The device has primary cutting tools (6) arranged on a casing surface of a working cylinder (5) that rotates in a preset direction. Secondary cutting tools (8.1-8.3) are arranged in a secondary cutting tool carrier (7), where material is crushed between the primary and secondary tools. The carrier concentrically encloses the cylinder and extends tills to a discharge area (A) for the material. The secondary tools are arranged in an inlet area (E) and the discharge area, where form of the secondary tools and/or positions of the secondary tools on the carrier are different in the areas.
