New heuristics for No-wait Flowshop Scheduling with Precedence Constraints and Sequence Dependent Setup Time

Abstract

This paper addresses a method to obtain the best sequence for no-wait flowshop scheduling with precedence constraints and sequence dependent setup time. The system is made up of a set of machines of various types and there is no interruption between tasks in a job. The objective is to determine the job sequence for processing with minimum makespan. The sequencing problem with precedence constraints and sequence dependent setup times is equivalent to the traveling salesman problem. A mixed integer programming (MIP) model is presented to obtain the best schedule. It is known that the MIP model for no-wait flowshop scheduling is NP-hard. Heuristic algorithms to gain the best job sequence are developed. From the experiments, it is found that the proposed algorithm generates the best job sequence efficiently.