There are two types of friction, both of which are important considerations in dynamic (moving) applications. When part movement is intermittent,the effects of breakout friction can cause excessively high pressures to develop. This pressure can tear portions of the seal that adhered to the gland wall causing seal failure.
In continuously moving applications, excessive o-ring running friction can cause heat to build up within the o-ring material itself. This causes swelling, which causes more heat to develop, and eventually results in material degradation and failure. For more information, consult the Operating Environment Factors section.