Modulation Instituteendeavor is that suggested by Morris Asimow. Engineering Design is a "purposeful...

Modulation Institute

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CONTENTS

Engineering design process and its structure.

Identification and analysis of need, product design specifications, standards of

performance and constraints.

Searching for design concepts, morphological analysis, brainstorming. Evaluation

of design concepts for physical reliability, economic feasibility and utility.

Detailed design:

Design for manufacture, assembly, shipping, maintenance, use, and recyclability.

Design checks for clarity, simplicity, modularity and safety. Standardization and

size ranges.

Reliability and robust design. Design organization and communication, . technical

reports, drawings, presentations and models.

Concept of manufacturing:

Classification of manufacturing processes. Fundamentals of casting.

Basic understanding of commonly used casting processes (sand casting,

investment casting and permanent mould casting processes).

Fundamentals of metal forming :

Hot and cold working, basic understanding of primary metal forming processes

(rolling, forging, extrusion and drawing processes, punching and blanking).



Fundamentals of metal cutting:

tool-work interaction for production of machined surfaces.

Classification of machining processes. Basic machining operations (turning,

shaping, planning, drilling and milling processes).



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: -

1. 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. 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

Continuous Products, and

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.



Requirements in a good product

• Customer Satisfaction

• Profit

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.



Definition of Design:

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”.

There have been many definitions suggested to describe what is meant by

Engineering Design. One which m ay best summarize all the aspects of the field of

endeavor is that suggested by Morris Asimow. Engineering Design is a "purposeful

activity directed towards the go al of fulfilling human needs, particularly those

which can be m et by technological factor, of our civilization."

According to (M. Asimow- "Introduction to Design," Prentice Hall) :-

The emphasis is placed on three important phrases which tell us what Engineering

Design is

(i) A purposeful activity.

(ii) Aimed at the satisfaction of human needs.

(iii) Based on technological factors. It is most important that we fully realize the

implications of these three features whenever a design project is presented to

us. It is well known that the profession or engineering exists to solve

problems presented to its m embers by the sound application of scientific

principles. It is required that these problem s be solved, within a defined

time limit and taking due account of economic, human and legal factors.

The second aspect which is accentuated in the above description is that of

"fulfilling human needs." This is the most important consideration in design

and is the prim ary reason for the existence of engineering. These needs can

be manifest in many different ways but we must always realize who it that



engineering should serve is. The third consideration separates Engineering

Design from other fields where hum an needs can b e satisfied by music,

literature, art, architecture and other artistic activities. Thus Engineering

Design is, by definition, limited to those areas where the logical

application of scientific principles is an essential method of solution. This

does not mean that artistic and aesthetic considerations are not taken into

account; merely that they are not the primary consideration in most cases.

Characteristics of Engineering Design :

There are a number of features which are necessary to recognize as constituting

the major characteristics of Engineering Design.

Engineering Design can be considered as being

1. Goal Oriented.

2. Variform

3. Constrained

4. Evolutive

5. Probabilistic

6.Value Comparative

7. Compromising

The Design Procedure :



The major stages of engineering design may be listed as

• NEED

• IDEA

• DECISION

• ACTION

That there is a NEED is established and defined, followed by the development of

IDEAS, the DECISION as to which alternative will be translated to reality by the

ACTIONS of the production team. The early stages of this process are basically

the mental process of idea creation and decision making. These processes have

been studied by psychologists who have defined the stages involved. It is true that

some people are "born inventors" who seem to always have creative thoughts

whereas there are others who have "never had an original idea in their lives. There

are m any people, however, who have the cap ability f or originality, but for one

reason or another, have never developed the facility. It is for this reason that, in the

early stages of design practice, it is valuable to adopt a conscious approach to the

development of a creative attitude. This will obviously be more effective if the

conscious efforts are those which will become automatic and subconscious efforts

with the passage of time.

It appears that the stages of thinking followed by creative people are as follows

• DEFINITJON OF NEED

• PERIOD OF INCUBATION

• CONCEPTION OF SOLUTIONS

• ANALYSIS OF IDEAS

• DECISION

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.

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,

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. 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.

Type of Designs:

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

• Variant Design

• 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.

1. 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.

2. 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.

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

1. Selection design

2. Configuration design

3. Parametric design

4. Original design

5. Re-design

6. 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

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

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