CHAPTER 1 DESIGN AND GRAPHIC

COMMUNICATION

OVERVIEW

A new machine structure or system must exist in the mind of the engineer

or designer before it can become a reality. The design process is an

exciting and challenging effort, during which the engineer-designer uses

graphics as a means to create, record, analyze, and communicate design

concepts or ideas.

Everyone on the engineering and design team needs to be able to

communicate quickly and accurately in order to compete in the world

market. Like carpenters learning to use the tools of their wade,

engineers, designers, and drafters must learn the tools of technical

drawing. The design team progresses through five stages in the design

process. To be a successful member of the design team, you must

understand the process and know your role.

While CAD has replaced traditional drafting toos for many design teams

the basic concepts of graphic communication remain the same. Your

proficiency in communicating using graphics will be valuable to you and to

your eventual employer.

Introduction

Engineering design is a process which requires a clear understanding of

the function and performance expected of the end product. It is a way of

conceiving and creating new ideas and then communicating those ideas to

others in a way that can be easily understood. This is accomplished most

efficiently through the use of graphics. Design can be used to reflect

personal expressions or to enhance product development.

1-1 Engineering Design

1. Individual Creativity

2. Study Patent Drawings

3. Examine Manufactured Products

4. Study the Natural World

5. Creativity and Teamwork

1.2 Design Concepts – Sources for

New Models

Design is the ability to combine ideas, scientific

principles, resources, and often existing products into

a solution of a problem. This ability to solve problems

in design is the result of an organized and orderly

approach to the problem known as the design

process.

The design process leading to manufacturing,

assembly. marketing, service, and the many activities

necessary for a successful product is composed of

several easily recognized phases. Although many

industrial groups may identify them in their own

particular way, a convenient procedure for the design

of a new or improved product is in five stages as

follows:

1. Identification of problem, need, or “customer.”

2. Concepts and ideas

3. Compromise/analysis solutions.

4. Models and/or prototypes.

5. Production or working drawings.

1.3 Design Processes

The design activity begins with the recognition of a problem and/or the

determination of a need or want for a product, service, or system and the

economic feasibility of fulfilling this need.

1.4 Identification of the Problem and the Customer

At this stage, many ideas are collected—reasonable and otherwise—for

possible solutions to the problem. The ideas are broad and unrestricted

to permit the possibility of new and unique solutions. The ideas may be

from individuals, or they may come from group or team brainstorming

sessions where one suggestion often generates many more ideas from

the group. As the ideas are elicited, they are recorded for future

consideration and refinement.

1.5 Identification of the Problem and the Customer

Various features of the many conceptual ideas generated in the

preceding stages are selected after careful consideration and combined

into one or more promising compromise solutions. At this point the best

solution is evaluated in detail, and attempts are made to simplify it so that

it performs efficiently and is easy to manufacture, repair, and even

dispose of when its lifetime is over.

1.6 Compromise / Analysis Solutions

A 3-D CAD model or scale model is

often constructed to study, analyze,

and refine a design. A full-size

working model made to final

specifications, except possibly for

materials, is known as a prototype.

The prototype is tested and

modified where necessary, and the

results are noted in the revision of

the sketches and working drawings.

Figure below shows a prototype of

the magnetic levitation train.

1.7 Models and Prototypes

To produce or manufacture a product, a final set of production or

working drawings is made, checked. and approved.

In industry the approved production design layouts are turned over to

the engineering department for the production drawings The

necessary views are drawn for each part to be made, and complete

dimensions and notes are added so that the drawings will describe

these parts completely. These are called detail drawings.

1.8 Production or Working Drawings

Design is an Iterative Process

• Begins with a

recognition of need for a

product, service, or

system

• During the idea phase

encourage a wide

variety of solutions

through brainstorming,

literature search, and

talking to users

• Best solutions are

selected for further

refinement

• Models or prototypes are

made and problems that

arise may require new ideas

to solve and a return to an

earlier stage in the process

• Finally drawings are

released to manufacturing

for production

Although people around the world speak different languages, graphic

communication has existed since the earliest of times. The earliest

forms of writing were picture forms, such as the Egyptian

hieroglyphics shown in Figure 1.16. Later these forms were simplified

and became the abstract symbols used in writing today.

Graphic representation has developed along two distinct lines: artistic

and technical. From the beginning of time, artists have used drawings

to express aesthetic, philosophic, or other abstract ideas. People

learned by looking at sculptures, pictures, and drawings in public

places. Everybody could understand pictures~ and they were a

principal source of information.

1.9 Communicating Using Graphics

1.10 Earlier Technical Drawing

Perhaps the earliest known

technical drawing in existence is

the plan view for the design of a

fortress drawn by the Chaldean

engineer Gudea and engraved on

a stone tablet.

1.11 Earlier Descriptive Geometry

Descriptive geometry uses

graphics and projections to

solve spatial problems.

Gaspard Monge (1746 –

1818) is considered the

inventor of the descriptive

geometry. While he was a

professor at Polytechnic

School in France, he

developed the principles of

projection that are now the

basis for technical drawing.

1.12 Modern Technical Drawing

In 1876 the blueprint process was introduced at the Philadelphia

Centennial Exposition. Up to this time, creating technical graphics was

more or less an art, characterized by fine-line drawings made to

resemble copperplate engraving, by shade lines, and by water-color

washes These techniques became unnecessary after the introduction of

blueprinting, and drawings gradually became less ornate to get better

results in reproduction. This was the beginning of modem technical

drawing. Technical drawing became a relatively exact method of

representation, often making it unnecessary to build a working model

before a device could be constructed.

1.13 Drafting Standards

Standards for the appearance of technical drawings have been

developed to ensure that they are easily interpreted across the nation

and around the world. As you learn to create technical graphics, you

will adhere to these standards. This will allow you to create drawings

which communicate clearly and cannot be misinterpreted by others.

In the United States the American National Standards Institute (ANSI),

the American Society for Engineering Education (ASEE), the Sodety of

Automotive Engineers (SAE), and the American Society of Mechanical

Engineers (ASME) have been the principal organizations involved in

developing the standards now in place. As sponsors, they have

prepared the American National Standard Drafting Manual—Y14,

which consists of a number of separate sections that are frequently

updated. (See Appendix I.)

1.15 Drafting

Drawings have accompanied and made possible technical advancements

throughout history. Today the connection between engineering and science

and the ability to visualize and communicate graphically is as vital as ever.

Engineers, scientists, and technicians need to be proficient in expressing

their ideas through technical graphics, using both sketching and CAD.

Training in the application of technical drawing is required in virtually every

engineering school in the world.

In most technical professions the ability to read a drawing is a necessity,

whether or not you produce drawings yourself. Technical drawings are

found in nearly every engineering textbook, and instructors often require

you to supplement calculations with technical sketches, such as free body

diagrams. So mastering a course in technical drawing using both sketching

and CAD will help you not only in your professional work, but also in many

courses.

Training is an essential part of continuing education and a wise

investment. Training enables you to:

work faster, smarter and become more productive

increase your engineering expertise and value to your

company and customers

make analysis and simulation an integral part of your design

process

take advantage of advanced software capabilities and

meet with other users to exchange ideas and techniques.

Knowledgeable users can then help companies speed up time to

market and make better, safer products at a lower cost.

Training and Continuing Education

1.16 Projections Modern technical graphics uses

individual views or projections to

communicate the shape of a 3-D

object or design on a sheet of

paper. You can think of every

drawing as involving the spatial

relationship of four things:

1. The observer’s eye, or the

station point

2. The object

3. The plane of projection

4. The projectors, also called

visual rays or lines of sight.

There are two main types of

projection—perspective and

parallel.

Classification of Projections

Engineering drawing can be a universal language to communicate your ideas.

The engineering design process uses sketching and CAD to communicate and record ideas.

A single CAD database can be used to produce many types of drawings and models used throughout the design process.

Summary