A column generation approach for pickup cycle formation in multi-head gantry-type compoennt placement tools

Abstract

We consider the pickup cycle formation problem for multi-head gantry-type component placement tools. The pickup cycle formation decision is to determine which components are picked up for each pick-and-place work cycle when the feeder arrangement is given. The objective is to minimize the total number of pickups, or equivalently maximize the number of simultaneously picked components for each access of a multi-head module. We formulate the problem as a set covering problem that has decision variables as many as the number of feasible pickup patterns of a cycle. We solve the integer programming formulation of the problem by a column generation method, of which subproblem for column selection is efficiently solvable in a polynomial time graph algorithm. Implementation details and computational results using real data are discussed. Significance: The pickup cycle formation problem of the multi-head gantry-type component placement tool to utilize the multiple heads is investigated. The efficient method based on column generation techniques for the problem will reduce the tool cycle time by minimizing the total number of pickups in a PCB assembly.