- The water drop type feed hammer mill SFSP series is a kind of advanced technology hammer mill, which consists of feed inlet , hammers, screen, rod and rotor. The hammers swing on the central rotor freely .The rotor spins at a high speed while material is sent into a feed hopper. The material is impacted by hammers and is thereby grinded and then falling through the mesh and the discharging port. It is widely used in foodstuff, chemical , fiber and other granular materials.