Tried and tested machines are in great use in foundries. Typically, the ZUFS block mill is integrated into the sand recovery system between the vibrating grate and the sand cooler. Through linearly directed high-energy vibrations, the sand blocks are crushed in the friction tank, mostly by rubbing against each other, and then crushed again to form sand. Oversized grains are then screened through thin screens that are easy to maintain, accessible and visible. Parts that cannot be chopped, such as casting residue, are automatically cycled out via a rear pneumatic closing baffle.