Parts manufactured by an injection molding process are

1
EMIS 5364/STAT 5344 Homework 12
Injection Molding
Parts manufactured by an injection molding
process are subjected to a compressive strength
test. Twenty samples of five parts are collected,
and the compressive strengths (in psi) are shown
in the following table.
2
EMIS 5364/STAT 5344 Homework 12
Injection Molding
Sample x1 x2 x3 x4 x5 1 83.0 81.2 78.7 75.7 77
.0 2 88.6 78.3 78.8 71.0 84.2 3 85.7 75.8 84.3
75.2 81.0 4 80.8 74.4 82.5 74.1 75.7 5 83.4 7
8.4 82.6 78.2 78.9 6 75.3 79.9 87.3 89.7 87.8 7
74.5 78.0 80.8 73.4 79.7 8 79.2 84.4 81.5 86.0
74.5 9 80.5 86.2 76.2 64.1 80.2 10 75.7 75.2
71.1 82.1 74.3 11 80.0 81.5 78.4 73.8 78.1 12
80.6 81.8 79.3 73.8 81.7 13 82.7 81.3 79.1 82.0
79.5 14 79.2 74.9 78.6 77.7 75.3 15 85.5 82.1
82.8 79.4 71.7 16 78.8 79.6 80.2 79.1 80.8 17
82.1 78.2 75.5 78.2 82.1 18 84.5 76.9 83.5 81.2
79.2 19 79.0 77.8 81.2 84.4 81.6 20 84.5 73.1
78.6 78.7 80.6
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EMIS 5364/STAT 5344 Homework 12
Injection Molding
(a) Establish x and R control charts for
compressive strength using these data. Is the
process in statistical control? (b) After
establishing the control charts in part a, 15
new subgroups were collected (Production Data)
and the compressive strengths are shown next.
Plot the x and R values against the control
limits from part a and draw conclusions.
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EMIS 5364/STAT 5344 Homework 12
Injection Molding
Production Data
Sample x1 x2 x3 x4 x5 1 68.9 81.5 78.2 80.8 8
1.5 2 69.8 68.6 80.4 84.3 83.9 3 78.5 85.2 78.
4 80.3 81.7 4 76.9 86.1 86.9 94.4 83.9 5 93.6
81.6 87.8 79.6 71.0 6 65.5 86.8 72.4 82.6 71.4
7 78.1 65.7 83.7 93.7 93.4 8 74.9 72.6 81.6 87.
2 72.7 9 78.1 77.1 67.0 75.7 76.8 10 78.7 85.4
77.7 90.7 76.7 11 85.0 60.2 68.5 71.1 82.4 12
86.4 79.2 79.8 96.0 75.4 13 78.5 99.0 78.3 71.4
81.8 14 68.8 62.0 82.0 77.5 76.1 15 83.0 83.7
73.1 82.2 95.3