Evolutionary algorithm for advanced process planning and scheduling in a multi-plant * Chiung Moon a , Yoonho Seo b, * a Department of Information and Industrial Engineering, Hanyang University, Ansan 425-791, South Korea b Department of Industrial and Information Engineering, Korea University, Seoul, South Korea Abstract Integration of process planning and scheduling is one of the most important functions to support flexible planning in a multi-plant. The planning and scheduling are actually interrelated and should be solved simultaneously. In this paper, we propose an advanced process planning and scheduling model for the multi-plant. The objective of the model is to decide the schedules for minimizing makespan and operation sequences with machine selections considering precedence constraints, flexible sequences, and alternative machines. The problem is formulated as a mathematical model, and an evolutionary algorithm is developed to solve the model. Numerous experiments are carried out to demonstrate the efficiency of the proposed approach. q 2005 Elsevier Ltd. All rights reserved. Keywords: Process planning and scheduling; Multi-plant chain; TSP with precedence constraint; Evolutionary algorithm 1. Introduction Many manufacturers now try to optimize the total system to cope with a global manufacturing. This trend brings the idea of supply chain, which is to optimize not only the plant operations but also the whole activities from a supplier to a customer. As a result, manufacturing companies nowadays are migrating from separated planning processes toward the more coordinated and integrated planning processes to provide high quality products at lower cost. Integration of process planning and scheduling is one of the most important problems for supporting the total optimization. The two functions are interrelated because both of them take part in the assignment of factory machines to production tasks. Hence, the actual process planning and scheduling 0360-8352/$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.cie.2005.01.016 Computers & Industrial Engineering 48 (2005) 311–325 www.elsevier.com/locate/dsw * This manuscript was processed by Area Editor Mitsuo Gen. * Corresponding author. Tel.: C82-2-3290-3393; fax: C82-2-929-5888. E-mail addresses: cumoon@ihanyang.ac.kr (C. Moon), yoonhoseo@korea.ac.kr (Y. Seo).