Standard Seals Performance Mainly Includes

standard seals Performance mainly includes

When we select a standard seal, the first consideration of the performance includes its tensile strength, tensile stress, elongation, elongation at break, tearing permanent deformation, and stress-strain curves. We collectively referred to as tensile strength. The so-called tensile strength is the maximum tensile stress when the specimen is stretched to fracture. The tensile strength (modulus) is the stress (modulus) reached at the specified elongation. The elongation is the deformation caused by the tensile stress of the specimen, expressed as a percentage of the ratio of the elongation to the original length. The elongation at break is the elongation at which the specimen is pulled off. The permanent deformation of the specimen is the residual deformation of the gauge part after the tensile fracture.

Then we consider the basic performance of the standard seal - hardness. The so-called hardness is the ability to resist the invasion of rubber outside the pressure. The hardness of the rubber is to some extent related to some other properties. For example, the higher the hardness of the compound, relatively speaking, the strength of the larger, smaller elongation, wear resistance is better, and low temperature performance is poor. High hardness rubber can be crushed under high pressure. Therefore, the appropriate hardness should be selected according to the working characteristics of the parts.

We know that the standard seal is often in a compressed state, then we have to consider the standard seal compression performance. Due to the viscoelasticity of the rubber, the compressive stress decreases with time, and the compressive stress is relaxed. After removing the pressure, the original shape can not be restored and the compression is permanent. In high temperature and oil medium, these phenomena are more significant. They will affect the sealing performance of the seal, seal is one of the important properties of the compound.

Our most commonly used is the brittle temperature, refers to the sample at low temperature by a certain impact when the rupture of the maximum temperature can be used to compare the low temperature properties of different compounds. However, due to the working condition of the rubber parts and the test conditions are different, the rubber brittle temperature does not mean that the minimum working temperature of rubber parts, especially in the oil medium. Second, the temperature is low temperature retraction temperature, is the test piece at room temperature to a certain length, and then fixed, quickly cooled to below the freezing temperature to reach the temperature balance after the release of the test piece, and a certain speed of temperature, record the test piece back The temperatures at 10%, 30%, 50% and 70% are expressed in terms of TR10, TR30, TR50 and TR70, respectively. Material standards generally TR10 as an indicator, and rubber brittle temperature close to. Another way to express low temperature properties of rubber is to determine its cold resistance. Generally, the sample is compressed at room temperature to a certain amount of deformation, and then frozen at a specified low temperature, and then unload the load to allow it to recover at low temperatures, the amount of recovery and compression ratio called compression cold resistance. The greater the coefficient, the better the cold resistance of rubber.