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Chapter 3: Quality Design & Control
1. Consider the design of a typical household refrigerator. Identify three different ways the
system may fail. What are three possible effects of each failure?
A. A typical household refrigerator, like many other common items in any home, is
many up of multiple parts and components. Being an item that is constantly in use
system failures can be quite common, such as frayed cabling, refrigerant leakage,
and compressor motor failures. While these everyday issues do not seem like a
big deal, for firms in the industry it can make or break increasing revenues and
economic profit. Lack of control or the lack of ensuring conformance to the
requirements while maintaining stable performance, is not only the cause of
customer dissatisfaction, but it can lead to lasting effects to a firm’s bottom line.
Frayed cabling can cause one’s refrigerator to stop working, which can then lead
to all of the owner’s food to become rotten. The rotten food will then have to be
thrown out and possibly hundreds of dollars will be going into the trash leaving
the company with one very unhappy customer or worse having that customer
happy with another firm. The refrigerant leak can not only stop your refrigerator
from cooling, but lead to the extra cost of having a repair service come out to fix
it, and in the meantime where would all that food go to stay fresh and not rot.
Lastly, a compressor motor failure usually happens when one of two things occur;
first, is because the compressor is too old and it is at the end of its useful life.
Second, is due to it overheating, which is caused by over stuffing or heavy usage.
Besides customer dissatisfaction, lack of control can lead to extra costs to the
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firm; for example, if they need to repair the refrigerator if it’s under warrantee,
and there are shipping costs, as well as labor costs associated with having the
firm’s employees work on repairs instead of being efficient elsewhere and
working on new refrigerators to be sold to continue making profit.
2. Identify five examples of poke-yoke in everyday products.
A. Poke-yoke originally designed by a Japanese manufacturing engineer named
Shigeo Shingo; is an approach for mistake proofing processes using automatic
devices or methods for avoiding simple human error. Poke-yoke can be broken
down into two aspects: prediction and recognizing that a defeat is about to occur
and providing that with a warning or detection. The Toyota Company has a great
system, which represents poke-yoke or Lean Philosophy; a poke-yoke device or
method just makes a mistake more impossible to happen in the first place, instead
of producing a defeat, detecting it, and then fixing it or throwing it out. The
automobile industry is a great example of how the concept of poke-yoke is
brought to life through radar and video cameras in newer models of cars, which
help with preventing collusions. Another concept is the automatic breaking
system, which stops the car if the brakes fail when an obstacle comes into the
driver’s way without enough time to take proper action. Airbags are a lifesaving
poke-yoke that can prevent death of the driver / passenger if they were to get into
a severe accident; EBS also is another example, which distributes the braking
power evenly, and minimizes uneven tear of the discs. Lastly, the seat belt is a
poke-yoke that assist in holding the passengers in place in case of a car accident.
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3. The following chart identifies 10 samples, in order, from the bottle station #2 of Tipsy
Vineyards Cabernet Sauvignon. The target level is 750ml, with a UCL=760ML and a
LCL=740ml.
A.
B. Did defects occur?
According to the upper and lower control levels there was one
sample that was outside of those levels, which was sample #7, 761ml.
C. Is there only “normal cause” variation or is there evidence of “special cause”
variation.
The common cause variation are all the samples within the two
control limits, but if a point falls outside of the control limits or if unusual
patterns such as shifts up or down, tends up or down, cycles, etc. those are
due to special causes. As mentioned in the previous question sample #7 is
725
730
735
740
745
750
755
760
765
1 2 3 4 5 6 7 8 9 10
Tipsy Vineyards:Bottle Station #2
Sample Measure
Mean (UL)
UCL
LCL
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the only sample outside of the limits and I believe it is due to special cause
variation.
D. In general terms, what should be done to improve the process?
There are several ways to make improvements on a process such as
enhancing value to the customer through new and improved products and
services; improving productivity and operational performance through
better work processes and reductions in errors, defeats, and waste;
improve flexibility, responsiveness, and cycle time performance; and
improve organizational management processes through learning.
Chapter 4: Quality Improvement
1. Check Sheet: Design and complete a check sheet identifying the types of interruptions
that occur when working on a project like this. How could such a sheet help you in
class?
Types of Interuptions Thursday Friday Sunday Total
Television | | 2
Phone Calls || ||| 5
Dragon City App || ||| | 6
Youtube Videos ||| |||| |||| 12
Facebook Logons ||| |||| ||||| 13
Work Activities ||||||| |||||| 15
Interactions with People |||| ||||||| ||| 16
Text Messages |||||||| ||||||||| |||| 25
Total 33 41 20 94
Interuptions When Working On A Project
Performance Survey
Cheek Sheet
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Measurement Materials Method
Environment Manpower Machine
Patient Late for
Appointment
Problem
Statement
Car stops
Call AAA
Wait for AAA
AAA fix Car
Babysitter
Cancelled
Wait for Him /
Her
Bad Roads
Slow Driving
Make Calls
Talk on Phone
Get a Sitter
Find Proper
Directions
Get back on
Route
Bad Weather
(Snow)
Traffic
Car Broke
Down
Rusty Pipes
Find a New
Sitter
Put Gas in Car
Drive to
Appointment
Took New Root/
Got Lost
Ran Out of Gas
Car Stops
Call for Help
Wait for Help
Didn't follow
Directions
Didn't know
new Area
Wrong time
Misses
Appoinment
Gets Call from
the Office
Get Ready
Leave House or
Location
Wrote Wrong
Time
This tool is great for gathering / analyzing data, it is simple to understand, and
can minimize the chances of error, or in this case the chance of getting
distracted. A check sheet is great for a classroom situations; a student would
be able to keep track on the lesson plan for that day, minimize the chance of
forgetting about a quiz or test, as well as, minimize the chance of having to do
a homework assignment or a project last minute, etc.
2. Construct a cause-and-effect diagram for patients being late for their appointments.
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3. Given the list of exams grades on Page 2, construct a Histogram. What does the
distribution tell you about the population?
A left skew means that the distribution is negatively skewed, this usually
means that all the collected data have a value less than 100. This also shows
that majority of the students performed very well on the exam because the
lower grades have the fewest about of students with those grades and the
majority of students have a grade within the higher intervals.
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Chapter 5: Quality Management and Planning
1. Draw an affinity diagram for the cause-and-effect diagram above
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2. Draw a tree diagram based on your affinity diagram that will help to operationally
alleviate the problem.
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Work Cited
Evans, James R. Quality & Performance Excellence. 6th ed. N.p.: Cengage Learning,
2011. Print.
Gitachu, David. "Poke Yoke Examples : Error-Proofing in Manufacturing & Daily Life."
HubPages. HubPages, n.d. Web. 17 Feb. 2015. <http://gitachud.hubpages.com/hub/Poka-
Yokemistakeproofing>.
Greg. "Poka-Yoke You Can't Go Wrong." The Toyota System RSS. The Toyota System,
12 May 2009. Web. 17 Feb. 2015.
"Learn About Quality." Quality Tools. ASQ, n.d. Web. 17 Feb. 2015.
<http://asq.org/learn-about-quality/quality-tools.html>.
