在競爭激烈市場環境中，企業提升自我競爭力用品質水準、客戶滿意度，來追求傑出品質是維持訂單和利潤的關鍵因素。最終成品好壞，除了有製造商的製程能力，也有供應商原物料品質，各個關鍵因素環環相扣。原物料的規格值變異程度大，在內部加工過程中容易產出瑕疵品，後端製程的重工或報廢品等量增加，導致成本上升、交貨時間延長，影響客戶滿意度、公司名譽。
慎選供應商對企業相當重要，穩健的品質是具備穩定的原物料，藉由製程能力指標評估原物料品質能否符合企業規範。製程能力指標普遍被應用於判斷製程產出是否在規格範圍內，在變異發生時能及早發現和改善製程，是品質保證的依據，也是判斷供應商是否為符合企業規範的廠商。
製程能力Spk指標是精確估計良率和製程的績效，在不相同的標準差與平均數，能有效地反應實際製流程良率，進而評估製程品質績效，對於產品或製造流程的品質給予保證。因此本論文選擇製程能力Spk 指標，應用於供應商的來料品質，判斷供應商的製程能力水平。
本論文導入Spk hat指標，找出滿足企業要求二個條件：第一、企業不接受的製程狀態，其供應商製程能力為差，企業允收產品的機率；第二、企業接受的製程狀態，其供應商製程能力為佳，企業允收產品的機率。推論出基本抽樣樣本數和拒絕域，來檢定供應商的製程能力和產品品質。
企業藉以抽取適當的樣本數量，來檢定供應商品質是否滿足廠內要求，不僅使得進料檢驗速度變快進而帶動入庫時間縮短與精簡檢驗人員的數量，也使得縮減進料檢驗區域的空間，提升空間的運用的靈活度。

Business corporation enhanced self-capability in quality control and customer satisfactionin competitive market condition. The key factor of order maintaining and profit earning is in how to seek outstanding quality. It is very important to select available vendors from stability
quality performance and constant raw material supplying. Process capability index can evaluate what quality material must achieve standard.
Process Capability Index Spk exactly identifies yield evaluation and process performance. It effectively shows real condition from standard deviation and mean calculation of statistics method. We use it to assess every process quality and also assure manufacture flow and product guarantee.
We imported Index Spk hat to figure out two requirements in this topic study. First, what probability will product be accepted although company can’t approve from weak supplier
process capability. Second, when vendor built up better process capability and qualified by company, we have image to permit good product percentage. We applied statistical inference to create normal sample number and rejection region to verify supplier process capability and product quality.
Company used suitable sample number extraction to judge what quality supplier must provide and fulfill factory’s claim. In this way, we speed up incoming quality control
duration time and also shorten time to release into inventory and downsize inspection work force. We finally promote flexibility space planning when operation zone will be released.

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