Ch. 1 Why Study
the Design Process?
MSDE324-Intermediate Design
Slide 1
KEY QUESTIONS
What can be done to design quality mechanical products on time
and within budget?
■
What are the ten key features of design best practice that will
lead to better products?
■ What are the phases of a product’s life cycle?
■ How are design problems different from analysis
problems?
■ Why is it during design, the more you know, the less design
freedom you have?
■ What are the Hanover Principles?
■
MSDE324-Intermediate Design
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1. Design Definition
▪ Design is that area of human experience, skill and
knowledge which is concerned with man’s ability to
mould his environment to suit his material and spiritual
needs.
• Design is essentially a rational, logical, sequential
process intended to solve problems or, as Jones put it:
• Initiate change in man-made things.
• Design could be viewed as an activity that translates an
idea into a blueprint for something useful, whether it's a
car, a building, a graphic, a service or a process.
MSDE324-Intermediate Design
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• The important part is the translation of the
idea, though design's ability to spark the
idea in the first place shouldn't be
overlooked
• Mechanical Design Process is focused on
design any types of object and techniques to
be applied to the design of any types of
mechanical objects
MSDE324-Intermediate Design
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Design Ability
• Because of the nature of design problems, designers tend to be
‘solution-focused’ (whereas scientists tend to be ‘problemfocused’).
• Designers actively manage and control the process of design.
Experienced designers
Novice designers
Make rapid, controlled exploration
of the problem
Can become ‘bogged down’
in data gathering and analysis
Move between solution concepts
and problem exploration
Can become ‘fixated’ on an early
solution concept
Maintain a broad view across
several sub-solution alternatives
Can concentrate on exploring
single sub-solutions in depth
Make designing look easy and
‘intuitive’
Need to practice and develop
basic techniques
MSDE324-Intermediate Design
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Why is Design Process important ?
• Continuous need for new, cost-effective, high quality
products
• Team work of more people from diverse expertise to
satisfy customer’s need.
• Global market fosters the needs to develop new products at
a very rapid and accelerating pace. → “requiring efficient
new product development”
• Poor design → 85% problems of new products due to not
working properly, taking too long to bring market, and
costing too much.
ex) mobile phone design → every three month
MSDE324-Intermediate Design
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2.Factors for Success or Failure of a Product
• Product design
• Business
• Production
These three factors are organized into three ovals as shown in Fig. 1.1.
– Product design →product function (form, materials, manufacturing
processes)
• Form →product’s architecture, its shape, its color, its texture, other
factors to structure
• Materials and Manufacturing process to produce products
– Business →product form and function →make money →sales forecasts
• What it does and how it looks.
• Sales is related to promotion, distribution, and price.
– Production systems depend on product function.
• Cost and price of product
MSDE324-Intermediate Design
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Business
Target
market
Promotion
Sales forecast
Product
form
Distribution
coverage
Price
Product
function
Manufacturing
processes
Materials
Cost/risk
Product design
Production
system
Production
Planning/
sourcing
Facilities
Production
MSDE324-Intermediate Design
Slide 8
1.2 Measuring the Design Process with
Product Cost, Quality, and Time to Market
• effective measures of design process-product cost, quality, and time to
market
–
Customers and management want cheaper, better, and faster.
ex1) Manufacturing cost of Ford Motor Company in Fig. 1.2
–
Design cost = 5% of manufacturing cost: small portion of manufacturing cost
ex2)The effect of design on manufacturing cost (Fig. 1.3)
• Effect of quality of design on manufacturing cost is greater than 5%.
• The design process can change the manufacturing cost by 50% (Xerox)or up to 75%.
Fig. 1.2
30%
15%
5%
Overhead
Design
Material
Labor
50%
MSDE324-Intermediate Design
Slide 9
The decisions made during the design process have a great
effect on the cost of product but cost very little
MSDE324-Intermediate Design
Slide 10
Effect of Design
• Determine directly material used, the good
purchased, the parts, the shape of those parts,
the product sold, the price of the products, and
the sales.
MSDE324-Intermediate Design
Slide 11
Design Process on Cost
(Xerox)
• 1960-1970: share market #1
• 1980: loose market significantly
– Japanese parts are 50% less than American or
European parts due to
• 10% material cost
• 15% process cost
• 25% the rest
• Product cost is committed early in the design
process and spent late in the process
MSDE324-Intermediate Design
Slide 12
Conceptual
design
80
Specification
development
60
40
Product
design
Percen tage of product cost committed
100
Cost incurred
20
0
Time
Figure 1.4 Manufacturing cost commitment during design.
Cost incurred=amount of money spent on the design of product
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What affects product quality?
*Quality is a composite of factors that are the
responsibility of the design engineer. (Table 1.1)
*Most important quality measures is “works as it should”.
*‘incorporate latest technology’, ‘has many features’ are
all measures of product function.
*‘Last a long time’ and other quality measures depends
on forms, materials, and manufacturing processes.
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Importance of Design
• Fallout from assembly line means components don’t meet
production specification, out of the design specification.
– Components that do not fit are poorly designed.
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Design changes
Company A
Company B
Begin
design
Figure
Release for
production
Time
Engineering changes during automobile development.
MSDE324-Intermediate Design
Slide 16
• Company B are for US automobile manufacturer.
• Company A is for Toyota.
• Changes occurring late in the design process are more
expensive than those occurring earlier.
• The curve B shows the company still designing the automobile
as it was being sold as a product.
• This causes tooling and assembly-line changes during
production and the possibility of recalling cars for retrofit,
both of which would necessitate significant expense, to say
nothing about the loss of customer confidence.
MSDE324-Intermediate Design
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• Design affects time to produce a new
product in addition to cost and quality.
Changes occurring late in the design process
more expensive than those occurring earlier.
• Design Axiom: Fail early, Fail often.
• Changes are required for a good design and
earlier changes are easier and less expensive
than changes made later.
• Designers cost little, their impact on
product cost, great.
MSDE324-Intermediate Design
Slide 18
10
9
8
7
6
5
4
3
2
1
0
//
Number of components per thousand
30
//
1981 1982 1983 1984 1985 1986 1989 1995
Figure Line fallout at Xerox.
MSDE324-Intermediate Design
Slide 19
Design effect on competitiveness in
market
• Xerox and Caterpillar reduced cycle of new
product development.
• Increasing quality and lowering costs can go
hand in hand.
MSDE324-Intermediate Design
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1. 3 The History of The Design Process
•
•
In simpler times, one person could design and manufacture an entire
product. →managing all the aspects of the design and
construction of the product.
By the middle of 20C-products and manufacturing processes are so
complex.
→ Different group people are responsible for marketing, design,
manufacturing , and overall management (Fig. 1.6)
Customers
Marketing
MSDE324-Intermediate Design
Engineering
design
Production
Slide 21
→ Single directional over-the-wall design method approach is
inefficient and costly and may result in poor quality products
→ In the late 1970 and early 1980, concept of simultaneous
engineering began to break the wall
-simultaneous development of manufacturing
process with the evolution of product
-manufacturing engineer to be the design team for
continuous interaction with design engineers
during the design process
•
•
•
•
Simultaneous engineering → concurrent engineering(1980)
In 1990, Integrated product and process design (IPPD)
Concurrent engineering is 80% company culture and only
20% computer support.
Six Sigma focuses on quality, developed by Motorola in 1980
MSDE324-Intermediate Design
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DFSS is a collection of design best practices
• Six Sigma uses statistical methods to account for and manage product
manufacturing uncertainty and variation.
• Key to Six Sigma methodology is the five-step DMAIC process (Define,
Measure, Analyze, Improve, and Control).
• Six Sigma brought improved quality to manufactured products. However,
quality begins in the design of products, and processes, not in their
manufacture.
• Recognizing this, the Six Sigma community began to emphasize quality
earlier in the product development cycle, evolving DFSS (Design for Six
Sigma) in the late 1990s.
MSDE324-Intermediate Design
Slide 23
Table 1.2 The ten key features of design best practice
1. Focus on the entire product life (Chap. 1)
2. Use and support of design teams (Chap. 3)
3. Realization that the processes are as important as the product (Chaps. 1 and 4)
4. Attention to planning for information-centered tasks (Chap. 4)
5. Careful product requirements development (Chap. 5)
6. Encouragement of multiple concept generation and evaluation (Chaps. 6 and 7)
7. Awareness of the decision-making process (Chap. 8)
8. Attention to designing in quality during every phase of the design process
(throughout)
9. Concurrent development of product and manufacturing process (Chaps. 9–12)
10. Emphasis on communication of the right information to the right people at the right
time (throughout and in Section 1.4.)
MSDE324-Intermediate Design
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1.4 The life of a Product
• Every product has a life history.(four phases)
Product development→ production and delivery→ product’s
use→ product after no longer useful
• The design process not only gives birth to product but is also
responsible for its life and death.
• In 1980, environmental issue started
• In the 1990s, some European countries have enacted
legislation that makes the original manufacturer responsible
for collecting and reusing or recycling its product when no
longer useful.
MSDE324-Intermediate Design
Slide 25
Product
development
Production
And delivery
Identify need
Manufacture
Plan for the
Design process
Assemble
Develop engineering
Specification
Distribute
Develop concepts
Install
Develop product
Use
End of life
Use
Operate in sequence 1
.
.
Operate in sequence N
Retire
Disassemble
Clean
Reuse or recycle
Maintain
Diagnose
Test
Repair
Figure 1.7 The life of a product.
MSDE324-Intermediate Design
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MSDE324-Intermediate Design
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5.The Many Solutions for Design Problems
EX1) What size SAE grade 5 should be used to fasten together two pieces of 1045
sheet steel, each 4 mm thick and 6cm wide, which are lapped over each other and
loaded with 100N?
EX2)Design a joint to fasten together two pieces of 1045 sheet steel, each 4mm thick
and 6 cmwide, which are lapped over each other and loaded with 100N?
Figure 1.9 A simple lap joint
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Instruction from the examples
• Difference between two examples due to Opening
clauses and the second one is easier than the first one
• Need more information on joint
• Ex 1describes the analysis problem requiring the
correct formula and right values (only one solution)
• Ex 2 describes a design problem, which ill –defined
in that problem statement does not give all the
information needed to find the solution. (if not
impossible for the best solution)
• All design problems are ill-defined.
• Design problems have many satisfactory
solutions and no clear best solution.
MSDE324-Intermediate Design
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The goal in design is to find a good solution that leads to a
quality product with the least commitment of time and other
resources.
•
•
•
Knowledge for design: Engineering physics and other technical areas and through
the observation of existing products
Design solution must a piece of working hardware-product.
A designer must develop a machine that, by definition, has the capabilities to meet
some need that is not fully defined.
Design process
Knowledge
Resulting
products
that meet
the need
Design
need
Design process paths
Physics
Materials
Electric
science
motors
Engineering
Thermodynamics
science Manufacturing
Welding processes Engineering
economics
design
Kinematics Pumps
Figure 1.10
Domain
knowledge
The many results of the design process.
MSDE324-Intermediate Design
Slide 30
1.6 The basic actions of problem solving
1. Establish the need or realize that there is a problem
to be solved
2. Plan how to solve the problem
3. Understand the problem by developing
requirements and uncovering existing solutions for
similar problems
4. Generate alternative solutions
5. Evaluate the alternatives by comparing them to the
design requirements and to each other
6. Decide on acceptable solutions
7. Communicate the results
MSDE324-Intermediate Design
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Communicate the results
■ New needs are established throughout the design effort because new design
problems arise as the product evolves. Details not addressed early in the process
must be dealt with as they arise; thus, the design of these details poses new
subproblems.
■ Planning occurs mainly at the beginning of a project. Plans are always updated
because understanding is improved as the process progresses.
■ Formal efforts to understand new design problems continue throughout the process.
Each new subproblem requires new understanding.
■ There are two distinct modes of generation: concept generation and product
generation. The techniques used in these two actions differ.
■ Evaluation techniques also depend on the design phase; there are differ- ences
between the evaluation techniques used for concepts and those used for products.
■ It is difficult to make decisions, as each decision requires a commitment based on
incomplete evaluation. Additionally, since most design problems are solved by
teams, a decision requires consensus, which is often difficult to obtain.
■ Communication of the information developed to others on the design team and to
management is an essential part of concurrent engineering.
MSDE324-Intermediate Design
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1.7 Knowledge and Learning During Design
• A design paradox: The more you learn the less freedom you have to use
what you know.
• The goal during the design process is to learn as much about the evolving
product as early as possible in the design process because during the early
phases changes are least expensive.
100
Percentage
80
Knowledge about
The design problem
60
40
Design
freedom
20
0
Time into design process
Figure 1.11 The design process paradox.
MSDE324-Intermediate Design
Slide 33
1.8 Design for Sustainability(DFS)
• design engineers have much control over what
products are designed and how they interact with the
earth over their lifetime. (developed in EXPO 2000)
: Design for the Environment(DFE)
• “Meeting the needs of the present without
compromising the ability of future generations to
meet their own needs.”
• You are responsible for the impact of your products
on others.
• The design process not only gives birth to a product
but is also responsible for its life and death.
MSDE324-Intermediate Design
Slide 34
The Hannover Principles
1.
2.
3.
4.
5.
6.
7.
8.
9.
Insist on rights of humanity and nature to coexist in a healthy,
supportive, diverse, and sustainable condition.
Recognize interdependence.
Accept responsibility for the consequences of design
Create safe objects of long-term value.
Create safe objects of long-term value.
Rely on natural energy flows.
Understand the limitations of design.
Seek constant improvement by the sharing of knowledge.
Respect relationships between spirit and matter.
MSDE324-Intermediate Design
Slide 35
EXERCISES
• 1.2 Identify the basic problem-solving actions
for
a. Selecting a new car
b. Finding an item in a grocery store
c. Installing a wall-mounted bookshelf
d. Placing a piece in a puzzle
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MSDE324-Intermediate Design
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