The diagram shows the auger flush with the bottom of the funnel and the agitation blade extending into the throat of the funnel. The auger featured shows larger diameter "overflights" in the hopper section. This assists the flow of an otherwise reluctant powder down to the funnel throat where the agitation blade can feed the flights of the smaller diameter parallel section. In most cases the agitation blade control will be set to "with fill" mode, stopping between fills to avoid overworking and compacting the powder. If the powder was highly aerated coming into the hopper, it might be necessary to switch to "continuous agitation" mode to assist removal of the air. A larger hopper volume will aid de-aeration and homogenisation by allowing greater residence time for the powder within the hopper.

If the powder were somewhat better flowing but not completely free flowing, a slightly different approach would be required.

This may be a good point to introduce a simple (but not completely foolproof) test for evaluating the flow characteristics of powders. If when you insert a pencil into the top of a container of powder and then remove it, the hole immediately collapses in on itself, then the powder would be deemed to be free flowing. If, however, a perfect impression of the pencil remains, then it is non-free flowing. Partial collapse might indicate an intermediate powder.

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