Rotary shaft seals, also known as oil seals, are small components that have a significant impact on machinery performance. They retain lubricants, seal out contaminants, and maintain system efficiency. Without them, the system could fail quickly, energy losses would increase, and machine downtime would become costly.
MSP Seals offers both standard and custom-engineered sealing solutions designed to protect equipment across industries. This guide explores the role of rotary shaft seals, the materials they’re made from, and how to determine whether a standard or custom option is best for your application.
Rotary Shaft Seals & Oil Seals: Essential for Machine Lubrication
Rotary shaft seals serve as one of the most critical lines of defense in any piece of rotating equipment, and are involved in all of the following:
- Lubricant retention. The primary role of an oil seal is to keep lubrication, such as grease or oil, inside the housing. Proper lubrication reduces friction and heat, ensuring that bearings and moving parts operate smoothly.
- Contaminant exclusion. Oil seals act as barriers against dirt, dust, moisture, and other foreign particles that could compromise machinery. Keeping contaminants out prevents premature wear and costly damage.
- System integrity. Seals maintain the correct pressure and fluid levels within a system. Consistent fluid management is essential for efficiency and long-term reliability.
- Friction reduction. Although seals must fit tightly around shafts, their materials and design minimize drag. This reduces energy loss and wear, especially at higher speeds.
- Dynamic and static sealing. Rotary seals handle both motion along the shaft (i.e., dynamic sealing) and the stationary housing (i.e., static sealing).
- Bearing protection. Bearings are among the most expensive and failure-prone components in rotating machinery. By retaining lubricant and blocking contaminants, seals directly extend bearing life.
- Adaptability to conditions. Seal performance depends on shaft speed, temperature, system pressure, and fluid type. Matching the seal to operating conditions is critical for success.
PTFE and Elastomer Seals: Choosing the Right Material for Your Application
Two major material categories dominate the rotary shaft seals market: elastomers and PTFE.
Elastomers (e.g., NBR, FKM). Elastomeric seals are made from flexible, rubber-like materials that use their elasticity to form tight seals. Nitrile (NBR) is widely used in general-purpose applications with petroleum-based oils, while Viton® (FKM) withstands higher temperatures and has broad chemical resistance. Elastomers are forgiving during installation and perform well at moderate speeds and temperatures.
Polytetrafluoroethylene (PTFE). PTFE is a thermoplastic known for its low coefficient of friction and exceptional chemical inertness. These seals work well in high-speed operations because they reduce drag and heat generation, unlike elastomers that wear out more quickly.
So, how do you know which is right for your application? Choosing the right seal material ensures efficiency, extends lifespan, and prevents costly breakdowns. Here are some key factors to consider when selecting materials:
- Chemical compatibility. Elastomers have limitations, while PTFE works with almost any fluid.
- Temperature range. Elastomers vary by compound, but PTFE generally offers the broadest range of temperature compatibility.
- Wear and friction. PTFE is self-lubricating, enabling higher shaft speeds. Elastomers require a film of lubricant.
- Installation. Elastomers are easier to install; PTFE installations require more precision and care.
- Pressure handling. PTFE, especially with reinforcement, can withstand higher pressures.
Custom and Standard Rotary Seals: Design, Sizing, and Material Expertise
While standard elastomer seals meet most requirements, more demanding environments and mission-critical applications call for specialized materials and custom designs. Consult with a materials expert at MSP Seals to get help choosing the exact compound for your needs. Here are some of the specialty materials we offer:
- FFKM (Perfluoroelastomer). FFKM withstands quite a few chemical medias and extreme heat, making it indispensable in chemical processing and semiconductor industries.
- Polyurethane (PU). Valued for its toughness and abrasion resistance, PU is commonly used in hydraulic applications exposed to high pressures.
- Aflas® (TFE/P). Resistant to strong bases, steam, and sour gases, this fluoroelastomer is a trusted choice in the oil and gas industry.
- Silicone (VMQ). Provides flexibility in both hot and cold environments, although it is less suited for abrasive or chemically aggressive fluids.
- HNBR (Hydrogenated Nitrile). A more durable form of nitrile rubber, HNBR performs well in automotive and oilfield applications where standard NBR fails.
- Application-specific compounds. Several of the specialty materials listed above are available in various grades and compounds that can be customized to meet specific operational needs and challenges.
Rotary Shaft & Oil Seals From MSP Seals
From standard elastomers to advanced compounds like PTFE and FFKM, the right material and design make all the difference in seal performance and durability.
MSP Seals supplies standard and custom-engineered rotary shaft seals to keep your systems running smoothly. Whether you need off-the-shelf components, on original equipment or application-specific solutions, our experts can guide you through material selection, sizing, and design. We offer PPAP capabilities. MSP Seals is ISO 9001:2015 and ISO 14001:2015 certified. Contact us or request more information to get started.
