Bi-objective cell loading problem with non-zero setup times with fuzzy aspiration levels in labour intensive manufacturing cells

In this study, four different bi-objective mathematical models are presented to solve the cell loading problem with setup times in labour-intensive cellular environments. The objectives of each model are minimizing the number of the tardy jobs and the minimizing the total manpower needed. Model I does the following four tasks simultaneously: (1) determine the number of cells to open; (2) determine cell size among alternatives for each opened cell; (3) assign products to cells (cell loading); (4) determine the sequence of products in each cell. The other three models are extensions of model I. Model II restricts all cells to the common cell size. Model III allows lot-splitting and model IV allows lot-splitting only if the entire job can be completed. Fuzziness stems from the fuzzy aspiration levels attained to both objective functions. Fuzzy mathematical models are developed for each crisp model and fuzzy achievement function is defined by different fuzzy operators.