A branch and bound algorithm for hoist scheduling of a circuit board production line

The article studies the scheduling problem of a material handling hoist in a circuit board production line. The existing models for the problem assume that the times required to perform inter-tank moves are given constants. However, as shown in a simple example, the optimal solutions obtained under this assumption may not be the actual optimal solutions. In this article the times for inter-tank moves are decision variables of a mixed integer program proposed for the problem. An efficient branch and bound algorithm is developed for solving the problem optimally. A numerical example is used to illustrate the algorithm. Computational experience with benchmark problems and randomly generated test problems is discussed.