Single screw feeders, particularly at low rates, can have an unsteady feed rate within one revolution of the screw, resulting in mass flow pulsation. Spiral or full flight single screw feeders exhibit this pulsation more commonly than other screw configurations.
Possible mechanical remedies include conical screw ends, rotating tubes, extended tubes, threaded spiral ends, paddles etc. Depending on the application, some are feasible, others not. Despite additional costs for these solutions there is always a residual pulsation.