you are a third year technical apprentice and you have been asked by y
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You are a third year technical apprentice and you have been asked by your supervisor to contribute to
the quality standards for particular products because your company feel that they need to develop their
quality processes. The company feel that using statistics will enable them to enhance the quality of
their product and so they are considering statistics to examine processes and wish you to evaluate
what is available and then to apply the best methods to a particular product. The company produce a small component that has a hole in it that is critical and checked with a plug
gauge. The company produce these in batches of 50 and initially carries out 100% inspection. The
company are concerned that the process is not in control and have asked you to investigate.
Table One gives the defects for 50 batches which you need to use to produce attribute control charts,
np and p charts.
Table Two gives the next 100 batches. You are expected to:
1. construct the control charts np and p using table one,
2. document your research into ways in which the data can be used to inform the company about
the process;
3. determine the extent that the process is under control using that data in table two
The tables on following pages give the actual sizes of the diameter "A" and length "B" of a stud that the
company produces on one of their CNC machines.
Design statistical variable control charts involving the mean and range, X and R charts for diameter A.
The measurements were taken in batches of 5 and recorded on the table as 1-5 first batch, 6-10 second
batch etc. Use the first 50 entries [10 batches] to do this.
1. construct the control charts X and R using this data,
2. document your research into ways in which the data can be used to inform the company about
the process;
3. determine the extent that the process is under control using the rest of the data in the table for
diameter A, remember these are in batches of 5.
Using the data in the table for the length B of the stud produce:
1. a statistical process capability chart for length B for the first 100 studs.
2. an evaluation regarding the machine's capability based on a calculation of Cp and Cpk for the
length of the stud, and how the process can be improved.
3. produce a modified control chart and plot the rest of the data from the table for the length B of
the stud
Produce a report that includes:
An evaluation of the use of the statistical methods possible and how they have influenced the
design and successful use of process control charts.
A Process Capability Study based on your outcomes from the data used from the table for the
length B of the stud.
The size for dimension A is 12.5mm ±0.3. The sizes given in the table are in millimetres. The size for
dimension B is 20.2mm ±0.2. The sizes given in the table are in millimetres. Table One
Batch
Batch
Number Output
100
100
100
1
2 3 4 5 6 7 8 9 23
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
Batch
Defects
17
19
11
3
2
17
15
13
14
5
2NFRAREamonn Hagang
12
19
14
18
17
14
20
20
15
19
16
14
11
9
3
6
5
20
20
17
5
18
8
4
6
18
17
7
11
9
19
19
20
7
5
9
7
20 Table Two
Batch
Number
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
Batch
Output
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
Batch Defects
19
20
12
15
12
18
17
15
18
15
19
11
4
12
11
3
17
5
13
15
17
7
10
14
17
5
15
11
4
11
4
14
16
11
14
2
16
6
12
16
9
10
16
9
3
13
15
13
15
8
Batch Number
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
Batch
Output
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
106
107
109
111
104
110
103
108
112
111
106
107
109
111
104
110
103
108
112
111
106
107
119
111
104
110
113
108
112
111
Batch Defects
2
10
21
13
3
3
6
2
10
5
14
12
14
16
7
14
6
2
9
19
8
14
12
17
13
13
9
18
18
5
7
17
12
16
12
13
9
12
18
5
8
14
12
17
18
17
9
18
17
6 TABLE 3
Dimension A
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
0 u 2 3 44 45 46 47 48 49 50
40
41
42
43
12.488
12.685
12.636
12.448
12.470
12.381
12.383
12.403
12.611
12.520
12.666
12.404
12.627
12.580
12.414
12.636
12.538
12.553
12.424
12.681
12.365
12.675
12.413
12.624
12.617
12.324
12.537
12.446
12.610
12.622
12.370
12.499
12.342
12.515
12.573
12.444
12.348
12.553
12.359
12.365
12.652
12.359
12.522
12.362
12.643
12.348
12.423
12.432
12.603
12.696
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
12.613
12.678
12.475
12.643
12.539
12.669
12.699
12.410
12.551
12.612
12.390
12.520
12.697
12.324
12.429
12.405
12.587
12.545
12.441
12.402
12.390
12.708
12.355
12.357
12.528
12.534
12.693
12.353
12.714
12.459
12.490
12.496
12.611
12.476
12.510
12.403
12.629
12.518
12.551
12.492
12.366
12.496
12.506
12.364
12.403
12.692
12.343
12.627
12.581
12.412
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
12.717
12.618
12.359
12.453
12.383
12.663
12.345
12.391
12.696
12.501
12.383
12.409
12.606
12.591
12.604
12.668
12.658
12.521
12.466
12.458
12.389
12.408
12.506
12.447
12.555
12.441
12.447
12.484
12.595
12.467
12.612
12.432
12.636
12.570
12.404
12.401
12.516
12.401
12.330
12.647
12.351
12.660
12.625
12.487
12.692
12.711
12.388
12.543
12.343
12.551
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
12.358
12.437
12.699
12.570
12.565
12.628
12.469
12.451
12.582
12.355
12.611
12.542
12.707
12.652
12.498
12.657
12.646
12.559
12.551
12.699
12.495
12.365
12.602
12.613
12.445
12.488
12.702
12.489
12.525
12.355
12.355
12.359
12.557
12.471
12.550
12.585
12.592
12.572
12.349
12.478
12.582
12.731
12.685
12.533
12.520
12.422
12.654
12.693
12.663
12.709
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
12.359
12.711
12.617
12.719
12.444
12.397
12.730
12.692
12.413
12.474
12.537
12.527
12.646
12.467
12.601
12.549
12.395
12.671
12.474
12.556
12.385
12.515
12.391
12.468
12.542
12.496
12.536
12.389
12.491
12.372
12.584
12.623
12.426
12.559
12.677
12.475
12.628
12.579
12.457
12.383
12.663
12.462
12.493
12.536
12.607
12.569
12.609
12.675
12.450
12.719