Component Pick and Place Scheduling for Surface Mount Device Placement Machine

摘要

This is a case study on improving the throughput of a pick and place surface mount device placement machine. These machines are designed to place electronic components onto a printed circuit board. The machines considered in this research are economical and medium speed machines that have four fixed feeder carriers, a fixed printed circuit board table, two vision cameras, a tool bank, a trash bin and a positioning arm head (i.e., a head that is moveable in both X and Y axes simultaneously) that is equipped with two pipettes. A nozzle (which is held by a pipette) is used to grasp the components for the pick and place operations. As nozzle change operations are very time consuming the constructive heuristic presented in this study gives priority to reducing the number of nozzle change operations in order to schedule the component pick and place operations when assembling printed circuit boards. Based on the average machine operation time provided by the machine manufacturer we compute the effectiveness of each pick and place operation type and assign a weighted value for each type of the operation. The nozzle pairs are ranked based on their effectiveness that indicates how many good pick and place operations can be performed by the nozzle pair. The heuristic begins by choosing the best nozzle pair to be applied. Computational results show that, on average, a weighted nozzle rank heuristic is superior to an ordered heuristic that was presented in the earlier research.