#1 What is the surface finish?
The surface quality reflects the roughness of a surface.
The sealing effect of an O-ring is created by pressing the O-ring between two sealing surfaces. The crushing of the O-ring causes tension in the O-ring. As a result, parts of the O-ring can be “rubbed off” by the roughness of the sealing surfaces.
In the case of O-rings, the term “abrasion” is used when tiny particles detach from the surface. The O-ring then gradually loses volume. On a small scale this is not a problem, but with heavy abrasion the volume is reduced so much over time that the sealing effect is no longer guaranteed and the O-ring ultimately fails.
#2 Why is the surface quality of O-rings so important?
The degree of abrasion on an O-ring depends, among other things, on the surface quality of the sealing surfaces. Smooth surfaces have a positive effect on the abrasion of an O-ring. Rough surfaces, on the other hand, have the effect of sandpaper and therefore have a negative impact on abrasion.
The surface quality should be as high as possible, especially for dynamic (moving) applications.