Die Filling of Aerated Powders

Executive Summary

Many particulate products are manufactured through powder compaction, in which die filling is a critical process stage as the die filling performance will determine the process efficiency and product quality. For aerated powders, the interaction between particle and the surrounding air could play an important role during die filling. Although die filling has attracted increasing attention over the last two decades, our understanding on die filling of aerated powders is still limited. In particular, how the system design will affect the die filling performance, how significant the presence of air will affect die filling behavior, and whether powders can segregate during die filling are still not well understood. To address these questions, both experimental and numerical investigation were carried out on this project, and this report summarise the key findings on these three aspects. This report contains 5 chapters: the first two chapters examine the effect of system design (die shape, size and orientation) with experimental work reported in Chapter 1, and numerical study in Chapter 2. The effect of air presence on die filling behavior was presented in Chapter 3 and Chapter 4, with chapter 3 focusing on theoretical modeling and Chapter 4 on measuring air pressure buildup in the die. Chapter 5 reports the size-induced segregation during die filling.

We would like to acknowledge IFPRI for financially supporting this project. We also would like to thank Michele Marigo and Tim Freeman for constructive discussions throughout this project.