Methods used to Control Friction
Squeeze
Both running and breakout friction are reduced when squeeze is reduced.
Durometer (Hardness)
Breakout friction decreases with DECREASING hardness. Running friction decreases with INCREASING hardness.
Cross Section
O-rings with smaller cross sections tend to produce less friction.
Lubrication
Seal adhesion can be minimized by the use of lubrication. Compatibility between the elastomer and lubricant should be predetermined to avoid seal shrinkage or swelling.
Compound Additives
Rubber can be compounded with additives such as oils, graphite, Teflon, etc. to lower the coefficient of friction.
Gland Machining
An optimum finished surface of 8 to 16 RMS will help to control friction. Finishes below 5 RMS will not hold the lubricant because it eliminates micropores.
Groove Width
By increasing the groove width, the seal will be allowed more room to expand perpendicular to the compressive force.
Material
Materials vary in their friction characteristics. For example, Teflon has a very low coefficient of friction. For more complete information on individual materials look in Section 6.
Pressure
Decrease system pressure to reduce the amount of running friction.
Gland Machining
An optimum finished surface of 8 to 16 RMS will help to control friction. Finishes below 5 RMS will not hold the lubricant because it eliminates micropores.
Groove Width
By increasing the groove width, the seal will be allowed more room to expand perpendicular to the compressive force.
Material
Materials vary in their friction characteristics. For example, Teflon has a very low coefficient of friction. For more complete information on individual materials look in Section 6.
Pressure
Decrease system pressure to reduce the amount of running friction.