They are usually used for pre-crushing of core sand blocks. The ZVFS block mill grinds the pre-crushed blocks into sand and must be connected downstream of the ZVFB series V-block mill. Larger pieces of metal in the sand must be removed using an upstream magnet. The tubers are fed into the machine from above. There are two V-shaped vibrating crusher plates in the machine. The (adjustable) width of the clearance between the crusher plates for precrushing tubers to the outlet.