A nozzle selection heuristic to optimise the hybrid pick and place machine

In this paper, we present a constructive heuristic to optimise the component pick and place operations of a hybrid pick and place machine, which is a new type of surface mount device placement machine. Since a nozzle change operation is very expensive (it significantly adds to the overall assembly time), the heuristic gives highest priority to minimising the number of nozzle changes. The ordered nozzle selection heuristic begins by choosing the best nozzle pair that is most effective for picking and placing components onto the printed circuit board (PCB). Next, we schedule all pairs of PCB points, that are expecting components from the chosen nozzle pair. Then the nozzle pairs are re-ranked based on the availability of component feeders and the PCB points that need to be scheduled. Again, the best nozzle pair is chosen and the previous steps are repeated. When none of the selected nozzle pairs can pick and place two components in a sub tour, we schedule the one component sub tour. Finally, when all the available PCB points, have been scheduled, we then reoptimise the schedule by minimising the nozzles changes. Computational results are presented