Powder compaction Hiestand tableting indices

Pharmaceutical compacts are complex structures that present difficult challenges when measuring their mechanical properties. Hiestand was a pioneer who quantified the compaction properties of pharmaceutical powders and (105-109) the result of his work are indices known as the Hiestand Tableting Indices. These indices are dimensionless numbers used to describe the mechanical properties and consolidation behavior of materials under compression and decompression. The three main Hiestand Tableting Indices are the bonding index, brittle fracture index BFl), and strain index. 

Hiestand Tableting Indices Likelihood of failure during decompression depends on the ability of the material to relieve elastic stress by plastic deformation without undergoing brittle fracture, and this is time-dependent. Those which relieve stress rapidly are less likely to cap or delaminate. Hiestand and Smith [Powder Technol., 38, 145 (1984)] developed three pharmaceutical tableting indices, which are applicable for gener characterization of powder com-pactiability. The strain index (SI) is a measure of the elastic recovery following plastic deformation, the bonding index (BI) is a measure of plastic deFormation at contacts and bond survival, and the brittle fracture index (BFI) is a measure of compact brittleness. 

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