Screw Conveyors

A screw conveyor is the most basic form of conveying, simply moving material from point “a” to point “b”.  Screw conveyors commonly handle reasonably dry to sludge type materials.  All screw conveyors require that the feed into the inlet be controlled.  The screw diameter, screw speed, and the housing loading determine the through put capacity of a screw.  Under normal conditions the housing loading is never greater than 45%.  If the feed rate into a screw conveyor surges, so will the discharge rate.  Depending on screw length and material being conveyed, if the surges are too frequent or they last too long, the screw drive, shafts, bearings, etc. may all be undersized.  It is important that a screw conveyor has effective product control at the inlet. Screw conveyors can range from simple diverters to conveyors moving materials long distances in one direction.  Along its length the conveyor may have several discharges.  The use of a slide gate enables the option of several discharge points from one conveyor.  When a screw conveyor cannot have an intermediate hanger then it is necessary to put the screw on an oversized pipe in order to keep the deflection of the screw to less than ¼” in the center.