Research On Production Scheduling Methords Of PCB Assembly Workshop

With the rapid development of electronic industry, tremendous demand for electronic products results in shorter production cycle of electronic products. As a key link of the production of electronic products, PCB Assembly process exist many complex situations, such as stringent delivery requirement from customer, multi-variety and small batch production and various suppliers, which leads to higher production process management requirement. As a core problem in PCB Assembly process management, PCB Assembly workshop scheduling problem is a key to improve productivity, reduce production costs and enhance enterprise’s competitiveness. Therefore, the research of PCB Assembly scheduling problem is of great theoretical significance and application value.Aimed at PCB Assembly scheduling problem with concern of order splitting, consider the demand of objectives such as production efficiency and customer satisfaction, a multi-objective optimization model integrating order splitting is established. The utility function method and Pareto optimal method are proposed respectively to solve the problem. In utility function method, considering the complexity of the problem, the scheduling process is divided into three hierarchical stages: order splitting, assembly line assignment and lot sequencing. An ant colony optimization is formulated to solve each stage of the scheduling problem and the three ant colony optimization is hierarchically integrated to form a three stage ant colony optimization(TSACO). In Pareto optimal method, the TSACO is improved to form the improved three stage ant colony optimization(ITSACO) to get the Pareto solution set of PCB Assembly multi-objective scheduling problem. Considering the decision maker will select a most suitable solution from the Pareto solution set, the Analytic Hierarchy Process- Fuzzy Evaluation(AHP-FE) approach is proposed to sequence the solutions in Pareto solution set.Due to the influence of dynamic events in actual production process, the original scheduling scheme can’t be smoothly implemented. Therefore, dynamic scheduling is a necessity. This charter considers the dynamic event of uncertain processing time and proposes a mathematical optimization model under this circumstance. An effective algorithm based on the rolling horizon procedure is proposed to solve the model. In order to reduce the frequence of rescheduling, the concept of due date deviation is introduced and a rolling horizon driven strategy based on due date deviation tolerance is designed. As to the rolling window mechanism, the rolling window based on operation is adopted. In order to ensure the computational efficiency of dynamic scheduling algorithm, an improved ant colony optimization(IACO) is proposed to overcome the traditional ant colony optimization’s shortcomings of long search time and easily trap into local optimal. On the one hand, a strategy of reducing the available routes of ants is used to restrict their movement so as to reduce ants’ searching cycle and find new solutions. On the other hand, illuminating function in state transfer possibility is improved to facilitate the exploration of low pheromone trail.Based on the research above, we design and develop a PCB Assembly workshop scheduling system with the background of a PCB Assembly enterprise in Suzhou. The methods proposed in this paper are verified with real production data. The results show that the scheduling methods shorten makespan and enhance lines’ utilization.