A multi-phase planning heuristic for a dual-delivery SMT placement machine optimization

This paper proposes a heuristic multi-phase approach to minimize the moving distance of gantries by balancing the workload of a dual-delivery surface mount technology (SMT) placement machine. The SMT placement machine under study is a rotary-head dual-gantry machine. Several practical factors are considered, such as the component-nozzle compatibility and the machine structure. The machine has two stations with a symmetric layout. Each station has a printed circuit board (PCB) conveyor belt, a fixed camera, an auto nozzle changer, a feeder base, and a movable gantry with several nozzle heads. In the pick-and-place assembly operation, two independent gantries alternately mount on one PCB. Most research in literature considers three main decisions in the SMT placement machine optimization: nozzle setup, feeder arrangement, and pick-and-place sequence. In this research, two more decisions are introduced into the dual-gantry problem: workload balance between gantries and gantry cycle scheduling. A hierarchical strategy is developed to solve the workload balance problem, including nozzle and component allocations. The other decisions, such as the feeder arrangement and the pick-and-place sequence, are made using existing heuristics. The experimental results show that this heuristic approach has advantages compared to other algorithms proposed in literature.