Batch Sizing and Scheduling in Serial Multistage Production Systems

The authors propose a procedure to model and determine the optimal batch sizes and their schedule in a serial multistage production process with constant demand rate for the final product. The model takes into consideration the batch setup time in each stage, the processing times of a batch as a function of batch size and production stage. It considers the holding and shortage costs of the final product, and the setup and processing costs at each stage of the production process. The objective is to maximize the net profit per unit of time derived from selling the final products. We report on extensive computational experiments that tested the impact of different factors on the objective function and the optimal batch size. A feature unique to this paper is the concentration on multistage serial systems consisting of hundreds of stages in the production process, in such systems a batch can spend from one to eight months in the production process. Batch sizing and scheduling has a great impact on the net revenues derived from the production facility. Due to the tight tolerances of the production process which are computer controlled, setup and processing times are deterministic