THE FORMATION OF SUBFAMILIES FOR MACHINE LOADING OF FLOW-LINE CELLS

Cellular manufacturing constitutes a key element of contemporary appro aches to manufacturing such as just-in-time and flexible manufacturing systems. In some settings, it may not be possible to release all memb ers of a family to a cell at the same time due to tooling, level of th e in-process inventory and limited machine buffer capacity constraints . When such constraints exist, one approach is to partition each famil y into subfamilies. In this research, we consider the effective partit ioning of a family of parts into subfamilies in cyclically scheduled c ells involving unidirectional material flow between machines laid out in a loop and where capacity constraints on tooling are present. The c riterion for forming subfamilies is the minimization of the total mach ine idle time. This criterion maximizes the rate of output of the cell as well as maximizing machine utilization. A batching approach to par t and tool change is utilized and all tool magazine set-ups are assume d to occur off-line while the cell is in operation. We present a model for the formation of subfamilies using the above criterion and develo p four heuristic approaches based on it. We then examine their effecti veness by conducting computational experiments over a wide range of re alistic situations generated by varying the characteristics of the-ope rating environment, tooling requirements and tool magazine capacity.