Breakout friction is an important consideration in intermittently moving applications. It can cause excessively high hydraulic pressures to develop. This pressure can tear portions of the seal that adhere to the gland wall when machine movement has been stopped for an extended period of time.

Once a system is up and running, the designer must then consider seal running friction as a potential source of problems. In continuously moving applications, excessive running friction can cause heat to develop, which results in o-ring swell. Once swelling occurs, more heat is generated from increased friction which causes additional swelling and seal failure. High running friction, in combination with high system pressures, may also produce excessive wear in soft metal parts.

Methods Used to Control Friction