【正文】 174。 Materials Quality PCS Training Rev 3 May 21 2022 Module 3: Statistical Process Control (SPC) Methodology 174。 Materials Quality PCS Training Rev 3 May 21 2022 2 PCS Elements Create Measurement Plan Establish Monitor (SPC) Implement Response Flow Checklist (RFC) Element 1 Element 2 Element 3 174。 Materials Quality PCS Training Rev 3 May 21 2022 3 Contents ? Introduction 簡介 – 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 如何計算管制界限 – SPC Trend Rules SPC法則 – When to Revise Control Limits 何時重新計算管制界限 ? 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 174。 Materials Quality PCS Training Rev 3 May 21 2022 4 What is SPC? ? Statistical 統(tǒng)計 – Anything that deals with the collection, analysis, interpretation amp。 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 amp。 people employed to attain process specification – 結(jié)合機器 ,治工具 ,方法 ,材料與人員來達到制程規(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 amp。 maintain a stable process, amp。 improve process capability. 174。 Materials Quality PCS Training Rev 3 May 21 2022 5 What is Stability? ? A process is said to be Stable if it has the following properties: ? 下列特性稱為穩(wěn)定 : – Pattern appears random 隨機出現(xiàn) – Constant process mean 平均值一定 – Uniform variability over time 變異程度不隨時間改變 – No trends, runs, shifts, erratic ups amp。 downs 不會偏向一邊 ? Important for many reasons: ? 穩(wěn)定性為何重要 ? – Increased productivity of engineering amp。 manufacturing personnel – 提高生產(chǎn)性 – Predictable, repeatable results within a specified range – 結(jié)果有重覆性 ,可預測 174。 Materials Quality PCS Training Rev 3 May 21 2022 6 What is a Control Chart? ? A trend chart with control limits ? 有管制界限的趨勢圖 ? Graphical representation of process performance, where data is collected at regular time sequence of production ? 數(shù)據(jù)依生產(chǎn)順序定時間收集 ,以圖表表現(xiàn)制程性能 ? Valuable tool for differentiating between mon cause and special cause variation ? 將一般變異與特殊變異區(qū)分開的有用工具 ? Evaluating whether a process is or is not in a state of statistical control ? 評估制程是否在統(tǒng)計管制中 ? It lets the data ?talk? by itself amp。 basis for datadriven decisions ? 讓數(shù)據(jù)說話並依數(shù)據(jù)導向作決定 174。 Materials Quality PCS Training Rev 3 May 21 2022 7 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 amp。 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 amp。 LCL: 制程穩(wěn)定情況下 , 制程性能的範圍 174。 Materials Quality PCS Training Rev 3 May 21 2022 8 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 amp。 do not accurately indicate 3 sigma control limits. See your site statistician for advice on calculation methods when assumptions are violated. 若假設不成立 ,則管制界限將沒有意義 174。 Materials Quality PCS Training Rev 3 May 21 2022 9 Test for Control Chart Assumptions 假設 ? Process Stability (no outliers) 穩(wěn)定性 – Screen out outliers from the database before puting final control limits by using a control chart. Any point beyond either control limit is an outlier. Report number of outliers screened. 計算管制界限前 ,將超出點排除 . 所有超出管制界限的點都是 outlier ? Normality 常態(tài)性 – Plot a normal probability plot of the data or overlay a normal curve over the histogram. Normally distributed data will roughly fall on a straight line. – Test for normality by using ShapiroWilk W test in JMP – 用 JMP W test 來計算常態(tài)性 174。 Materials Quality PCS Training Rev 3 May 21 2022 10 ? Select appropriate type of control chart to be used ? 選擇合適的管制圖型態(tài) ? Gather data to establish the control chart. ? 收集數(shù)據(jù)建立管制圖 – A minimum of 30 subgroups is required over a time frame as determined by the sampling plan. – 抽樣計劃至少收集 30組數(shù)據(jù) ? Plot the data in time order on a Trend Chart ? 依序在趨勢圖上描點 How to Setup a Control Chart? (I) 174。 Materials Quality PCS Training Rev 3 May 21 2022 11 ? Compute the control limits amp。 plot them on the trend chart ? 計算管制界線並畫在圖上 ? Outliers identification amp。 exclusion ? 超出點的確認與排除 – Exclude the Outof Control (OOC) points or outliers for which there are verified/confirmed special causes from the chart – 由於顯示是特殊原因造成故將排除超出點 – Repute the control limits, excluding the OOC points – 重新計算管制界限 – If there are fewer than 30 points remaining at any time, collect more data. It?s very important that the control limits are calculated using at least 30 subgroups. – 若資料點少於 30再繼續(xù)收集 . 這是很重要的 How to Setup a Control Chart? (II) Note: Refer to Appendix A for Control Charts for Limited Production, . 30 subgroups. 174。 Materials Quality PCS Training Rev 3 May 21 2022 12 ? Validate the puted control limits against data collected by replotting the control