Introduction
An oil seals is a sealing element used to seal rotating or reciprocating parts. Its main function is to prevent lubricating oil or other fluids from leaking along the shaft, and also to prevent external contaminants from entering the machine.
Main features of oil seals
The outer surface of the oil seal is cylindrical to ensure static sealing of the cavity – a rubber outer edge with a metal skeleton is used; an outer edge with an exposed metal skeleton is used, and most of them need to be polished and plated with an anti-corrosion coating.
The spring-loaded sealing lip ensures the sealing reliability of the dynamic and static sealing of the shaft. As a result of long-term development and research, the sealing lip structure of the oil seal has been improved to excellent performance, thereby improving the sealing reliability in a wider load range.
Adding dust lips, or multiple dust lips in special cases, can prevent external contaminants and dust from invading.
Transportation and assembly of oil seals
Transportation of oil seals
1. Oil seals are precision components. Improper assembly and storage will affect their performance.
The following should be noted when transporting and storing oil seals:
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;
Avoid direct sunlight and do not place near high temperature heat sources, as this will cause rubber aging;
Oil seals must not be scattered at will, pay attention to dust and soil prevention, and ensure that the oil seals are in a closed or covered state;
When transporting and using oil seals, in order to prevent the oil seals from deforming and the springs from falling off, please do not give excessive impact;
Oil seals cannot be tied with thin ropes, nor hung on nails or metal wires, which will damage the sealing lip;
Oil seals must not be placed in humid places, which will cause metal parts to rust;
Do not place seals near TVs and places that produce ozone;
Please do not rub the lip end with your fingernails or hard objects to prevent damage to the sealing lip;
Assembly of oil seals
No matter how appropriate the design of the installation part of the oil seal and the selection of the oil seal are, if the assembly is rough, the intended function of the oil seal cannot be fully exerted.
When installing the oil seal, the outer surface should be coated with appropriate lubricant, and the lip should be coated with suitable clean grease. For oil seals with dustproof lips, the main and auxiliary lips should be filled with suitable clean grease before assembly.
The sealing lip end of the oil seal should face the sealing medium side, and it is forbidden to assemble in reverse.
When the oil seal is inserted into the seat hole, it should be pushed in with a special tool to prevent the position from being skewed.
Various measures should be taken to prevent the lip from being damaged at the threads, keyways, splines, etc. where the lip of the oil seal passes, and it should be assembled with special tools.
The oil seal should be placed horizontally in the seat hole and pressurized evenly. Do not tilt and force it.
Leakage of oil seals
When leaking from the oil seal is found, the leaking part should be confirmed. If it is not leaking from the oil seal, it is sometimes mistaken for leakage due to reasons other than leakage such as grease adhesion. The main reasons for oil seal leakage:
1. The sealing medium makes the rubber swell, reducing the hardness of the rubber, thus causing premature aging and wear of the oil seal;
2. The corrosion from the shaft to the sealing lip area will leave a permanent hidden danger of failure for the sealing performance of the sealing system;
3. The lubricant fails and the system is in a dry running state, causing the sealing lip to wear quickly;
4. Comprehensive aging, both the rubber elastomer and the sealing medium age;
5. “Oil carbon” dirt is formed at the sealing lip, causing the oil seal sealing lip edge to be lifted, causing leakage failure of the sealing system;
6. The sealing lip edge of the oil seal no longer follows the vibration of the shaft surface and the beating of the shaft;
7. Contaminants are permanently embedded in the sealing edge from the inside and outside of the seal, causing premature wear of the shaft surface and the sealing lip edge;
8. The irregular assembly process causes the contact surface of the shaft surface to be damaged, causing premature wear of the sealing lip;
When the oil seal leaks, it should focus on analyzing the different leakage situations and take different measures. Leakage at different stages of oil seals should be classified as follows:
1. Watertight, no moisture can be seen on the oil seal;
2. Wet, a moisture film appears on the sealing edge area that does not affect the sealing function, but the moisture film does not extend to the back;
3. Wet, the moisture film extends to the back and forms water droplets, but has not yet dripped continuously;
4. Measurable leakage, a small identifiable flow rate can be seen flowing out of the back of the oil seal outside the cavity;
5. Temporary leakage, a short-term failure of the sealing system, for example, 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 be filled with too much grease between the sealing lip and the dust lip.
Conclusion
Oil seals are key components to ensure the normal operation of mechanical equipment. Correct selection, installation and maintenance are essential to extend the service life of oil seals and improve mechanical efficiency. With the development of technology, the materials and designs of oil seals will continue to improve to meet more diverse application needs.
