Definition: Adhesion is the process of material transfer between mating tooth surfaces due to micro-welding and tearing.
Identification: Teeth appear undamaged if adhesive wear is mild, or severely damaged if scuffing occurs. SEM shows smooth microplateaus between furrows under mild adhesive wear.
Discussion: Adhesion is a wear process. Mild ahesive wear during run-in is normal, and typically subsides after it removes local surface asperities. Severe adhesive wear is referred to as scuffing, and is discussed here.
Prevention: Decrease surface roughness. Run-in new gears. Drain, flush, and replace oil after run-in.