Control - Casio fx-7400G PLUS Booklet

Q-2 Component Quality Variation Control (X-R Control Chart)
Use the values in the data sheet to determine the mean (X) and range (R) for each of the data
groups. Next, use the X control chart coefficient table below to determine the A
coefficients in accordance with the number of measured values in each group (sample size n).
Using these coefficients, determine the upper control limit (UCL) and lower control limit (LCL) for
the mean value (X) and range (R) as shown below, and create the control chart.
X Control Chart Coefficient Table
X Control Chart
*X is the mean of the mean values (X)
R Control Chart
[Calculation]
1897.978
X = ––––––––– = 75.919,
25
A = 0.58, D = 2.11 (For sample size n = 5).
2 4
X Control Chart
R Control Chart
Sample Size n
2
3
4
5
6
7
8
9
10
UCL = X + A • R, LCL = X – A
2
.
UCL = D • R, LCL = D
4
2.09
R = ––––– = 0.084
25
UCL = 75.919 + 0.58 × 0.084 = 75.967
LCL = 75.919 – 0.58 × 0.084 = 75.870
UCL = 2.11 × 0.084 = 0.177
A D
2 3
1.88 — — —
1.02 — — —
0.73 — — —
0.58 — — —
0.48 — — —
0.42 0.08
0.37 0.14
0.34 0.18
0.31 0.22
• R
2
• R
3
– 61 –
, D , and D
2 3
D
4
3.27
2.57
2.28
2.11
2.00
1.92
1.86
1.82
1.78
4