Screening is the separation of a mixture of various sizes of grains into two or more classifications by means of a screening surface.
The screening surface may consist of woven wire, silk or plastic cloth, and perforated or punched plate. Wire cloth is generally specified by the Mesh size which is the number of openings per linear inch.
The screening process can be archived with revolving screens, mechanical shaking screens, vibrating screens and oscillating screens.
Air separators make use of high velocity air to separate different partial sizes.
Magnetic separators use magnets to separate ferrous particles from a mixture.