A Heuristic Algorithm for Minimizing the Expected Makespan in Two-Machine Flow Shops with Fuzzy Processing Time

Production scheduling, with the objective of minimizing the makespan, is an important task in manufacturing systems. In the past, the processing time for each job was usually assumed to be exactly known, but in many real-world applications, processing times may vary dynamically due to human factors or operating faults. Fuzzy programming theory has been developed for flow shop scheduling problems with uncertain processing times. In this article, the processing times are described by triangular fuzzy numbers. A new heuristic algorithm is also developed and presented which draws upon Johnson’s algorithm, the interval numbers concept, and an improved version of McCahon & Lee’s algorithm. Numerical examples will be presented to show the effectiveness of the proposed algorithm as compared with McCahon and Lee’s algorithm