What causes permanent deformation of silicone rubber O-ring seals?

Silicone rubber O-ring is the most widely used sealing product, and its production process is relatively simple, using a variety of materials.

1.Due to different formulations of silicone rubber O-rings, the tightening and stretching amounts of silicone rubber O-rings produced by different manufacturers are also different. When a product is in a long-term compressed state, there will be a scenario of compressive stress relaxation, which gradually expands over time. The longer the time, the smaller the amount of compression and stretching, resulting in insufficient elasticity and leakage. The most direct method is to increase the cross-sectional size of the product, but it can also lead to an increase in the structural size of the product.
2.The correlation between temperature and the relaxation process of silicone rubber O-ring seals. Temperature is very important for the relaxation degree of silicone rubber O-ring seals. Regardless of the rubber material, it will accelerate its aging rate at high temperatures. When the temperature in the environment is higher and the product deformation exceeds 40%, the silicone rubber O-ring will slowly lose its elasticity, leading to leakage. These sealing rings will experience initial stress during the installation of silicone rubber O-ring seals in equipment. They will remain dormant for a long time and gradually relax as the temperature decreases. In some cases, they may dissipate with a sharp drop in temperature. Even if the rubber material is resistant to low temperatures, the stress generated at 20 degrees Celsius will not exceed 25%. Therefore, when setting the initial stress for installing silicone rubber O-ring seals, the factor of working environment temperature should be fully considered.

3.Compared with the above two factors, the influence of medium working pressure on the deformation of silicone rubber O-ring is greater. This is the most common situation that causes deformation of silicone rubber O-ring under various working conditions. With the development of hydraulic equipment, the pressure of hydraulic medium increases. Long term operation of silicone rubber O-ring in this high-pressure environment will lead to irreversible deformation. In this high-pressure environment, the deformation of rubber material will increase with the increase of temperature. The working fluid pressure is an important factor causing permanent deformation of silicone rubber O-ring seals. Therefore, suitable pressure resistant rubber materials should be selected according to the working pressure during design. The greater the homework pressure, the higher the hardness and high pressure resistance of the materials used.