What is an oil seal

Oil Seal Overview

Oil seals are mechanical components designed to seal lubricating oil. Their primary function is to isolate lubricated parts within a transmission system from output components, effectively preventing oil leakage. Oil seals are classified into static and dynamic types, with dynamic seals commonly used for reciprocating parts. A typical example is the TC oil seal, which features a rubber-covered, double-lip design and a self-tightening spring.

Classification of Oil Seals

• Monoblock Type: Manufactured as a single unit for standard applications.
• Assembled Type: Allows for free combination of backbone and lip materials, suitable for special or demanding applications.

Material Selection for Oil Seals

• Nitrile Rubber (NBR): Heat- and abrasion-resistant, suitable for temperatures from -30°C to 120°C. Stable with various lubricating oils and oil-gas mixtures, but incompatible with phosphate ester-based hydraulic oils.
• Polyacrylate Rubber (ACM): Oil- and heat-resistant, operates from -30°C to 150°C. Suitable for lubricants with extreme pressure fluids.
• Fluorine Rubber (FPM): Excellent aging and oil resistance, functions from -20°C to 250°C. Performs well with oils containing extreme pressure additives, but has poor cold resistance.
• Silicone Rubber: Excellent resistance to both high and low temperatures, operating range from -70°C to 260°C.
• Polytetrafluoroethylene (PTFE): Outstanding chemical and thermal stability, suitable for -200°C to 300°C, ideal for harsh environments.

Characteristics and Applications

Nitrile rubber and fluoroelastomer are the most widely used oil seal materials. Nitrile rubber is cost-effective but less abrasion-resistant, while fluoroelastomer offers superior high-temperature resistance. When selecting materials, consider compatibility with the working medium, operating temperature range, and the ability of the lip to follow the rotating shaft. Notably, the lip temperature of an oil seal is typically 20°C to 50°C higher than the medium temperature during operation, which should be considered when choosing materials. Oil seals are widely used in automobiles, machinery, hydraulic systems, and other fields, serving as critical components to ensure the proper functioning of equipment.