製程能力指標被視為測量產品品質與績效極為有效且良好的方法，但是單一的指標是不夠充份完整的去評估一個具有多重品質特性產品的製程能力。因此，許多學者提出一些能同時監控多品質特性產品的品質分析圖表。可是他們的研究存在一些限制與缺點，第一，有些分析圖表只能適用在具有對稱望目型態品質特性的產品。第二，大部分的研究僅侷限應用在具有單一型態品質特性的產品，然而實際上大部分的產品往往同時具有數個望小型、望大型、以及望目型品質特性。第三，少數研究使用的製程能力指標並無法敏感地反映製程的精確度。第四，一些提出的方法僅根據指標的估計量就結論製程是否達到要求的能力水準，這樣的推論是非常不值得信賴，因為他們並沒有考慮到產品檢驗的方式尤其是忽略了抽樣檢驗時所產生的誤差。因此，為了改善這些缺點，本篇研究分別在全部檢驗與抽樣檢驗兩種情況下提出製程能力監控表(PCMC)。在全部檢驗下，我們建構一個製程能力監控表來評估整個產品的狀況包括非對稱望目型、望小型、以及望大型等品質特性。在抽樣檢驗的情況下，我們又設計 與 兩種製程能力監控表分別適用於產品具有對稱與非對稱型態品質特性。選擇適當的製程能力監控表，不僅能夠合理地反映具有對稱望目型、非對稱望目型、望小型以及望大型等品質特性的產品製程能力，更能夠依照製程能力指標在圖表上的落點指出該製程的精確度。它們將幫助製程工程師更方便去檢視所有品質特性的製程能力是否達到預設的水準，對於不滿意的製程能夠即時發現並進一步採取改善的措施來提升整體製程能力。

Process capability indices (PCIs) can be viewed as an effective and excellent means of measuring product quality and performance, but one single PCI is not sufficient for evaluating an entire product with multiple characteristics. Hence, many scholars have continually been proposing some graphical analysis charts which can simultaneously monitor all quality status for a product with multiple characteristics. However, there are some limitations and shortcomings in this. Firstly, some charts only expressed suitably at symmetric tolerances for the nominal-the-best processes. Secondly, most studies were limited to discussing one single type of quality characteristic. Otherwise, in practice, most products simultaneously have numerical quality characteristics including smaller-the-better, larger-the-better, and nominal-the-best specifications. Thirdly, a few process capability indices used in their charts don’t have enough sensitivity to reflect the accuracy and precision of the process. In the fourth place, some studies simply used the estimators of the indices to determine a point on the charts and then judged whether the processes met the capability requirement. These approaches are highly unreliable, since they don’t consider the methods of inspection and consequently the sampling errors are ignored. In order to improve these shortcomings, the set of Product Capability Monitoring Charts (PCMCs) are proposed in this study, which consider two types of PCMCs, i.e. full inspection and sampling inspection respectively. In full inspection, we construct a PCMC to assess the all quality status of an entire product with bilateral asymmetric tolerances, smaller-the-better and larger-the-better multiple quality characteristics. In the sampling inspection, we construct PCMC and PCMC to assess all process capabilities for products with symmetric tolerances and asymmetric tolerances respectively. Selecting the suitable PCMC, not only reasonably reflects process capabilities of an entire product, but also points out the capability for accuracy with respect to the positions of the indices. They can help the manufacturing engineers to check more conveniently whether the process capabilities satisfy preset level or not. Furthermore, quality improvement actions are taken with respect to unsatisfactory processes to enhance the entire process capability.

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