Research On Methods Of Production Planning Scheduling And Control For Bottleneck Optimization In High-mix Flow Manufacturing Of PCB Workshop

For the mode of high-mix and low-volume customized production,reasonable production and operation control is required to ensure effective lean production with multivariety.The PCB manufacturing for urgent orders and sample production involves typical high-mix and low-volume production,and it is characterized with complex production process and variable product mix.Under this circumstance,the objective of lean and highmix flow manufacturing cannot be successfully realized by the traditional empirical extensive production management methods.Therefore,methods from further R&D on the advanced production planning and operation control are urgently needed.This paper focuses on some in-depth studies on shop-floor production planning scheduling and control methods appropriate for the production of PCB with high-mix.Based on the Theory of Constraints(TOC)and Workload Control(WLC),combined with simulation technology of Digital Factory,a framework of the production planning and control is proposed for the flow manufacturing with high-mix and low-volume.An overall research scheme of production planning scheduling and control methods is established for bottleneck management and control of mixed-flow PCB production.The current research focuses mainly on mathematical models,algorithm design,experimental analysis and system application,and makes the following contributions.(1)To solve the problem of job balancing and scheduling in PCB electroplating mixedflow production line with a constrained hoist,a mixed integer programming model aiming at minimizing the makespan is established.An improved tabu search(ITS)algorithm is designed based on the standard tabu search.The effectiveness of the ITS algorithm is verified with experimental cases.Further,the correlation between the product-mix ratio,the rates of the tank and hoist utilization in the PCB electroplating production line is studied.Also,a task sequencing method is proposed based on the use of the optimized template sequence with an appropriate ratio of product-mix,with its effectiveness and practicability verified in solving the problem of PCB electroplating production line scheduling.(2)To solve the problem of planning and scheduling control on the bottleneck of mixedflow production,the task grouping of similar products,order splitting and batching in the actual production process are taken into consideration,with its corresponding mathematical model aiming at minimizing the makespan and tardiness established.Combined with the characteristics of the task template sequence,a guided tabu search(GTS)algorithm is designed.To verify its effectiveness,the comparison is made between the proposed algorithm and several classical metaheuristic algorithms on case problems of different sizes.Furthermore,the proposed algorithm is successfully applied in a practical case.(3)Aiming at the two-stage PCB electroplating mixed-flow production line scheduling problem,which is characterized with high energy consumption,a two-stage electroplating multi-objective optimization scheduling model is established for energy saving.The model aims at minimizing the total weighted tardiness and energy consumption.Based on the improvement of the spider monkey optimization(SMO)algorithm,a hybrid multi-objective Pareto spider monkey optimization(HPSMO)algorithm is designed.For the first time,the SMO algorithm is applied to the discrete multi-objective optimization problem.The performance of this HPSMO algorithm is compared with several classical metaheuristic algorithms on case problems of different size to verify its effectiveness.Based on this,the application of this proposed algorithm has been successfully carried out in a practical case.(4)With respect to the PCB production system with a major direction in process flow and multiple bottlenecks,and with consideration on the bottleneck shifting caused by the variation of order combination,an innovative order release control strategy is proposed based on the comprehensive use of the method from WLC.This strategy bases on process switching and is more suitable for the current production system.Through a large number of simulation experiments,it is verified that the proposed strategy can ensure the high bottleneck utilization rate while improving the on-time delivery rate and throughput efficiency.Therefore,the strategy can provide a reliable instrument for leveraging the bottleneck scheduling optimization.(5)According to the planning requirements of a real-world PCB workshop,the above research results support the corresponding optimization algorithm and strategy design,which provide an effective production planning and scheduling scheme for the case company.This case fully verifies that the proposed planning scheduling and control methods in this paper have good practical application value.Finally,the main contributions to related fields and main innovation points in the research results are summarized.Besides,some future research directions are pointed out.