If the moisture content and viscosity of raw material are high, the milled material shall be easily adhere to both sides of the grate screen hole and liner plate so as to result in decrease of the milling chamber space and  low pass rate of the screen hole, so material blockage occurs.

Solution: the raw material can be pre-heated at the inlet by installing a drying equipment or it is dried in the sunlight so as to reduce the moisture content of the material. When the material hardness is larger and not easy to be milled or the feed particle size exceeds the feed size limit, the discharge outlet will also be blocked if the milling effect is not sufficient between the impact plate and the hammer.