Design and Manufacturing - Study Notes

Chapter 1

DEFINITION OF ENGINEERING DESIGN

1.1 Introduction:

The economic future of India depends on our ability to design, make and sell competitive products.

Excellent design and effective manufacture are the pre-requisites of a successive industry. There is a

general impression that the quality of Indian products can still be improved. The fact that consumers

have lost their confidence on Indian-made products cannot be denied. This problem can be solved only

by designing and manufacturing better products through improved methodology. Keeping this in view,

the subject Design and manufacturing purpose to present the methods and procedures of design and

manufacture.

Although engineers are not the only people who design things, the professional practice of engineering

is largely concerned with design. It is usually said that design is the essence of engineering.

The ability to design is both a science and an art. The science can be learned through procedures

developed by eminent scholars. But the art can be learned only by doing design.

Types of Products

A product is the tangible end result of a manufacturing process and is meant for satisfying human needs.

The product can be classified as follows: -

Convenience goods

These are less expensive and are clustered around shops and restaurants. These can be purchased at

consumer's convenience.

E.g. Cigarette, Candy, Magazines etc.

2. Shopping goods

These are expensive and people buy it less frequently.

E.g. Jewelry garments etc.

3. Specialty goods

These are purchased, taking extra pain.

E.g. Rare objects like stamps.

4. Industrial goods.

These are items used in the production of other items.

Eg: Raw materials.

Another way of classifying products is into,

(a) Continuous Products, and

(b) Discrete products

The continuous products are those which are produced in a continuous fashion. For example, plates,

sheets, tubes and bars etc are produced in very long lengths, and then these are cut into desired

lengths.

On the other hand, discrete products are produced one after another, each in separate units.

On the basis of the output product, the Industry is usually named as continuous industry and discrete

industry.

1.3 Requirements in a good product

Customer Satisfaction

Profit

How to achieve customer satisfaction?

-The product should function properly.

-It must have desired accuracy

-It must have desired reliability

-It must be easy to operate

-It must be serviceable

-It must make minimum space utilization

-It must withstand rough handling

-Pleasant appearances.

-Reasonable price.

How can it be profitable?

-It must be easy to manufacture

-The raw material must be cheap and easily available

-The manufacturing process has to the decided on the basis of quantity to be produced

-It must use standard parts

-It must be easy to pack and distribute.

1.4 Definition of Design: (S 94)

Designing is such a vast field that it is defined in several ways. Various definitions of designing as

pronounced by well-known designers are

Design is that which defines solutions to problem which have previously been solved in a different way

Design is the conscious human process of planning physical things that display a new form in response

to some pre-determined need.

Design is an act of collecting all pertinent information for the production of goods and services to meet

some human need.

The design of any component includes two things,

Product design

Process design

The product design involves the development of specification for a product that will be functionally

sound, good in appearance, and will give satisfactory performance for an adequate life.

The process design involves developing methods of manufacture of the products so that the component

can be produced at a reasonably low cost.

1.5 History of Design Process

Design by Single Person

Over-the-wall design

Simultaneous Engineering

Concurrent Engineering

Integrated design and Manufacture.

In olden times one person could design and manufacture an entire product. Even for a large project such

as the design of a ship or a bridge, one person had sufficient knowledge of the Physics, Materials and

manufacturing processes to manage all aspects of the design and construction of the project. This

period is referred to as the period of design by single person in the history of design.

By the middle of the 20th century products and manufacturing processes became so complex that, one

person could not handle all aspects of design and manufacturing. This situation led to over-the-wall

design process.

In this method each functional departments were separated from others, as shown by wall. There was

only one-way communications between Customer, Marketing, Engineering Design and production

department. The customers throw' their needs to marketing department. The marketing department

may throw the customer needs to the design department, in many instances, orally. The Engg. Design

department may conceive a design and hands it over to the manufacturing sections. The manufacturing

department interprets that design and makes the product according to what they think suitable.

Unfortunately, often what is manufactured by a company using over-the-wall process is not what the

customers had in mind. This is due to lack of interaction between the different departments. Thus, this

single direction over-the-wall approach is inefficient and costly and may result in poor quality products.

By the early 1980's the concept of simultaneous engineering emerged. This philosophy emphasized

simultaneous development of the manufacturing process- the goal was the simultaneous development

of the product and the manufacturing process. This was accomplished by assigning manufacturing

representatives to be members of design team, so that they could interact with the design engineers

throughout the designs process.

In the 1980's the simultaneous design philosophy was broadened and called concurrent engineering. A

short definition of concurrent engineering is the simultaneous progression of all aspects, at all stages of

product development, product specification, design, process and equipment etc. In concurrent

engineering the primary focus is on the integration of teams of people having a stake in the product,

design tools, and techniques and information about the product and the processes used to develop and

manufacture it. Tools and techniques connect the teams with the information. Although many of the

tools are computer-based, much design work is still done with pencil and paper. In fact, concurrent

engineering is 80% company culture and 20% computer support.

With the advent of computer technology, drastic changes have taken place in the field of design and

manufacturing. The result was a completely integrated design and manufacturing system. This system

makes a good use of technologies such as CAD/CAM, FMS etc. The computer integrated manufacturing

systems (CIMS) moves towards the Factory of the future'. CIMS is necessary for better quality, efficiency

and productivity.

QUESTIONS

How can you explain the term design? Explain the process of mechanical design. Discuss the role of

creativity in the design process (S'94, 8M)

The design of product is ..........customer expectations. (S'99, S'94)

.get first preference in design

Ans. Functional requirements (S'93)

Explain the meaning of

Conceptual design

Functional design

(iii) Production design. Give suitable examples for each. (S'03)

CHAPTER - 2

TYPES OF DESIGNS

2.1 The design can be classified in many ways. On the basis of knowledge, skill and creativity required in

the designing process, the designs are broadly classified into three types

Adaptive Design (W 95, 97, 98 00)

Variant Design (S 97, 99)

Original Design

Adaptive Design

In most design situations the designer's job is to make a slight modification of the existing design. These

are called adaptive designs . This type of design needs no special knowledge or skill. E.g. converting

mechanical watches into a new shape.

Variant Design

This type of design demands considerable scientific training and design ability, in order to modify the

existing designs into a new idea, by adopting a new material or a different method of manufacture. In

this case, though the designer starts from the existing designs, the final product may be entirely

different from the original product.

E.g. converting mechanical watches into quartz watches. Here a new technology is adopted.

Original Design

Here the designer designs something that did not exist previously. Thus, it is also called new design or

innovative design. For making original designs, a lot of research work, knowledge and creativity are

essential. A company thinks of new design when there is a new technology available or when there is

enough market push. Since this type of design demands maximum creativity from the part of the

designer, these are also called creative designs.

2.2 On the basis of the nature of design problem, design may be classified as

Selection design

Configuration design

Parametric design

Original design

Re-design

Selection Design.

It involves choosing one or more items from a list of similar items. We do this by using catalogues.

Eg. -Selection of a bearing from a bearing catalogue

-Selection of a fan for cooling equipment

-Selecting a shaft.

Configuration / Layout / Packaging Design (W 97, S'02)

In this type of problem, all the components have been designed and the problem is how to assemble

them into the completed product. This type of design is similar to arranging furniture in a living room.

Consider the packing of electronic components in a laptop computer. A laptop computer has a

keyboard, power supply, a main circuit board, a hard disk drive, a floppy disk drive and room for two

extension boards. Each component is of known design and has certain constraints on its position. For

example, the extension slots must be adjacent to the main circuit board and the keyboard must be in

front of the machine.

Keyboard

Main Circuit board

Extension slots

Floppy drive

Power supply

The different components are shown above. The designer's aim is to find, how to fit all the components

in a case? Where do we put what? One method for solving such problems is to select a component

randomly from the list and position it in the case so that all the constraints on that component are met.

Let's take keyboard first. It is placed in the front. Then we select and place a second component. This

procedure is continued until we reach a conflict, or all the components are in the case. If a conflict

arises, we back up and try again. Two potential configurations are shown above.

Parametric Design

Parametric design involves finding values for the features that characterize the object being studied.

Consider a simple example

We want to design a cylindrical storage tank that must hold 4 m 3 of liquid.

The volume is given by

V = r 2 l

The tank is described by the parameters, radius 'r', and length l .

Given V = 4 m 3 = r 2 l

r 2 l = 1.273

We can see a number of values for the radius and length, that will satisfy this equation. Each

combination-values of r and l gives a possible solution for the design problem.

Original Design

As described in an earlier section, an original design in the development of an assembly or component

that did not exist before.

Redesign

The redesign is a modification of an existing product to meet new requirements. It is same as adaptive

design. Most design problems solved in industry are for the redesign of an existing product. Suppose a

manufacturer of hydraulic cylinders makes a product that is 0.25m long. If the customer needs a cylinder

0.3m long, the manufacturer might lengthen the outer cylinder and the piston rod to meet this special

need.

2.3. On the basis of the objective or strategy the designs are of following main types.

Production Design

Functional Design

Optimum Design

Production Design

In production design , the designer designs something in such a way that the cost of producing the

product is minimum. That is, the first responsibility of the designer is reduction of production cost.

Hence, a production designer is concerned with the ease with which something can be produced, and

that at a minimum cost.

Functional Design W93

In functional design , the aim is at designing a part or member so as to meet the expected performance

level.

Functional design is a way of achieving given requirements.- but the same may the unproducible or

costly to produce. A good designer, then, has to consider the production aspects also. A product

designed without keeping all these aspects into account, wastes time, money and efforts.

Optimum Design [W 95]

It is the best design for given objective function, under the specified constraints.

2.4 On the basis of the field/ area or the domain of design, the following types are important.

Mechanical Design

Machine Design

System Design

Assembly/sub-assembly design

Computer aided design

Mechanical Design

It means use of scientific principles, technical information and imagination in the design of a structure,or

machine to perform prescribed functions with maximum economy and efficiency.

Machine Design

It is the process of achieving a plan for the construction of a machine.

System Design

System Design is an iterative decision making process to conceive and implement optimum systems, to

solve problems and needs of society.

Assembly/sub-assembly design [S 93]

In the design of Assembly/sub-assembly the major criterion is the fulfillment of functional requirements.

The assembly has to be designed to meet broad technical parameters and purpose for which it was

meant.

The characteristic features are:

The total number of parts used in the design must be minimum.

Sub-assemblies should be capable of being built separately in order to give maximum manufacturing

flexibility.

Standard parts may be used.

Flexible parts should be avoided, as they are easily damaged during handling and assembly.

Computer aided design [CAD]

It is a design methodology in which the designs take the advantages of digital computer to draw

concepts, analyze and evaluate data etc. Computers are largely used in a design office for simulation and

prototype study. In modern design, computers have become an indispensable tool.

Other types of designs are

Probabilistic Design

Industrial Design

Probabilistic Design [S 96]

It is a design approach in which design decisions are made using statistical tools. Generally, the external

load acting on a body, the properties of materials etc are liable to vary. In probabilistic design, the

designer takes into account the variations of such parameters.

Industrial Design [W 93]

It is the design made by considering aesthetes, ergonomics and production aspects.

Questions

1. What are the characteristics features of system design, assembly/sub-assembly design and

component design? Explain briefly with the help of examples. [S'93, 5M]

2. Distinguish between functional design and industrial design. [W'93]

3. Discuss the meanings of conceptual design, creative design, adoptive design and variant design. [S'97]

4. What are the three main types of design? Give a comparative analysis. [W'00, W '97]

Explain the difference between creative design, adoptive design and variant design. [S'02 W'98]

Designing for function involves the use and knowledge of ..

Ans. Eng. Sciences [W '94]

8. Explain the meaning of

Conceptual design, (ii) Functional design and (iii) production design. Give suitable example of each.

[S0'3]

10. Explain layout design. [S0'2]

Chapter 3

DESIGN PROCESS AND ITS STRUCTURES

3.1. Introduction

Developing a manufacturable product is not an easy job. This chapter presents some methods that help

achieve quality products. Rather than making a detailed study, only an overview of designing process is

attempted here.

3.2. Features of design process

The following features can be observed in a design process.

Iteration

Decision-making

Conversion of resources

Satisfaction of need

Design is completed in many phases. In each phase, repeated attempts are required to accomplish the

aim. A satisfactory conclusion can be reached on, only after a number of trials.

Decision-making is essential for a designer to select one out of several. A designer often comes across

several equally acceptable alternatives to meet some end. In such conflicting situations, designer has to

make the best decision.

In any design process, there is conversion of resources such as time, money, talent, materials and other

natural resources.

All designs are aimed at satisfying some human need. Needs, whether important or unimportant is the

starting point of design.

3.3. How a design is born?

In a broad sense there are two methods by which a design comes into existence.

Design by evolution (Traditional Design)

Design by innovation (Modern Design)

Design by evolution

This implies the traditional method of design in which the objects and articles that we see around has

taken its present form by gradual change of time. If one looks at history it can be seen that most of the

tools, equipments, implements, took a long time to acquire their present form. Things changed gradually

with the passage of time. Each change was made to rectify some defects or difficulties faced by the

users. Bicycles, calculators, computers, steam locomotives etc. all went through a process of evolution in

which designers tried one concept after another. Even today this process is being used to some extent.

However, this evolutionary process is very slow. i.e., it took a very long period of time to occur even a

slight modification. The main reason for this slow evolutionary process of design was the absence of

proper information and design data records.

In modern design situations the evolutionary methods are not adequate because of the following

reasons.

1. The traditional designing did not consider the interdependence of products. They were concerned

about only one component /product. But in the modern world, the existence of one product is

dependent on another in some way or other.

2. In the past, production was on small scale. Thus the penalty of a wrong design was tolerable. But, in

the present time, production is on large-scale basis. As a result, any penalty of a wrong design will cost

great loss.

3. Requirements of the customers of today's world changes so frequently. Traditional design lags behind

the advanced product & process technologies available today.

5. Traditional design methods cannot cope with competitive requirements of the modern world.

Due to the above reasons modern design problem cannot be handled by traditional methods.

Design by Innovation

Since the traditional design method failed to cope with modern design requirements, nowadays almost

all designs are made by innovation. i.e., developments of a product by following scientific and

purposeful effort.

The innovative design is entirely different from the past practice of evolutionary design. Here the

designer's task is greatly magnified. He has to design and create something, which did not exist yet. Here

he tries to solve the design problem in a systematic and orderly manner. This approach is similar to

analytical problem solving.

However, an innovative designer faces the following difficulties.

1. He has to collect and evaluate information on a product, which is non-existing yet.

2. Necessity of analyzing complicated interaction of components.

3. He has to make predictions regarding its performance.

4. He has to ensure the technical and economical feasibility of the product.

Notwithstanding the above difficulties, there are eminent experts like Morris Asimow, J.E. Shigly, Dieter

etc have attempted to systematize the design process. This systematized steps in design process is

called Morphology of Design . The best way in which any problem can be solved is to break up the

problem and to try for a solution in an analytical method. This approach of problem solving is also

adopted in the Morphology of design.

3.4. Problem-solving Methodology

Knowingly or unknowingly we follow six basic actions when we try to find solution of any problem.

1. Establish or convince ourselves that there is' a problem. Or we understand that a solution is needed.

2. Plan how to solve this problem

3. By analyzing the problem we decide what is actually required from the problem-solver. Or we decide

the requirements.

4. Generate alternative solutions.

5. Evaluate the alternatives.

6. Present the acceptable solution.

3.5. Morphology of Design.

Morphology means a study of form or structure'. Morphology of design refers to the time based

sequencing of design operations. It is a methodology of design by which ideas about things are

converted into physical objects. The logical order of different activities or phases in a design project is

called the morphology of design.

3.6. Design Process- Simplified Approach

A simplified approach to designing as outlined by Morris Asimow is given below. According to him the

entire design process in its basic forms consists of five basic elements as given below.

Design operations imply the various processes done during designing. These

include

Searching for possible alternatives systems to satisfy a need.

Formulating a model for analysis purpose.

Materials selection, etc.

But in order to carryout the above processes (i.e., design operations) a lot of information is required.

The required informations may be broadly classified into two.

1. General Information

E.g. Scientific Laws

Information on market trends etc.

2 . Specific information .

E.g. Information on manufacturer's catalogue

Materials science handbook etc.

Once the designer has obtained the necessary information he can start design operations. The design

operations give outcome s. The outcome may be in the form of

Computer print outs, or drawings.

Next stage is the evaluation of this outcome. The purpose of evaluation is to decide whether this

outcome is able to meet the need. Here a comparison between the capabilities of the outcome and the

need is carried out. If the outcome is sufficient to meet the need, the designer goes on to next step,

otherwise the design operation is repeated

3.7 Detailed Morphology of Design

A design project goes through a number of time phases. Morphology of design refers to the collection of

these time phases. The morphology of design as put forward by Morris Asimow can be elaborated as

given below. It consists of seven phases.

Phase 1. Feasibility Study.

This stage is also called conceptual design. A design project always begins with a feasibility study. The

purpose and activities during feasibility study are

To ascertain there really exists a need [ie the existence of need must be supported by necessary

evidences, rather than the outcome of one's fancy]

Search for a number of possible solutions

Evaluate the solutions

i.e. is it physically realisable?

Is it economically worthwhile?

Is it within our financial capacity?

Phase 2 Preliminary (Embodiment) Design.

This is the stage art which the concept generated in the feasibility study is carefully developed. The

important activities done at this stage are:

Model building & testing

Study the advantages and disadvantages of different solutions.

Check for performance, quality strength, aesthetics etc.

Phase III: Detail Design

Its purpose is to furnish the complete engineering description of the tested product. The arrangement,

from, dimensions, tolerances and surface properties of all individual parts are determined. Also, the

materials to be used and the manufacturing process to be adopted etc. are decided. Finally, complete

prototype is tested.

Phase IV: Planning for manufacture

This phase includes all the production planning and control activities necessary for the manufacture of

the product. The main tasks at this phase are

Preparation of process sheet, i.e. the document containing a sequential list of manufacturing

processes.

Specify the condition of row materials.

Specify tools & machine requirements.

Estimation of production cost.

Specify the requirement in the plant.

Planning QC systems.

Planning for production control.

Planning for information flow system etc.

Phase V: Planning for Distribution

The economic success of a design depends on the skill exercised in marketing. Hence, this phase aims at

planning an effective distribution system. Different activities of this phase are

Designing the packing of the product.

Planning effective and economic warehousing systems.

Planning advertisement techniques

Designing the product for effective distribution in the prevailing conditions.

Phase VI Planning for Consumption/use

The purpose of this phase is to incorporate in the design all necessary user- oriented features. The

various steps are

Design for maintenance

Design for reliability

Design for convenience in use

Design for aesthetic features

Design for prolonged life

Design for product improvement on the basis of service data.

Phase VII: Planning for Retirement.

This is the phase that takes into account when the product has reached the end of useful life. A product

may retire when

It does not function properly

Another competitive design emerges

Changes of taste or fashion

The various steps in this phase are

Design for several levels of use

Design to reduce the rate of obsolescence.

Examine service-terminated products to obtain useful information.

3.8. Methods of Innovative Design

As we know, innovative design is an organized, systematized and logical approach for solving a design

problem. There are two design methods for innovative design.

Design by creative design route

Engineering Design

Design by creative routs [Creative Design]

This is a design method that demands maximum creativity' from the part of the designer. Hence this

method is also called creative design. Here the designer finds solutions to problems by allowing his

creativity aspects grow in a particular manner.

Creativity [S94, W95, W98, S03]

Majority of designs belong to variant design, where the designer simply modifies an existing system. But

the success of engineering design depends on the modes of thinking and acting distinctively different

from others. A creative designer is distinguished by his ability to synthesize new combinations of ideas

and concepts into meaningful and useful forms. Design is commonly thought of as a creative process

involving the use of imagination and lateral thinking to create new and different products.

Qualities of a creative designer [S96, S00, S03]

The creative designer is generally a person of average intelligence, a visualiser, a hard worker and a

constructive non-conformist with average knowledge about the problem at hand.

Generally, a creative designer has the following qualities.

Visualization ability.

Creative designers have good ability to visualize, to generate and manipulate visual images in their

heads.

Knowledge

All designers start their job with what they know. During designing, they make minor modifications of

what they already know or, creative designers create new ideas out of bits of old designs they had seen

in the past. Hence, they must have knowledge of past designs.

Ability to manipulate knowledge

The ability to use the same knowledge in a different way is also an important quality of a designer.

Risk taking

A person who does not take the risk of making mistakes cannot become a good designer. For example,

Edison tried hundreds of different light bulb designs before he found the carbon filament.

Non-conformist

There are two types of non-conformists:-constructive and obstructive. Constructive non-conformists are

those who take a firm stand, because they think they are right. Obstructive non-conformists are those

who take a stand just to have an opposing view. The constructive non-conformists might generate a

good idea. But the obstructive non-conformists will only slow down the design process. Creative

designers are constructive non-conformists, and they want to do things in their own way.

Technique

Creative designers have more than one approach to problem solving. They are prepared to try

alternative techniques, till they reach a satisfactory solution.

Motivation

They always motivate others in the design team. In such a favourable environment creativity is further

enhanced.

Willingness to practice

Creativity comes with practice. Creative designers are ready to practice for a long enough period.

Roadblocks to Creativity

Fear of making a mistake

Unwillingness to think and act in a way other than the accepted norm.

Desire to conform to standard solutions.

Unwillingness to try new approaches

Fear of criticism

Lack of knowledge

Overconfidence due to past experience

Unwillingness to reject old solutions

Fear of authority

Difficulty in visualization

Inability to distinguish between cause and effect

Inability to collect complete information

Unwillingness to be different

Methods to enhance Creativity

Use of analogy

Asking question from different view points

Memories of past designs

Competitive products

Deliberate day-dreaming

Reading science fictions, etc.

Intuition [S'01]

Intuition means sudden ideas or flashes of inspiration and involves complex associations of ideas,

elaborated in subconscious mind. Intuitive ideas lead to a large number of good and even excellent

solutions.

Creative Design Route [W95, 94, 98, 9'00]

Creative design route is the procedure through which a creative design is born. The success of this

design lies with the creativity of the designer. Creative design route can be practiced by following the

sequences shown in figure.

During preparation period, the designer analyses the need and collect all the necessary information

required at various stages.

Concentration is the period when the designer digests all the aspects of the problem situation and tries

various possible combinations.

The next step is the incubation period. The designer relaxes away from the problem for some time.

Illumination is the sudden insight and throwing up with a solution.

The final step is the verification. Now, testing and inspection of the design is done and the details are

completed.

For a designer using creative methods for design, habitual or familiar methods must be avoided.

(ii) ENGINEERING DESIGN (W 96)

Another procedure for obtaining innovative design is Engg. Design. Apart from creativity-approach, this

is a logical and intellectual attempt to solve design problems. It largely depends on discoveries and laws

of science.

The different steps in Engg. design process is given below: -

Recognition of need

Definition of the problem

Gathering of Information

Conceptualization

Evaluation of concepts

Communication of the design

Since all design projects are meant for satisfying some need, any design work starts withRecognition of

the need . The need for a design is initiated by either a market requirement, the development of a new

technology or the desire to improve an existing product.

Once the need has identified, the next step is to define the design problem . This is the most critical step

in the design process. The definition of the problem expresses as specifically as possible, what the

design is intended to accomplish. It should include objectives and goals, definitions of any special

technical terms, the constraints on the design and the criteria that will be used to evaluate the designs.

The success of a design project depends on the clarity in the definition of the problem. Need Analysis is

the technique used to define the problem(Chapter 6).

The next step is collecting information. In many phases of deign process a large quantity of information

may be required. The required information can be obtained from textbooks, journals, or other agencies

(See Art. 6.4)

The conceptualization step involves, finding several design ideas to meet the given need. Inventiveness

and creating is very important in this step.

The different ideas conceived are weighted and judged in the evaluation step. The advantages and

disadvantages of each idea against its performance, cost aesthetics etc is valued.

After evaluation, the best design is emerged. This final design with every detail is furnished in last step-

ie communicating the design.

Common features between Creative Design & Engg. Design (W.94)

The preparation phase in creative design and need analysis in Engg. Design is more or less common.

Both steps deal with analyzing the need.

In both design methods brainstorming and Synetics can be applied.

Reviewing is applicable in both design methods.

For both deigns, the success depends on the clarity with which the need statement is prepared.

Testing and inspection is applicable for both designs.

Difference between Creative Designs & Engg, Designs (W 94)

Intelligence is not a must for creative design-but the same is desirable in Engg. Design.

Creative design is based on use of analogy and synthesis of alternatives but engineering design is

based on proven laws and past experience.

Creative design involves phases like incubation, illumination but no such philosophy is followed in

engineering designs.

Creative person is highly intuitive and independent in thinking and usually resists working in group

but engineering designers like teamwork.

Customs, habits and traditions are enemies of creativity but the same are required in engineering

design.

3.9. Divergence, Transformation & Convergence (S'97 5M)

The entire design process can be said to have composed of three distinct phases Viz. Divergence,

Transformation and Convergence phases.

The problem definition, need analysis and conceptualization etc. aims at generating as many ideas as

possible to solve a given design problem. Thus, these activities belong to the Divergence phase.

That activity wherein the concept is converted into physical object is termed as transformation phase.

The convergence is a narrowing process, where the best optimal solution is tried for, by eliminating

unwanted ideas.

3.10. Design Process Using Advanced Technology (W00)

Although Engineering is a major sector of the economy in a developing country. It has not been

benefited greatly from advances in computer technology. Engineers still use computers only in

peripheral tasks, such as drafting and analyzing, but not in making fundamental design decisions.

Current computer tools such as computer-aided drafting' are restricted to the end of the design process

and play no fundamental role in aiding design. It aids only in the final drafting of the specifications.

Computer-aided Design, (CAD) means a class of tools for crating drawing, or the physical description of

the object. CAD systems have been sophisticated and 2D and 3D models are available.

The CAD allows the designer to conceptualize objects more easily. The design process in CAD system

consists of the following stages.

Geometric modeling

Analysis and optimization

Evaluation

Documentation and drafting.

QUESTIONS

How can you explain the term design? Explain the process of mechanical design. Discuss the role of

creativity in the designs process. (S94. 8M)

The mechanical design process normally has six stages and amongst them the three stage are ----- -----

- ------- (S99, S94, 1 M)

What is morphology of design? Explain the various steps with the help of block diagram (W.95)

The three stages of design are (W 96)

State the different phases that are involved in morphology of design (S.96)

Briefly discuss the concept of creativity as applicable for solving design problems (W 98. 6M)

What makes the design process tortuous? Explain (W 99, 6M)

The creative design process can be considered to be (S93)

Discuss creativity and creative design. Use examples to explain. (W 95)

What do you understand by intuition (S 01)

Draw a flow-chart showing different stages of engineering design. Explain why some stages are

repeated several times. (S.93.5M)

What feedback loops provide information for the redesign of products and the productive systems.

(W'93)

The process of design by evolution adopted by craftsman is a ..

Ans. Slow process of design development (W'94)

With suitable examples, compare Design by evolution' and Design by innovation'. (S 96)

Enumerate the steps in Engg. Design process and explain (W'96)

Justify the statement with reasons Modern design problems cannot be handled by traditional

methods'. (S'97, W'98)

Good design requires both------ --------.

Ans. Analysis and Synthesis. (S'93)

Define creative design routes. What are the stages of these routes, Explain these in brief. (S'00)

Explain the process involved in creativity. What are the various qualities of creative designer? Give the

brief description of these. (S'00).

What do you mean by creative design routes. Write down the different statements about creativity

and creative designers. (S'01)

Compare the design synthesis and design analysis. Explain the basics procedure of design synthesis

giving suitable examples. (S '02).

What are the common features and differences between creative design activities and Engg? Design

activities. Explain briefly with the help of examples. (W'94)

Discuss the divergence, transformation, and convergence phases in the design of a new product.

(S'97)

What are the three different stages in the design process? Explain with example. (W'99)

What are the most important steps involved in the design process? Explain? (W'00)

What are the methods currently being adopted for design process using advanced technology? (W'00)

Name various phases in design morphology. Explain these in brief. (S'01)

Explain Engg. Design (S'01)

What major steps are involved in design process? Briefly explain each one (W'01).

What do you understand by the design process? List out the various phases involved and explain them

briefly. (S'02)

Give the checklist for an engg. Design problem. (W'98)

___ is one of the most powerful aids to creativity in design.

(Use of analogy) (W '94).

What do you understand by the term creativity? What are its requirements? ('03).

Discuss the stages in engineering design process with the help of example. (S 05)

Explain Design processes. Illustrate the steps followed with the help of a figure. Also explain the flow

of work during the design process. (W 05, 8M)

What do you understand by morphology of design'? Discuss the phases of feasibility study,

preliminary design and detailed design. (W '05. 8M)

CHAPTER 4

IDENTIFICATION OF NEED

4.1. What is a need?

A need can be defined as a personnel unfulfilled vacancy which determines and organizes all

psychological and behavioral activities in the direction of fulfilling the vacancy

A product can be product and marketed only if it is needed' by the customer. A person buys a pen

because he needs' to write. A patient needs' something that can cure his illness. These examples show

that needs are nothing but a scarcity or problem or wants felt by a person, device or a system. In fact a

designer's goal is to find solutions to such problems

4.2. Hierarchy of Human needs (W' 96)

Maslow developed a hierarchy of human needs as given below

1. Physiological needs

- These are the basic needs of the body- For example, thirst, hunger, sex, sleep etc.

2. Safety and security needs

For a person whose physiological needs are met, the new emerging needs are safety needs. These

include, protection against danger, threat etc.

3. Social needs

Once the physiological and safety needs are met, the next dominant need is social need. For example

he/she want to love and be loved, he want to be in group, etc.

4. Psychological needs

These are the needs for self-respect and self- esteem, and for recognition.

5. Self-fulfillment needs

These are the needs for the realisation of one's full potential through self-development, creativity, and

self-expression.

4.3. Identification/Recognition of Needs (W 96)

The beginning of any design process is the recognition of need or problem. When a turner hears an

awkward noise from some part of the lathe he identifies/ recognises a need. i.e. the lathe requires

repair. When the sales personnel observes that their customers are always complaining of poor

performance of the products, a need to develop a better product is identified. Similarly, when the

customers are unsatisfied with the present model', a new need is recognised.

Needs can be identified from,

Careful market analysis

Statements made by politicians from their observations

Interpretations of a community's requirements

Trends in other parts of the world

4.4. Variety of Needs [S'00]

Following are the needs, which can generate ideas for the development of new products.

(i). Variation of an existing product.

This could be a change in a single or a few parameters of an existing product.

Eg - Changing the length of a cylinder.

-Changing the power of a motor, etc.

Improvements in the existing product.

This implies the need to redesign some of the features of an existing product. Such needs can arise,

when

-Customers want a new feature or better performance than existing features

-A vendor can no longer supply components or materials that had been used so far

-Manufacturing or assembly departments identifies a quality improvement

-Invention of a new technology that can be incorporated in the existing design.

(iii) A change in production model

Whenever the production model changes from job-shop to mass, a corresponding change in product

design may be demanded. For example, there is more tendency to buy off-the shelf components for

short-run products.

Whatever may be the situation, a company has to identify or locate a need before the production of any

device. This crucial step is called Recognition/ Identification of need.

Examples:

1. With the free-entry of Chinese products to Indian market, manufacturers in India recognize a need to

sell their products at a lower price.

2. When a company observes that their products do not perform well, the company recognizes a need

to re-design it.

4.5 Need Statement

Once the need has recognized, the next step is to prepare the need statement. It is a general statement

specifying the problem for which a solution is required. In other words-It is the objective of design,

expressed in the form of a statement.

Need Statement Examples [S 93]

Give one need statement for each of the following

Bicycle

Voltage stabilizers

Personnel Computer

i). Bicycle: -

The need statement for a bicycle could be A device for a common person to travel reasonable distance

comfortably with least effort The initial cost should be low- and be as light as possible, have

adequate life, be easy to maintain etc

(ii). Voltage stabilizer

A solid state noiseless electrical device of adequate power rating to provide continuously an output at

constant voltage, accepting the input power at varying voltage between the limits__and__volts . The

indications for input and output voltage levels may be provided.

iii). Personnel Computer

A computing device to accept input data, manipulate it according to a set of instructions and provide

the desired output on CRT and printer

Questions

1. List hierarchy of human needs that motivate individuals. [W'96]

2. Give one need statement for each of the following

Bicycle (ii) Voltage stabilizer (iii) Personnel Computer [S'93]

3. Explain the steps involved in identification of a problem by a designer [S'96]

4. Every product is made in response to.of individual or society.

Ans. needs [S'97]

5. Enumerate and explain variety of needs which can generate ideas for the

Development of new product. [S'00]

CHAPTER 5

PRODUCT PLANNING

5.1 Introduction

Once the top management of an organisation recognized a need to develop a product, it will go for

product design, only if,

- the purposed product will guarantee a handsome profit

- the market conditions are favorable in respect of competition.

- the necessary resources are available

- the purposed design is worthwhile.

5.2 Feasibility Study.

The starting point of a design project is a need. Once the need has been identified, the company has to

ensure the worth of the project. Feasibility study is a preliminary analysis for making a decision

regarding the design project, to be forwarded or not. If the feasibility study reveals that the proposed

design project does not bring comfortable revenue, or the design demands huge investments beyond

the capacity of the organisation, the project is dropped.

5.3 .Product Planning [S 01]

Planning is the process used to develop a scheme for scheduling and committing the resources of time,

money and people. A plan shows how a project will be initiated, organized, co-coordinated and

monitored. A product plan is a decision-making as regards to the design and manufacture of a product,

by considering the revenues from different products. For example assume that a company already

manufacturing 3 products, say P 1 , P 2 and P 3 identifies a need to design a new product N'. Owing to

the design and manufacture of the new product, the production volume, and hence revenue from

products P 1 , P 2 ,and P 3 may be affected (due to re-allocation of company resources such as raw

materials, machineries). In this situation, the company has to decide a time-schedule for the design and

manufacture of the new product. Such plan made by the management is called the product plan. It must

contain the time-as well as resource allocation for each of the products. More over it will result in

optimum and efficient use of resources. After the product plan in made, the management begins a

project for a new product design.

5.4. Organisation Of Design Group

The complexity of mechanical devices has grown rapidly over the last 200 years. For example Boeing 747

aircraft (which has over 50,000 components) required over 10 thousand persons' years of design time.

Thousands of designers worked over a three-year period on the project. These show that, design work is

generally done by a team or group. A design team may include thousands of design and manufacturing

engineers, material scientists, technicians, purchasing agents, drafters, and quality control specialists, all

working over many years.

The first phase in any design process is identification of needs. Needs may be identified by market

survey, the desire to improve an existing product or even by the development of a technology.

Since any design activity consumes company resources like money, people and equipments etc. the

planning of these resources is the next phase after need- identification. Planning means allocation of

resources such as money, people etc. The first step in planning is to form a design team.

5.5. Members of Design Team

Following is a list of individuals needed in a design team. Their titles may vary from company to

company.

1. Design Engineer.

This person is responsible for suggesting ideas for the proposed product. For that, he must clearly

understand needs for the product as well as its engineering requirements. Hence, he must posses both

creative and analytical skills. He must be an engineering graduate having vast experience in the

particular product area.

2. Marketing Manager.

He is responsible for success of the product in the market. He is a link between the product and the

customer. He always sees whether the customer like this product?

3. Manufacturing Engineer.

He knows the best manufacturing process suitable for the production of the particular product. He can

give advice on the various manufacturing processes available in the industry.

4. Detailer

In many companies the design engineer is responsible for specification development, planning,

conceptual design and the early stages of product design. The project is then turned over to detailers

who finishes the details, develops manufacturing and assembly documents.

5. Drafter

A drafter aids the design engineer and detailer by making drawing of the product. In many companies

the detailer and the drafter are the same individual.

6. Technician.

The technicians aid the design engineer in developing test-apparatus, performing experiments etc.

7. Materials Specialist.

In some products, the choice of the material is based on availability. In some other cases, a certain

material is to be chosen according to some features of the product. Material specialist can give advice

on properties of different materials.

8. Quality Control Specialist.

A quality control specialist observes how well the product meets specifications. This inspection is done

on finished products as well as raw materials purchased from vendors.

9. Industrial Engineer.

Industrial designers are responsible for how a product looks and how well it interacts with customers.

They generally have background in fine arts and in human factor analysis.

10. Assembly Manager.

The assembly manager is responsible for putting the product together. Note that assembly process is an

important aspect of product design.

11. Suppliers' Representative.

As part of product development, the company may purchase components or sub-assemblies from out-

sources. In that case, the representative of the supplier of the specified component must be included in

the design team

5.6 Organisational Structure of Design Teams

Since a design project requires individuals with different fields of expertise, they can be organised into

different structures. Listed below are the five organisational structures. The number in the bracket

shows the percentage of design projects that use that particular organisation structure.

1. Project matrix, (28%)

It is an organisation structure having the features of project and matrix organisations.

2. Functional matrix (26%)

It is another organisational structure obtained by combining functional as well as matrix organisations.

3. Balanced Matrix (16%)

Here the project manager and functional manager work together. A project manager is assigned to

oversee the project, and the responsibility and authority for completing the project rests with functional

managers.

4. Project Team (16%)

A project manager is put in charge of a project team composed of a core group of personnels from

several functional areas or groups assigned on a full time basis.

5. Functional Organisation (13%)

Each project is assigned to a relevant functional area or group within a functional area. A functional area

focuses on a single discipline.

5.7. Task Clarification [S 01]

A project plan is a document that defines the tasks necessary to be completed during a design process. A

project plan is used to keep the project under control. It helps the design team and management to

know how the project is actually progressing.

There are five steps to establish a plan. They are,

Identify the task

State the objective of each task

Estimate Personnel's, time, resources required.

Develop a sequence for these tasks.

Estimate product development cost.

Step 1 Identify the tasks

In the first step of the planning of the design project, the different tasks needed to bring the problem

from its initial state to the final products are identified. The tasks are the activities to be performed

during the design process. Given below is a list of tasks drafted by a design team, for the development of

a certain product.

a. Collect and evaluate customer requirements and competition scenario.

b. Establish two concepts for product development.

c. Develop final prototype.

d. Test prototype No1 and select one design for finalisation.

e. Redesign and produce proto type No2.

f. Field test prototype No2.

g. Complete production documentation.

h. Develop marketing plan.

i. Develop quality control procedures.

j. Prepare patent applications.

k. Establish product appearance.

l. Develop packaging.

Step .2. State the objective for each task.

Even though the tasks are initially identified, they need to be refined to ensure that the results of the

activities are the stated objectives. For example, for the task No. (a) above, the objective is to collect

information required for developing specification.

Step 3: Estimate the Personnel, Time & other Resources Required.

Completion of each of the tasks listed above will consume resources such as personnel, time etc. An

estimate of the requirement of resources may look like:

Task Personnel/time

Collecting data Two market surveyors, two months

Concept generation Two designers, two week.

Step 4 Develop a Sequence for the tasks

The next step is scheduling of tasks-the purpose is to ensure that each task is completed, before its

result is needed. CPM is the best method to accomplish this.

Step 5 Estimate Product Development Cost

On the basis of the above steps, the costs for developing the product can be estimated. Normally design

cost is only about 5% of manufacturing cost.

The above plan developed in the early stage of the design has to be refined as the project progresses.

Questions

1. Market research is necessary before starting the production of any product.

(True) [S '97]

2. Write a short note on Product planning and task classification. [S '01]

Brainstorming

Brainstorming - Idea Hunting by a Group of Persons.

Brainstorming is by far the most widely used tool to stimulate creative thinking. It was developed in

the 1940s by the American advertising executive Alex Osborn who believed that anyone could learn to

generate creative solutions for a wide variety of problems.

Brainstorming is a group method of ideation in which stress is laid on the quantity of ideas

generated. Members are asked to generate a large number of ideas while criticism is kept under

check. Participants are encopuraged to build upon the lideas of others, but not knock out them

down.

Perhaps the most important benefit of "Brainstorming" in complex problems is the identification

of the categories of solution concepts.

===========================================

brainstorming process

brainstorming technique for problem-solving, team-building and creative process

Brainstorming is a great technique for generating creative ideas. Generally performed in groups, it's a

fun way to get lots of fresh ideas out on the table and get everyone thinking and pulling together.

To start out, keep the group on the small side( 4 - 8 ). The participants should be relatively at ease

with one another, and as you continue to brainstorm together over time, they'll become more

comfortable throwing out off-the-wall ideas--which often generate the best results.

Begin by choosing a facilitator to record the ideas on large, poster-size sheets of paper that can be

stuck to a bulletin board or along the walls of the room.

This will keep all the ideas clearly visible. And follow these important ground rules:

Suspend criticism. All ideas, no matter how crazy they may seem, should be encouraged and

recorded without comment or criticism from the group. The general goal of brainstorming is

to collect as many ideas as possible, making quantity much more important than quality at

this initial stage.

Postpone evaluation. Brainstorming sessions are not the time or place to evaluate the merits

of the ideas suggested. So don't suspend the process to evaluate the projected results of any

single idea.

Build on others' ideas. At their best, brainstorming sessions are fast-paced and fun.

Participants should try to build each consecutive idea on the previous ones. This can

sometimes result in surprising twists and turns.

brainstorming process

1. Define and agree the objective. 2. Brainstorm ideas and suggestions having agreed a time limit. 3. Categorise/condense/combine/refine. 4. Assess/analyse effects or results. 5. Prioritise options/rank list as appropriate. 6. Agree action and timescale. 7. Control and monitor follow-up.

------------------------------------------------------------------------------------------------------

Brainstorming

Brainstorming is a powerful tool used by teams and businesses around the world. The concept was

first introduced by Alex Osborne in the 1940s.

Brainstorming is a tool for generating ideas. It is an activity in which all members of a group (whether

it be a work team, classroom, committee, etc.) contribute to a list of problems to be solved or

solutions to a problem.

Brainstorming helps to get a lot of ideas into discussion in a short amount of time. Brainstorming may

look unstructured, but to be effective, there should be some ground rules.

These can include:

- Set a time limit on the brainstorming session.

- Don't let participants get sidetracked. Now is not the time to critique ideas that are being suggested.

- Be sure that everyone speaks freely.

- Be sure everyone contributes.

- Let the participants, not the leader, do the talking.

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Design and Manufacturing Notes Chapter 1

DEFINITION OF ENGINEERING DESIGN

1.1 Introduction:

The economic future of India depends on our ability to design, make and sell competitive products.

Excellent design and effective manufacture are the pre-requisites of a successive industry.

There is a general impression that the quality of Indian products can still be improved. The fact that

consumers have lost their confidence on Indian-made products cannot be denied.

This problem can be solved only by designing and manufacturing better products through improved

methodology. Keeping this in view, the subject Design and manufacturing purpose to present the

methods and procedures of design and manufacture.

Although engineers are not the only people who design things, the professional practice of engineering

is largely concerned with design. It is usually said that design is the essence of engineering.

The ability to design is both a science and an art. The science can be learned through procedures

developed by eminent scholars. But the art can be learned only by doing design.

1.2 Types of Products A product is the tangible end result of a manufacturing process and is meant for

satisfying human needs.

The product can be classified as follows: -

1. Convenience goods

These are less expensive and are clustered around shops and restaurants. These can be purchased at

consumers convenience. E.g. Cigarette, Candy, Magazines etc.

2. Shopping goods

These are expensive and people buy it less frequently. E.g. Jewellary garments etc.

3. Specialty goods

These are purchased, taking extra pain. E.g. Rare objects like stamps.

4. Industrial goods.

These are items used in the production of other items. Eg. Raw materials.

Another way of classifying products is into, (a) Continuous Products, and (b) Discrete products

The continuous products are those which are produced in a continuous fashion. For example, plates,

sheets, tubes and bars etc are produced in very long lengths, and then these are cut into desired

lengths.

On the other hand, discrete products are produced one after another, each in separate units. On the

basis of the output product, the Industry is usually named as continuous industry and discrete industry.

1.3 Requirements in a good product

1. Customer Satisfaction 2. Profit

How to achieve customer satisfaction? -

The product should function properly.

-It must have desired accuracy

-It must have desired reliability

-It must be easy to operate

-It must be serviceable

-It must make minimum space utilization

-It must withstand rough handling

-Pleasant appearances.

-Reasonable price.

How can it be profitable?

-It must be easy to manufacture

-The raw material must be cheap and easily available

-The manufacturing process has to the decided on the basis of quantity to be produced

-It must use standard parts

-It must be easy to pack and distribute.

1.4 Definition of Design: (S 94)

Designing is such a vast field that it is defined in several ways.

Various definitions of designing as pronounced by well-known designers are --:

Design is that which defines solutions to problem which have previously been solved in a different

way

Design is the conscious human process of planning physical things that display a new form in

response to some pre-determined need.

Design is an act of collecting all pertinent information for the production of goods and services to

meet some human need.

The design of any component includes two things, (i) Product design (ii) Process design The product

design involves the development of specification for a product that will be functionally sound, good in

appearance, and will give satisfactory performance for an adequate life. The process design involves

developing methods of manufacture of the products so that the component can be produced at a

reasonably low cost.

1.5 History of Design Process

(i) Design by Single Person

(ii) Over-the-wall design

(iii) Simultaneous Engineering

(iv) Concurrent Engineering

(v) Integrated design and Manufacture. In olden times one person could design and manufacture an

entire product.

Even for a large project such as the design of a ship or a bridge, one person had sufficient knowledge of

the Physics, Materials and manufacturing processes to manage all aspects of the design and

construction of the project. This period is referred to as the period of design by single person in the

history of design.

Cus

to

me

rs.

Ma

rket

ing

Eng

g.

Des

ign

Pro

duc

tion

By the middle of the 20th century products and manufacturing processes became so complex that, one

person could not handle all aspects of design and manufacturing. This situation led to over-the-wall

design process. In this method each functional departments were separated from others, as shown by

wall. There was only one-way communications between Customer, Marketing, Engg. Design and

production department.

The customers throw their needs to marketing department. The marketing department may throw the

customer needs to the design department, in many instances, orally. The Engg. Design department may

conceive a design and hands it over to the manufacturing sections. The manufacturing department

interprets that design and makes the product according to what they think suitable. Unfortunately,

often what is manufactured by a company using over-the-wall process is not what the customers had in

mind.

his is due to lack of interaction between the different departments. Thus, this single direction over-the-

wall approach is inefficient and costly and may result in poor quality products. By the early 1980s the

concept of simultaneous engineering emerged. This philosophy emphasized simultaneous development

of the manufacturing process- the goal was the simultaneous development of the product and the

manufacturing process. This was accomplished by assigning manufacturing representatives to be

members of design team, so that they could interact with the design engineers throughout the designs

process. In the 1980s the simultaneous design philosophy was broadened and called concurrent

engineering.

A short definition of concurrent engineering is the simultaneous progression of all aspects, at all stages

of product development, product specification, design, process and equipment etc. In concurrent

engineering the primary focus is on the integration of teams of people having a stake in the product,

design tools, and techniques and information about the product and the processes used to develop and

manufacture it. Tools and techniques connect the teams with the information. Although many of the

tools are computer-based, much design work is still done with pencil and paper. In fact, concurrent

engineering is 80% company culture and 20% computer support. With the advent of computer

technology, drastic changes have taken place in the field of design and manufacturing.

The result was a completely integrated design and manufacturing system. This system makes a good use

of technologies such as CAD/CAM, FMS etc. The computer integrated manufacturing systems (CIMS)

moves towards the Factory of the future. CIMS is necessary for better quality, efficiency and

productivity.

QUESTIONS

1. How can you explain the term design? Explain the process of mechanical design. Discuss the role of

creativity in the design process (S94, 8M) 2. The design of product is ..........customer expectations.

(S99, S94)

3. .get first preference in design

Answer---. Functional requirements (S93)

4. Explain the meaning of (i) Conceptual design (ii) Functional design (iii) Production design. Give suitable

examples for each. (S03)

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CHAPTER 2

TYPES OF DESIGNS

2.1 The design can be classified in many ways. On the basis of knowledge, skill and creativity required in

the designing process.

The designs are broadly classified into three types

(i) Adaptive Design (W 95, 97, 98 00)

(ii) Variant Design (S 97, 99)

(iii) Original Design

(i) Adaptive Design

In most design situations the designers job is to make a slight modification of the existing design. These

are called adaptive designs. This type of design needs no special knowledge or skill. E.g. converting

mechanical watches into a new shape.

(ii) Variant Design

This type of design demands considerable scientific training and design ability, in order to modify the

existing designs into a new idea, by adopting a new material or a different method of manufacture. In

this case, though the designer starts from the existing designs, the final product may be entirely

different from the original product. E.g. converting mechanical watches into quartz watches. Here a new

technology is adopted.

(iii) Original Design

Here the designer designs something that did not exist previously. Thus, it is also called new design or

innovative design. For making original designs, a lot of research work, knowledge and creativity are

essential. A company thinks of new design when there is a new technology available or when there is

enough market push. Since this type of design demands maximum creativity from the part of the

designer, these are also called creative designs.

2.2 On the basis of the nature of design problem, design may be classified as:

(a) Selection design

(b) Configuration design

(c) Parametric design

(d) Original design

(e) Re-design

(a) Selection Design. It involves choosing one or more items from a list of similar items. We do this by

using catalogues. Eg. -Selection of a bearing from a bearing catalogue -Selection of a fan for cooling

equipment -Selecting a shaft.

(b) Configuration / Layout / Packaging Design (W 97, S'02)

In this type of problem, all the components have been designed and the problem is how to assemble

them into the completed product. This type of design is similar to arranging furniture in a living room.

Consider the packing of electronic components in a laptop computer. A laptop computer has a

keyboard, power supply, a main circuit board, a hard disk drive, a floppy disk drive and room for two

extension boards. Each component is of known design and has certain constraints on its position. For

example, the extension slots must be adjacent to the main circuit board and the keyboard must be in

front of the machine.

Key

boa

rd

Mai

n

Circ

uit

boa

rd

Ext

ens

ion

slot

s

Flo

ppy

driv

e

Po

wer

sup

ply

The different components are shown above. The designers aim is to find, how to fit all the components

in a case? Where do we put what? One method for solving such problems is to select a component

randomly from the list and position it in the case so that all the constraints on that component are met.

Let's take keyboard first. It is placed in the front. Then we select and place a second component. This

procedure is continued until we reach a conflict, or all the components are in the case. If a conflict

arises, we back up and try again. Two potential configurations are shown above.

(c) Parametric Design Parametric design involves finding values for the features that characterize the

object being studied. Consider a simple example We want to design a cylindrical storage tank that

must hold 4 m3 of liquid. The volume is given by V = r2 l The tank is described by the parameters, radius

'r', and length l. Given V = 4 m3 = r2 l r2 l = 1.273 We can see a number of values for the radius and

length, that will satisfy this equation. Each combination-values of r and l gives a possible solution for the

design problem.

(d) Original Design As described in an earlier section, an original design in the development of an

assembly or component that did not exist before.

(e) Redesign The redesign is a modification of an existing product to meet new requirements. It is same

as adaptive design. Most design problems solved in industry are for the redesign of an existing product.

Suppose a manufacturer of hydraulic cylinders makes a product that is 0.25m long. If the customer

needs a cylinder 0.3m long, the manufacturer might lengthen the outer cylinder and the piston rod to

meet this special need.

2.3. On the basis of the objective or strategy the designs are of following main types.

A. Production Design

B. Functional Design

C. Optimum Design

A. Production Design In production design, the designer designs something in such a way that the cost

of producing the product is minimum. That is, the first responsibility of the designer is reduction of

production cost. Hence, a production designer is concerned with the ease with which something can be

produced, and that at a minimum cost.

B. Functional Design W93 In functional design, the aim is at designing a part or member so as to meet

the expected performance level. Functional design is a way of achieving given requirements.- but the

same may the unproducible or costly to produce. A good designer, then, has to consider the production

aspects also. A product designed without keeping all these aspects into account, wastes time, money

and efforts.

C. Optimum Design [W 95] It is the best design for given objective function, under the specified

constraints.

2.4 On the basis of the field/ area or the domain of design, the following types are important.

1. Mechanical Design

2. Machine Design

3. System Design

4. Assembly/sub-assembly design

5. Computer aided design

1. Mechanical Design It means use of scientific principles, technical information and imagination in the

design of a structure,or machine to perform prescribed functions with maximum economy and

efficiency.

2. Machine Design It is the process of achieving a plan for the construction of a machine.

3. System Design System Design is an iterative decision making process to conceive and implement

optimum systems, to solve problems and needs of society.

4. Assembly/sub-assembly design [S 93] In the design of Assembly/sub-assembly the major criterion is

the fulfillment of functional requirements. The assembly has to be designed to meet broad technical

parameters and purpose for which it was meant.

The characteristic features are: The total number of parts used in the design must be minimum. Sub-

assemblies should be capable of being built separately in order to give maximum manufacturing

flexibility. Standard parts may be used. Flexible parts should be avoided, as they are easily damaged

during handling and assembly.

5. Computer aided design [CAD] It is a design methodology in which the designs take the advantages of

digital computer to draw concepts, analyze and evaluate data etc. Computers are largely used in a

design office for simulation and prototype study. In modern design, computers have become an

indispensable tool.

Other types of designs are Probabilistic Design Industrial Design

Probabilistic Design [S 96] It is a design approach in which design decisions are made using statistical

tools. Generally, the external load acting on a body, the properties of materials etc are liable to vary. In

probabilistic design, the designer takes into account the variations of such parameters.

Industrial Design [W 93] It is the design made by considering aesthetes, ergonomics and production

aspects.

Questions 1. What are the characteristics features of system design, assembly/sub-assembly design and

component design? Explain briefly with the help of examples. [S'93, 5M] 2. Distinguish between

functional design and industrial design. [W'93]

3. Discuss the meanings of conceptual design, creative design, adoptive design and variant design. [S'97]

4. What are the three main types of design? Give a comparative analysis. [W'00, W '97]

5. Explain the difference between creative design, adoptive design and variant design. [S'02 W'98]

6. Designing for function involves the use and knowledge of .. Ans. Eng. Sciences [W '94]

7. Explain the meaning of (i) Conceptual design, (ii) Functional design and (iii) production design. Give

suitable example of each. [S0'3]

8. Explain layout design. [S0'2]

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Chapter 3

DESIGN PROCESS AND ITS STRUCTURES

3.1. Introduction

Developing a manufacturable product is not an easy job. This chapter presents some methods that help

achieve quality products. Rather than making a detailed study, only an overview of designing process is

attempted here.

3.2. Features of design process

The following features can be observed in a design process.

* Iteration

* Decision-making

* Conversion of resources

* Satisfaction of need

Design is completed in many phases. In each phase, repeated attempts are required to accomplish the

aim. A satisfactory conclusion can be reached on, only after a number of trials. Decision-making is

essential for a designer to select one out of several. A designer often comes across several equally

acceptable alternatives to meet some end. In such conflicting situations, designer has to make the best

decision. In any design process, there is conversion of resources such as time, money, talent, materials

and other natural resources. All designs are aimed at satisfying some human need. Needs, whether

important or unimportant is the starting point of design.

3.3. How a design is born?

In a broad sense there are two methods by which a design comes into existence.

a. Design by evolution (Traditional Design)

b. Design by innovation (Modern Design)

a. Design by evolution

This implies the traditional method of design in which the objects and articles that we see around has

taken its present form by gradual change of time. If one looks at history it can be seen that most of the

tools, equipments, implements, took a long time to acquire their present form. Things changed gradually

with the passage of time. Each change was made to rectify some defects or difficulties faced by the

users. Bicycles, calculators, computers, steam locomotives etc. all went through a process of evolution in

which designers tried one concept after another. Even today this process is being used to some extent.

However, this evolutionary process is very slow. i.e., it took a very long period of time to occur even a

slight modification.

he main reason for this slow evolutionary process of design was the absence of proper information and

design data records.

In modern design situations the evolutionary methods are not adequate because of the following

reasons.

1. The traditional designing did not consider the interdependence of products. They were concerned

about only one component /product. But in the modern world, the existence of one product is

dependent on another in some way or other.

2. In the past, production was on small scale. Thus the penalty of a wrong design was tolerable. But, in

the present time, production is on large-scale basis. As a result, any penalty of a wrong design will cost

great loss.

3. Requirements of the customers of todays world changes so frequently. Traditional design lags behind

the advanced product & process technologies available today.

4. Traditional design methods cannot cope with competitive requirements of the modern world. Due to

the above reasons modern design problem cannot be handled by traditional methods.

b. Design by Innovation

Since the traditional design method failed to cope with modern design requirements, nowadays almost

all designs are made by innovation. i.e., developments of a product by following scientific and

purposeful effort. The innovative design is entirely different from the past practice of evolutionary

design. Here the designers task is greatly magnified. He has to design and create something, which did

not exist yet. Here he tries to solve the design problem in a systematic and orderly manner.

This approach is similar to analytical problem solving. However, an innovative designer faces the

following difficulties.

1. He has to collect and evaluate information on a product, which is non-existing yet.

2. Necessity of analyzing complicated interaction of components.

3. He has to make predictions regarding its performance.

4. He has to ensure the technical and economical feasibility of the product. Notwithstanding the above

difficulties, there are eminent experts like Morris Asimow, J.E. Shigly, Dieter etc have attempted to

systematize the design process.

This systematized steps in design process is called Morphology of Design. The best way in which any

problem can be solved is to break up the problem and to try for a solution in an analytical method. This

approach of problem solving is also adopted in the Morphology of design.

3.4. Problem-solving Methodology

Knowingly or unknowingly we follow six basic actions when we try to find solution of any problem.

1. Establish or convince ourselves that there is a problem. Or we understand that a solution is needed.

2. Plan how to solve this problem

3. By analyzing the problem we decide what is actually required from the problem-solver. Or we decide

the requirements.

4. Generate alternative solutions.

5. Evaluate the alternatives.

6. Present the acceptable solution.

3.5. Morphology of Design.

Morphology means a study of form or structure. Morphology of design refers to the time based

sequencing of design operations. It is a methodology of design by which ideas about things are

converted into physical objects. The logical order of different activities or phases in a design project is

called the morphology of design.

3.6. Design Process- Simplified Approach

A simplified approach to designing as outlined by Morris Asimow is given below. According to him the

entire design process in its basic forms consists of five basic elements as given below.

Ge

ner

al

Info

rma

tion

Spe

cific

Info

rma

tion

Des

ign

Op

era

tion

s

Out

co

me

Eva

luat

ion

No

Yes

GO

TO

NE

XT

STE

P

Design operations imply the various processes done during designing. These include Searching for

possible alternatives systems to satisfy a need. Formulating a model for analysis purpose. Materials

selection, etc. But in order to carryout the above processes (i.e., design operations) a lot of information

is required.

The required informations may be broadly classified into two.

1. General Information E.g. Scientific Laws Information on market trends etc.

2. Specific information. E.g. Information on manufacturers catalogue Materials science handbook etc.

Once the designer has obtained the necessary information he can start design operations.

The design operations give outcomes. The outcome may be in the form of Computer print outs, or

drawings. Next stage is the evaluation of this outcome. The purpose of evaluation is to decide whether

this outcome is able to meet the need. Here a comparison between the capabilities of the outcome and

the need is carried out. If the outcome is sufficient to meet the need, the designer goes on to next step,

otherwise the design operation is repeated.

3.7 Detailed Morphology of Design A design project goes through a number of time phases. Morphology of design refers to the collection of

these time phases. The morphology of design as put forward by Morris Asimow can be elaborated as

given below.

It consists of seven phases.:

I. Feasibility study

II. Preliminary Design

III. Detail design