SPC-ADVANCED80-92（PPT 12页）.ppt

1、X-R 控制图,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LCL,解释控制图,Change in level,Change in variability,解釋控制圖,- 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。 - 再計算控制限。,控制上限,(UCL),控制下限,(LCL),控制上限,(UCL),控制下限,(LCL),受控過程,不受擯過程,Test 1. One Point Beyond Zone A,Test 2. Nine Points in a Row on One Side of the Center Line,Test 3. Six P

2、oints in a Row Steadily Increasing or Decreasing,Test 4. Fourteen Points in a Row Alternating Up and Down,x,x,x,x,x,x,控制图失控检验,Test 5. Two Out of Three Points in a Row in Zone A or Beyond,Test 6. Four Out of Five Points in a Row in Zone B and Beyond,Test 7. Fifteen Points in a Row in Zone C (Above an

3、d Below Centerline),Test 8. Eight Points in a Row on Both Sides of Centerline with None in Zone C,x,x,x,x,x,x,x,控制图的失控检验,控制图失控检验,One point above UCL,Two out of three successive point here or above,Four out of five successive point here or above,Seven out of eight successive point here or above,One p

4、oint above LCL,Two out of three successive point here or bellow,Four out of five successive point here or bellow,Seven out of eight successive point here or bellow,3s,2s,1s,-3s,-2s,-1s,0,34.1%,13.6%,34.1%,13.6%,2.2%,2.2%,0.1%,0.1%,Seasonal Trends: These could be caused by systematic changes like: te

5、mperature, 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 line. These are usually due to underestimating the process variability or “over-control” , where operators

6、 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.,控制图的趋势判断规则,Changes in process means: These are usually due to the introduction of new operators, machines, procedures, etc

7、. Can also happen because of process improvements.,Upward/Downward Trends: Continuous trending on the same direction. These are usually caused by component wear among others.,控制图的趋势判断规则,“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.,控制图的趋势判断规则,製 程 控 制,對特殊原因採取的措施 1.即時