Since 2006, Focus on rubber seals

Several problems in sealing design have to be paid attention to

by:ORK      2022-10-16
1. Sealing material The sealing material should meet the requirements of the sealing function. Due to the different media to be sealed and the different working conditions of the equipment, the sealing materials are required to have different applicability. The requirements for the sealing material are: ① The material has good compactness and is not easy to leak the medium; ② It has appropriate mechanical strength and hardness; ③ It has good compressibility and resilience, and small permanent deformation; No hardening, no brittle cracking; ⑤ Good corrosion resistance, can work for a long time in acid, alkali, oil and other media, its volume-hardness change is small, and does not adhere to the metal surface; ⑥ Small friction coefficient, wear resistance Good; ⑦ has the softness that is fully attached to the sealing surface; ⑧ has good aging resistance and is durable; ⑨ is convenient to process and manufacture, cheap and easy to obtain. Obviously, it is impossible for any one material to fully meet the above requirements, but materials with excellent sealing properties can meet most of the above requirements. Rubber is the most commonly used sealing material. In addition to rubber, graphite tape, PTFE and various sealants are suitable for sealing materials. There are several problems in sealing design. 2. Processing technology Good processing technology and molding technology are effective means to ensure the dimensional accuracy and surface characteristics of seals and to improve the resistance to gymnasium and wear resistance. Processes related to sealing include molding, dipping, spraying, sintering, welding, electroplating, and surface heat treatment. The same material, if the processing technology is different, its characteristics will be very different. As far as the most commonly used molding process in the manufacture of seals is concerned, if the pressed finished product has large errors in shape, size, etc., and there are flashes and burrs on the parting surface, it is very unfavorable for sealing. Taking the rubber O-ring as an example, it is sealed by a given amount of compression deformation. If the necessary amount of compression deformation cannot be guaranteed due to poor dimensional accuracy, leakage will occur. In addition, since the O-ring is installed on the sealing part in a pre-stretched state, when the motion friction heats up, the O-ring does not expand but shrinks (the rubber in the stretched state shrinks under heat, which is called the Joule effect), which is also known as the Joule effect. The amount of compression deformation during operation may be reduced and leakage may occur. Therefore, the dimensional accuracy must be strictly controlled in the design, and various influencing factors, such as the dimensional accuracy, surface roughness and grain direction of the parts in contact with the seal, should be considered. 3. Friction, wear and lubrication Friction and wear are inevitable problems in contact dynamic seals. The seal of the contact type dynamic seal is in contact with the sealed part, and friction occurs due to relative movement, which leads to heat generation and wear of the surface of the parts, which is the main reason for leakage and damage to the seal. Therefore, the selection of lubricating hydraulic pressure and lubricant has become a problem that must be carefully considered in seal design. Self-lubricating methods are generally selected, such as fillers impregnated with various lubricants, impregnated graphite, and polytetraethylene with a small friction coefficient. When the medium has lubricity, it is lubricated with the medium itself. Company website: https://www.orksealing.com/
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