In bulk solids feeding, the familiar endless belt is known primarily for its central role in weigh belt feeding where an inlet gate shears material into a shallow bed prior to weighing and speed-controlled discharge.
A belt feeder has relatively little innate material handling capability, though. Floodable powders may surge through the belt feeder, and sticky, fibrous or otherwise hard-to-flow materials may become caught up in the inlet sec¬tion. This material handling limitation leaves the unaided belt able to control only relatively well behaved, free-flowing materials. However, most plastics applications calling for a belt’s compactness and/or high-rate capability typically involve the handling of pelletized, granular or flaked resins, all of which usually pose few problems for handling by belt.
Where material flow characteristics do pose a problem, the use of a rotary or other type of pre-feeder may extend the handling capabilities of the belt approach in instances where the use of the belt is desired or necessitated for other reasons such as where headroom is limited.
The belt approach may also serve as a material handling strategy all on its own when applied as the metering element in loss-in-weight feeding where a downsized belt conveyor is weighed along with hopper and material.