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In our life, O-rings are widely used. Depending on the purpose and performance, we will consider many factors, such as hardness, elongation, compression and so on. Of course, the specific performance, we Haisheng rubber can be determined according to customer requirements or O-ring working environment, and then customized customer-specific rubber. So how do we choose the formula for different O-rings?
According to the different pressures in the sealing system, rubber materials for O-rings with different hardness are designed. High pressure rubber should be used for high pressure, and medium or low hardness rubber should be used for low pressure. In order to improve product quality and service life, rubber hardness has been serialized in national standards. For example, nitrile rubber for hydraulic systems, except for special requirements, the rubber hardness is divided into 60 ° ± 5 °, 70 ° ± 5 °, 80 ° + 5 °, and 88 ° + 5 ° (Shore A). Hardness level to meet different pressure requirements. Generally 60 ~ 0 is low hardness, product is medium hardness, 88 is high hardness, when the sealing pressure is in the range of 30 ~ 60MPa, the hardness of O-ring is 85 ~ 90.
As an O-ring used for sealing, in addition to considering the hardness of the rubber, it is also required that the rubber must have good comprehensive properties, and the compression set must be small, especially for high-hard rubbers, and good process performance is also essential. The design of high-hardness rubber compounds generally requires a large amount of carbon black to be filled, and the large amount of carbon filled to the west will cause difficulties in the rubber mixing process. The Mocha heat during the rubber mixing process is large, and the rubber is easy to scorch. At the same time, a large amount of carbon black will reduce the rubber elasticity and increase the compression set. Therefore, the selection and coordination of the vulcanization system and the filling system in the compound formula is very important. As far as nitrile rubber is concerned, in order to improve the heat resistance of the rubber compound, reduce compression set, and improve other properties, low sulfur (less than 0.5 parts) high acceleration and sulfur-free and peroxide-free vulcanization systems are currently used. Low sulfur formula combined with thiurams and sulfenamides, or thiurams or thirolls, vulcanizates have good physical and mechanical properties and heat resistance, have small compression set and are not easy to scorch.
As for the design of medium and low hardness rubber compound formulas, based on the principle of simplifying the series of rubber compound formulas as much as possible, and striving for a small number of basic formulas, the method of delivering more carbon black and softener is used to design and test the medium and Low hardness grade rubber, in order to achieve the purpose of not only facilitating production management, but also meeting the requirements of use.
The O-rings of different formulas have different functions. Our Haisheng Rubber will customize the formulas according to customer requirements or according to the specific use of the O-rings. We have professional engineers from Haisheng Rubber to tailor your O-rings to meet your needs.
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