O-ring seal with abrasive grain wear

When the gap of the seal has relative motion, dust and sand in the working environment, etc. are adhered to the surface of the piston rod and brought into the cylinder with the reciprocating motion of the piston rod together with the oil film, becoming abrasive particles that invade the surface of the O-ring, accelerating the wear of the O-ring so that it loses its sealing properties. In order to avoid this situation, the Dust Ring must be used at the outstretched shaft end of the reciprocating seal.

The roughness of the sliding surface is a direct factor affecting the friction and wear of the O-ring surface.

Generally speaking, the surface is clean friction and wear is small, so the sliding surface roughness value is often very low (Ra0.2-.050μm). However, tests show that the surface roughness is too low (Ra less than 0.050μm) and will bring adverse effects on friction and wear. This is because a tiny surface dimple maintains the necessary lubricant film. Therefore the appropriate surface requirements have to be selected. The material of the sliding surface also has an effect on the life of the O-ring. The harder the sliding surface material, the higher the wear resistance and the ability to maintain the finish, the longer the life of the O-ring seal. This is also an important reason why the surface of the piston rod of a hydraulic cylinder is chrome plated.

In dynamic sealing devices, friction and wear are important influencing factors of O-ring damage. The degree of wear depends mainly on the amount of friction. When the fluid pressure is tiny, the amount of O-ring friction depends on its pre-compression.

The increase in friction force causes a lot of frictional heat between the rotating or reciprocating shaft and the O-ring seal. Since most O-rings are made of rubber, the thermal conductivity is extremely poor. Therefore, the frictional heat will cause the aging of the rubber, resulting in the failure of the O-ring and destroying its sealing performance. Friction can also cause damage to the surface of the O-ring and reduce the compression. Severe friction can quickly cause surface damage to the O-ring and loss of sealability.