【正文】 Treatment of OOC Points ? The corresponding equipment shall be shutdown ? 相關(guān)的設(shè)備應(yīng)停機(jī) – if the OOC situations cannot be solved nonconforming parts are produced –假如失控點(diǎn)情況無(wú)法解決 不合格品被產(chǎn)生 – per control chart RFC ? If any individual data values falls outside the process specification limits, then disposition the affected material per the requirements specified in the respective process specification or put the material onhold for engineering disposition. 51 174。 Materials Quality PCS Training Rev 3 May 21 2023 Given example: UCLcurrent = LCLcurrent = Newly collected data resulted the following: UCLcalc = LCLcalc = ?runrun(calc) = MR / 3 = / 3 = UCL Change Ratio= (UCLcalc UCLcurrent) / ?runrun(calc) = LCL Change Ratio = (LCLcurrent LCLcalc) / ?runrun(calc) = = Indicates a need to change the current control limits! Change Ratio Example 174。 Historical data identifying inline or EOL problems ? Used to determine process capability 57 174。 Materials Quality PCS Training Rev 3 May 21 2023 Exercise 3 0 20 40 60 80 100 120 140 160 180 200 0 2 4 6 8 spec spec control control 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 61 174。 Materials Quality PCS Training Rev 3 May 21 2023 LSL USL A B Tail Closer to Spec Limit Cpk = B/A A = 3s B = LSL x ? Cpk pares the upper half of the distribution to the upper spec lower half of the distribution to the lower spec Measuring Process Capability: Cpk 65 174。 Materials Quality PCS Training Rev 3 May 21 2023 Measuring Process Capability ? A minimum of 30 data points are needed before calculating process capability indices ? Always use a histogram or with specification limits to visually represent the process distribution capability 63 174。 Materials Quality PCS Training Rev 3 May 21 2023 Spec Limits vs. Control Limits Spec Limits ? Based on performance required of the product ? What the customer wants “what we want” ? Tells us when to disposition the product/material ? Apply only to individual (raw) data values Control Limits ? Based on actual historical process performance ? What the process delivers “what we get” ? Tells us when to take action on the process/equipment ? Apply to summary statistics (. : Xbar, std dev, range, etc. charts) Never use spec limits on a control chart! 59 174。 Materials Quality PCS Training Rev 3 May 21 2023 Specification Limits ? The region where product is known to function well in terms of performance, yield, reliability, or other desired oute – Acceptable range of values for a product parameter – Define what is acceptable/unacceptable product ? Determined by – Design requirements simulation models – Engineering judgement (typically product eng. integration) – Customer agreement/requirements – Data driven validation: 187。 Materials Quality PCS Training Rev 3 May 21 2023 Change Ratio ? A change ratio may be utilized to detect when the current limits may be inappropriate 可以計(jì)算 change Ratio 來(lái)判斷目前管制界限是否合適 LCL Change Ratio = (LCLcurrent LCLcalc) / ?runrun(calc) UCL Change Ratio = (UCLcalc UCLcurrent) / ?runrun(calc) ? A large negative change ratio suggests tightening a control limit 若負(fù)值很大 ,建議縮小管制界限 ? A large positive change ratio suggests widening the control limit 若正值很大 ,建議放寬管制界限 Note: ?runrun(calc) = / 3 53 174。 Materials Quality PCS Training Rev 3 May 21 2023 Trend Rule Remendations ? Only use the trend rules that signal process instabilities for which you are capable of responding ? 在你有能力反應(yīng)處理的不穩(wěn)定制程 ,才使用趨勢(shì)規(guī)則 ? Justification needed for not using other SPC trend rules ? Std dev range charts may choose not to react to Point LCL, however a LCL on these charts can be valuable for detecting metrology problems or unexpected process improvement ? 若點(diǎn) LCL可能被認(rèn)為不須要處理 ,然而這些點(diǎn)卻可以告訴我們察覺(jué)儀器量測(cè)問(wèn)題或非預(yù)期性的制程改善 49 174。 Materials Quality PCS Training Rev 3 May 21 2023 SPC Trend Rules Rule 7: 15 (or more) consecutive points are within 1 std dev of the CL 規(guī)則 7: 連續(xù) 15點(diǎn)在 1標(biāo)準(zhǔn)差內(nèi) Uses: Detects a decrease in process variation 用途 : 察覺(jué)制程變異的降低 Example: 45 174。 Materials Quality PCS Training Rev 3 May 21 2023 SPC Trend Rules Rule 3: 6 consecutive points steadily increasing or Decreasing 規(guī)則 3: 連續(xù) 6點(diǎn)持續(xù)上升或下降 Uses: Detects strong trends 用途 : 察覺(jué)強(qiáng)烈趨勢(shì) Example: UCL CL LCL 41 174。 Materials Quality PCS Training Rev 3 May 21 2023 Control Chart Trend Rules 趨勢(shì)規(guī)則 Purpose: ? Improve the responsiveness of the control chart ? 增進(jìn)管制圖的反應(yīng) ? Detect more subtle shifts in the process more quickly ? 更快地察覺(jué)制程中細(xì)微的變化 ? Detect irregularities beyond normal 3? that indicate nonrandomness in process ? 察覺(jué)在正常 3? 界限內(nèi)的非隨機(jī)性變化 37 174。 Materials Quality PCS Training Rev 3 May 21 2023 Ti m eDataC o ns e c u t iv e l ot sa re v e ry s imi l a rLo t s far a par t ma ybe v e ry dif f e re nt? Timerelated condition where consecutive data values are correlated (. dependent) 連貫的數(shù)據(jù)有關(guān)連性 ? Data values collected nearby in time are very similar 鄰近時(shí)間的數(shù)據(jù)非常相似 ? Data values collected far apart in time may be very different 較久時(shí)間的數(shù)據(jù)差異大 ? Tend to drift over time。 Materials Quality PCS Training Rev 3 May 21 2023 Notes : ? The MRMethod describes how the control limits are calculated assuming equal (or nearequal) sample sizes. If the sample sizes vary by more than 50 % of each other, you should consult a statistician. ? MRMethod的管制線(xiàn)是假設(shè)抽樣數(shù)相同的情況下得出的 . 若抽樣數(shù)差異超過(guò) 50%時(shí) ,則須請(qǐng)較統(tǒng)計(jì)學(xué)家 . ? np Chart is applicable when all subgroups have constant sample sizes. In terms of practicali