuring a 40 mm bore and a highly compact 52 mm outer diameter, it delivers an extremely slim 7 mm cross-section. This open-type design is specifically engineered for internal machinery applications where the bearing operates within an already sealed housing, such as an oil bath or centralized lubrication system. By omitting the sealing components, the 6808 Open achieves the lowest possible starting and running torque, making it the premier choice for ultra-high-speed, space-constrained assemblies where frictional losses must be completely minimized.

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Details

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