Multiobjective decision making approach for determining alternate routing in a flexible manufacturing system

In a Flexible Manufacturing System a particular operation on a job can be performed at several machines because of inherent capability of the machines to load multiple tools. There is a choice in the system as to which workstation each operation should be performed. Any entering workpiece therefore has the choice of several different routes. In such a complex scenario productivity could be improved by selecting an efficient routing under computer control.

This paper formulates the problem as a Coal Programming model which provides a way of striving towards several objectives simultaneously. Thus the goals to be considered are - (i) to satisfy the forecasted demand, (ii) to minimize the material movements and (iii) to minimize the workload imbalance on all the machines. The solutions obtained on solving this model specify the efficient routing to be implemented. Non-preemptive penalty values are considered for comparing the goal programming formulation with prevailing single criterion objective formulations. Appropriate reasoning for the determined penalty values for the deviations from each goals are given.

An illustrative example is considered to study alternate routing under multiple criteria. Lastly, utilization of the goal programming tool lies in evaluating the different layouts and determining the best layout. The layout with minimum workload imbalance and comparatively less material movement is recommended to be the best layout.