Product family formation by matching Bill-of-Materials trees

Formation of product families is of great importance for manufacturing systems which rely on commonality and similarity between products for improving efficiency and productivity. Existing techniques for product family formation are based on similarity measures such as components commonality but none of them consider similarity of the product structure which directly affects the assembly system configuration and the sequence of assembly operations. A novel Bill-of-Materials (BOM) trees matching integer programming model is introduced to address commonality of components as well as their hierarchical assembly structure. A product Bill-of-Materials is a structured tree representing its components and their assembly relationships. BOMs are traditionally used for Material Requirement Planning (MRP); however, they have other useful applications in product modeling and variety management. A product BOM trees matching model, inspired by well-established techniques used in the field of biology for comparing phylogenetic trees, has been developed. Hierarchical clustering is applied to form groups of product families based on the pair-wise similarities obtained by matching BOM trees. The proposed method is applied to a case study of six centrifugal pumps for demonstration and analysis. The benefit of considering structural similarity in family formation for assembly products, in terms of having a better utilized assembly process when compared to the grouping based on plain component commonality, is highlighted.