Research On Simulation And Scheduling Strategy In ARRAY Manufacturing System For TFT-LCD Fab

In the huge TFT-LCD Fab, the ARRAY manufacturing system is very complex with some special charateristics, such as re-entrance phenomenon, high uncetainty and multiple optimized objectives, etc.ARRAY manufacturing system is recognized as one of the most complex manufacturing systems in the world, existing lots of differences in comparation with traditional production line.Not like Japan and Korea, these main LCD production areas, manufacturing system of TFT-LCD Fab in China is still in the initial stage. The lag of manufacturing system planning and neglect of manufacturing system scheduling have resulted in poor performance of manufacturing systems, high cost and low market competition.Under this situation,some basic researches in connection with the Fifth-Generation ARRAY manufacturing system have been done in this paper.First, because of difficulty of quantifying ARRAY manufacturing system's performance analysis, a computer simulation model with two-dimensional animation has been established for this production line by using object-oriented simulation technology, based on eM-Plant in this paper. The simulation model is composed with three parts:prodution object layer, scheduling control layer and data analysis layer. By simpliying the original physical model reasonably, production object layer is established containing AGV, processing machines, mechanical hands, storage spaces, etc. A lot of control programs have been written for release policies and real time scheduling rules(including machine dispatching and vehicle dispatching) by using SimTalk in scheduling control layer.By loading these SimTalk programs in prodution object layer, work for controlling this simulation model has been done. Some control rebars such as bottleneck-analyzer, logistic recording table,chart for coefficient of machine utilization are established in data analysis layer.Some dynamic targets such as average production cycle, work in process, throughput, machine efficiency can be analyzed in this layer to find the problems in this manufacturing system.Second, in this paper, father study about scheduling strategies of ARRAY manufacturing system has been done. For a single product release, a release rule for bottleneck stocker's WIP balancing(RRWB) has been established to balance the WIP in Fab. For machine Dispatching, this paper has completed a compound priority dispatching strategy(CPDS).For vehicle dispatching, a dispatching rule for bottleneck stocker first(DRBF) has been established. By loading these arithmetic programs above into the simulation model, a new optimal simulation model has been established. The old strategies in the Fab include: Constant Release Interval(CONRIN), First IN First Out(FIFO), First Encountered First Serve(FEFS), etc.The simulation results show that:the optimal model has cut down the production cycle time, reduced the work in process, increased the productivity component, optimized some other important targets and also solved some practical problems just like lower productivity and high work in process in this manufacturing system.