What Is Oil Seals?

- Feb 07, 2018-

Oil seals – often called grease, fluid or dirt seals – close spaces between stationary and moving components in mechanical equipment, helping prevent lubricant escape. They also stop harmful contaminants from entering machinery, particularly in severe environments. Vital components of practically every type of machine and vehicle in operation, oil seals protect all types of precision-constructed, close-fitting ball, sleeve and roller bearings.

In precision bearings, oil seals help prevents lubricants from escaping the bearings or a specific area. In machine components, oil seals help prevents abrasives, corrosive moisture and other harmful contaminants from entering machinery. They also help stop intermixture of two different mediums, such as lubricating oil and water.


Oil seals are generally divided into single type and assembly type. The assembly type is the skeleton and lip material can be freely combined, and is generally used for special oil seal.

The sealing function, characteristics, structure type, working state and sealing mechanism of the oil seal can be divided into various forms and different ways. But generally speaking, the rotary shaft lip seal is called oil seal.

Performance and application

Oil seals are used for automobile engines and geared motors, and are designed mainly to prevent oil leakage from the end of a rotating shaft, or dust intrusion from the outside air.

Oil seals serve to prevent the leakage not only of lubricants, but also water, chemicals, and gas from "gaps" in machinery. Oil seals also serve to prevent the intrusion of dust, soil and sand from the outside air.

Oil seals are indispensable sealing devices and are used in various fields, including automobiles, aircraft, boats and ships, railroad vehicles, construction machinery, farm machinery, petrochemical plants, and electrical home appliances.


(1) The oil seal is simple in structure and can be molded in one time. Even the most complex oil seal, the manufacturing process is not complicated. The metal skeleton oil seal just by stamping, gluing, mosaic, molding and other processes will be combined a metal and rubber into the required oil seal.

(2) Oil seal is light weight and less consumable. Each oil seal is a combination of thin wall metal parts and rubber parts. The material consumption is very small, so the weight of each oil seal is very light.

(3) The installation position of the oil seal and the axial size is small, which is easily processed and make the machine compact.

(4) The sealing performance of the oil seal is good and long the service life.

(5) The oil seal is easy to disassemble and convenient inspection.