Study On Optimization Of PCB Assembly Time In Surface Mount Manufacturing

In the production of electronic product, it is an important way to use advanced optimization technology to make reasonable scheduling and optimal control on the assembly line and the devices on it. Therefore, it is of great theoretical significance and application value that exploration and study on related theoretical issues and optimization methods about optimizing operation of SMT line and mounter, which is the key device in SMT line.With SMT production in electronic manufacturing as research background, this paper studies optimization problem of PCB assembly time in the surface mount manufacturing. The optimization problem has a certain highly associated sub-problems involved, which makes it very complicated and hard to solve. So, this paper investigates mainly how to make a targeted study of the optimization problem, build its mathematical model and design effective solving method for it according to specific production. This study focused mainly on the following aspects:1. A survey study on the optimization problem in surface mount manufacturing. The paper makes a systematic analysis, classification, comparison and summary on content, ideas and methods of past research work. Thereby, the optimization problem is divided into a certain line optimization problems on difference levels, which are to be deeply analyzed and discussed.2. A study on optimization problem and solving method of PCB assembly time of single mounter. Firstly, this paper points out the limitation of strong constraints in past solving methods and relaxes the limitation. Secondly, the optimization problem is decomposed into two sub-problems, named Feeder Assignment Problem and Pick-And-Place Sequencing Problem respectively, whose mathematical models and solving methods are studied separately. According to such research foundation, as well as relationship between the above two sub-problems, two optimization algorithms based on heuristic search and scatter search respectively are constructed to solve both two sub-problems synthetically to obtain an approximate optimal solution. The results show that the former algorithm can obtain good results in short length of time, and the latter can obtain much better results in a relatively longer time. 3. A study on optimization problem and solving method of PCB assembly scheduling under low-volume and high-mix production. Making clear the main factor on PCB assembly time in low-volume and high-mix production, the paper builds for the problem a mathematical programming model with minimizing machine setup time as the optimization goal. The optimization problem has characteristics of a traveling salesman problem, and belongs to NP-complete combination problem. Three algorithms are presented to solve the problem to determine a optimal assembly sequence of different PCB types. Performance of the three algorithms is evaluate and compared with each other by simulation tests. The results of numerical experiment show that Scatter Search Algorithm charactered by evolution search has good performance and is more suitable for solving such kind of optimization problems.4. A study on optimization problem and solving method of load balancing in a SMT flow line. Firstly, hardness and related viewpoints abount this optimization problem are analyzed, and the basic problem-solving idea is determined. Then, an integer programming model is built on the features of flow-line production and optimization problem. Two optimization algorithms based on heuristic search and scatter search respectively are purposed to solve this problem to determine a optimial component-type assignment to machines in the line. The numerical experiments are used to verify feasibility and effectiveness of both algorithms. The results show that the former algorithm can output moderately good solutions, and the latter can obtain much better solutions, especially for middle-scale or large-scale instances.In the end, the research achievement is summarized and some considerable questions and the future work of study on optimization problem in surface mount manufacturing are presented.The dissertation is supported by the State Key Program of National Natural Science Foundation of China"Research on the Key Technology of Vision Detection and Optimal Control Oriented to the Precise Electronic Assembly Lines"(Grant No. 60835001) and the National Natural Science Youth Foundation of China"Research on Production Optimization and Scheduling Method in Surface Mounting Lines"(Grant No. 60804053).