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<p>1. The main reason for the failure of <a href="https://www.jdoseal.com/jdseal-nbr-fkm-vmq-o-ring" rel="noopener noreferrer" target="_blank">O-ring</a> seal</p><p>(1) The sealing groove design is unreasonable;</p><p>(2) O-ring is not compatible with the medium used;</p><p>(3) The size of O-ring seal is incorrectly selected;</p><p>(4) The O-ring seal cannot be sufficiently lubricated.</p><p>In addition, because the force of the sealing ring is more complicated, some reasons are difficult to diagnose and judge. If necessary, test and study its material and use environment.</p><p><br></p><p>2. Common failure forms and solutions</p><p>(1) O-rings are flat after use</p><p>①The main reason is that the material elasticity and heat resistance of the sealing ring are poor. After the O-ring is used in the working medium of the hydraulic system for a period of time, the sealing ring is often over-expanded and the pressing force increases. This is because in the production process of the seal ring, the rubber vulcanization is not complete enough, so under the action of pressure, the three sides of the seal ring section are pressed into a flat shape;</p><p>②The solution should adopt low coagulation rubber materials. Under normal working conditions, use heat-resistant rubber materials (due to friction during work) such as nitrile rubber, neoprene, etc.; confirm that the sealing ring material should be compatible with the medium used, and check the physical properties of the sealing ring. Meet the design requirements.</p><p><br></p><p>(2) O-ring seal wear</p><p>① Reasons This failure form mostly occurs in seals with relative movement and vibration, which can be judged by observing the wear of the contact part of the sealing ring and the sliding surface. The main reasons are: the sealing sliding surface is rough, leading to premature wear of the sealing ring; the sealing sliding surface is too smooth, making the seal poorly lubricated; the oil system contains polluting particles;</p><p>②The solution is manufactured according to the recommended processing roughness, to ensure that the sliding surface and the sealing ring are sufficiently lubricated during the movement (mainly internal lubrication), to ensure the accuracy of the filter in the system, and to use O-ring material with better wear resistance , Such as polyurethane rubber.</p><p><br></p><p>(3) O-rings are hardened and oxidized by heat</p><p>①The reason is that the working temperature exceeds the normal range of use, which hardens the elastomer, evaporates and oxidizes the plasticizer, and causes the sealing ring to produce small surface cracks perpendicular to the direction of the applied pressure, resulting in local dents or cracks. This failure is mainly due to the static and dynamic seals exposed in the air or the seal rings in contact with other air pollutants;</p><p>②The solution uses materials with better oxidation resistance and high temperature resistance to reduce the working temperature of the system oil.</p><p><br></p><p>(4) Protrusion, bite and spiral failure of O-ring seal</p><p>①The main reason for the protruding and biting failure: the sealing gap is too large, the system pressure exceeds the sealing pressure strength or the retaining ring is not added, the sealing ring material does not meet the design hardness requirements, and the sealing groove processing size of the sealing ring does not meet the standard requirements , The selection of the sealing ring is inappropriate (the size of the sealing groove is too large) and so on. The main reasons for spiral failure: the concentricity of the parts is too low, the lubrication is not enough, the sealing ring material is too soft, when some parts of the sealing ring are sliding while the other part is rolling, causing distortion or cracks;</p><p>②The solution is to reduce the sealing gap and choose the appropriate size</p><p>O-shaped sealing ring to ensure that the concentricity of the parts meets the design requirements; the sealing groove is processed in strict accordance with the standard, using enhanced composite seals, such as combination gaskets, using sealing ring materials that meet the design requirements or adding to prevent the O-shaped sealing ring from being extruded The retaining ring.</p><p><br></p><p>(5) O-ring is damaged during installation</p><p>① Reasons This situation often occurs in dynamic and static seals. The main reason is that there are sharp edges or corners on the sealing groove or the chamfers introduced do not meet the standard, and no lubricant is applied during installation, so that the sealing ring is cut, twisted or stuck by the sharp cutting edge, and the surface is concave (or convex). ) Marking, peeling or peeling phenomenon;</p><p>②Solution: Process the sealing groove in accordance with the design requirements, and no sharp edges should be left. When installing, apply lubricating oil to the groove and the sealing ring. When the O-ring passes through the thread, cover the thread with a metal foil or tape, etc. , So that the sealing ring can be inserted smoothly.</p>
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