【正文】 ch 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. 11 174。s mon to have single measurement spaced time apart Control Charts For Variables 計量型 每次量測費時或昂貴 ,使同一段時間內(nèi)量測多次不適當(dāng) 每次量測值都非常相近 ,同一段時間內(nèi)量測多次 14 174。 Plots the mean of the X values in the sample 187。 Plots the standard deviation of a sample 187。 Materials Quality PCS Training Rev 3 May 21 2023 Computing Control Limits for X S Chart ? Obtain at least k = 30 subgroups ? 獲得至少 30組子群組 ? Compute the Mean for each subgroup of size n ? 計算每子群組 (個數(shù) n)的平均值 ? Compute the Standard Deviation for each subgroup ? 計算每子群組 (個數(shù) n)的標(biāo)準差 ? Compute the Moving Range for each subgroup mean, MRXi = | Xi Xi1 | ? 計算每子群組平均值的移動全距 ? Compute the Moving Range for each subgroup range, MRSi = | Si Si1 | ? 計算每子群組標(biāo)準差的移動全距 18 174。CL (X) = X 187。LCL (S) = S 20 174。 Materials Quality PCS Training Rev 3 May 21 2023 Exercise 1 Open the dataset . Compute the XS control limits using JMP for lead width. What are the control limits? Is the process stable? 24 174。 Materials Quality PCS Training Rev 3 May 21 2023 p Chart Concept ? It plots proportion of defective units in a sample ? 每一抽樣點是以不良率來描點 ? The proportion of defective units in a sample can be in terms of fraction, percent or dpm ? 不良的比率可以是分數(shù) ,%,dpm來表示 ? It allows us to chart production processes where sample size cannot be equal ? 不同的抽樣數(shù)是允許的 28 174。LCL (p) = p ? When LCL 0, put LCL = 0 or N/A ? Draw the control limits on p chart 29 174。 Materials Quality PCS Training Rev 3 May 21 2023 Interpretation of p Chart Some special causes affecting the p Chart: 超出管制界限的原因 : ? Changes in variable data specifications ? 規(guī)格變更 ? Changes in inspection procedures ? 檢驗方法變更 ? Changes in technician skills, . new technicians ? 測試員變更 ? Changes in pieceparts quality ? 零件品質(zhì)變更 33 174。 Materials Quality PCS Training Rev 3 May 21 2023 sigma方法計算管制界限 ? N = the number of lots, ? = the mean from the ith lot (i = 1,2,...,N), ? = the mean of the lot means, ? = the standard deviation of the lot means, where xiSxxxNiiN? ??1? ?Sx xNxiiN????? 211UCL x S x? ? 3CL x?LC L x S x? ? 3Compute the control limits using: 36 174。 Materials Quality PCS Training Rev 3 May 21 2023 SPC Trend Rules Rule 2: 9 consecutive points on the same side of the centerline 規(guī)則 2: 連續(xù) 9點在中心線同側(cè) Uses: Detects small shifts or trends 用途 : 察覺微小 /趨勢性的偏差 False alarm rate: % 機率 :% Example: UCL CL LCL 40 174。 Materials Quality PCS Training Rev 3 May 21 2023 SPC Trend Rules Rule 6: 4 out of 5 consecutive points on the chart are more than 1 std dev away from the CL 規(guī)則 6: 連續(xù)同側(cè) 5點中 ,4點超出 1標(biāo)準差 Uses: Detects moderatesized changes 用途 : 察覺中度改變 False alarm rate: % 機率 : % Example: 44 174。 Materials Quality PCS Training Rev 3 May 21 2023 Trend Rule Remendations 建議 ? All control charts should at least use the 1st rule: – Point UCL or Point LCL ? 至少須使用第 1 條 ? For an automated SPC system with automated application of SPC trend rules, it?s highly remended to add 5th rule to detect large shifts in mean, (. 2 out of 3 rule) ? 若 spc系統(tǒng)是自動的 ,非常建議增加第 5 條 ? Add other rules depending upon – process knowledge – ability to respond – criticality of the monitor – sensitivity requirements for the monitor ? Intel does remend as a goal to use rules 1, 2, 5, 6 when appropriate ? Intel建議使用 1, 2, 5, 6 條 48 174。 Materials Quality PCS Training Rev 3 May 21 2023 When to Revise Control Limits? Control limits should be reviewed periodically (monthly or quarterly) offline to assess if they need updating. A minimum of 30 data points are needed before recalculating control limits. 應(yīng)定期 (月 ,季 )審查管制表來確定是否須要更新 . 重新計算前須至少收集 30數(shù)據(jù)點 Repute control limits when – a significant process change is implemented – current control limits too wide or too narrow 重新計算管制界限 – 制程重大改變 – 管制界限太寬或太窄 52 174。 Materials Quality PCS Training Rev 3 May 21 2023 Process Capability 200 400 600 800 1000 1300 10 30 50 LSL USL 25 50 75 50 150 250 350 LSL USL ? Process capability is the ability of a process to meet specifications. A process must be stable before its capability can be puted. Not Capable Capable ? A capability index is a statistic that quantifies describes the capability of a process 56 174。 Materials Quality PCS Training Rev 3 May 21 2023 Control Limits ? Calculated from data, based on actual process performance ? Describe the natural range of performance of a stable process ? Describe the amount of natural process variation ? Used to determine process stability 58 174。 Materials Quality PCS Training Rev 3 May 21 2023 0 2 4 6 8 0 20 40 60 80 100 120 140 160 180 200 spec spec control control Interpretation : Y/N _____Stable _____Capable Interpretation : Y/N _____Stable _____Capable Exercise 3 0 2 4 6 8 0 20 40 60 80 100 120 140 160 180 200 spec spec control control 62 174。 Materials Quality PCS Training Rev 3 May 21 2023 C p k = 0 . 7 .C p k = 1 . 0 .C p k = 1 . 3 .? The value of Cpk is affected by: – where the process is centered – process variation ? The higher the Cpk value, the bette