應用多變量製程能力指標於多品質特性之新速製程

Abstract

由於市場需求隨時變化，使得產品的壽命週期縮短，以往的大量生產方式將會導致生產過剩。因此製造商為降低庫存成本，必須有有更快速的方式才滿足市場需求。而零工式（job shop）的少量多樣式的生產方式，則可滿足這樣的目標。這種少量多樣的製程稱做新速製程（short run production），而新速製程正逐漸取代傳統大量生產的製程。因此，由於生產技術的進步，產品的複雜度也逐漸增加，以單一品質特性來衡量產品的品質已不敷需求。傳統上以單一品質特性衡量製程能力的指標公式，是建立在製程服從常態分配的假設下，而新速製程不一定符合常態分配假設，且因抽樣數少也難以檢定其是否適配常態分配，因此傳統製程能力指標公式並不適用於衡量具有多品質特性的新速製程。截至目前為止，中外文獻也僅止於探討大量生產型態的多品質特性之製程能力指標，對於新速製程的探討也僅限於單一品質特性。因此本研究的主要目的是發展出一個適用於多品質特性新速製程的多變量製程能力指標計算流程，以合理估算多品質特性新速製程的製程能力。

Under the mass production environment, the conventional capability indices are utilized to evaluate the process performance. In the job-shop production environment ( or short run production ), in order to evaluate the performance of the short run production, the capability indices need to be revised for small samples. Because the product complexity has been increased recently, the process capability analysis for multiple quality characters of the product becomes important. Some multivariate capability indices have been developed under the assumption of multivariate normal distribution. However, this is not always true in the short run production environment. Therefore, the purpose of this study is to develop a multivariate capability index for short run production. A case study is also presented to illustrate the effectiveness of the proposed multivariate capability index for the short run production.