TABLE OF CONTENTS Abrasion occurs in two modes, referred to as the two-body and three-body abrasive wear processes.[7] Two-body abrasion refers to a hard, rough material sliding against a softer one. The hard surface digs into and removes material from the softer one. An example is a file used to contour a metal part. Three-body abrasion refers to the introduction of hard particles between two sliding surfaces, at least one of which is softer than the particles. The hard particles abrade material from one or both surfaces. Lapping and polishing are in this category. Abrasion is then a material removal process in which the affected surfaces lose mass at some controlled or uncontrolled rate.
Uncontrolled Abrasion Machine parts that operate in clean environments can be designed to minimize or eliminate abrasive wear through proper selection of materials and finishes. Smooth, hard materials will tend to not abrade soft ones in two-body contact. Smooth finishes minimize abrasion at the outset and, unless hard particulate contaminants are later introduced to the interface in service, that situation should continue.
Controlled Abrasion In addition to designing systems to avoid abrasion, engineers also design them to create controlled abrasive wear. Controlled abrasion is widely used in manufacturing processes. Two-body grinding is perhaps the most common example, in which abrasive media such as silicon carbide (Carborundum) are forced against the part under high sliding velocities to remove material and control size and finish. Cam surfaces...
