The importance of seals to different industries

Although rubber and plastic Seals are small, their role makes them become the basic components and accessories in the main industries of the national economy such as national defense, chemical industry, petroleum, coal, transportation and machinery manufacturing, and occupies a very important position in the development of the national economy.

1. Classification by function: divided into shaft seals, hole seals, dust-proof seals, guide rings, fixed seals, and rotary seals

2. Classification by material: divided into nitrile nitrile rubber, EPDM rubber, fluororubber, silica gel, fluorosilicone rubber, nylon, polyurethane, engineering plastics, etc.

The storage room temperature of the seals is preferably below 30 °C to avoid high temperature aging of the seals; 2. The seals must be stored in a sealed package to avoid contact with moisture or dust in the air; 3. The seals must be protected from strong light exposure , to avoid the seals being eroded by ozone in the air or prematurely aging. The factors affecting the performance of various seals are different, such as mechanical seals (packing seals, etc.) affecting factors such as temperature, medium, wear, and pressure.

(1) Select the appropriate seal material and hydraulic oil, as well as the adaptability to the working temperature and the compatibility of the oil
(2) The geometric position accuracy (concentricity) of the sliding parts relative to the seal is high, the material is good (such as hard chrome plating) and the surface roughness is fine, which can prolong the service life.

① For the Oil Seals used in hydraulic pumps and motor journals, not only the roughness of the sliding surface is required to be within Ra of 0.25m, but also hard chrome plating is required on the surface, and the diameter of the oil seal lip needs to be adjusted according to the specific conditions. Adjust the spring force to make it tight enough, and use a mounting sleeve or a thin gasket to protect the sealing ring during installation to prevent the lip from rolling and twisting, causing the spring to slip out. ②The inner surface of the hydraulic cylinder is usually processed by rolling, which not only improves the surface roughness, but also makes the surface hardened by cold work, which is beneficial to prolong the service life of the sealing ring. In addition, the pressure used, the length and type of the sliding surface also have a great influence on the service life. Therefore, the "regular inspection" time should be decided according to these conditions. ③ The sealing surface is required to be well lubricated to prevent dirt from invading people. The use of fluids that meet the specified cleanliness levels and the correct installation method are also necessary conditions.
hydraulic seals play a vital role in the integration of hydraulics and pneumatics. If the seals of a hydraulic and pneumatic component product are not good enough, then this hydraulic and pneumatic component product is not a good product. There are many factors that affect seals. First of all, pressure is an important factor affecting the quality of seals. The level of pressure and the length of pressure cycle changes have a great impact on seal damage (such as extrusion). The higher the pressure, the greater the effect of other factors on the performance of the seal, such as temperature, speed, seal material, clearance between the piston and cylinder, and clearance between the piston and cylinder head. Another is temperature and friction. It is difficult to describe the maximum use temperature and minimum use temperature of a seal material, because it is the result of the combined influence of a series of factors. For the different working temperatures of the piston and the piston rod, they should be selected differently. Another is the surface roughness of the seal product, the characteristics of the surface, the pressure, the medium, the temperature, the material of the seal, the type of the seal and the speed of movement, which are all factors that affect the seal. The last one is surface treatment. Experience has shown that the characteristics of the cylinder piston and piston rod surface have a very large impact on the life of the seal. Surface properties are often defined by the value of surface roughness RA, which is the arithmetic mean of the absolute value of the deviation of the surface shape from the centerline. However, these values do not fully represent the effect of surface conditions on seals, because even under the same roughness, different surface shape characteristics can lead to different degrees of seal wear on seals.