O-ring Heat Resistance And Oil Resistance
O-ring is a simple structure, wide specifications, the need for a large number of a sealed product.
O-ring seal quality of life depends on dimensional accuracy and rubber. General requirements of the compound has a certain mechanical strength, tear resistance and good heat resistance, oil resistance, chemical resistance and the use of conditions to have a smaller compression permanent deformation, is its main indicator.
According to the use of requirements, generally have heat, oil requirements, the use of rubber to the most.
Require high temperature (such as 150 ~ C-l90 ℃) oil seal products can use acrylic rubber. Requirements for higher temperature oil-resistant rubber products with fluorine rubber, heat-resistant silicone rubber.
When the working pressure is high, the method of increasing the hardness of the O-ring compound is to increase the filling amount of the carbon black, but the filling amount is too high, the mixing is difficult and the basic physical properties of the vulcanizate are damaged,
In the case of the use of the same rubber, such as nitrile rubber, in order to improve the heat and oil resistance, reduce the compression of permanent deformation, can be used peroxide (such as the use of DCP) curing system or effective sulfur vulcanization system (low sulfur high) The These two kinds of curing system can generate more carbon-carbon bond cross-linked structure and single sulfur bond cross-linking structure, effectively improve the heat resistance of vulcanized rubber and oil resistance, reduce the compression of permanent deformation.
O-type sealing ring heat-resistant, oil-resistant compound formula filling reinforcement system, the use of less active thermal cracking carbon black, sprayed carbon black or semi-reinforced carbon black, these carbon black is characterized by coarse particles , Rubber elasticity is good, low heat, low compression and permanent deformation, and a large number of filling, reducing the cost of plastic materials. Such as the use of O-ring seals in the dynamic conditions, the need to increase the tear resistance, and can be part of the high activity of high wear-resistant carbon black.
O-ring materials are mainly butyl nitrile rubber NBR and fluorine rubber FKM, fluorine rubber is more suitable for high temperature conditions.
In addition to the material, O-ring is a very important indicator of its hardness, generally used Shaw hardness to represent, ranging from 60 to 90 or so, the greater the value that the higher the hardness. In the same pressure, the higher the hardness, anti-extrusion (deformation or even tear) the stronger the ability. Therefore, you should use the higher hardness of the O-ring.
However, the market common O-rings are made of butyl cyanide rubber, Shore hardness is generally around 70, it is difficult to meet a considerable part of the working conditions.