Simulation of mixed-model PCB assembly lines with group setup and bypass conveyors

Recent technological innovations, namely the development of new solder pastes with increased tack life and the introduction of bypass conveyors, facilitate the use of mixed-model lines in printed circuit board (PCB) assembly. This paper presents a simulation study comparing PCB assembly lines operating in conventional batch and in mixed-model assembly mode. For the latter case, a novel group setup strategy is developed. In the first stage, component types and placement operations for each type of PCB are assigned to the machines in the assembly line with the objective of balancing the workload. In the second stage, PCB types with similar component requirements are clustered into setup families. In addition, the feeder-slot assignment for each setup family and the sequence of placement operations for each PCB type are determined. In the final stage, a cyclical mixed-model production schedule is established. The performance of the proposed solution approach is evaluated by means of a simulation study. Two alternative material flow systems are investigated: a serial conveyor which directly links one machine to the other and a flexible one that allows to bypass downstream machines in the line.