Advanced process planning and scheduling with precedence constraints and machine selection using a genetic algorithm

This paper deals with integrated process planning and scheduling problems with minimizing makespan for a flexible flow manufacturing where alternative operations sequences with precedence constraints and alternative machines. The problem is formulated as a mathematical model which includes operation sequencing, machine selection, and operation scheduling. The integrated planning of having more than one machine to perform the same operation and precedence constraints for sequences increases the size of the solution space, and consequently, makes the problem even more complex. We develop a new genetic algorithm approach using topological sort to solve the model efficiently. Schedules with operations sequences and machine selections are currently decided by the proposed approach. Some experimental results are presented for various problem sizes and parameter settings to describe the performance of the proposed approach.