Abrasion is also known as abrasion (Abrasion), is a surface of the protrusions or knot disease (Protuberance) in the other surface relative sliding occurs, resulting in displacement or plow (Plowing) and cause the migration of materials. The resulting wear particles are generally free. Another reason for the wear of abrasive wear is the presence of extraneous "third substances" (such as extraneous friction sand, loose oxides or other substances buried between the contact surfaces and solid impurities in the lubricant) between the contact pairs, When the resulting wear. The former is the wear of two objects; the latter is the wear of three objects. In general, abrasive wear is due to the hard rough surface or the presence of a third substance between the two contact surfaces.