The basic steps of drawing control chart1, Collecting data and groupingDatas are collected from the production processafter 5MIE are fully fixed and standardized.As for mean control chart,when the sample size nof each group is less than or equal to 10, in general,group number k is equal or greater than 25.2007.4CThe first step26
2007.4 The first step 1、Collecting data and grouping Datas are collected from the production process after 5MIE are fully fixed and standardized. The basic steps of drawing control chart As for mean control chart,when the sample size n of each group is less than or equal to 10, in general, group number k is equal or greater than 25. 26
Measured valueAverageRangeDatXnXiXiX2RiSample ID1X11XInX12….2X21X22X2n…..kXk1Xk2Xkn.2007.4GData sheet27
Data sheet 2007.4 Sample I D Measured value Average Range X X . X X R x x x x x x k x x x 1 2 n i i 11 12 1n 21 22 2n k 1 k 2 k n 1 . 2 . . . . . Dat a 27
2, Calculating the sample average and samplerange of each groupn2i=1,2,....,kx.iinj=1R, = max(xi jminxij1≤j≤n≤j<n2007.4The second step28
T 2007.4 he second step 2、Calculating the sample average and sample range of each group = = n j i i j x n x 1 1 i =1,2,.,k i j j n i j j n i R x x = − 1 1 max min 28
3, Calculating average sample mean and averagesample range of the total sample groupk>Xxn=1kI2R=R;k12007.4The third step29
The third step 2007.4 3、Calculating average sample mean and average sample range of the total sample group = = k i i x n X 1 1 = = k i Ri k R 1 1 29
4, Calculating control limitUCL = D4RUCL = x+ A,RRchart3 CL = RxchartCL = xLCL=x-A,RLCL = D,R<0Numerical tables of coefficient A(n)2356478910n1.8810.5771.0230.7290.4830.4190.3730.3370.308A(n)D3(n)0.0760.1360.3370.3082.2822.1153.2672.5752.0041.9241.8641.8161.777D4(n)2007.4GThe fourth step30
The fourth step 2007.4 4、Calculating control limit n 2 3 4 5 6 7 8 9 10 A(n) 1.881 1.023 0.729 0.577 0.483 0.419 0.373 0.337 0.308 D3(n) 0.076 0.136 0.337 0.308 D4(n) 3.267 2.575 2.282 2.115 2.004 1.924 1.864 1.816 1.777 Numerical tables of coefficient A(n) = − = = + LCL x A R CL x UCL x A R xc 2 2 hart = = = 0 hart 3 4 LCL D R CL R UCL D R Rc 30