Characterizing the powder punch-face adhesive interaction during the unloading phase of powder compaction

The objective of this work is to measure the adhesive force profile between a punch face and powder compact in-die during the decompression phase of a tablet compaction process. An instrumented punch was developed for use on a single station compaction fixture mounted on a universal testing machine. Adhesive force-displacement profiles were measured for acetaminophen, ibuprofen, lactose, mannitol, several grades of micro-crystalline cellulose, and blends containing magnesium stearate as a lubricant. The degree of compact solid fraction, the number of compacts produced in a row, and concentration of magnesium stearate in the blends affected the adhesive force profiles. The maximum adhesive force increased with increasing compact solid fraction and decreasing magnesium stearate concentration. An increase in the number of compression cycles increased the adhesive force between the powder compact and punch face, but the compression speed did not play a significant role in the adhesive interaction, at least over the range of speeds examined in the current work. [Display omitted] •A novel instrumented punch for measuring powder-punch adhesion is described.•The adhesive force-displacement data follow a bi-linear relationship.•Maximum adhesive force increases linearly with compact solid fraction.•Maximum adhesive force decreases with the addition of magnesium stearate.•Adhesion increases with number of compression cycles.