AUTOMATED GENERATION AND ANALYSIS OF POWDER COMPACTION DIAGRAMS

The compaction diagram is a useful characterization tool for measuring the strength of powder agglomerates (e.g. granules) and characterizin g the microstructural development of powder compacts in dry forming op erations. The current work describes a new method for the rapid measur ement and analysis of compaction diagrams. A computer-controlled testi ng machine was used to collect crosshead versus load data during powde r compaction in a uniaxial die. The net crosshead translation during l oading included the permanent compaction of the powder plus the combin ed elastic deflections of the powder compact and the testing apparatus . In order to compensate for the elastic deformation in the testing ap paratus, baseline data were collected by compressing an empty die and were subtracted from the net crosshead position. At the high pressure endpoint, the elastic deformation in the powder compact (i.e. springba ck) is the difference between the adjusted crosshead position and the thickness of the pellet after ejection from the die. At intermediate p ressures, mathematical models were used to estimate the springback. Th is approach resulted in improved accuracy, significant time savings an d an expanded scope of analytical capability compared to other methods of generating compaction diagrams.