To develop a microscopic understanding of the role of cyclic fluidization and compaction in making spherical and dense granules by Pressure Swing Granulation, numerical simulation was conducted with our private code (SAFIRE21) using realistic parameter values determined by a micro-particle interaction analyzer. The values of the spring constant and coefficient restitution obtained from this experimental measurement were 300-790 N/m and 0.9 respectively. The results obtained by the discrete element method simulation showed that collision frequency and collision force in a fluidized bed were insufficient to cause deformation of the granules but were significant in shaping the granules spherically. (c) 2013 Elsevier Ltd. All rights reserved.