In this paper, the impact of machine failures on production lines in a closed-loop supply chain systems is examined. For this purpose, a new method is proposed for scheduling manufacturing workshops in a supply chain systems. | A robust optimization approach for scheduling a supply chain system considering preventive maintenance and emergency services using a hybrid ant colony optimization and simulated annealing algorithm Uncertain Supply Chain Management 7 2019 251 274 Contents lists available at GrowingScience Uncertain Supply Chain Management homepage uscm A robust optimization approach for scheduling a supply chain system considering preventive maintenance and emergency services using a hybrid ant colony optimization and simulated annealing algorithm Aidin Delgoshaeia Armin Delgoshaeib Aisa Khoushniat Aramc and Ahad Alid a Department of Industrial Engineering Kharazmi University Tehran Iran b Khaje Nasir Toosi University of Technology Tehran Iran c University Putra Malaysia Malaysia d Lawrence Technological University United States CHRONICLE ABSTRACT Article history Machine failures during production period may impose thousands to millions of dollars to a Received June 22 2018 manufacturing system. In this paper the impact of machine failures on production lines in a Accepted September 25 2018 closed-loop supply chain systems is examined. For this purpose a new method is proposed for Available online scheduling manufacturing workshops in a supply chain systems. The aim is to determine the October 3 2018 Keywords best production plans in a manufacturing system by considering alternative preventive Facilities planning and design maintenance programs while machine failures can affect system performance. To solve the Supply Chain Scheduling model a hybrid Ant Colony and Simulated Annealing algorithms is developed and the results Machine Failure are compared with branch and bound method. Our findings show that the condition of emerging Preventive Maintenance machine failure affects machines capacity which yields to lost sale. The impacts of using appropriate preventive maintenance on reducing lost sale is also examined. The results indicate that the proposed .