Associate Professor, Dep. of Industrial Engineering, Mazandaran University of Science and Technology, Babol, Iran
M.Sc., Dep. of Industrial Engineering, Mazandaran University of Science and Technology, Babol, Iran
Ph.D. Student, Dep. of Industrial Engineering, Firoozkooh Branch, Islamic Azad University, Firoozkooh, Iran
This article addresses a multi-stage flowshop scheduling problem with equal number of unrelated parallel machines. The objective is to minimize the makespan for a given set of jobs in the system. This problem class is NP-hard in the strong sense, so a hybrid heuristic method for sequencing and then allocating operations of jobs to machines is developed. A number of test problems are randomly generated and results obtained by proposed heuristic are compared with optimal solutions reported by the Lingo 8.0 package applying the branch & bound approach. The results show that the proposed hybrid method is more efficient when the problem sizes have been increased.