Screw conveyors are of simple, relatively low cost construction compared to other conveyor systems. Screw conveying systems consist of a helical flight fastened around a pipe or solid shaft, mounted within a tubular or U-shaped trough. As the screw rotates, material heaps up in front of the advancing flight and is pushed through the trough. Particles in the heap next to the flight surface are carried part way up the flight surface, and then flow down on the forward-moving side of the heap.
These conveyors can handle a wide variety of solid particles ranging from lumps to powders. Lumpy, sticky, or fibrous materials may cause problems in a screw conveyor.
Screw conveyors serve the manufacturing industry in a wide variety of applications: conveying, distributing, collecting, mixing, heating, cooling, elevating, batching, blending, aerating, and providing crystallization or coagulant action.