多種生產週期時間派工方法之探討

Abstract

晶圓代工廠如果能規劃多種生產週期時間產品不僅可以吸引顧客，也可以減少緊急訂單插單的情形。目前的文獻在遇到短生產週期產品時是以緊急工單的方式，給予短生產週期產品優先權；然而如此可能會造成短週期產品提前產出而長週期產品延遲產出的情形。本研究利用最小餘裕時間派工法則的觀念，修正發展出一個能控制多種生產週期時間的派工法則，藉由分析剩餘加工步驟機台群的利用率來找出哪些機台群需要等待較久的時間，給予權重使得剩餘加工步驟需等待較久的工單可以優先通過，並利用簡單的等候理論模式來修正瓶頸機台群，使得模式能夠更精確。 模擬結果顯示本研究提出的修正餘裕時間派工法則，在延遲工單數和延遲總時間方面，相較於先進先出、最早的交期、最小餘裕時間和最小餘裕比值有較佳的績效。在生產週期時間標準差方面，本研究提出的修正餘裕時間派工法則，相較於先進先出、最早的交期、最小餘裕時間也有較佳的績效。

This research develops a dynamic dispatching rule called Slack_Weight for IC foundries in order to improve the on-time delivery of multiple cycle time products. That is, wafer lots are assigned different manufacturing cycle time based on customers’ demands. For example, wafer lots are grouped into three classes：shorter cycle time lots、regular cycle time lots, and longer cycle time lots. Customers can place their orders with a particular cycle time and price. With considering the utilization of a machine group and the number of machines in the machine group, we classify the machine groups into three classes. Corresponding to each class, a particular value of weight is assigned to represent the waiting time of a lot in queue at a machine group. Then we sum up the values of weight of the machine groups that are used to process the remaining steps of a particular lot in queue at a certain machine group. And the slack_weight of this lot is defined by dividing the slack-time with the total weights. The processing priorities are determined by the value of slack_weight. Simulation results show that the proposed Slack_Weight dispatching rule is better than other dispatching methods in literature.