What Are The Difference From Sealed Bearings Vs Shielded Bearings

In industrial machinery, bearings promote smooth rotation and reduce friction between moving parts. Sealed  bearings vs shielded bearings are two common types of bearings that are often used in a variety of applications. While they may appear similar at first glance, each type has unique characteristics and benefits that apply to specific operational needs. Achieve optimal bearing performance by taking a closer look at the differences between sealed and shielded bearings.

What Are Sealed Bearings

Sealed bearings are specially designed bearings whose main feature is the integration of seals inside the bearing that completely enclose the rolling elements (such as balls, rollers or rollers) and the lubricant inside the bearing. These seals are usually made of rubber or synthetic materials and are fixed to the outer ring of the bearing by molding or pressing. Sealed bearings are designed to prevent external contaminants (such as dust, dirt, moisture and other environmental factors) from entering the bearing cavity, thereby protecting the rolling elements and lubricant from contamination and corrosion. This helps to extend the life of the bearing and also avoids the need for regular maintenance. Sealed bearings are typically used in applications where contamination is a serious problem, such as automotive, industrial and agricultural equipment.

What Are The Advantages Of Sealed Bearings?

Sealed bearings offer numerous benefits compared to other bearing types, mainly in the following areas:

Excellent Contaminant Protection:

Sealed bearings are designed to prevent the intrusion of external contaminants like dust, dirt, and moisture. The integrated seals keep the rolling elements and lubricant enclosed, protecting them from contamination and corrosion, which in turn extends the bearing’s lifespan.

Long Lubricant Life With Sealed Bearings:

The sealed design helps maintain the lubricant inside the bearing for extended periods. This reduces the risk of lubricant degradation caused by external contaminants, leading to longer lubrication intervals and lower maintenance costs.

Reduced Maintenance Requirements:

Because sealed bearings effectively block external contaminants, the interior remains cleaner, requiring less frequent cleaning and lubrication. This reduction in maintenance efforts results in lower maintenance costs and efforts.

Suitability for Harsh Environments:

Sealed bearings are particularly well-suited for harsh operating conditions, including high temperatures, high humidity, and dusty environments, due to their superior contaminant protection.

Improved System Reliability:

The stability and reliability of sealed bearings enhance the overall stability and reliability of mechanical systems. This makes them an ideal choice for applications demanding high stability and reliability in mechanical equipment.

What Are Shielded Bearings?

Shielded bearings are a common type of bearing whose design is characterized by metal caps or retainers partially covering the outer ring of the bearing around the outer ring to provide protection for the rolling elements. These metal caps or retainers are typically used to cover one or both sides of the bearing, while the other side of the bearing remains open, allowing the rolling elements to run freely inside.

What Are The Advantages of Shielded Bearings

Shielded bearings offer several benefits over other bearing types, including:

Contaminant Protection:

Shielded bearings feature metal shields that prevent larger contaminants like dust and dirt from entering the bearing while allowing for ventilation and heat dissipation. This helps protect the rolling elements and lubricant from contamination, thereby extending the bearing’s lifespan.

Reduced Lubricant Loss:

The shields help to retain lubricant within the bearing, reducing the likelihood of lubricant loss. This can lead to longer lubrication intervals and decreased maintenance frequency.

Lower Maintenance Requirements:

With improved protection against contaminants and better lubricant retention, shielded bearings require less frequent maintenance compared to open bearings. This reduction in maintenance needs translates to lower maintenance costs and efforts.

Improved Durability:

The shields provide an additional layer of protection, enhancing the bearing’s durability in various operating conditions. This makes shielded bearings suitable for applications with moderate exposure to contaminants and limited maintenance access.

Cost-Effective Solution:

Shielded bearings offer a cost-effective alternative to sealed bearings, providing a good balance between protection and ventilation. They are ideal for applications where complete sealing is not necessary but some level of protection is required.

Versatility:

Shielded bearings are versatile and can be used in a wide range of applications, from industrial machinery to automotive components, where moderate protection against contaminants is needed.

Shielded bearings, on the other hand, are bearings that have a metal shield or plate that covers the open side of the bearing. While shielded bearings offer some protection against contaminants, they are not completely sealed like sealed bearings. This means that shielded bearings are not as effective at protecting against dust, dirt, and moisture.

One of the main advantages of shielded bearings is their lower friction and heat generation compared to sealed bearings. This allows for smoother operation and increased efficiency, making shielded bearings ideal for applications that require high speeds or low torque. Shielded bearings also tend to be more cost-effective compared to sealed bearings.

However, the lack of complete sealing in shielded bearings means that they are more susceptible to contamination. This can lead to premature wear and reduced lifespan, especially in applications where the bearings are exposed to harsh conditions. Shielded bearings also require more frequent maintenance and re-lubrication compared to sealed bearings.

Performance Comparison Of Sealed Bearings Vs Shielded Bearings

Sealed bearings and shielded bearings both offer protection against contaminants such as dirt and moisture, which can extend the life of the bearing and improve its performance. However, there are some key differences between the two types of bearings that can affect their performance in different applications.

Sealed bearings have rubber or metal seals that completely enclose the bearing, providing maximum protection against contaminants. This design helps to retain lubrication inside the bearing and prevent dirt and moisture from entering, which can reduce wear and damage to the bearing surfaces. Sealed bearings are ideal for applications where the bearing will be exposed to harsh environments or where maintenance is difficult, as they require less frequent re-lubrication and are generally more durable than shielded bearings.

On the other hand, shielded bearings have metal shields that cover only part of the bearing, leaving a small gap for lubrication to escape and contaminants to enter. While shielded bearings offer some protection against contaminants, they are not as effective as sealed bearings at preventing dirt and moisture from entering the bearing. This can lead to increased wear and damage to the bearing surfaces, especially in harsh environments or high-speed applications.

In terms of performance, sealed bearings generally have lower friction and higher load capacity than shielded bearings, as the seals help to retain lubrication and reduce friction between the bearing surfaces. This can result in smoother operation, longer bearing life, and improved overall performance in a wide range of applications. Additionally, sealed bearings are often quieter and require less maintenance than shielded bearings, making them a popular choice for industrial and automotive applications.

What Are The Difference In The Maximum Speed Of Sealed Bearings Vs Shielded Bearings?

When selecting a suitable bearing, one of the key factors to consider is the maximum operating speed of the bearing. Two types of bearings commonly used in various industrial applications are sealed bearings and shielded bearings. There is also a difference in rotational speed between the two.

One of the key differences between sealed bearings and shielded bearings is their maximum speed ratings. The maximum speed of a bearing is the highest speed at which the bearing can operate without experiencing premature failure or damage. This speed is typically specified by the bearing manufacturer and is influenced by factors such as the type of lubrication used, the material of the bearing, and the design of the bearing.

In general, sealed bearings have lower maximum speed ratings compared to shielded bearings. This is because the seals on sealed bearings create more friction and resistance, which can limit the speed at which the bearing can operate. On the other hand, shielded bearings have less resistance and therefore can operate at higher speeds.

For example, a typical sealed bearing may have a maximum speed rating of 12,000 RPM, while a shielded bearing of the same size and construction may have a maximum speed rating of 15,000 RPM. This difference in maximum speed can be significant in applications where high speeds are required, such as in motors, pumps, and compressors.

It is important to note that the maximum speed ratings of bearings are just guidelines, and the actual operating speed of a bearing may be lower depending on factors such as the load, lubrication, and operating conditions.

Conclusion

When selecting a suitable bearing, factors such as maximum speed, contaminant protection, and lubrication requirements need to be considered. If the application requires a high level of contaminant protection and the speed requirements are not particularly stringent, then sealed bearings may be a more appropriate choice. For applications with high speed requirements but relatively low contaminant protection requirements, shielded bearings may be more suitable. However, the selection of the appropriate bearing type still needs to take into account the specific requirements of the application, environmental conditions, and the influence of other factors.

References

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