retracted from the opening 20 thus clearing the entire cross section of the supply channel 15 this allows the severed part 35 of the bale of rubber 14 to be conveyed by force of gravity to the second comminuting step in the direction of the arrow 34 where in the cutting mill 1 fine comminuting takes place once a cutting cycle is completed the cutting unit 17 is returned to its first end position by extending the cylinder piston units 30 and thus to the starting position for the next cutting cycle shifting between two end positions the knife frame 22 thus executes a sled like linear movement transversely to the supply channel 15 during the comminuting process whereby for the feeding of the cutting unit 17 the opening 20 is cleared by the knife 26 and closed by the retaining element 28 and for cutting and further conveying of the material the opening 20 is closed by the knife 26 and opened by the retaining element 28 further the relation movement between the knife 26 and the retaining element 28 forms a shield thus during the commuting process by the cutting mill 1 the material 14 is substantially prevented from entering the supply channel.