NSK 6808DDUM Deep Groove Ball Bearing (Double-Sided Contact Seals)

Basic Info

The NSK 6808DDUM is a high-performance deep groove ball bearing renowned for its superior sealing technology. It features double-sided contact rubber seals (the DD suffix denotes double contact seals), which provide better grease retention and protection against water and dust compared to shields. Pre-lubricated with NSK's proprietary high-performance grease, it is suited for applications demanding high cleanliness, quiet operation, and long life.

Key attributes

Origin

China

Brand

NSK

Bearing Type

Single Row Deep Groove Ball Bearing

Bore Diameter

40 mm

Outer Diameter

68 mm

Width

15 mm

Seal Type

Double-Sided Contact Rubber Seals (LLU / DD)

Cage Material

Engineering Plastic (Nylon 66)

Ring Ball Material

Vacuum Degassed High Carbon Chrome Steel

Dynamic Load Rating

16.8 kN

Static Load Rating

11.6 kN

Limiting Speed

8,000 r/min

Customer reviews

Sophie Laurent · Global Sourcing Specialist

Sourcing for our budget-line desktop printers requires a strict balance of cost and functional reliability. Your standard series bearings have been used in over 500,000 units of our 'ProPrint 200' model. The field return data related to bearing failure remains well below our target threshold, confirming their value for high-volume applications.

Robert Kim · Acoustic Engineering Manager

The low-vibration bearings supplied for our document scanner feed rollers have effectively resolved inconsistent paper feeding issues. Compared to previous solutions, the mechanical noise measured during operation decreased by 5 dB(A), significantly improving the user experience in quiet office environments. The product consistency across batches is also excellent.

Carlos Mendez · Facilities Maintenance Director

For the large exhaust fan motor bearings in the factory systems we maintain, regreasing was previously required every 12 months. After switching to your company's long-life, pre-lubricated sealed bearings, they have run continuously for 18 months, and vibration monitoring data remains within the acceptable range. This provides a reliable basis for extending our planned maintenance cycle to 24 months, optimizing operational costs.

Product Description

Product Characteristics:

The core advantage of the NSK 6808DDUM lies in its highly effective contact seal system.The sealing lip precisely contacts the inner ring shoulder,forming a powerful barrier that effectively prevents grease from leaking out and blocks the ingress of external liquids(like water droplets)and fine dust.This design makes it exceptionally suitable for operation in humid or contaminated environments.The bearing is made from vacuum degassed steel,ensuring high purity and long fatigue life.The optimized internal geometry(raceway curvature,ball size,and count)delivers higher load capacity and lower noise levels.The pre-filled grease ensures virtually maintenance-free operation throughout the bearing's service life and maintains stable lubrication performance over a wide temperature range,significantly enhancing equipment reliability.

Product Specifications:

This bearing has a bore diameter of 40 mm,an outer diameter of 68 mm,and a width of 15 mm,belonging to a thin-section series that aids in equipment miniaturization.Its dynamic load rating is 16.8 kN,and the static load rating is 11.6 kN.Due to the slight friction from the contact seals,its limiting speed is 8,000 r/min(grease lubricated),which still meets the needs of most industrial applications.The standard radial clearance is the CN group.The seal material is typically Nitrile Rubber(NBR),known for good oil and wear resistance.The cage is made from high-performance engineering plastic(e.g.,glass-reinforced nylon 66),offering advantages like self-lubrication,light weight,impact resistance,and low noise.

Product Applications:

The NSK 6808DDUM is widely used in applications requiring high sealing reliability.In the automotive industry,it is a key component in wheel hub units,alternators,and starter motors.Industrially,it is used in submersible pumps,underwater robots,food and beverage processing equipment(requiring water and corrosion resistance),and on machine tool transmission shafts.Additionally,its requirements for low noise and cleanliness are perfectly met in office automation equipment(e.g.,high-performance printers,scanners)and medical devices.It is the ideal solution for precision drive systems that may be exposed to moisture,chemical vapors,or high concentrations of dust.