What is sealed ball bearings and Why Do We Use Them?

Sealed spherical roller bearings are defined by having sealing shields mounted on the external edge of the sides of the bearing. These protect against external contamination and keep the lubricant in place.

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Both bearings are designed to withstand high loads; however, sealed bearings benefit from the enclosure that helps extend their service life. Understanding both bearing types and which is needed for a specific application is essential when sourcing suppliers. 

At Bearing & Drive Systems, we're committed to providing global sourcing network solutions that help you find the authentic bearing that your customers need now. 

So suppose you're looking for a type of spherical roller bearing for your next project.

What's your next best step?

You can get in touch with a sales rep about your bearing needs or submit a support ticket. We can help reduce any downtime for your customers and guarantee authenticity and quality.

In the meantime, keep reading for more information about spherical roller bearings (Sealed vs. Non-sealed), design attributes, and their many applications...

Spherical Roller Bearings (Sealed vs. Non-sealed/Open Bearing)

The main difference between the two bearings is the sealed spherical roller bearing has a highly effective double-lip seal that keeps lubricants in and contaminants out.

Both types are designed for high-load capacity, with the sealed versions offering an additional advantage. Because the seal keeps dirt and other contaminants out, it can offer a longer operating life of the bearing or prevent premature bearing failure.

Sealed bearings can be considered lubricated for life, which eliminates the need for a relubrication process.

Sealed Bearing Design Attributes and Benefits

Sealed spherical roller bearings are cost-effective, offer a higher level of cleanliness, and are a space-saver. Let's look at a few attributes sealing can contribute to...

1. Reliable protection against external contamination

Many contaminants can cause problems with a bearing. Dirt, sand, and water are the most common ones you run into, but chemicals and corrosives can also damage bearings. 

Let's consider environmental influence ...

Dust and dirt can contaminate a bearing at an aggressive rate. Be sure to use proper sealing techniques to prevent this type of contamination. 

Another instance where proper sealing is crucial is with aggressive media or water. When dissolved water in lubricant materials absorbs with a bearing, it can cause etching and microcracks. When this occurs, it can reduce the bearing integrity.

Sealing is the extra step to protect against external contaminants. Using a sealed spherical bearing will prevent external contamination.

2. Lubricant kept in place

Adequately sealed bearings guard against contamination and ensure the lubrication isn't destroyed. 

Sealed spherical roller bearings are supplied with the proper lubricant or grease and then sealed (closed). This process allows the bearing to be lubricated properly from the start. 

Lubrication reduces friction and abrasion, prolongs service life, and keeps contaminants away from the rolling elements. 

3. Improved maintenance intervals

Fewer maintenance requirements are essential when dealing with hard-to-reach places where a bearing can be located. Carrying out less maintenance with the grease in a sealed bearing is cost-efficient (less grease consumption) and safer overall (remove any injury risk).

More applications become available when less maintenance is required. Since businesses/customers rely on bearings for their operation, any downtime can lead to a higher cost or delays in their production process.

4. Easier handling 

Sealed bearings result in easier handling during mounting. The worry is less for contamination.

5. Space-saving

A bearing with integral seals requires less space. This also opens up other applications for the sealed bearing to be used.

Spherical Roller Bearings Applications 

Spherical roller bearings are used in highly demanding environments' extremely tough running conditions.

The bearings are used in applications prone to misalignment or shaft deflection (bending of the shaft under specific circumstances, such as an axial load). They are known to tolerate the misalignment between the shaft and housing.

With being able to handle misalignment, spherical roller bearings are sourced for a variety of mechanical uses. 

Everyday use for this bearing includes mining equipment, construction equipment, and textile machinery, and more...

"Spherical roller bearings have a wide range of use-cases. They are used in applications where heavy loads, moderate to high speeds, and possible misalignment occur. Examples are off-road vehicles, pumps, mechanical fans, marine propulsion, wind turbines, and gearboxes." [source]

Conclusion

The spherical roller bearing has the central role of taking dual-directional thrust and movement versatility. Its primary function is to reduce friction between the components while allowing for misalignment. 

The added sealed spherical roller bearing extends the life of the bearing, improves productivity, and can be used in countless industrial applications. 

As every roller bearing is slightly different with unique characteristics, it is critical to understand their differences before applying to equipment. 

BDS offers a range of roller bearings for you to source. Our global sourcing network enables you to get the bearing you need according to your order requirements without any hassle. 

For more information, please visit sealed ball bearings.

Open bearings

An Open bearing usually operates in an environment where the bearing is immersed in fluids such as lubrication oil. Open bearings do not have seals or shields and they expose the inner raceways, cages, and balls to the environment. Examples would be open bearings used to support shafts in gearboxes and transmissions where lubrication is constant and present.

Shielded Bearings

A shielded Bearing is used in any environment where contamination is not a major issue. Usually specified for applications where the designer desires low starting and running torque as well as enclosing the bearing limiting the ingress of minor contaminants such as dust.

Shielded bearings are often found in electric motors, fans, power tools, and office machinery. The shield has no contact with the inner ring where a small gap exists allowing for low starting and running torque. Shielded bearings are commonly specified with oil lubrication and usually starting and running torque is a consideration.

Sealed Bearings

Manufacturers use various designs for achieving the proper fitment and the degree of protection provided by the seal.

Why specify one over enclosure type of another and why is it important?

Bearing seals have two main functions: to prevent lubricating oil from leaking out and to prevent dust , water and other contaminants from entering the bearing. Bearings have to be adequately lubricated to prevent direct metallic contact between the rolling elements, raceways and cages to prevent wear and to protect the bearing surfaces against corrosion.

Sealed Bearings 

Bearings with shields or seals filled with grease are widely used. Grease has the advantage over oil that its more easily retained and takes longer to be compromised than oil.

Sealed bearings have the advantage of being lubricated for life, are suitable for normal and light loads with moderate to low speeds. Sealed bearings generally have a low production cost and maintain no need for relubrication or greasing.

As such these bearings are used widely in electric motors, fan motors, and automation equipment.

Seal Types

When selecting a seal the following factors need to be taken into consideration:

• the type of lubricant( oil or grease)
• seal peripheral speed
• shaft fit
• space constraints
• seal friction

As mentioned seals are broken down into non-contact and contact types.

Non-Contact Seals and Shields

Non contact seals and Shields will demonstrate a small gap between the inner diameter of the seal/shield and the inner ring of the bearing. In order to improve the seal the gap is filled in with lubricant.

Contact Seals

Contact seals accomplish their sealing action through contact pressure ( the lip) which is made of Buna N rubber normally. Contact seals are by far the best way to seal a bearing.

Being far superior contact seals are efficient, although they demonstrate higher friction torque and result in temperature rise coefficients being higher. When the portion of a contact seal rotates while in contact with the shaft the allowable seal peripheral speed varies depending on seal type.

Lubrication is necessary at the contact surface between the lip portion of the contact seal and the shaft. Ordinary lubricant can be used for this purpose.

As demonstrated the most commonly specified types of enclosures for bearings are:

• rubber seals
• steel shields
• open

In some cases your application may require an OPEN bearing to have a seal on one side and be open on the other side. A seal may be required on the outside facing the environment and the open side is facing inward. 

The reason may be to reduce drag or starting and running torque while still protecting the bearing. 

The challenge for sealing bearings is to seal the bearing by protecting the bearing from contaminants and running efficiencies.

Advantages of Sealed Bearings 

Sealed bearings offer multiple benefits in various applications:

Contamination Protection
Sealed bearings are particularly effective at preventing external contaminants, such as dust, dirt, and moisture, from entering the bearing. This is essential in environments where contamination can significantly reduce bearing life.

Lubrication Retention
They are designed to retain the lubricant inside the bearing. This helps in maintaining the correct amount of lubrication throughout the bearing's service life, thus reducing the need for regular maintenance and relubrication.

Extended Bearing Life
By preventing contamination ingress and retaining lubrication, sealed bearings can significantly extend the bearing life compared to their open counterparts.

Reduced Maintenance
The sealed design minimizes maintenance intervals, providing cost and time savings.

Versatility
Sealed bearings are suitable for a wide range of applications, especially where external contamination is a major concern.

Difference Between Bearing Shields and Bearing Seals 

Bearing shields and seals are both designed to protect bearings from external contaminants and retain lubrication, but there are distinct differences:

• Construction
  Shields are typically made of metal and fit into a groove on the outer ring without making contact with the inner ring. Seals, on the other hand, are made of elastomeric material and make light contact with the inner ring, providing a barrier.

• Protection Level
  Seals offer a higher degree of protection from contaminants and moisture due to their contact nature. Shields provide protection primarily from larger contaminants but are less effective against fine particles and moisture.

• Friction
  Since seals have contact with the inner ring, they generate more friction than shields. This may result in slightly higher operating temperatures for sealed bearings compared to shielded ones.

• Lubrication
  Sealed bearings are often pre-lubricated, making them maintenance-free for many applications. Shielded bearings might need occasional relubrication.

Comparison Between Sealed and Shielded Bearings 

The choice between sealed and shielded bearings will depend on the specific requirements of the application. While sealed bearings offer superior protection and maintenance advantages, shielded bearings can be more suitable in situations where minimal friction and operating temperature are crucial. It's essential to assess the operational environment and demands before making a selection.

If you want to learn more, please visit our website Thrust Roller Bearings manufacturer.