Model reduction techniques for the scheduling of multistage fast-moving consumer goods plants

Fast-moving consumer goods (FMCG) plants must be highly flexible due to their multiproduct nature and frequent portfolio changes with season or consumer preferences. Due to the multipurpose nature of the plant equipment units, there is often a need for changeover activities and these can increase the complexity of scheduling problems. The objective of this paper is to present two approaches to decrease the number of changeover activities. The first approach aims to reduce the flexibility of multipurpose equipment units by minimising the number of operations performed on each unit. The second approach emphasises on sequencing operations on units in multistage processes. The conditions under which task sequencing can be applied before optimisation, without compromising the solution optimality, are discussed. The results of these approaches tested against a case study indicate their effectiveness in reducing the model size and the computational effort for optimisation, enabling the solution of an industrial example which previously could not be solved.