Knowledge about oil seals

Oil seal leakage

   When a leak is found from the oil seal, first check the location where the leak occurred. If the leak is not from the oil seal, it may be mistaken

for a leak due to reasons other than oil adhesion. The main reasons for oil seal leakage:

1. Because the dimensional tolerance does not meet the standard specifications, the static sealing surface of the outer edge of the oil seal and the cavity is deformed;

2. Due to the harsh working conditions, the material is cracked, especially the crack on the sealing edge of the oil seal;

3. The hardness of the rubber increases due to the harsh working conditions and the incompatibility between the rubber elastomer and the working medium, or the hardness of the elastomer is too high;

4. The sealing medium swells the rubber and reduces the hardness of the rubber, thereby causing premature aging and wear of the oil seal;

5. The corrosion from the shaft to the sealing lip area will leave a permanent hidden trouble for the sealing performance of the sealing system;

6. The system is in a dry running state due to the failure of the lubricant, so that the sealing lip is rapidly worn;

7. Comprehensive aging, both rubber elastomer and sealing medium are aging;

8. "Oil carbon" dirt is formed at the sealing lip, so that the sealing lip of the oil seal is lifted up, causing leakage failure of the sealing system;

9. The sealing lip of the oil seal no longer follows the vibration of the shaft surface and the runout of the shaft;

10. Contaminants are permanently embedded in the sealing edge from the inside and outside of the seal, causing premature wear of the shaft surface and sealing lip;

11. The irregular assembly process causes the contact surface of the shaft surface to be damaged, resulting in premature wear of the sealing lip;

12. The sealing edge is damaged during storage, transportation and assembly.

When the oil seal leaks, it should focus on analyzing the different situations of its leakage, so as to take different measures. The leakage of oil seals at different stages should be divided into:

1. Impermeable to water, no moisture can be seen on the oil seal;

2. Wet, a moisture film that does not affect the sealing function appears in the sealing edge area, but the moisture film does not extend to the back;

3. Moisture, the moisture film expands to the back and forms water droplets, but it has not dripped continuously;

4. Measurable leakage, it can be seen that there is an identifiable small flow of liquid flowing from the back of the oil seal outside the cavity;

5. Temporary leakage, short-term failure of the sealing system, such as caused by contaminant particles under the sealing edge, which can be washed away during continued use;

6. Obvious leakage, temporary leakage causes the sealing lip and dust lip to add too much grease between the sealing lip and the dust lip.

The spilled grease appears as a visible leak outside the system. In addition, the cause of leakage is analyzed according to the time course of the oil seal's use and operation, such as: early damage that leaks at the beginning of use; premature damage that begins to leak after a short period of use; damage that leaks during work after a long period of use and leakage damage at the end of the design life of the oil seal, etc.

Transport and assembly of oil seals

The oil seal is a precision component, and improper assembly and storage will affect the performance. When transporting and storing oil seals, pay attention to:

1. Do not open the original packaging, pay attention to whether the packaging is damaged, and try to keep the oil seal in the original packaging before assembly;

2. Avoid direct sunlight, and do not place it near a high temperature heat source, because this will cause the rubber to age;

3. The oil seal should not be scattered at will, pay attention to dust and soil protection, and ensure that the oil seal is in a closed or covered state;

4. When transporting and using the oil seal, in order to prevent the deformation of the oil seal and the falling off of the spring, please do not give excessive impact;

5. The oil seal should not be tied with a string, nor should it be hung on a nail or metal wire, which will damage the sealing lip;

6. Do not put the oil seal in a damp place, which will cause the metal parts to rust;

7. Do not place the seal near the TV and where ozone is generated;

8. Please do not rub the end of the lip with fingernails or hard objects to prevent damage to the sealing lip.

The assembly of the oil seal, no matter how appropriate the design of the installation part of the oil seal and the selection of the oil seal, if the assembly is rough, the intended function of the oil seal cannot be fully exerted. When assembling, pay attention to:

1. When installing the oil seal, the outer surface should be coated with appropriate lubricant, the lip should be coated with suitable clean grease, the oil seal with dust lip should be filled with suitable clean grease between the main and auxiliary lips, and then to assemble;

2. Place the sealing lip end of the oil seal towards the sealing medium side, and avoid reverse assembly;

3. When the oil package is inserted into the seat hole, it should be pushed in with a special tool to prevent the position from being skewed;

4. Various measures should be taken to prevent damage to the lip at the threads, keyways, splines, etc. where the oil seal lip passes, and special tools should be used to assemble it;

5. The oil seal should be placed in the seat hole horizontally and pressurized evenly. Do not push it by tilting.