A material-saving and robust approach for obtaining accurate out-of-die powder compressibility

Cosima Hirschberg, Shubhajit Paul, Jukka Rantanen, Changquan Calvin Sun

Research output: Contribution to journalArticle


Density is an important material property for evaluating, or developing a tablet formulation. In-die compressibility data can be obtained using a small amount of powder with the help of a compaction simulator. However, compacts undergo volume expansion upon ejection from die. Therefore, accurate out-of-die compressibility profiles cannot be directly obtained from the in-die data. By splitting the tablet elastic recovery into three components (in-die axial, out-of-die axial, radial), we have shown that the in-die elastic recovery is linearly dependent on the compaction pressure within the range investigated, and the out-of-die elastic recovery is a material constant. Hence, we have developed a two-step data treatment (the Hirschberg-Sun approach) for deriving an accurate out-of-die compressibility profile from in-die and out-of-die data of two tablets compressed at a low and a high compaction pressure. The broad applicability of the approach was verified with a larger number of diverse materials.

Original languageEnglish (US)
Pages (from-to)903-909
Number of pages7
JournalPowder Technology
StatePublished - Feb 1 2020


  • Compaction simulator
  • Compressibility
  • Elastic recovery
  • In-die
  • Out-of-die
  • Tablet density

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