what are rotary shaft seals | Insights by Polypac

1. What Are Rotary Shaft Seals?

Rotary shaft seals, also known as lip seals or oil seals, are mechanical components designed to prevent the leakage of lubricants and the ingress of contaminants in rotating equipment. They consist of a sealing lip that maintains contact with the shaft, a metal case that provides structural support, and a garter spring that ensures consistent pressure on the sealing lip. These seals are crucial in applications such as pumps, gearboxes, and motors, where they protect bearings and other components from damage caused by fluid leakage or contamination.

2. What Are the Different Types of Rotary Shaft Seals?

Rotary shaft seals come in various designs to suit different applications. Common types include:

• Single Lip Seals: Feature a single sealing lip and are suitable for low-pressure applications.
• Double Lip Seals: Incorporate an additional lip to provide extra protection against contaminants.
• Metal-Cased Seals: Have a metal outer casing for enhanced durability, often used in harsh environments.
• Fabric-Reinforced Seals: Utilize fabric materials to reinforce the sealing lip, offering improved strength and flexibility.

3. What Materials Are Used in Rotary Shaft Seals?

The materials used in rotary shaft seals are selected based on the specific requirements of the application, including temperature range, chemical exposure, and mechanical stresses. Common materials include:

• Nitrile (NBR): Offers good resistance to oils and fuels, suitable for temperatures ranging from -30°C to +100°C.
• Fluorocarbon (Viton): Provides excellent resistance to high temperatures and aggressive chemicals, effective from -20°C to +220°C.
• Hydrogenated Nitrile (HNBR): Combines the properties of nitrile and hydrogenation, offering enhanced resistance to heat and chemicals, with a temperature range of -40°C to +150°C.
• EPDM: Known for its resistance to water and steam, suitable for temperatures from -50°C to +150°C.

4. How Do Rotary Shaft Seals Function?

Rotary shaft seals function by maintaining a tight contact between the sealing lip and the rotating shaft, creating a barrier that prevents fluid leakage and contaminant ingress. The sealing lip is typically preloaded to ensure consistent contact, and the garter spring applies radial force to keep the lip in contact with the shaft. This design allows the seal to accommodate minor shaft misalignments and surface imperfections, ensuring effective sealing performance over time.

5. What Are the Common Challenges in Selecting Rotary Shaft Seals?

When selecting rotary shaft seals, procurement professionals often face challenges such as:

• Material Compatibility: Ensuring the seal material is compatible with the operating environment, including exposure to specific chemicals and temperature ranges.
• Pressure and Speed Requirements: Choosing seals that can withstand the operational pressures and speeds without compromising performance.
• Durability and Wear Resistance: Selecting seals that offer long service life and resistance to wear, reducing maintenance costs and downtime.
• Installation and Maintenance: Considering seals that are easy to install and maintain, minimizing operational disruptions.

6. How Do Environmental Factors Affect Rotary Shaft Seals?

Environmental factors such as temperature fluctuations, exposure to chemicals, and the presence of dust or water can significantly impact the performance and longevity of rotary shaft seals. For instance, high temperatures can degrade seal materials, while chemical exposure can cause material swelling or hardening. Additionally, contaminants like dust and water can compromise the sealing surface, leading to premature failure. Therefore, selecting seals made from materials with appropriate resistance properties and ensuring proper installation and maintenance are crucial for optimal performance.

7. What Are the Advantages of Choosing Polypac for Rotary Shaft Seals?

Polypac offers several advantages for rotary shaft seals, including:

• Customized Solutions: Tailored seal designs to meet specific application requirements, ensuring optimal performance.
• High-Quality Materials: Use of premium materials that provide enhanced durability and resistance to harsh operating conditions.
• Expert Engineering Support: Access to experienced engineers who can assist in selecting and designing the most suitable seals for your needs.
• Comprehensive Testing: Rigorous testing procedures to ensure seals meet industry standards and perform reliably in various applications.

Data Sources

• Seal & Design, Inc. (October 2025)
• Colonial Seal Company (October 2025)
• Lagersmit (October 2025)
• FTL Technology (October 2025)
• American High Performance Seals (November 2025)
• Bal Seal Engineering (November 2025)
• Fairway Seals (October 2025)
• 123bearing (November 2025)
• Valley Seal Company (October 2025)
• AnySeals (October 2025)
• Max Spare Limited (October 2025)