Screw conveyor is with simple structure, small sectional area, good sealing ,reliable working and low fabrication cost ,so as to feed materials in the middle and discharge materials outside . The conveying direction can be reversely, also can transport materials from the opposite direction .During the conveying process, screw conveyor also can agitate,mix ,heat and cool materials . There also can set up a gate valve to adjust the flow rate of materials. Most common the shafted screw conveyor is not used to transport perishable,viscosity and easy to cake materials . In the conveying process, materials are easy to be crushed,so screw shell and screw flights are easy to be worn out . Moreover, screw conveyor’s power is not big . We need leave a proper clearance between screw shell and screw flight as well as ensure the good sealing of covers.