TFT-LCD模組廠生產規劃系統之構建

Abstract

薄膜電晶體液晶顯示器(Thin Film Transistors Liquid Crystal Display；簡稱TFT-LCD)之製程步驟共分為三個主要階段。其中，模組廠(Module Assembly)位於最終階段且為最接近顧客的生產環境，其生產產品總類繁多，因此滿足顧客需求為其經營策略；但模組廠之瓶頸工作站換線時間高達6個小時，所以如何建構ㄧ個良好的生產規劃系統，來有效減少換線次數，使產出最大化。 對於此課題，本系統共建構三個模組來加以因應，分別是「產能規劃模組」、「物料規劃模組」與「生產規劃與排程模組」。首先，在「產能規劃模組」中，考量模組廠瓶頸機台的最大可用產能與換線時間相當長等限制，建構ㄧ線性規劃模式，用以求解各期產品加工數量與順序表，使其充分利用瓶頸，達到產出最大化之目標。「物料規劃模組」則是在求解出各期產出目標之後，對模組廠所需要之原物料進行備料，以防止機台無料生產，導致在製品上升與機台利用率下降。最後，在「生產規劃與排程模組」裡，由於混線生產比專線生產多考慮了換線因素，造成在進行估算生產週期時間時，有相當大的變異，因此分別運用Conway估計式與queueing Model M/M/s來求算各工作站混線與專線的生產週期時間。 實驗結果顯示，本文的生產規劃系統不僅可有效減少換線次數、充分利用瓶頸資源，且可達到產出最大化之目標；而在生產週期時間估算方面，亦有相當良好的成效。整體而言，本文建構的生產規劃系統，可快速獲知模組廠生產之產品別及數量，且提供一良好生產週期時間之依據。

The manufacturing process of TFT-LCD mainly consists of three stages. Among them, module assembly is the final stage of the whole production process and is most close to customers. Since module assembly produces various products, its scheduling strategy is to meet customers’ demand. However, the setup time of bottleneck workstation is very long and is up to 6 hours. The key of such problem is to construct a good production planning system to reduce the number of setups and to maximize the throughput. To solve the problem, the proposed system comprises three modules: capacity planning module, material planning module, and production planning and scheduling module. In the capacity planning module, we construct a linear programming (LP) model which considers the constraints such as the maximum capacity of bottleneck machine and long setup time. The planning results contain the production quantity of each product type and the production sequence at each time period. With the throughput target for time period, material planning module is to get the material ready for dispatch in order to avoid the drop in machines’ utilization rate and the increase in WIP level. Finally, since the mix line needs to consider the set-up operation, variation in cycle time is very large and the estimation is more difficult. Therefore, the production planning and scheduling module applies queueing M/M/s Model and Conway estimation to calculate the production cycle time in both the mix line and the dedicate line of each workstation. Experimental result shows that our production planning system not only can reduce the number of setups efficiently and utilize the bottleneck effectively, it can also maximize the throughput and estimate the cycle time rather accurately. Overall, our production planning system can arrange product type and quantity of module factory quickly and provide a good reference of production cycle time.