Abrasion is a surface breakage event where irregular surfaces of particles are removed. It produces smoothed surfaces/particles by comminuting irregular edges. Depending on the application, abrasion can be a desired or undesired process, and may happen either naturally or intentionally. For example, in some industries where spherical particles are end products, abrasion can be a desired process but in some process industries it is undesired because it produces dust, which makes it difficult for handling, as well as increasing the potential for losses of material. In some cases, natural phenomena (weathering, time dependent effect, age, and contact) can abrade materials and sometimes abrasion of materials is enhanced by applying energy. The loss of surface layers of particles due to weathering can be considered as a natural abrasion process whereas the use of mills to generate fines are considered as abrasion via applied energy.