封閉式流程生產線多指標績效評量之共同權重分析

Abstract

本研究評量封閉式流程生產線的績效評量，針對兩製程封閉式流程生產系統，我們可將其分為三類的績效評量指標：第一類指標為第一階段子製程的投入指標；第二類指標為中間項目指標，該指標於第一階段子製程扮演產出指標，並於第二階段子製程扮演著投入指標；第三類指標為第二階段子製程的產出指標。 封閉式流程表示其投入與產出全由生產系統內部所提供與需求。開放式流程就是其各製程有多項投入指標與產出指標可由內部與外部所提供與需求。 在各別的子製程中，減少其投入指標值並且增加其產出指標值可以增進該子製程的生產力。然而對於中間項目指標，調整此指標使得各子製程之生產力能同時提升，明顯存在著衝突。本研究利用發展一共同權重之分析法，管理者可以決定出一組共同權重，使得整體製程之全部生產線的績效值最佳化。此即，各項生產線都是採用相同一組的權重。各項生產線於各子製程之績效值計算方式為加權總和之產出（即虛擬產出）與加權總和之投入（即虛擬投入）之比值。而我們稱虛擬產出與虛擬投入間的差額為虛擬差額。在評量此兩階段生產系統時，可以使得各生產線虛擬差額之總和量最小化。於是管理者可以根據績效值的大小進行排序，從中選擇進行投料生產的產線，促使整體績效的提升。之後本研究將此兩階段生產系統的概念進一步延伸至多階段的生產系統。

This research is dealing with the performance evaluation for a set of production lines in a closed flow shop production system. There are three set of performance indices in a two-stage closed flow shop production system. The first and the third set of indices are the input of the first production stage and the output of the second production stage, respectively. The second set of indices also called as intermediate indices since it plays as the outputs of the first production stage and the inputs of the second production stage. Close flow shop’s provides a set of input items and demands a set of output items all by the internal part. But open flow shop for all the processes of each production line, external of the production system provides a set of input items and demands a set of output items, respectively. In each individual production stage, reduce the inputs and increase the outputs would improve the productivity of the stage. There exists a conflict to determine the volume of the intermediate indices if one tries to improve the productivity of the two stages at the same time. This research introduces a procedure to determine the weights for the three set of indices so that the overall efficiency of the two-stage production system is maximized for the overall products. All the products employ a common weight for each index. The efficiency of each production stage of a product is the ratio of sum of its weighted outputs (virtual output) to the sum of its weighted inputs (virtual input). The positive difference between of the virtual input and output is its virtual gap. The sum of the virtual gaps of all products in the two-stage production system is minimized. Rank the products according to their efficiencies therefore one can select the products to be manufactured to improve the overall efficiency.