Abstract
The compressibility of powders was evaluated by using residual die wall pressure and measuring the binding strength of the compacted powders.
The binding strength was reflected in a saturated curve as the compaction pressure increased. However, the residual die wall pressure increased in proportion to the compaction pressure. These phenomena explained the capping behaviors during tableting.
In the binary mixed powders, the binding strength changed in a complicated way, but the residual die wall pressure changed simply with the composition of the mixture. The ratio of these two values was defined as the capping index, and the actual capping tendency was defined as the capping ratio. Good correlation was observed between this index and ratio.
