Model Simulation of Powder Compaction by Complex Mold Based on Deformation Behavior of Free Particles Measured by Compression Test

Abstract

Discrete element method (DEM) is one of the excellent procedures for model simulation of behavior of granular assemblies. A two-dimensional DEM simulation of powder compaction by a complex mold was conducted by considering the deformation behavior of individual particles measured by a compression test of free particles. Spherical copper particles were used as a model material in this study. The particles (particle size ranges from 38 to 125microns) were individually compressed between parallel platens to measure compressive load and displacement in the loading direction. From the measured load and displacement data, force-displacement relations at contacts between the particles, and between the particles and mold wall were determined. In the simulation, the two-dimensional complex mold consisting of three stages (upper stage:3-mm wide and 1-mm deep, middle stage:2-mm wide and 1-mm deep, lower stage:1-mm wide and 1-mm deep) was charged with the copper powder consisting of spherical particles with size range of 50 to 200microns and was pressed under four press conditions. Forces at all contacts were calculated by using the determined force-displacement relations and each particle's position was traced by solving equations of motion for each particle. Pressure at each wall of the mold and density distribution in the powder compact were calculated as results of the simulation. It was found that the increase in the pressure at each wall corresponds to the increase in the density of the powder near the wall.

Process Modeling in the Pharmaceutical Industry using the Discrete Element Method

“…Other results show the effects of powder characteristics such as friction,140, 152, 278 particle‐to‐die size ratio,152 effect of shoe speed,140 and the effect of air pressure 140, 166. The compression of materials within a die has been studied139, 279–285 while others have investigated compression in a periodic system to eliminate die wall effects 286–288. Rearrangement of particles during the compaction process has also been shown to be important 75, 283, 289, 290.…”