Job Scheduling for Hybrid Assembly Differentiation Flow Shop to Minimize Total Actual Flow Time considering Multi-Due-Dates

The hybrid assembly differentiation flow shop is a three-stage flow shop system with machining, assembly and differentiation stages. The machining stage produces k parts in independently unrelated dedicated machines. After k parts of a job completed, they are assembled at the assembly stage and assigned to dedicated machines for a final process. At the end, several types of finished products are resulted. The finished products should be delivered at their respective different due dates. The problem is to find a schedule considering multi due dates, and the criterion of minimizing total actual flow time. This paper proposes a model for job scheduling in a hybrid assembly differentiation flow shops and its algorithm for solving the problems. The initial solution is defined using SPT-based heuristic and it is optimized using variable neighbourhood descend method. The proposed model is tested using a set of hypothetic data. The solution shows that the algorithm can solve the problems effectively.