Abstract
The study has been done on the optimum design of mulling process for the foundry return sand, using a hybrid control system. First, mulling process of return sand is analysed, compared with the characteristics of new sand one presented in the previous paper. Secondly, the hybrid control system is proposed to optimize both control time and precision in the mulling process. Namely, feedforward control by Fuzzy theory is applied for first water addition conducted in the nonlinear region, while adaptive predictive control is used for the feedback control in the linear region. Finally, the usefulness of the proposed approach is demonstrated for the optimization of the return sand mulling process by control experiments.