Bearing Shields and Seals: Protection for Maximum Performance
Bearings are vital components in mechanical systems, and their lifespan depends directly on protection against external agents such as dust, moisture, and debris. Shields and seals are designed to provide this protection, ensuring efficiency, durability, and reduced maintenance costs. In this article, VICAN presents the types of shields and seals, explaining their detailed characteristics and the best applications for each case.
Why is protection essential?
Bearings are subject to several adverse factors that can compromise their performance:
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Corrosion: Caused by moisture ingress or contact with water.
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Premature wear: Caused by solid particles such as dust and debris.
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Operational inefficiency: Accumulation of contaminants affecting smooth movement.
Proper shielding or sealing prevents these issues, promoting greater durability and reliability in operation.
Types of Shields and Seals
1. Shielded Bearings (ZZ or Z)
Description: Equipped with metal shields, either on one side (Z) or both sides (ZZ).
Material: Usually stainless steel or coated carbon steel, resistant to extreme temperatures.
Function: Provides a physical barrier against solid particles (dust and debris) while allowing internal lubricant to circulate freely.
Applications:
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Industrial machinery
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Electric motors
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High-speed fans
Advantages:
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Excellent for dry, high-temperature environments
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Low maintenance
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Good heat dissipation
Disadvantages:
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Limited protection against liquids and humid environments
2. Sealed Bearings (RS or 2RS)
Description: Seals made of nitrile rubber (NBR), Viton, or other resistant polymers; available on one side (RS) or both sides (2RS).
Function: Complete sealing, blocking solid particles, liquids, and moisture.
Applications:
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Water pumps
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Automotive systems (axles and wheel hubs)
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Agricultural machinery exposed to dust and rain
Advantages:
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Excellent sealing in environments with high exposure to contaminants
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Superior durability in wet applications
Disadvantages:
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Generates more resistance to movement, which can affect high-speed systems
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May require specific materials for high temperatures
3. Teflon-Sealed Bearings (TS or 2TS)
Description: Teflon® (PTFE) seals, a low-friction, chemically resistant material, applied on one side (TS) or both (2TS).
Function: Combines sealing against solids and liquids with minimal friction operation.
Applications:
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Precision equipment like 3D printers and CNC machines
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Drone and robotics systems
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Machinery for chemical and pharmaceutical industries
Advantages:
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High chemical resistance, ideal for corrosive environments
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Very low friction, even at high speeds
Disadvantages:
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Higher cost
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May be less effective against liquids under high pressure
4. Polymer-Protected Bearings
Description: External components made of engineering polymers like PEEK or nylon, offering light protection against contaminants and corrosion resistance.
Applications:
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Medical and laboratory equipment
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Food processing machinery
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Systems exposed to moderately aggressive chemicals
Advantages:
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Lightweight and corrosion-resistant
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Quiet, low-friction operation
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Suitable for food-contact or light chemical exposure
Disadvantages:
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Lower heat resistance compared to metals
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Less durable under high-impact or heavy-load conditions
5. Ceramic-Coated Bearings
Description: Metal components coated with thin ceramic layers (zirconium oxide or silicon nitride), improving wear and corrosion resistance.
Applications:
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Chemical and petrochemical industries
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High-speed machinery and precision systems
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Marine environments and salt spray exposure
Advantages:
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Superior wear and oxidation resistance
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Reduced friction, improving energy efficiency
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Longer service life under severe conditions
Disadvantages:
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Higher cost
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Can be more brittle in constant-impact applications
6. Solid-Lubricated Bearings
Description: Contain embedded solid lubricants like graphite, molybdenum disulfide, or PTFE, eliminating the need for periodic lubrication.
Applications:
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Industrial equipment under extreme temperatures
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Vacuum or high-pressure environments
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Conveyor systems in hard-to-reach maintenance areas
Advantages:
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Continuous operation without relubrication
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Excellent performance in extreme temperatures
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Resistant to harsh conditions like dust and chemicals
Disadvantages:
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Lower efficiency at ultra-high speeds
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Higher initial cost
7. Open Bearings
Description: No shields or seals, fully exposing internal components.
Function: Designed for clean or protected environments where there’s no contamination risk.
Applications:
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Laboratory machinery and internal precision systems
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Housings with external protective covers
Advantages:
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Lower movement resistance, ideal for high speeds
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Allows visual inspection and easy maintenance
Disadvantages:
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Fully vulnerable to dust, moisture, and contaminants
How to choose the ideal protection?
Consider the following when selecting shielding or sealing:
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Environment: Presence of dust, moisture, or chemicals
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Operating speed: High-speed systems require low movement resistance
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Maintenance: Hard-to-reach locations benefit from robust protections
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Cost: Advanced protections cost more but reduce maintenance expenses
Smart Choice: Combining Protection and Lubrication
When selecting a bearing, consider the application and operating conditions to determine the best combination of shielding, sealing, and lubrication:
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Clean, high-speed environments: Open or shielded bearings may be sufficient if lubrication is regular.
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Humid or contaminated environments: Sealed bearings are essential to protect internal lubricant and ensure performance.
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High-precision or submerged systems: Advanced seals like Teflon® (TS) are ideal, offering chemical resistance and total sealing.
Shields and seals are essential for ensuring bearing performance and durability. From metal shields to rubber or Teflon® seals, choosing the right protection can prevent failures and improve system efficiency.
If you need help selecting the ideal bearing for your application, contact VICAN’s team — we’re ready to provide the best solutions!
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