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Chapter 12
Managing Production Operations
DISCUSSION QUESTIONS
12-1. Q: Distinguish between quality of design and quality of conformance.
A: Quality of design measures the extent to which fitness for use is incorporated into the
12-2. Q: Research to find out why 6σ methods allow for a 1.5 σ shift in the mean when
determining process performance? Does this make the organization to appear to perform
better than the customer is experiencing?
12-3. Q: (a) In your School of Engineering, determine which engineering curricula require a course
in statistics, and estimate the proportion of engineers that graduate literate in statistics or (b)
survey engineers and other employees in your company to estimate how many were trained
in statistics in school or on the job.
A: Answers will vary, but should lead to discussion. Part of the goal of discussion is the
12-4. Q: Distinguish between the statistics of attributes and the statistics of variables, and
comment on how they are applied in process control charts and in sampling.
12–5
Q: The involvement of production workers in quality circles seems to conflict with the
concept of Frederick W. Taylor, founder of scientific management, that managers should
define how work is to be done and workers simply perform as they are instructed and trained.
Comment.
A: Taylor’s failure to involve the ideas of workers in developing better methods for them to
do their jobs is the largest single criticism of his work, and stems apparently from his
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No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher.
12–6
Q: State the essence of Taguchi’s teaching.
A: The commentary on Taguchi in the text is an oversimplification of his teaching. However,
12-7. Q: Examine Deming’s 14 points and select three or four you consider most effective in
assuring product quality. Explain your reasoning.
12-8. Q: What do you see as some of the organizational changes that have occurred as quality has
matured into the twenty-first century? Answers could include some of the following:
A: ISO 900 series of quality management standards was revised to increase emphasis on
12-9. Q: For most of the middle of this century U.S. factories were the most productive in the
world. What has happened to change this?
A: Volumes have been written on why the U.S. has lost its productivity advantage. Tables
12-2 and 12-3 simply show that manufacturing output per labor hour increased in Japan and
Western Europe far faster from 1960–1985 than it did in the United States, although
12-10. Q: Distinguish between the methods used in (a) time study of existing tasks, (b) time study
of proposed new tasks, and (c) work sampling.
A: (a,b) The classical time study method involves taking a task currently being done,
breaking it into elements, and taking time measurements of a typical employee doing the
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No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher.
12-11. Q: Identify three types of maintenance and distinguish between them.
A: Corrective maintenance is repair work undertaken because of breakdown or failure.
12-12. Q: Discuss how Total Productive Maintenance relates to other concepts developed in this
chapter.
12-13. Q: Where might engineering knowledge and skills be valuable in each of the following
functions: (a) human resources management, (b) purchasing, and (c) other materials
management activities?
A: (a) Engineering talents are valuable in the human resources management tasks of
relate to the production process.
PROBLEMS
12-1. Q: Tomatoes are packaged in a can designed to hold a nominal 28 ounces of product. Five
cans sampled randomly were found to contain 28.3, 27.3, 29.1, 28.5, and 27.8 ounces of
product. Calculate the mean value and range of sample data, and (b) calculate the variance
and standard deviation of the sample.
A: (a) As shown in the table below, the mean is Σx/n = 141.0/n = 28.2, and the range is (29.1
– 27.3 =) 1.8.
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No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher.
12-2. Q: An ‘x–bar’ control chart is developed for recording the mean value of a quality
characteristic using a sample size of three. The control chart has control limits (LCL and
UCL) of 1.000 and 1.020 pounds respectively. If a new sample of three items has weights of
1.023, 0.999, and 1.025, what can we say about the lot (batch) it came from?
12-3. Q: The specification limits for the length of a meter stick are 1000 { 0.5 mm. To understand
if the manufacturing process is in control, once every hour the lengths of five meter sticks are
measured. Samples from the last 16 hours of production are provided in the table below.
a. Construct an appropriate control chart. Does the process appear to be in control?
b. Does the process appear to be meeting customer specifications?
c. What is (are) your recommended action(s) for this process?
A. a)
x-bar-bar
r-bar
999.69
0.61
UCL
1000.05
1.30
LCL
999.34
0.00
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No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher.
b) No, the process is not centered at the customer’s specifications and the variability is
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
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r chart
Range Upper Limit R-bar Lower Limit