O-rings are the most widely used of all sealing products,with relatively simple production processes and a wide range of materials. O-rings typically create a seal by deforming under compression. During installation, they generate contact pressure with the sealing surface. When this pressure exceeds the pressure of the sealing medium, a seal is established; when it is less, leakage occurs.

Extensive testing has revealed that most O-ring damage is not due to the design or pressure. A well-designed, unilateral increase in pressure will not damage the O-ring. The fundamental cause is the permanent deformation of the O-ring under the high temperature and high pressure of the operating environment, as well as the bite caused by squeezing into gaps.

The reasons for permanent deformation of O-rings are as follows:

(1) Factors of compression and stretching of O-rings

Due to the different formulations of O-ring rubber, the compression and stretching of O-rings produced by different companies are also different. When the product is under long-term compression, it will produce the imagination of compressive stress relaxation. This phenomenon will gradually expand over time. The longer the time, the smaller the compression and stretching, making it less elastic and causing leakage. The most direct way to change it is to increase the cross-sectional size of the product, but it will also lead to the increase of the product structure.

(2) The relationship between temperature and the relaxation process of O-rings

Temperature is very important for the relaxation of O-rings. Regardless of the rubber material, high temperature will accelerate its aging speed. The higher the temperature in the environment, the greater the deformation due to air compression. When the product deformation exceeds 40%, the O-ring will gradually lose its elasticity and cause leakage. When the O-ring is installed, there will be initial stress. These will gradually disappear with the long-term relaxation of the sealing ring and the gradual decrease in temperature. In some cases, they may disappear with a sharp drop in temperature. Even if the rubber material is resistant to low temperatures, the stress generated at 20 degrees will not be greater than 25%. Therefore, when setting the initial stress when installing the O-ring, the temperature factor of the working environment must be fully considered.

(3) The influence of medium working pressure on O-ring deformation 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 pressure of the hydraulic medium is getting higher and higher. The O-ring will be permanently deformed if it works in this high-pressure environment for a long time. This deformation is irreversible. Therefore, different materials should be selected for different working pressures. Choose relatively pressure-resistant rubber materials. Correspondingly, in order to cope with higher working pressures, the hardening degree of the sealing ring made of pressure-resistant materials will also increase.

The pressure of the working medium is the primary factor causing permanent deformation of O-rings. The operating pressures of modern hydraulic equipment are increasing. Prolonged exposure to high pressure can cause permanent deformation of O-rings. Therefore, when designing, appropriate pressure-resistant rubber materials should be selected based on the operating pressure. The higher the operating pressure, the higher the hardness and high-pressure resistance of the material should be.

Before selecting materials, we must clearly understand the operating environment in which the customer's rubber O-ring will be used. This allows us to comprehensively consider factors such as the material's wear resistance and high-pressure resistance to formulate a custom-made rubber compound. If you have any further questions, please visit our official Haisheng Rubber website for inquiries.