A common type of failure for dynamic O-rings is abrasion. Abrasion may also be called wear, and is generally found in dynamic seals subject reciprocating, oscillating, or rotary motion. Abrasion is different from compression set in that the O-ring cross section is not flattened to the shape of the groove. Rather, the flatness is isolated to the worn areas.
Abrasion may also be seen by a wear pattern on the O-ring, in the direction of the moving hardware components.
Abrasion can result from debris or a burr in the cavity.
In general, abrasion of O-ring seals is caused by one or more of the following:
1. Improper finish of the surface in dynamic contact with the O-ring. This surface finish may be too rough, acting as an abrasive, or too smooth, causing inadequate lubrication due to inability of surface to hold lubricant.
2. Improper lubrication provided by system fluid.
3. Excessive temperatures.
4. Contamination of system fluid by abrasive particles.
Suggested solutions to problems caused by abrasion are:
1. Use proper surface finish (see surface finish in Dynamic Seals section).
2. Provide adequate lubrication by use of proper system fluid.
3. Consider use of internally lubricated O-rings to reduce friction and wear.
4. Check for contamination of fluid and eliminate source. Install filters if necessary.
5. Consider changing to an O-ring material with improved abrasion resistance, such as Polyurethane, Carboxylated Nitrile, and HNBR materials.