Main causes of permanent deformation of O-rings
1) The relationship between compression rate and stretching amount and permanent deformation
2) The relationship between temperature and O-ring tensioning process
3) Medium working pressure and permanent deformation The compression permanent deformation rate of the O-ring material is related to temperature. When the deformation rate reaches 40% or more, leakage will occur, so the heat resistance of several glues is: nitrile rubber 70°C, EPDM rubber 100°C, fluorine rubber 140°C. Therefore, all countries have regulations on the permanent deformation of O-rings. The dimensional changes of national standard rubber material O-rings at different temperatures are shown in the table. O-rings of the same material have a lower compression set at the same temperature as O-rings with large cross-sectional diameters. The situation with oil is different. Since the O-ring is not in contact with oxygen at this time, it occurs in a dynamic sealing state. If the O-ring is properly assembled and the conditions of use are suitable, it is generally not easy to roll or twist under reciprocating motion, because the contact area between the O-ring and the groove is larger than the area of the frictional contact sliding surface, and the resistance of the O-ring itself can prevent deformation. . The distribution of friction also tends to keep the O-ring stationary in its groove because static friction is greater than sliding friction and the groove surfaces are generally not as rough as the sliding surfaces. The resistance of the O-ring itself prevents deformation. The distribution of friction also tends to keep the O-ring stationary in its groove because static friction is greater than sliding friction and the groove surfaces are generally not as rough as the sliding surfaces. The resistance of the O-ring itself prevents deformation. The distribution of friction also tends to keep the O-ring stationary in its groove because static friction is greater than sliding friction and the groove surfaces are generally not as rough as the sliding surfaces.