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O-rings are the most widely used of all sealing products, and the production process is relatively simple, with more materials used. O-ring is a typical sealing effect caused by deformation. When the pressure is greater than the pressure of the sealing medium, the sealing effect is generated when the pressure is greater than the pressure of the sealing medium.
It has been found in many tests that most of the causes of o-ring damage do not come from the design or pressure of the o-ring. If a good design only increases the pressure unilaterally, it will not cause an o-ring. The root cause of the damage is due to the permanent deformation of the o-ring under the high temperature and high pressure of the working environment and the bite caused when it is squeezed into the gap.
The causes of permanent deformation of o-rings are as follows:
(1) Factors of compression and extension of o-ring
Due to the different formulations of o-ring compounds, the compression and elongation of o-rings produced by different companies are also different. Products under the long-term compression state will produce the compressive stress relaxation imagination, this phenomenon will gradually expand with time, the longer the time, the compression and stretching amount will be smaller, making it less elastic and causing leakage. It appears that the most direct way to change is to increase the cross-sectional size of the product, but it will also cause the product to increase in structure.
(2) Relationship between temperature and relaxation process of O-ring
The temperature is very important for the relaxation of the o-ring. No matter what kind of rubber material, it will accelerate its aging speed at high temperature. When the temperature in the environment is higher, the deformation of the gas compression will be greater. When the product deformation exceeds At 40%, the o-ring will slowly lose its elasticity, causing leakage. When installing o-rings, there will be initial stress. These will fall asleep after a long time relaxation of the seal and the temperature gradually decreases, and in some cases may disappear with the rapid decrease in temperature. Even if the rubber material is low temperature resistant, compared with the stress generated at 20 degrees, it will not be greater than 25%. Therefore, when setting the o-ring, the initial stress must be fully considered in the working environment.
(3) Influence of working pressure of medium on deformation of o-ring
Compared with the above two factors, the pressure of the medium has a greater impact on the deformation of the o-ring. It is the most common situation that causes the deformation of the o-ring in all working conditions. With the development of modern hydraulic equipment, the hydraulic medium The pressure of the O-ring is increasing. When the o-ring is working in such a high pressure environment for a long time, it will cause permanent deformation of the o-ring. This deformation is irreversible, so different materials should be selected for different working pressures. Select a relatively pressure-resistant rubber material. Correspondingly, in order to cope with higher working pressure, the hardening degree of the pressure-resistant material's sealing ring will also increase.
The pressure of the working medium is the main factor causing permanent deformation of the O-ring. The working pressure of modern hydraulic equipment is increasing. Prolonged high pressure will permanently deform the O-ring. Therefore, appropriate pressure-resistant rubber materials should be selected according to the working pressure when designing. The higher the working pressure, the higher the hardness and high pressure resistance of the materials used.
Therefore, before selecting materials, we must clearly understand what kind of working environment the customer places the rubber O-rings. In this way, we comprehensively consider the abrasion resistance and high pressure resistance of the required materials to match the customers with rubber materials. , Customize products that suit customers. If you have any questions, welcome to our Haisheng Rubber website
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