The repeated compression of powders

Powders were subjected to repeated compression in a tablet press, the ejection mechanism of which had been disconnected. The force detected at the upper punch was found to change with successive compressions, the magnitude of the change being dependent on the powder, the compressive force and the interval between compressions. Repeated compression also caused a change in tablet crushing strength. With compression intervals of 1.2 s, all substances showed an significant increase in strength. With longer time intervals, the increase was reduced and in some cases, a diminution in strength occurred. (C) 1997 Elsevier Science B.V.