A PRODUCTION PLANNING AND SCHEDULING SYSTEM AT A CHEMICAL-TESTING LABORATORY

There has been much interest recently in production scheduling models, where batching and sequencing issues are considered simultaneously. In this paper, we describe the development of a production planning and scheduling system in a surprisingly complicated production environment, a chemical testing laboratory. The process for testing water and soil samples in this laboratory consists of an instrument analysis stage, wherein both batching and sequencing issues must be addressed. The production control system we developed to help manage it consists of a capacity allocation module, a batching and sequencing module, a detailed sample scheduling module and various databases. We also developed a simple formula to dynamically determine batch sizes using a resource pricing approach and a priority rule to sequence these batches. The batching and sequencing procedure based on these ideas was evaluated against two alternative heuristic procedures on many randomly generated problems and was shown to perform very well. This paper describes the details of the production process, the characteristics of the new production control system, the development of the batching and sequencing heuristic and some directions for future research.