Design and Engineering class notes for KTU students

Design and Engineering
Dr A Selvakumar M Tech MBA Phd

Module 1
Design Process:- Introduction to Design and Engineering Design, Defining a Design
Process-:Detailing Customer Requirements, Setting Design Objectives, Identifying Constraints,
Establishing Functions, Generating Design Alternatives and Choosing a Design.
Module 2
Design Thinking Approach:-Introduction to Design Thinking, Iterative Design Thinking
Process Stages: Empathize, Define, Ideate, Prototype and Test. Design Thinking as Divergent-
Convergent Questioning. Design Thinking in a Team Environment.
Module 3
Design Communication (Languages of Engineering Design):-Communicating Designs Graphically,
Communicating Designs Orally and in Writing. Mathematical Modeling In Design, Prototyping and
Proofing the Design.
Module 4
Design Engineering Concepts:-Project-based Learning and Problem-based Learning in
Design.Modular Design and
Life Cycle Design Approaches. Application of Biomimicry,Aesthetics and Ergonomics in Design. Value
Engineering, Concurrent Engineering, and Reverse Engineering in Design.
Module 5
Expediency, Economics and Environment in Design Engineering:-Design for Production, Use, and
Sustainability.
Engineering Economics in Design. Design Rights. Ethics in Design
SYLLABUS CREDITS:2

Assessment Pattern
Continuous Internal Evaluation (CIE) Pattern:
Attendance : 10 marks
Continuous Assessment Test (2 numbers) : 25 marks
Assignment/Quiz/Course project : 15 marks
End Semester Examination (ESE) Pattern:
There will be two parts; Part A and Part B.
Part A : 30 marks
part B : 70 marks
Part A contains 10 questions with 2 questions from each module, having 3 marks for each
question. Students should answer all questions.
Part B contains 2 case study questions from each module of which student should answer any
one. Each question carry 14 marks and can have maximum 2 sub questions.

Engineering Design: Definition
Accreditation Board for Engineering and Technology (ABET).
• The ABET definition states that engineering design is the
process of devising a system, component, or process to meet
desired needs.
• It is a decision-making process (often iterative), in which
the basic sciences, mathematics, and engineering sciences
are applied to optimally convert resources to meet a
stated objective.
Among the fundamental elements of the design process is
• the establishment of objectives and criteria,
• synthesis,
• analysis,
• construction,
• testing, and
• evaluation.
Design is the process of
conceiving and planning that
does not exist.

1. Adaptive design:
Adaptation of existing designs
 development has practically ceased
 minor modifications
Design activity of this kind demands no special knowledge or skill, and
the problems presented are easily solved by a designer with ordinary
technical training.
Example
a) Elevator: which has remained
conceptually for some time now.
the same technically and
a) Washing machine: This has been based on the same conceptual
design for the last several years and varies in only a few
parameters, such as its dimensions, materials, and detailed power
specification
DESIGN LEVELS

DESIGN LEVELS
2. Development design:
 Considerably more scientific training and design ability
are
needed for development design.
 The designer starts from an existing design, but the
final outcome may differ markedly from the initial product.
Examples of this development could be
• from a manual gearbox in a car to an automatic one and
• from the traditional tube-based television to the
modern plasma and LCD versions.

DESIGN LEVELS
3. New design:
• Only a small number of designs are new designs.
• This is possibly the most difficult level in that generating a
new concept involves mastering all the previous skills in
addition to creativity and imagination, insight, and
foresight.
Examples of this are
• the design of the first automobile, airplane, or even the
wheel (a long time ago).
List the entirely new designs which have been
introduced over the last decade.

• Social Media
• Space X
• Bit Coin
• Capsule endoscopy
• Block chain technology
• Mobile OS
• 3D printing
• Drone
• Electric cars

DESIGN CHALLENGES
Design is scientific and creative process: Albert Einstein asserted that imagination is more important than
knowledge, for knowledge is finite whereas imagination is infinite.
No matter how good the manufacturing, production, sales, etc. are, if a product is poorly
designed, the end product still will be a bad idea and will ultimately fail, as no one likes to
purchase a bad idea.
The first thing that a consumer will usually look at before deciding to purchase
something is its design and ‘how it looks’.
This will be followed by the reliability and quality of the item, then by the price.
Think about how people choose to buy a coffee machine or even a mobile phone.
• Technology: Advanced brewing technology with mesh filter
• Easiness to use: High temperature Glass carafe with water level indicator
• Safety: Non slip feet - firm rubber legs for better grip on the surface
• Illuminated on/off switch
• Aesthetics
• Price

DESIGN CHALLENGES
Investing money and resources at the design stage
yields the biggest return on investment of a product.
One of the reasons for this is that changes can be
made easily at this early stage, whereas later on,
changes in the manufacturing methods and so on
could be extremely costly—both in time and money
Throughout history, humans have been
successfully designing artifacts to satisfy the
needs of civilization. History is full of great designs
and inventions. Recently, design has been driven to
meet an existing requirement, to reduce a hazard or
an inconvenience, or to develop a new approach.

Not all that engineers build has become successful; occasionally, catastrophic failures
occur. A few of the well-publicized disasters associated with engineering systems are as
follows
• The Chernobyl nuclear power plant disaster occurred in 1996. According to the World Health Organization (WHO),
this lead to the evacuation and resettlement of over 336,000 people, 56 direct deaths, 4000 thyroid cancer
cases among children, and approximately 6.6 million people highly exposed to radiation.
• The Challenger space shuttle exploded in 1986 after an O-ring seal in its right solid-rocket booster failed. This
caused a flame leak, which reached the external fuel tank. The space shuttle was destroyed in 73 seconds after
takeoff, and all crew members died.
• The loss of the cabin roof during the flight of a Boeing 737 in 1988 caused one crew member to be blown out of
the airplane. Age and the design of the aircraft, which relied on stress to be alleviated by controlled breakaway
zones, were ultimately to blame.
• A crack in an engine pylon caused the loss of an engine and the subsequent crash of a DC-10 airplane in
1979, killing 273cpeople. The design layout of the fuel tanks was the cause of the Concorde crash in 2000, killing
113 people. When the aircraft struck debris on the runway, the tire that subsequently exploded caused a
tank to rupture. The Concorde’s airworthiness certificate was revoked, and all Concorde airplanes remained grounded
for 15 months. This eventually contributed to the demise of supersonic passenger planes
DESIGN CHALLENGES

Walton lists the reason for failures in most engineering
designs:
• Poor understanding of the problem to be solved.
• Incorrect design specifications
• Faulty manufacturing and assembly
• Error in design calculations
• Incomplete experimentation and inadequate data
collection
• Errors in drawings
• Incorrect or overextended assumptions.
• Faulty reasoning from good assumptions.
DESIGN CHALLENGES

Why do many people fail at design?
One of the answers is that design is inherently difficult and a major challenge. Designers
not only have to have the creative and technical skills to develop an idea to become a
reality, but they also need to predict the future in some ways.
They need to predict each step of the product’s life from visualization to realization and finally
to the end of its life cycle and how it will be disposed of and/or recycled. This means that a
designer needs to develop a product that sponsors will like and fund (and so on and so
forth) all the way down to the distributors, vendors, users, operators, and society as a whole.
Predicting whether people will like and use a product developed by the designer
somewhat of a challenge.
It is for these reasons that the systematic design process was introduced to help guide the
designer to achieve his/her goals without hindering creativity.

To design is to create a new product that turns into profit and benefits
society in some way. The design process is a sequence of events and
a set of guidelines that helps define a clear starting point that takes
the designer from visualizing a product in his/her imagination to
realizing it in real life in a systematic manner—without hindering
their creative process.
DESIGN PROCESS
The ability to design requires both science and art.

The design of a device or system can be done in one of two ways:
1. Evolutionary change: A product is allowed to evolve over a period of time
with only slight improvement. This is done when there is no
competition. The creative capabilities of the designer are limited.
2. Innovation: Rapid scientific growth and technological discoveries
as well as competition among companies for their slice of the market
have placed a great deal of emphasis on new products, which draw
heavily on innovation. The creative skills and analytical ability of the
design engineer play an important role.
DESIGN PROCESS

The invention of the telephone was a truly innovative design.
Since its invention, many then tried to evolve and hence improve
it over many decades, but very little actually changed until the
next innovative and technological jump occurred, and that was
the mobile phone. This created a whole new market along with
new competition, and since then, this technology has
been evolving once more—every once in a while showing signs of
new innovation, such as the inclusion of cameras and video-
calling and the integration of personal digital assistant (pda),
internet access, and mp3 facilities into one device.
Proficient designers control evolution and innovation so they
occur simultaneously. Although the emphasis is on innovation,
designers must test their ideas against prior design. Engineers
can design for the future but must base results on the past.

STEP -1: Detailing Customer Requirements
1. Identify and abstract the statement of need.
2. Identify data sources for your search.
3. Further clarify the statement of need.
4. Identify Standard Industrial Classification
(SIC) codes for the industry.
5. Find what is available in the market
that may provide you with leads to produce
a better product.
6. Conduct market surveys and market
analysis for your product development
The engineer is a person who applies
scientific knowledge to satisfy
humankind’s needs.
Engineering Design Process make sure that what you are developing is
what the customer needs

Challenge: Problems are not specifically stated
• It is necessary to formulate a clear, exact statement of
the problem in engineering words and symbols.
• It is also necessary to isolate the problem form the
general situation and to delineate its form.
• This definition should clearly identify every aspect of
the problem on which attention should be
concentrated.
• The nonessential should be stripped away, and the
individual characteristics of the problem should
be differentiated.
• It should be determined whether or not the
immediate problem is part of the larger problem. If it
is, its relationship to the total part should be
determined.

PROBLEM DEFINITION: NEED STATEMENT

GATHERING INFORMATION: CLARIFYING THE NEED
The analysis requires a thorough study of the total market. This includes its trend,
competition, volume, profit, opportunities, consumer needs, and some indication of
customer feeling for the product. Market analysis must be conducted at the start
of the design process. It serves as a mechanism to define further the need
statement and provides an opportunity for designers to review other attempts at
solving the problem at hand, if they exist. Remember, the majority of designs are
development designs. Thus, knowing what others have provided as a solution is very
important before you attempt to offer your own solution.
1. Direct search: This involves obtaining information directly
from the consumer, manufacturers, salespeople, and so forth.
The information is collected by interviews and surveys.
2. Indirect search: Information is collected from public sources,
such as
patents, journal reports, government analysis, and newspapers
RELEVANT INFORMATION RESOURCES

CONDUCTING MARKET ANALYSIS
In the product development process, market research is conducted
initially to assess market potential, market segments, and product
opportunities and to provide production cost estimates and
information on product cost, sales potential, industry trends, and
customer needs and expectations. The search has the following steps:
1. Define the Problem
2. Develop a Strategy
3. Organize and check the information gathered
METHODS FOR
MARKET
SURVEY
1. Focus
group
meetings
2. Telephone
interviews

1. Define the Problem
a. Are you developing a new product or solving a problem in an existing product?
Remember, you are not providing a solution, you are redefining a problem.
b. Who are your customers, and why would they want/need to buy the product
(e.g., time saver, utility, unique value)?
c. What are the main needs of these customers?
d. In one sentence and in your own words (abstraction of the need statement),
define the problem at hand.
e. How are you goingto go about getting your product to
customers (e.g., development cost, time, manufacturing, production
investment, etc.)?
2. Develop a strategy
Write a Plan It is important to realize that the search process is not linear. For example, while
searching the business literature for information on industry trends, you may come across the text of an
interview that directly identifies some customer needs for the product under investigation. This
information can be very useful if properly contextualized. Thus, it is important to know the framework

3. Organize and check the information gathered
a. Products
i. Product names ii. Patents iii. Pricing iv. Parts breakdown v. Product features vi.
Development time.
b. Companies
i. Major players ii. Company financials for major players
• Annual reports—Yearly record of a publicly held company’s financial condition. Information
such as the company’s balance sheet, income, and cash flow statements are included.
•10K reports—This is a more detailed version of the annual report and is the official annual
business and financial report filed by public companies with the Securities and Exchange
Commission. The report contains detailed financial information, a business summary, a list
of properties, subsidiaries, legal proceedings, etc.
c. Industry
i. Trends ii. Labor costs iii. Market-size industry facts—Pieces of information gained
from various sources that help to clarify anything about the industry
d. Market information
i. Market reports ii. Market share of major companies in industry iii. Target markets
of major competitors iv. Demographics
• Age • Geographic location • Gender • Political/social/cultural factors
e. Consumer trends

NEED STATEMENT
Design and build a device/machine that will crush aluminum cans. The
device must be fully automatic (i.e., all the operator needs to do is load cans into the
device; the device should switch on automatically). The device should
automatically crush the can, eject the crushed can, and switch off (unless more cans
are loaded). The following guidelines should be adhered to.
 The device must have a continuous CAN-feeding mechanism.
 CANs should be in good condition when supplied to the device (i.e., not
dented, pressed, or slightly twisted).
 The CAN must be crushed to one-fifth of its original volume.
 The maximum dimensions of the device are not to exceed operator height .
 Performance will be based on the number of CANs crushed in one minute.
 Elementary school children (K and up) must be able to operate the device safely.
 The device must be a stand-alone unit.
 The total cost of the device should not exceed the given budget

Although the need statement is relatively clear, the design team did several
interviews with the client, asked questions, and carefully listened to the client’s
responses in order to determine the goal of the intended device. In parallel, the
design team conducted a full market survey to assess similar products as well
as to consider all the potential ‘stakeholders’ or customers. Here is a short
summary of the market analysis
Potential Customers
• Schools
• Colleges
• Hospitals
• Hotels
• Resorts
• Shopping malls
• Playgrounds and recreational areas
• Apartments, dormitories
• Sports arenas
• Office buildings
• Residential homes
MARKET RESEARCH

Companies That Have Similar Devices (Selection)
• Edlund Company, Inc. (159 Industrial Parkway, Burlington, Vermont), Mr. R. M. Olson (President)
• Prodeva Inc. (http://prodeva.com)
• Enviro-Care Kruncher Corporation (685 Rupert St., Waterloo, Ontario, N2V1N7, Canada)
• Recycling Equipment Manufacturer (6512 Napa, Spokane, Washington, 99207)
• Kelly Duplex (415 Sliger St., P.O. Box 1266, Springfield, Ohio, 45501)
• Waring Commercial (283 Main St., New Hartford, Connecticut, 06057)
• DLS Enterprises (P.O. Box 1382, Alta Loma, California, 91701
INDUSTRIAL CODES TO BE FOLLOWED : Food industry code and safety
Trends
The aluminum industry produces approximately 100 billion cans a year in the USA. This
number has been flat for the past 13 years. In 2007, 54 billion of the cans were returned for
recycling. According to the Aluminum Association, at a recycling rate of 53.8 percent, the
aluminum can is by far the most recycled beverage container in the United States.
Although this recycling figure has been rising steadily for the past six years, it actually
represents a drop in recycling rates from the previous decade (66.8% in 1997 and 62.1% in
2000), even though the same quantities were produced per year

Around 56 patents are listed for the past 15 years. A Web-based patent
search (Section 4.3.1) will show the details. Here is an example of an old design
back in 1981.
US Patent No: 4,436,026, Empty Can Crusher:2
An empty CAN crusher for crushing and flattening empty cans, comprising an
inlet, a chute, a stopper device, a pressing device and a forked chute.Empty cans
supplied in the crusher are crushed and flattened by the pressing device and are
sorted into aluminium cans and steel cans by means of a magnet embedded in the
pressing device, which fall down into respective receptacles through the forked
Chute.
PATENTS

 A WATER PURIFIER
1) AN AUTOMOBILE SHOW ROOM
2) WATER HEATER
3) STAPLER
4) WET GRINDER
5) LADDER
6) COFFEE VENDING MACHINE
7) MOBILE PHONE
8) PORTABLE FM RADIO
9) TABLE FAN
10) WHEEL CHAIR
11) PUNCHING MACHINE
12) BAKING MACHINE
13) WATER HEATER
14) THERMO FLASK
15) REFRIGERATOR
16) SHOPPING TROLLEY
17) LAPTOP
18) WATER SPRAYER FOR GARDENING
19) AIR CONDITIONER
20) JU ICE MIXER
21) HAND DRILLING MACHINE
• LIST OUT THE CONSUMER REQUIREMENTS
FOR
THE ITEM
• COLLECT ALL THE RELEVANT INFORMATIONS FOR
MANUFACTURING THIS ITEM AS PER THE NEED OF
THE CUSTOMER.
• LIST THE DESIGN OBJECTIVES AND THE
DESIGN CONSTRAINTS
• LIST OUT THE FUNCTIONAL REQUIREMENTS
AND THE MEANS TO ACHIEVE IT
• PREPARE ALTERNATIVE DESIGNS POSSIBLE
FOR THE ITEM. SELECT THE OPTIMUM DESIGN.
ASSIGNMENT 1

 WATER PURIFIER
Pure, clean and safe drinking water isn’t available easily these days. Growing population, industrial
development and environmental degradation are all causes for this. Given this situation, it becomes
even more important for us to be aware of purification techniques and the available water purifiers in the
market to ensure that our drinking water is of good quality.
A lot of minerals are found naturally in water and are important for the human body but consuming an
excess amount of it can cause many diseases. A good water purifier removes the excess salts,
suspended particles and microbes, and retains its essential vitamins and minerals. With so many
manufacturers in the water purification industry these days, it is difficult to know which is good, which
isn’t and which meets necessary standards.
Both water filters and water purifiers work on the same mechanical principle. They first suck up raw
water which is contaminated, filter out impurities ranging from sediments to micro-organisms and then
dispense clean water. However there is one big difference between the two – a purifier can remove
viruses and bacteria that filters cannot remove. Some purifiers use chemicals and others use an electro-
static charge to kill or capture viruses.

 WATER PURIFIER
The purification procedure reduces the concentration of contaminants such as suspended particles,
parasites, bacteria, algae, viruses, and fungi.
Find out the level of contamination in water. For this get a laboratory water analysis done on your
drinking water. This will include a general water test, which comprises finding out total coliform
bacteria, nitrate/nitrites, pH, Total Dissolved Solids (TDS), fluoride, organic carbon contaminants
(pesticides, industrial pollution etc.). Best quality filters and membranes are expensive.
Decide whether you want a filter that weeds out dissolved minerals in the water or a purifier that kills the
bacteria or a machine that does both.
1. Is the product accredited by a renowned institution such as NSF, WQA and FDA?. The product’s standard:
Acclaimed institutions such as National Sanitation Foundation (NSF), Water Quality Association (WQA), Food and
Drug Administration (FDA), etc., give accreditation to water purifiers- this is a safety mark for consumers. The
India task force of WQA- Water Quality Association has a list of Indian brands with accreditation
2. How often the sediment filter/membrane needs to be cleaned or changed?
3. What is the warranty on the parts of the machine and how many free services does the company offer?
4. If it is a RO purifier, what is the filtering speed? (It is advisable to buy a high speed filter that ensures good flow of
water).

Prepare a list of design objectives.
a. Cost effectiveness
b. Safety
c. Can detect chemical imbalance
d. Fewer repairs
e. Easy to repair when needed
f. Long lasting
g. Affordable
h. Low damage
i. Low or no contamination
j. Takes up least possible space
k. Safe for humans
l. Safe for environment
m. Gets the job done
n. Can correct problems in least time
o. Low maintenance
p. Cleans high volume of water
q. Efficient
Step 1 WATER PURIFIER ORGANISING CONSUMER REQUIREMENTS: OBJECTIVE TREE

FUNCTIONAL STRUCTURE FOR AUTOMATIC COFFEE MACHINE

Step 1. Express the overall function for the design in terms of conversion of inputs and outputs: The key is
to determine what needs to be achieved by the new design and how it is to be achieved. This can be
accomplished by representing the product or device (to be designed) simply as a black box, which converts given
inputs to desired outputs. The black box specifies all the functions required to convert the input into output. It is
important not to place any restrictions on the function. Such restrictions limit the solution space or system
boundary. For example, the function “push from A to B” restricts the solutions from ejecting, throwing, rolling,
lifting, or even catapulting the object from A to B. Thus, it is important to widen the solution space or system
boundary as much as possible. It is important to try to ensure that all the relevant inputs and outputs are listed
clearly. As mentioned earlier, they can be classified as flows of materials, energy, and information.
Step 2. Break down the overall function into a set of essential sub-functions: The conversion of the set of
inputs into the set of outputs at the main function level is usually very complex. Thus, the black box needs to be
broken into subtasks or sub-functions. The break-up depends on the experience of the designer, availability of
components capable of performing specific tasks, and the latest technologies. In specifying sub-functions, it is
necessary to express the task as a verb plus a noun (e.g., amplify signal, count items, decrease speed, increase
diameter) or an action noun (e.g., actuator, loader, etc.). Each sub-function has its own input(s) and output(s).
DETAILED PROCEDURE TO ESTABLISH FUNCTIONAL STRUCTURE

Step 3. Draw a block diagram showing the interactions between sub-functions: A block
diagram consists of all sub-functions separately identified by enclosing them in boxes. They are
linked by their inputs and outputs in order to satisfy the overall function of the product or device
that is being designed. In other words, the original black box of the overall function is redrawn as a
transparent box in which the necessary sub-functions and their links can be seen. When
drawing this diagram, we decide how the internal inputs and outputs of the sub-functions are
linked so that we may make a feasible working system. We may find that inputs and outputs may
have to be juggled and perhaps redefined, and some sub-functions may need to be reconnected. It is
advised that different types of lines (continuous, dotted, and dashed lines) be drawn to indicate
the different types of flows (material, energy, and information) within the block diagram.

Step 4. Draw the system boundary:
In drawing the block diagram, we also need to make decisions about the precise extent and location of the
system boundary. For example, there can be no loose inputs or outputs in the diagram, except those that
cross the system boundary. The boundary now needs to be narrowed again because of its earlier
broadening during the consideration of inputs, outputs, and overall function. The boundary has to be
drawn around a subset of the functions that have been identified in order to define a feasible product. It is
also possible that the designer may not have complete freedom when drawing the system, since it may be
restricted by the customer.
Step 5. Search for appropriate components for performing each sub-function and its interactions: If
the sub-functions have been defined adequately and at an appropriate level, then it should be possible to
identify a suitable component for each sub-function. The identification of a component will depend on the
nature of the product or device. For example, a component can be a mechanical, electrical, or
combination device. A microprocessor based electronic device can substitute some older versions of
electromechanical devices. Since the function analysis method focuses on functions, new devices can be
substituted at later stages of design or development.

Function structure for grocery cart.

Function structure of
washer/dryer machine

Reverse Osmosis: This system of water purification has
several criteria against it when it comes to the market in
question. First, the membrane required for reverse osmosis is
expensive, often proprietary, and must be replaced over time
resulting in a significant maintenance expense to the user.
Secondly, reverse osmosis is slow, often taking several hours to
produce a few gallons of pure water.
Distillation: Though distillation is simple and inexpensive, the
power and time requirements of evaporating and condensing
large amounts of water are detrimental to its use. As a further
danger, volatile organic compounds are not removed by the
evaporation/condensation process but transfer into the new
vessel ahead of the water that is being purified. Thus, this
system is slow, requires large amounts of power, and fails to
purify the water of a significant class of toxins.

Boiling: Though in many ways boiling is an effective way of killing bacteria, it presents similar
shortcomings to distillation. In this case, the volatile organic compounds are lost to the atmosphere, but
the non-volatile inorganic pollutants are concentrated in the vessel as water is boiled off and the volume
decreases. Thus, as with distillation, boiling is slow, requires high energy input, and fails to remove a
significant class of toxins including lead, mercury, and cadmium.
Chlorination: Though it is quick, simple, and can be removed after sterilizing water by an activated
carbon filter, chlorine does not successfully kill certain kinds of bacteria (Cryptosporidium, for
instance 7 ). Furthermore, chlorine can be involved in side reactions in the water it is added to
leading to chlorination by-products which are toxic. Thus, chlorination is both ineffective against an
important cause of traveler’s illness and it may, in certain cases, increase the danger of the drinking
water it due to chlorination by-products. It is possible that a combined chlorination/carbon
filtration system might be effective, but the chlorine would be quickly consumed as well as
accelerating the rate of carbon filter fouling. These arguments effectively limit any reasonable
ventures toward such a solution.

DESIGN ALTERNATIVES AND SELECTION PERFORMANCE SPECIFICATION METHOD
The following are the steps in producing a set of specifications using the performance specifications
method.
Step 1. Consider the different levels of generality of solution that might be applicable:
Specifications that are set at too high a level of generality may allow inappropriate solutions to be
suggested. However, specifications which are too tight may remove all of the designer’s freedom and
creativity for the range of acceptable solutions. This level of limitation may also be connected with the
definition of the customer you are dealing with, because the customer may also limit the class and the set
of specifications.
For example, designing a space shuttle puts the designer on a tighter limit of specification. Another
example that demonstrates this point involves the design of an air jet for civilian use. Such a design has a
different set of requirements than designing an air jet for military use. Recognizing the customer’s needs is an
important factor in defining the range for the set of requirements. The level of generality could be reserved
through the development of the objective tree. Different types of generality levels can be listed from the most
general to least general and may be demonstrated as a. Product alternatives b. Product types c. Product
features

Let us consider an example to illustrate these levels. Suppose that the product in question is a
domestic aluminum-can disposal device. At the highest level of generality, the designer would be free
to propose alternative ways of disposing of aluminum cans, such as crushing, melting,
shredding and chemical. There might even be freedom to move from the concept of one can to
multican or from domestic to factory. At the intermediate level, the designer would have much more
limited freedom and might only be concerned with different types of can crushers, such as foot
operated or automatic. At the lowest level of generality, the designer would be constrained to
consider only different features within a particular type of crusher, such as if it hangs on the wall or is
self-standing, processes one or multicans in one step, and so on. Thus, at this level of developing
specifications, designers need to review the need statement and objective tree in order to ana lyze
where the objective tree stands with respect to the mentioned levels.

Step 2. Determine the level of generality at which to operate:
In general, the customer/client determines the level of generality at which the designer may operate. For
example, the customer may ask the designer to design a safe, reliable aluminum-can crusher. Here,
the customer has already established the type of product, and constraints are placed on the type of
aluminum can disposable unit: It must be a crusher. Hence, the set of requirements will follow for a
can crusher, not a disposable can unit. It should be noted however that sometimes customers may
state a solution to a product such as ‘can crusher’, where in fact, they do not really care whether the
cans are crushed or not, but they actually just need a product that disposes cans efficiently. Therefore,
it is important to communicate with the customer to ensure that the apparent limits imposed by
them are really necessary, as they may have simply not considered other alternatives. This
further emphasizes the need to accurately define the problem before suggesting possible solutions.

Step 3. Identify the required performance attributes: For clarifying the customer
statement, objective trees, function analysis, and market analysis are used. Objective
trees and functional analysis determine the performance attributes of the product.
Some of the requirements in the customer statement are “must meet” (called demands)
and others are “desirable” (called wishes). Solutions that do not meet the demands are not
acceptable solutions, whereas wishes are requirements that should be taken into
consideration whenever possible. Pahl and Beitz developed a checklist that can be
used to derive attributes along with objective trees and function analysis. Once the
attributes are listed, dis tinguish whether the attribute is a demand or a wish, and
then tabulate the requirements.

(Pahl and Beitz)
Checklist for
drawing up a
requirement list.

Step 4. State succinct and precise performance requirements for each attribute: The attributes
that can be written in quantified terms must be identified. The performance limit should be attached to
the attribute. The limits may be set by the customer statement or by federal and government agency
standards. These attributes may include, but are not limited to, maximum weight, power output,
size, and volume flow rate. For presenting the specifications, use a metric-value combination (i.e., size
less than ).
For wishes and demands that do not have defined value attached to the metric, we use the quality-
function-deployment method (QFD).

Stage 1 QFD house of
quality chart
Region 1 The prioritized requirements established are listed as rows
along with their importance ratings (1 to 9, 9 being the most important).
You have done this through question/answer sessions with the customer
and through discussion sessions with the design team to develop the
objective tree. Market research, function analysis, and the performance-
specification method also help in this effort. In cases where a company is
launching/designing a new product where there is no particular
customer at hand, gathering attributes could be done through direct
interaction with prospective customers by conducting
• Product clinics: Customers are quizzed in depth about what they like
and dislike about a particular product. User surveys also can be used
here.
• Hall test (tests conducted in the same hall): Various competing
products are arranged on display, and customers are asked to inspect
the products and give their opinions.

Region 2 Specifications established are listed as columns.
Region 3 Each specification is then rated as a CORRELATION to each requirement. This is to find out how
well each specification addresses each requirement. If there is NO correlation, the grid space is left blank. If
there is a slight or weak correlation, rate as 1. If there is medium correlation, rate as 3. If there is
high/strong correlation, rate as 9. ONLY blank, 1, 3, or 9, are valid options in the relationship matrix region.
Region 4 Engineering specifications may have relationships between each other. For example, a powerful
engine is also likely to be a heavier engine. This interaction is added as a roof to the matrix. Region 4 is this
correlation matrix. It also identifies specifications that are in conflict with each other. Once again, correlation
ratings of 1, 3, or 9 are used, but in addition to this and the blank, if there is a conflict, then a ‘ - ’ sign
should be placed between the conflicting specifications.
Region 5 Depicts target values for the specifications to improve over competitors: The market analysis may be
important at this stage to identify the market limits.
Region 6 The absolute importance ratings of the specifications as measured against the prioritized
requirements. This is achieved by multiplying each specification rating by its corresponding requirement
importance rating and adding up the respective columns to get the absolute importance rating for that
specification.

Region 7 The relative importance ratings and these values
are the absolute importance ratings weighted relative to each
other. Here, the highest absolute rating becomes the
benchmark value and is given a relative importance of 9. All
other specifications are then compared to this value.
Therefore, in Figure, there are four requirements (Safe,
reliable, low cost, and pleasing appearance). Assume that
these requirements derive five specifications, and these are
mapped in the columns as shown in the chart. The
calculation for the absolute importance rating of specification 1
is (1 X 9) + (1 X7) + (9 X 2) + (3 X 5) = 75
At first glance it may seem that specification 1 is the most
important specification, as it is relevant to all of the
requirements in some way. However, it is also somewhat
unsafe (the most important requirement according to the
importance rating).

Specification 2 however is only relevant to one requirement (safety), but it
highly correlates with this requirement. As a result, it yields an
absolute importance rating of 81. This becomes the important
specification to focus on, followed by specification 1.
Specification 4 is the least important specification, as it only focuses on
low cost and good looks but has nothing to do with the safety or
reliability of the product.
You can see from this simple example, the QFD chart focuses you on
the most important specifications. Since specification 2 has the highest
absolute importance rating, nine becomes the relative importance
rating, and all other specifications are weighted down against this
specification. Hence, the relative importance rating for specification 2
would be calculated by (75/81) X 9 = 8 (rounded down to the nearest
whole number).

Region 8 The benchmark value of each requirement is measured against
competing products in the market. The objective here is to determine how the
customer perceives the competition’s ability to meet each of the requirements.
Usually, customers make judgments about the product in terms of comparison
with other products. This step is very important because it shows opportunities for
product improvement. The market analysis you have conducted should play a vital
role in this step. In many instances, students who do not conduct extensive market
analysis find it hard to complete this step accurately.

In QFD, consumers are the most important factor, and
the design should be arranged in a manner to meet
their satisfaction. The Kano model can be used to
measure customer satisfaction. In the Kano model,
customer satisfaction is measured
by the product
function, as shown in Figure. The Kano model was
developed by Dr. Noriaki Kano in the early 1980s. In the
Kano model, there are three different types of product
quality that give customer satisfaction: basic quality,
performance quality, and excitement quality. With basic
quality, customers’ requirements are not verbalized,
because they specify assumed functions of the device.
The only time a customer will mention them is if they
are missing. If they are not fully implemented in the
final product, the customer will be disgusted with it. If
they are included, the customer will be neutral.
KANO MODEL

An example is the requirement that a bicycle should have brakes.
The performance quality refers to customers’ requirements that
are verbalized in the form that indicates the better the
performance, the better the product. The excitement quality
involves those requirements that are often unspoken, because the
customer does not expect them to be met in the product. However, if
they are absent, customers are neutral. If the customers’
reaction to the final product contains surprise and delight at the
additional functions, then the product’s chance of success in the
market is high.

Design and Engineering class notes for KTU students

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