Rotational molding is a process for manufacturing hollow or open-sided plastic products using a rotating mold subjected to heating and then cooling. The process is attractive for the production of stress-free objects at a competitive cost. In this article, a modified model for heat transfer in rotational molding is proposed, which assumes that the heat transfer at the mold-powder interface is because of convection, whereas the powder particles are heated up by conduction. Heat transfer through the mold-air contact is also included. A source-based formulation is used for modeling the layer-by-layer nonisothermal deposition of plastic. The reduced heat transfer due to warpage is calculated by using a modified heat transfer coefficient. Good overall agreement is found between the cycle times as predicted by the model and the experimental data. The model is then used for calculating the cycle time for particulate composites, based on their effective properties. A reduction in the cycle time is observed in the case of reinforced composites. This is attributed to the increase in thermal conductivity of the particulate composites and the reduced mass fraction of the polymer. Numerical calculations of the cycle time for the glass-bead reinforced composites are found to be in good agreement with the experimental results. POLYM. ENG. SCI., 48:2188-2197, 2008. (C) 2008 Society of Plastics Engineers