According to the different pressure in the sealing system, the rubber compound with different hardness for O-ring was designed.High hardness rubber compound should be selected for high pressure, medium hardness or low hardness rubber compound should be selected for low pressure.In order to improve the quality and service life of products, the hardness of rubber compound has been serialized in national standard.For example, in addition to special requirements, the hardness of nitrile rubber for hydraulic system is divided into four hardness levels: 60 ° ± 5 °, 70 ° ± 5 °, 80 ° + 5 ° and 88 ° soil 5 ° to meet the requirements of different pressures.Generally, 60 ~ 0 is low hardness, the product is medium hardness and 88 is high hardness. When the sealing pressure is within 30 ~ 60MPa, the hardness of O-ring is 85 ~ 90.
 


 
    As a sealing O-ring, in addition to considering the hardness of the compound, it also requires that the compound has good comprehensive performance, and the compression set should be small, especially for the high hardness compound. Good process performance is also essential.In order to design a high hardness rubber compound, a large amount of carbon black is generally needed. However, a large amount of carbon filling in the West will bring difficulties to the rubber mixing process.At the same time, a large amount of carbon black can reduce the elasticity of rubber and increase the compression set.Therefore, the selection and coordination of curing system and filling system are very important.As far as NBR is concerned, in order to improve the heat resistance of the compound, reduce the compression set and improve other properties, low sulfur (less than 0.5 phr) and sulfur free and peroxide curing systems are mostly used.In terms of the design of medium hardness and low hardness rubber compound formula, based on the principle of simplifying series compound formula as far as possible, on the basis of striving for a small amount of basic formula, the medium and low hardness rubber compound was designed and tested by changing the amount of carbon black and softener, so as to achieve the purpose of convenient production management and meet the use requirements.

2020-07-28

Show you the performance of different O-rings

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