The ORB2000-A vibrating disc mill can be used to grind down all brittle, dry and non-caking materials to analytical fineness. Break-down in the ORB2000-A high-energy mill is done in a discontinuously operating tungsten carbide grinding bowl with a sample charge capacity of up to 2000 ml. The grinding tools take the form of impact rings and a grindstone fitted into the grinding bowl so as to be freely movable. The grinding bowl is made to vibrate eccentrically and horizontally in a circle 100 mm indiameter by a centrifugal drive, exerting on the material to be ground forces up to 50 times as great as the acceleration of gravity. The very high acceleration forces acting on the grinding tools cause them to rotate one about the other like planets. This sets up enormous impact, friction and shear effects between the walls of the grinding tools, enabling the sample material to be ground down very quickly to the required analytical fineness.