Converting assembly lines to assembly cells at sheet metal products: insights on performance improvements

With the current emphasis on short product delivery lead times and customized product configurations, there is a need to design and implement systems that can quickly assemble small batches of customized product. While some plants are converting their assembly lines to assembly cells to achieve this goal, the reasons for the improvement resulting from conversion have not been well documented or understood, making it difficult to know when and where assembly cells are applicable. This research adds to the sparse body of the literature in this area by examining the planned conversion of a multi-model assembly line to a set of parallel assembly cells in a real plant. Previous theory is used to explain why the proposed cells are expected to outperform the current assembly line. Simulation models based on data collected from the plant are then used to estimate the marginal impact each factor change had on the estimated performance improvement resulting from the conversion to cells. Additional simulation experiments are performed to explore the possibility of changing the current line configuration instead of converting to assembly cells, and to extend the results to environments that may exist in other plants. The generalizability of the results to other plant environments is also discussed.