Cascading flowlines and layout modules: Practical strategies for machine duplication in facility layouts

The standard approach for design of a layout for a high-variety low-volume (HVLV) manufacturing facility has been to use either a from–to chart or a multi-product process chart to design a process layout or a cellular layout, respectively, for the facility. Considerable research has focused on making a go–no go decision to implement any one of these two traditional layouts as the preferred layout for an HVLV manufacturing facility. This paper introduces a variety of Hybrid Cellular Layouts (HCLs) which integrate the attributes of the traditional functional, cellular and flowline layouts. The mathematical models and methods for design of two HCLs – cascading flowline layout and modular layout – are discussed in detail. Unlike the standard models in the literature, the design of the cascading flowline layout introduces a novel string-to-graph aggregation and planar graph embedding method that allows machine duplication in the layout. Similarly, the design of the modular layout introduces a substring clustering method instead of the standard method of cluster analysis to form part families using the complete routings of the parts. For each HCL, results from an industry project are presented to demonstrate the real-world viability of the concepts, methods and software developed to support the design of HCLs for high-variety low-volume manufacturing facilities.