The document describes workable problems being developed for teaching design for manufacturability (DFM) concepts. The problems depict poorly designed products with many DFM flaws. Students review the designs, identify issues, and suggest improvements. Initial classroom use found that students enjoyed the visual puzzles. The problems helped develop skills in visual thinking and DFM principles. They also revealed gaps in students' other engineering fundamentals occasionally. The authors plan to publish a workbook with example problems to further DFM education.

1. TP05PUB233
TECHNICAL PAPER 2005 Society of Manufacturing Engineers ■ One SME Drive ■ P.O. Box 930
Workable Problems for Design for
Manufacturability and DFX Education
author(s)
ALVIN POST
THURIA NARAYAN
Arizona State University Polytechnic Campus
Mesa, Arizona
abstract
Design for manufacturability (DFM) concepts can be taught in several ways. One
approach is to provide examples of poorly designed products to students to review
and improve. Although textbook examples of DFM are abundant, relatively few workable
problems are available to instructors. A set of open-ended, workable DFM problems
is being prepared at Arizona State University with support from the Society of
Manufacturing Engineers. This article describes the exercises and observations from
their initial classroom use.
conference
CIMEC (CIRP) 2005/3RD SME INTERNATIONAL CONFERENCE
ON MANUFACTURING EDUCATION
June 22-25, 2005
San Luis Obispo, California
terms
Design for Manufacturability
Design for Excellence
Design Education
Dearborn, MI 48121 ■ Phone (313) 271-1500 ■ www.sme.org

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This Technical Paper may not be reproduced in whole or in
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herein.

3. WORKABLE PROBLEMS FOR DESIGN FOR MANUFACTURABILITY
AND DFX EDUCATION
Alvin Post and Thuria Narayan
Department of Mechanical and Manufacturing Engineering Technology
Arizona State University Polytechnic Campus
Mesa, Arizona
KEYWORDS
DFM, DFX, Design education
ABSTRACT
Design for manufacturability (DFM) concepts
can be taught in several ways. One approach is
to provide examples of poorly designed products
to students to review and improve. Although
textbook examples of DFM are abundant,
relatively few workable problems are available to
instructors. A set of open-ended, workable DFM
problems is being prepared at Arizona State
University with support from the Society of
Manufacturing Engineers. This article describes
the exercises and observations from their initial
classroom use.
INTRODUCTION
Product and process design is identified as a
key competency for manufacturing engineers by
the Society of Manufacturing Engineers (SME).
Design for manufacturability (DFM) and related
topics such as design for serviceability, often
referred to collectively as DFX, are important
components of this competency. A modest
number of textbooks and reference books
devoted to DFX are available (Andreasen 1983,
Bakerjian 1992, Boothroyd 1997, Bralla 1995
and 1998, Nikkan Kogyo Shimbun Ltd, 1988),
and case studies or before-and-after examples
are often used as a pedagogical tool in the
classroom. However, the number of examples is
limited, and in most cases examples consist of a
poor design side by side with an improved
design. As useful as these are, they do not
afford an opportunity for students to think
through designs on their own. It may be useful to
have a selection of unsolved DFX problems for
students to work through. An effort is underway
at Arizona State University East's Mechanical
and Manufacturing Engineering Department to
prepare a set of such exercises, as a small part
of a larger SME Manufacturing Education Plan
grant.
DFX EXERCISES
These exercises consist of depictions of
familiar assemblies – a flashlight, a fan, etc. –
that are deliberately drawn to show poor DFX
practices. Each drawing has many DFM/DFX
flaws. These are open-ended design problems
for which many different solutions exist. After
introduction of DFX principles, an instructor can
work through an example with student
participation. Students can then be given a

4. different example, and asked to identify the DFX
weaknesses or suggest improvements, by
making brief annotations on the drawings.
FIGURE 1. A SAMPLE DFX PROBLEM, A POORLY
DESIGNED FLASHLIGHT.
In Figure 1, there are perhaps a dozen design
flaws, ranging from unnecessary parts to
inefficient use of the design flexibility offered by
molding processes. Drawings like this will likely
include a few additional notes or part names.
ADDED EDUCATIONAL BENEFITS
In addition to the practice these exercises
provide for DFX, they can also help students
develop their ability to visualize and work with
complex 3-D geometries. Many of the examples
have molded or cast parts, and creative use of
the flexibility that comes with these additive
technologies can often improve the product
design.
GRADING
The focus is on correct responses – grading
can be as simple as placing a checkmark next to
each appropriate annotation, and totaling up the
number of checkmarks. The highest number of
checkmarks in a class can be the criterion for a
100% score. Good design often emerges from a
collection of newly generated ideas, many of
which are discarded along the way. In an effort
to encourage the free thinking and creativity
necessary for good design, it is suggested that
incorrect responses be overlooked; no grading
penalty need be imposed.
OBSERVATIONS FROM INITIAL
CLASSROOM USE
The authors have informally used a few
samples to teach or test DFX skills in design
classes. As suggested above, DFX principles
were introduced first, and the instructor then
worked through an example in class, beginning
with suggestions solicited from students. Later, a
different problem was given as a quiz. The
authors have done this in several design project
classes with a total of perhaps 200 students.
There is a fairly wide spread in scores,
suggesting that some DFX training is needed to
do well on these exercises, and common sense
alone is insufficient. Students seem to enjoy the
problems more than standard written ones,
perhaps because they involve visual thinking
instead of verbal thinking, or because grading
rewards come from their correct responses,
without penalty for the poor ones. The problems
are certainly more like a puzzle than typical
college exercises, and so provide a welcome
change of pace. They seem to be fun.
The exercises occasionally turn up some
unexpected weaknesses in the students'
educations. For example, in an example
consisting of a mechanism inside a copy
machine, a wire is shown screwed to a sheet
metal plate at the top of the picture, with the
label "ground wire". Surprisingly, 10-15% of the
mechanical students solving this problem, at two
very different institutions, note that the wire
should be placed "at the bottom" instead of the
top, because it's a "ground" wire. Similar
misunderstandings were observed for other
electrical basics, prompting the instructor to
begin with more basic concepts when presenting
material about electrical fundamentals.
CONCLUSION
Workable graphic DFX problems are being
prepared for student use with the assistance of
the SME Education Foundation. The examples
2

5. will consist of poor designs relative to
manufacturability and assemblability , although a
few well-designed devices may be included for
reference. A workbook of such problems, with
some summarized DFX guidelines, may be
available in the future. Preliminary versions of
these open-ended problems were well received
by students. Although quantitative evidence of
educational effectiveness has not been
documented, practice with these problems is
expected to improve DFX skills.
REFERENCES
Andreasen, M., Kahler, S., and Lund, T., (1983),
Design for Assembly, IFS Publications Ltd., U.K.
Bakerjian, R., (1992) Tool and Manufacturing
Engineering Handbook (vol 6) Design for
Manufacturability, Fourth Edition, Mc Graw-Hill
Book Co.
Boothroyd, G., Dewhurst, P., and Knight, W.
(1997), Product Design for Manufacture and
Assembly, Marcel Dekker, New York.
Bralla, J.G., (1998), Design for Manufacturability
Handbook, McGraw-Hill, New York.
Bralla, J.G., (1995), Design for Excellence, New
McGraw-Hill, New York.
Nikkan Kogyo Shimbun, Ltd., Ed. (1988) Poka-
Yoke, Productivity, Inc.
AUTHORS’ BIOGRAPHIES
Alvin Post, Ph.D., P.E., received a doctorate in
mechanical engineering from the University of
Hawaii. He has extensive industrial experience
as a machine design engineer.
Thuria Narayan received a Bachelors degree in
Mechatronics engineering from Bharathiar
University, Tamilnadu, India in 2004 and is
currently pursuing a masters degree in the
Mechanical and Manufacturing Engineering
Department at Arizona State University. Her
areas of interest are design and automation.
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