A mill is a device that breaks solid materials into smaller pieces by grinding, crushing, or cutting , The discharge die gap a of the grinding machine is used for the ground solid matter in , A slightly inclined or horizontal rotating cylinder is partially filled with balls, usually stone or metal, which grind material to the necessary.
A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, or rock dust , The earliest crushers were hand-held stones, where the weight of the stone provided a boost to muscle , Crushers are used to reduce particle size enough so that the material can be processed into finer particles in a grinder.