Flowability

What affects the flowability of bulk materials?

Flowability is an important material property for the design of feeding and conveying systems. For example, free-flowing granules behave very differently from fine or cohesive powders, which may tend to compact, adhere, or form bridges.

A bulk material's flowability is influenced by various factors. These include particle size, particle shape, and particle size distribution, as well as moisture content and bulk density. External factors like storage duration, compaction, and environmental conditions can also alter flow behavior.

Why is flowability important for feeding?

To ensure consistent feeding, bulk material must flow from hopper to feeder reliably and evenly. If the material flow is uneven or interrupted by bridging, the feeder cannot dispense the material consistently and reproducibly.

Flowability thus influences the selection and design of the feeder. For example, depending on material properties, screw or vibrating feeders may be used. For poor-flowing bulk materials, additional discharge aids or agitators may be required to ensure a reliable flow of material.

How can flowability be assessed?

Flowability cannot be fully defined by a single material characteristic. Various parameters and test methods can be used for evaluation, including bulk density, compacted bulk density, angle of repose, and shear tests. Which method is suitable depends on material and respective application.

For feeding technology, the question is not merely whether a bulk material can generally be considered good- or poor-flowing. Its actual behavior under the specific process conditions is crucial. A feeding solution suitable specifically for the respective material and application helps ensure a consistent material flow and reliable feeding processes.