Assignment:
A Lean Six Sigma black belt project results in a lower defective rate at the final inspection of a plastic molded component. Thirty days of data presented in the following table.
(a) Create the appropriate control chart for the improved process. Apply only Western Electric runs rule 1 for determining non-random patterns. Assume any p estimate that violates Western Electric runs rule 1 has an assignable cause, omit it from the next control limit estimate, and repeat this process plotting a control chart until all p estimates are in control.
(b) Based on the characteristics of the Phase 1 control chart, discuss the design of a control chart for Phase 2 future production.
|
Day
|
Units
Inspected
|
Units
Defective
|
Day
|
Units
Inspected
|
Units
Defective
|
|
1
|
200
|
7
|
16
|
100
|
0
|
|
2
|
150
|
1
|
17
|
200
|
6
|
|
3
|
250
|
7
|
18
|
200
|
3
|
|
4
|
150
|
1
|
19
|
200
|
8
|
|
5
|
200
|
4
|
20
|
200
|
5
|
|
6
|
200
|
4
|
21
|
200
|
5
|
|
7
|
250
|
8
|
22
|
100
|
1
|
|
8
|
150
|
1
|
23
|
250
|
8
|
|
9
|
250
|
7
|
24
|
200
|
3
|
|
10
|
150
|
3
|
25
|
100
|
1
|
|
11
|
100
|
0
|
26
|
200
|
4
|
|
12
|
250
|
6
|
27
|
250
|
8
|
|
13
|
200
|
4
|
28
|
250
|
5
|
|
14
|
100
|
0
|
29
|
150
|
10
|
|
15
|
250
|
7
|
30
|
250
|
5
|