Abstract
The difference between dual-gantry and single-gantry surface-mount placement (SMP) machines is that dual-gantry machines exhibit higher complexity and more problems due to their additional gantry robot, such as component allocation and collision. This paper presents algorithms to prescribe the assembly operations of a dual-gantry multi-head surface-mount placement machine. It considers five inter-related problems: (i) component allocation; (ii) automatic nozzle changer assignment; (iii) feeder arrangement; and (iv) pick-and-place sequence; it incorporates a practical restriction related to (v) component height. The paper proposes a solution to each problem: (i) equalizing “workloads” assigned to the gantries, (ii) using quantity ratio method, (iii) using two similarity measurement mechanisms in a modified differential evolution algorithm with a random-key encoding mapping method that addresses component height restriction, (iv) and a combination of nearest-neighbor search and 2-opt method to plan each placing operation. This study reports an experiment that involved the processing of 10 printed circuit boards and compared the performance of a modified differential evolution algorithm with well-known algorithms including differential evolution, particle swarm optimization, and genetic algorithm. The results reveal that the number of picks, moving distance of picking components, and total assembly time with the modified differential evolution algorithm are less than other algorithms.
Highlights
The number of components placed on high-density printed circuit boards (PCBs) has been increasing, which has resulted in the increased use of surface-mount technology (SMT) during the production process of PCBs
Machines with SMT are called surface-mount placement (SMP) machines, which are advantageous for their precision, speed, and efficiency in PCB production compared with manual assembly methods
When placing the components on a PCB, the relatively lower components have to be placed first; unlike those methods, the current study included the consideration of the height restrictions in SMP processing and proposed an effective modified differential evolution (MDE) algorithm to optimize the scheduling of SMP machines in order to cover processing problems more comprehensively
Summary
The number of components placed on high-density printed circuit boards (PCBs) has been increasing, which has resulted in the increased use of surface-mount technology (SMT) during the production process of PCBs. Optimization of dual-gantry multi-head SMP machines creates various problems, and the main problem affecting operating efficiency is divided into three sub-problems, namely the component allocation problem, the feeder arrangement problem, and the component pick-and-place sequence problem. Innovated a hierarchical restricted balance (HRB) heuristic method to determine the optimal nozzle and feeder decisions in order to minimize the moving distance of gantries of a dual-delivery SMT placement machine. The experimental results declared that the proposed algorithm produced a 23.32% distance saving on average for the single-nozzle-type problem in comparison with the large clusters of operations heuristic method He et al [8] introduced workload balance between gantries and gantry cycle scheduling two decisions, and the proposed heuristic multi-phase approach was used to minimize the moving distance of gantries by balancing the workload of a dual-delivery.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
