Abstract
A model die shoe filling system has been employed to characterise the flowability of a range of commercial powders. The filling rig mimics some features of a typical industrial die filling process. Qualitative and quantitative studies were undertaken using a high speed video system and by determining the variation of the mass delivered to the die as a function of shoe velocity. The critical velocity, i.e. the velocity above which incomplete filling is achieved, was determined for each powder. Experiments were carried out in air and in vacuum to determine the influence of air flow and pressure on the filling behaviour. The size of the die cavity and the height of powder in the shoe are shown to have an influence on the mass–velocity relationship; and therefore the critical velocity. Equations are presented which allow the results generated using a standard die to be extrapolated to other die geometries.
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