Wear

Damage that involves the cumulative and gradual removal of material from surfaces. Three types of wear are described below:

Abrasive Wear – Damage that occurs when surfaces are in contact and undergo relative motion, and cutting or abrasion by hard particles (usually a contaminant) remove material from the surfaces.
Adhesive Wear – Damage that occurs when two surfaces are in contact and undergo relative motion, and high loads and/or temperatures cause asperities on these two surfaces to weld together and then immediately separate, removing material from one or both surfaces. Adhesive wear can be mild (frosting), moderate (scuffing), or severe (galling, scoring, seizing).
Corrosive Wear – Damage that occurs when chemical reactions at a surface result in the removal of material. Corrosion can be localized (e.g., pitting) or general (not local).
Electrical Discharge Wear – Removal of material from solid surfaced due to sparks or high-amperage electrical discharge.
Erosive Wear – Progressive loss of material from the surface or edge of a solid component when a liquid or a large number of solid particles impinge upon it..
Fatigue Wear – Wear of a solid surface that is caused by fatigue, i.e., repeated heavy loading that causes dents, cracks, fracture and removal of fragments from a metal surface.
Fretting Wear – Wear that occurs as a result of fretting, i.e., small amplitude oscillations or vibrations between two solid surfaces that are in contact.
Polishing Wear – Occurs when very fine hard particles in a lubricant remove material from a solid surface, producing a brightly polished surface.