The combined seal is a seal composed of two or more components. All the components of the combined seal can be regarded as consisting of two parts: the main seal and the auxiliary seal. We usually say that the combined seal is a sealing structure form composed of a main sealing ring and an elastomer or coupled with a retaining ring and a guide ring. This type of seal is often called a extrusion seal. Materials are mainly rubber, polytetrafluoroethylene, polyurethane, polyformaldehyde, nylon, phenolic cloth resin and so on.
The principle of combined sealing
The sealing effect between the sealing ring and the metal surface is realized by the support force after the extrusion of the elastomer, and can be compensated when the sealing ring is worn. It has excellent self-sealing effect and has good sealing effect for low pressure and high pressure. At low pressure, the sealing effect is realized by the preloading force of the elastomer. At high pressure, the sealing effect is automatically improved with the increase of the pressure of the hydraulic oil. Good seals require good structural design and material properties. The elasticity and wear resistance of the main sealing ring material are better, the elasticity of the elastomer material is better, the resistance to permanent deformation is strong, and the resistance to extrusion of the retaining ring and guide ring material is better.
Therefore, we need to design a good structure and choose high-quality materials, especially the elasticity and wear resistance of the main sealing ring material, so that we can use a good combination of seals.