A solution method for the production planning and scheduling problems of a job shop

This paper investigates the production planning and scheduling problems of a job shop. In general, the solution of the production planning problem is fed into a scheduling problem, and thus from the point of finding the feasible solution, it is important to consider the capacity constraints of the scheduling level when solving the production planning problem. In this paper, a heuristic solution method for the problem is proposed. The key points are to estimate the net available production time by subtracting unavoidable idle time from the maximum available production time, and the maximum production quantity for the selected products. The production planning problem is first solved considering the net available production time and maximum production quantity. The scheduling problem is then solved with the corresponding solution of the production planning problem. The last step is to revise the net available production time and add the maximum production quantity constraint. The proposed method repeats these three steps and stops if the feasible solution is obtained or the number of iterations reaches a specified maximum value. Computational experiments clarified the applicability of this method.