A device for grinding input material is provided with a supporting disk rotating around an axis of rotation within a housing. On the supporting disk, in its circumferential area, first grinding tools are arranged concentrically, axially opposite from which second grinding tools are arranged, forming a radial grinding gap. During operation of a device in accordance with the invention, the grinding tools execute a motion relative to one another. In accordance with an embodiment, the first grinding tools be fastened over an interchangeable ring to the supporting disk, wherein the interchangeable ring is fastened removably to the supporting disk concentric to the axis of rotation and on which the first grinding tools are arranged.