Page 108 - Six Sigma for electronics design and manufacturing

Six Sigma and Manufacturing Control Systems
Parts
Sample
Average
X
1
4
2
3
R
no.
5
14
11
11.50
12
12
16
12.50
7
9
11
11
2
9
10.25
10
12.25
12
3
11
12
14
14.00
12
16
14
14
4
15
10
19
13
14.25
9
4
7 1 2 3 4 5 6 13 9 Table 3.2 Control chart limit calculations example Range 77
13
12.50
10
14
13
8 18 11 14 11 13.50 7
9 13 13 11 12 12.25 2
10 12 10 14 12 12.00 4
11 13 10 14 17 13.50 7
12 13 15 10 10 12.00 5
13 16 10 10 11 11.75 6
14 15 15 13 14 14.25 2
15 16 10 14 15 13.75 6
16 12 11 14 9 11.50 5
17 14 10 13 11 12.00 4
18 11 16 13 14 13.50 5
19 12 10 12 13 11.75 3
20 13 10 10 11 11.00 3
21 14 14 10 13 12.75 4
22 13 13 9 10 11.25 4
23 13 13 13 17 14.00 4
24 15 12 15 13 13.75 3
25 15 12 15 13 13.75 3
Totals 315.50 111
The averages of X and R are calculated by dividing the column to-
tals of X and R by the number of subgroups.
– –
X = (SUM OF X s)/number of subgroups
– –
X = 315.50/25 = 12.62
R = (SUM OF R’s)/number of subgroups
R = 111/25 = 4.44
Using the control chart (Table 3.1), the control limits can be calcu-
lated using n = 4 as follows:
X Control limits
– –
UCL x = X + A 2 R = 12.62 + 0.73 · 4.44 = 15.86