The Mechanics of the Screw Feeder

The screw feeder is considered as a measuring device for dry fragmental materials. Expressions are obtained for volume delivered and torque required, in terms of the dimensions and coefficients of friction involved. Limited confirmation has been obtained in experiments using coal. The cases where the tube is eccentric to the screw axis and where fine material can pass the wing-tip are examined. Improvement in screw feeder design appears possible.