DeGarmo's Materials and Processes in Manufacturing
12th Edition
ISBN: 9781118987674
Author: J. T. Black, Ronald A. Kohser
Publisher: WILEY
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Textbook Question
Chapter 12, Problem 18RQ
In a sigma chart, are σ values for the samples normally distributed about
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The data shown in Table 1 are the deviations from nominal diameter for holes drilled in a
carbon-fiber composite material used in aerospace manufacturing. The values reported are
deviations from nominal in ten-thousandths of an inch.
(a) Set up and R charts on the process. Is the process in statistical control?
(b) Estimate the process standard deviation using the range method.
(c) If specifications are at nominal ±100, what can you say about the capability of this
process? Calculate the PCR Cp
Table 1. Hole Diameter Data
Sample
Number X1 X2
1
2
3
4
5
6
7
8
9
10
11
12
14
15
16
17
18
19
20
-30 +50
0
-50
-10 -10
+20
-40
0
0
-30
0
+20
0
0
+70
0
+10
+40
+30
+30
+30
+10
0
+20
+50
+50
-20
+50 -60
+10
0
0
+20
+10 -20
-10
0
+20
X3 X4 X5
-30
+20
+30
+50
+40
+20
+30
+20
+30
+20
+30
0
+20
+10 +40
+10 +10
-10 +50
-10 -30
-10
+50
+40
0
+30
-10
0
+30
+30
-20
+50 +30 +10
+40
+20
0 +30
+10 +30
-20 +30
+30
+20
-20 +50
+20
+10
-40 +20
-20
-10
-10
0
-20
+10
+10 +50
0
+10
A student measures a quantity many times and calculates his mean as µ = 23 and his standard
deviation as σ = 1.
(a) What fraction of his readings would you expect to find between:
(i) 22 and 24?
(ii) 22.5 and 23.5?
(iii) 20 and 25?
(iv) 24 and 25?
(b) What is the probability that some of his measurements will be less than 20.6?
1. The mean and standard deviation of a process are known to be μ 200 and o = 10. Calculate
specification limits that should contain at least 99% of the population assuming:
a. Nothing is known about the distribution shape (Cheyshev).
b. The distribution is unimodal (Camp-Meidell).
c. The distribution is normal.
Chapter 12 Solutions
DeGarmo's Materials and Processes in Manufacturing
Ch. 12 - Define accuracy or precision in terms of a...Ch. 12 - What does the nature of the process refer to?Ch. 12 - Suppose you have a pistol�shooting process that...Ch. 12 - Review the steps required to make a PC study of a...Ch. 12 - Why do not standard tables exist detailing the...Ch. 12 - Here are some common, everyday processes with...Ch. 12 - Why might the diameter measurements for holes...Ch. 12 - What are some common manufactured items that may...Ch. 12 - What are common reasons for sampling inspection...Ch. 12 - Fill in this table with one of the four following...
Ch. 12 - Now explain why when we sample, we cannot avoid...Ch. 12 - Which error can lead to legal action from the...Ch. 12 - Define and explain the difference between andX and...Ch. 12 - What is Cp, and why is a value of 0.80 not good?...Ch. 12 - Prob. 15RQCh. 12 - What are some of the alternatives available to you...Ch. 12 - Cpk is another process capability index. How does...Ch. 12 - In a sigma chart, are σ values for the samples...Ch. 12 - What is an assignable cause, and how is it...Ch. 12 - Why is the range used to measure variability when...Ch. 12 - How is the standard deviation of a distribution of...Ch. 12 - In the last two decades, the quality in...Ch. 12 - Figure 12.15 shows a bimodal check sheet...Ch. 12 - Control charts use upper and lower control limits....Ch. 12 - In Figure 12.10, what are the USL and the LSL,...Ch. 12 - What are four major branches (fishbones) on a...Ch. 12 - How does variation in the measuring device...Ch. 12 - What are Taguchi or factorial experiments, and how...Ch. 12 - How does the Taguchi approach differ from the...Ch. 12 - Why are Taguchi experiments so important compared...Ch. 12 - Explain what happed to improve the process inÂ...Ch. 12 - In Table 12.1, explain MOâ€�COâ€�MOO....Ch. 12 - What is a quality circle, and how might you apply...Ch. 12 - Which of the seven QC tools is being used inÂ...Ch. 12 - Go to a subway restaurant and develop a process...Ch. 12 - What do you estimate the standard deviation of...Ch. 12 - Is the dashed line in the figure labeled mean the...Ch. 12 - From the information given in the discussion and...Ch. 12 - What is the most glaring error in the figure, and...
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