【正文】 ty, p Chart can/should be used when sample sizes are equal as p carry more meaning than of rejected units (np) ? P Chart也可以是相同抽樣數(shù) Computing Control Limits for p Chart 30 174。 Materials Quality PCS Training Rev 3 May 21 2023 Computing Control Limits for p Chart with MRMethod ? Obtain at least k = 30 subgroups or lots. Data collected in of units inspected of units rejected. ? 至少 30組子群組 .以檢驗(yàn)數(shù)與拒收數(shù)來收集數(shù)據(jù) ? Compute the defective rate from the ith lot (i = 1,2,...,k), pi = of units rejected / of units inspected ? Compute the control limits using: 187。 Materials Quality PCS Training Rev 3 May 21 2023 Interpretation of X S Chart Some special causes of outofcontrol for ? X Chart – Changes in machine setting or adjustment – 參數(shù)設(shè)定被調(diào)整 – MStoMS technique inconsistent – Changes in material – 材料變化 ? S Chart – Machine in need of repair or adjustment – 機(jī)器須維修 – New Mses – Materials are not uniform – 材料一致性不夠 25 174。 Materials Quality PCS Training Rev 3 May 21 2023 Observations Mean Moving Range S. D. Moving Range Subgroup 1 2 3 4 5 (X bar) (MRX ) (S) (MR S ) 1 2 3 : : 30 Average ? X Chart UCL (X) = X + = + () = CL (X) = X = LCL (X) = X = () = Example of Computing Control Limits for X S Chart ? S Chart UCL (S) = S + = + () = CL (S) = S = LCL (S) = S = () = 21 174。LCL (X) = X = = = Computing Control limits for X S Chart S Chart 187。 Materials Quality PCS Training Rev 3 May 21 2023 Computing Control limits for X S Chart ? Compute the Overall Mean, X = (X1 + X2 + X3 ... + Xk) / k ? Compute the Average of Range, S = (S1 + S2 + S3 ... + Sk) / k ? Compute the Average of Moving Range for the mean, MRX = (MRX2 + MRX3 + MRX4 ... + MRXk) / (k 1) ? Compute the Average of Moving Range for the range, MRS = (MRS2 + MRS3 + MRS4 ... + MRSk) / (k 1) = 19 174。以抽樣的標(biāo)準(zhǔn)差描點(diǎn) 187。以抽樣的平均值描點(diǎn) 187。 Materials Quality PCS Training Rev 3 May 21 2023 Why MR Method is used to determine Control Limits for Mean Variability (Range Standard Deviation) Chart? 為什麼要使用移動(dòng)全距方法 ? ? Most batch production processes have a larger runtorun variation than withinrun variation 批量性生產(chǎn)時(shí) ,子群組間的變異大多會(huì)大於子群組內(nèi)的變異 ? Traditional control chart formulas developed in the 20?s by Walter Shewhart considerably underestimate control limits, . too narrow 傳統(tǒng)的方法將使管制界限太窄 15 174。 Materials Quality PCS Training Rev 3 May 21 2023 ? Validate the puted control limits against data collected by replotting the control chart with data new control limits – Do the limits detect known problems? – 界限可以查覺已知的問題嗎 ? – Are the limits too sensitive? Would they flag problems you do not know how to react to? – 界限是否太敏感 ? 是否有問題你不曉得如何處理 ? ? Use the control limits established to monitor the critical parameter identified ? 使用建立的管制圖來追蹤確認(rèn)重要參數(shù) ? For each parameter, every machine should have a separate control chart with separately puted control limits ? 對(duì)每一參數(shù) , 每臺(tái)機(jī)器應(yīng)有一獨(dú)立的管制圖與管制界限 How to Setup a Control Chart? (III) 12 174。 Materials Quality PCS Training Rev 3 May 21 2023 Control Chart Assumptions ? Process Stability ? 制程穩(wěn)定 – The process must be in statistical control ? Normality ? 常態(tài)分布 – The underlying process distribution is normal Note: If the assumptions are not met, the control limits calculated are misleading do not accurately indicate 3 sigma control limits. See your site statistician for advice on calculation methods when assumptions are violated. 若假設(shè)不成立 ,則管制界限將沒有意義 8 174。 Materials Quality PCS Training Rev 3 May 21 2023 What is SPC? ? Statistical 統(tǒng)計(jì) – Anything that deals with the collection, analysis, interpretation presentation of numerical data – 關(guān)於數(shù)據(jù)資料的收集 ,分析 ,解釋與表現(xiàn) – Gaining information for making informed decisions – 取得資訊來作有效的決定 ? Process 制程 – Combination of machines, tools, methods, materials people employed to attain process specification – 結(jié)合機(jī)器 ,治工具 ,方法 ,材料與人員來達(dá)到制程規(guī)格 – A similar procedure/event that is happening repetitively – 重覆發(fā)生的事件 /類似程序 ? Control 管制 – To keep something within a desired condition – 使某事 /物保持在想要的情況 – Make something behave the way we want it to behave – 使某事 /物依我們所想的來執(zhí)行 The use of statistical techniques such as control charts to analyze a process, take appropriate actions to achieve maintain a stable process, improve process capability. 4 174。174。 Materials Quality PCS Training Rev 3 May 21 2023 Contents ? Introduction 簡(jiǎn)介 – What is SPC 什麼是 SPC? – What is Stability 什麼是穩(wěn)定性 ? ? What is a Control Chart 什麼是管制圖 – How to Setup a Control Chart 如何建立管制圖 – Type of Control Charts Available 管制圖的種類 – How to Calculate the Control Limits 如何計(jì)算管制界限 – SPC Trend Rules SPC法則 – When to Revise Control Limits 何時(shí)重新計(jì)算管制界限 ? Process Capability Study 制程能力研討 – Spec limits VS Control Limits 規(guī)格界限 vs. 管制界限 – Stability VS Capability 穩(wěn)定性 vs. 能力 ? Control Chart Reduction/Elimination 減少管制圖 ? SPC Expectations 3 174。 Materials Quality PCS Training Rev 3 May 21 2023 Control Limits A typical control chart consists of three lines : 典型管制圖有三條線 : Upper Control Limit (UCL) Center Line (CL) Lower Control Limit (LCL) CL: The average (measure of location) process performance when the process is incontrol CL:制程的平均性能 UCL LCL: The range of ?usual? process performance when the process is stable. Lines drawn 3 standard deviations (3 sigma) on each side of the center line. UCL LCL: 制程穩(wěn)定情況下 , 制程性能的範(fàn)圍 7 174。 Materials Quality PCS Training Rev 3 May 21 2023 ? Compute the control limits plot them on the trend chart ? 計(jì)算管制界線並畫在圖上 ? Outliers identification exclusion ? 超出點(diǎn)的確認(rèn)與排除 – Exclude the Outof Control (OOC) points or outliers for whi