ABSTRACT
Breaking-in, running-in, and wearing-in are examples of tribological transitions. They are characterized by changes in friction and wear with time, numbers of sliding cycles, or sliding distance. Transitions may occur under lubricated or unlubricated conditions. The attributes of friction transitions are (a) changes in the nominal magnitude of the friction force, (b) the time that a tribosystem requires to reach steady state or some other distinct condition such as seizure or coating wear-through, and (c) the characteristics of short-term uctuations in the friction force.
