In recent years, bead foaming technology has been of great interest to researchers because it represents a breakthrough in the production of low density plastic foamed components that have a complex geometrical structure. This helps to expand the market for plastic foams by broadening their applications. Despite earlier, valuable studies on the characterization and manufacture of bead foams, there has been little investigation of the critical parameters in the foamed bead manufacturing process. To provide an insight into the mechanism behind bead foaming technology, a lab-scale autoclave system for foamed bead manufacturing is developed and the critical processing parameters were studied. Foamed beads were obtained under various processing conditions with this lab-scale system while using carbon dioxide as the blowing agent. The cellular morphology and melting/crystallization behaviours of the beads are examined and discussed. (C) 2012 Elsevier B.V. All rights reserved.