The function of the seal is to close the gap where oil leaks out of the box and prevent dust, sand and other dirt from invading the inside of the box. However, if installed or used improperly, oil leakage may easily occur. Affect the normal operation of the machine, causing burned bearings, broken gears, broken drive shafts or other serious failures.

Seals can be roughly divided into rotating shaft oil seals, water seals, dust rings, piston and piston rod seals, etc. In daily life, they are often used for dustproof, waterproof, and soundproofing. In industrial machinery and equipment, they are often used for oil sealing, waterproofing, and dustproofing.