CHAPTER 1 DESIGN AND GRAPHIC COMMUNICATION

CHAPTER 1
DESIGN AND GRAPHIC
COMMUNICATION
Introduction
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.
1-1 Engineering Design
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.
1.2 Design Concepts – Sources for
New Models
1.
2.
3.
4.
5.
Individual Creativity
Study Patent Drawings
Examine Manufactured Products
Study the Natural World
Creativity and Teamwork
1.3 Design Processes
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.
1.4 Identification of the Problem
and the Customer
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.
1.5 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.
1.6 Compromise / Analysis Solutions
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.
1.7 Models and Prototypes
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.
1.8 Production or Working Drawings
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.
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
1.9 Communicating Using Graphics
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.
1.10 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 and Continuing Education
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.
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
Summary

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.