SPC统计高级教程(4个共)4.ppt

1、SPC-advanced training courseX-R 控制图控制图SPC-advanced training course過程控制過程控制a) 計算及繪畫控制限- 樣本容量低於7時，極差並沒有LCLSPC-advanced training courseU CLLCLAvgU CLLCLAvgChange in levelChange in variabilitySPC-advanced training course解釋控制圖解釋控制圖 - 確定是否有不受控的情況確定是否有不受控的情況 - 檢查過程記錄，找出並列明任何特殊原因。檢查過程記錄，找出並列明任何特殊原因。 - 再計算控制

2、限。再計算控制限。控制上限控制上限(UCL)中線中線控制下限控制下限 (LCL)控制上限控制上限 (UCL)中線中線控制下限控制下限 (LCL)受控過程不受擯過程SPC-advanced training courseUCLLCLAABCCBUCLLCLAABCCBUCLLCLAABCCBUCLLCLAABCCBTest 1. One Point Beyond Zone ATest 2. Nine Points in a Row on One Side of the Center LineTest 3. Six Points in a Row Steadily Increasing or De

3、creasingTest 4. Fourteen Points in a Row Alternating Up and DownxxxxxxSPC-advanced training courseUCLLCLAABCCBUCLLCLAABCCBUCLLCLAABCCBUCLLCLAABCCBTest 5. Two Out of Three Points in a Row in Zone A or BeyondTest 6. Four Out of Five Points in a Row in Zone B and BeyondTest 7. Fifteen Points in a Row i

4、n Zone C (Above and Below Centerline)Test 8. Eight Points in a Row on Both Sides of Centerline with None in Zone CxxxxxxxSPC-advanced training courseUCLLCLAABCCBOne point above UCLTwo out of three successive point here or aboveFour out of five successive point here or aboveSeven out of eight success

5、ive point here or aboveOne point above LCLTwo out of three successive point here or bellowFour out of five successive point here or bellowSeven out of eight successive point here or bellow3s s2s s1s s-3s s-2s s-1s s034.1%13.6%34.1%13.6%2.2%2.2%0.1%0.1%SPC-advanced training course20100Observation Num

6、berUCLLCL201 00Observation NumberUCLLCLSeasonal Trends:These could be caused by systematic changes like: temperature, operator fatigue, voltage or pressure fluctuations, etc.Mixtures:A clear indication is when most of the points are close to the control limits, and almost no points near the center l

7、ine. These are usually due to underestimating the process variability or “over-control” , where operators intervene with the process frequently trying to respond to inherent variability instead of assignable causes. This also occurs when controlling two processes on the same chart.SPC-advanced train

8、ing course201 00Observation NumberUCLLCL1 51 050Observation NumberUCLLCLChanges in process means:These are usually due to the introduction of new operators, machines, procedures, etc. Can also happen because of process improvements. Upward/Downward Trends:Continuous trending on the same direction. T

9、hese are usually caused by component wear among others. SPC-advanced training course20100Observation NumberUCLLCL“White Space”:Points tend to cluster around the mean. Usually caused by: (1) incorrect control limits (overestimating process variability), (2) continuous improvements paying-off. Limits should be recalculated when this situation is found.SPC-advanced training course製製 程程 控控 制制 對特殊原因採取的措施