Simulation of closed-loop manufacturing systems focused on material balances

For achieving sustainable circulation of products, closed-loop manufacturing systems where products are made from used products, parts and materials taken back from the market, as well as new ones, should be established. Focusing on factories, the complicated fluctuations of amount, quality, and timing of these taken-back resources make effective planning and control of these factories very difficult. The purpose of this study is to derive rules and conditions for operating these closed-loop factories efficiently, through a simulation focused on material flow, with these various kinds of fluctuations. As a result of the simulation, we found that the capacity of inverse processes and criteria for parts reuse decide the smoothness of the material flow.