Martin Sprocket (Arlington, TX) offers products designed to regulate the rate of material flow from a hopper or bin. The company has uniform diameter screws, tapering diameter screws, variable diameter or variable pitch screws, and more. For fine free-flowing materials, the company suggests the uniform diameter screws; for material with lumps and dead space in flow, a tapering diameter screw can be used. Components such as shrouded or curved cover plates are also available.
Check out www.martinsprocket.com to learn more.