Grouping and sequencing of machining operations for high volume transfer lines

Transfer lines are costly assets used for manufacturing of voluminous quantities of a dedicated discrete product following a predefined process plan. This paper deals with the problem of optimal grouping, sequencing and utilization of the dedicated machinery that goes into such transfer lines. A time objective function has been utilized. Handling time, which is an important component of cycle time, is assumed to be comprised of tool change time, time required to reposition and transport the workpiece and refixturing & reloading time. A new mixed integer linear programming model is developed to solve the problem with the aforementioned objectives while respecting a set of constraints, which include machine loading, tool allocation, tool magazine limit, takt time limit and precedence & inclusion constraints. A numerical case study is utilized to illustrate the functionality of the model.