Basic Engineering Graphics unit 1.pdf

Introduction
Engineering graphics is the geometric representation of
solutions, engineering systems and components according to
required national and international standards of practice. It
can be read and understood by all who have the knowledge
of drawing principles. These drawings are produced with
the purpose of solving specific human needs. Examples of
such needs include agricultural (food), energy, shelter,
transportation, health care, education, etc. Engineering
graphic is technically referred to as engineering drawing.
Like every other language, engineering graphics is primarily
the language of engineers for conveying ideas on technical
issues to others.

Cont.
Since engineering graphics are standardized (i.e.
furnished with standard symbols, national and
international standard practice as well as codes), they
display the exact picture of an object and convey the
same ideas to every trained personnel across the nations
of the world. Despite the social or economic or cultural
or language barriers, drawings can be effectively used in
other countries, in addition to the country where they
are prepared. Hence, engineering drawing is the
universal language of all engineers. Therefore,
engineering drawings must be correctly drawn.

Cont.
 This module covers producing drawings or similar
graphical representations where the critical
dimensions and associated tolerances and design
specifications are predetermined. It applies to any of
the full range of engineering disciplines. All work is
carried out under supervision.
 This module covers the units:
 Drawing specifications
 Assembly layout and general drawings
 Sectioning
 Dimensioning
 Engineering part lists

Learning Objective of the Module
 Identify drawing requirements
 Prepare assembly, layout and detail drawings
 Draw sections through simple engineering
components
 Select physical dimensions from manufacturer
hand books
 Prepare engineering part lists

Unit one: Drawing Specifications
1.1. Design Information
Design is the realization of an idea, or the resolution of
requirements, through means of communication such as
drawings, plans, specifications and models. These can then be
used to enable items to be created or issues resolved.
Design information is any information produced during the
design process (typically by architects, engineers, contractors
and other suppliers) in order to communicate or develop the
design, or to inform decisions or to allow construction to take
place.
The term ‘design’ does not only refer to aesthetics and will
also include functional, performance, structural, construction
and other aspects of the project.

Cont.
Architects will typically be responsible for leading the
process of preparing design information (although
engineers may lead the process if the project relates
predominantly to infrastructure, if there are particularly
complex services or systems and so on) showing the
arrangement of the design and how different aspects of
it are coordinated and integrated.
Structural engineers will produce a structural design that
comprises a general structural arrangement showing
foundations, column and beam sizes, and column to
beam connections etc. Services engineers will produce
layouts that show duct runs and sizes, boiler locations,
pipe work and so on. Specialist suppliers and sub-
contractors may produce details for specialist aspects of
the project such as cladding, escalators and lifts and so
on.

Cont.
Therefore Design is the process of conceiving or
inventing ideas mentally and communicating those ideas
to others in a form that is easily understood. Most often
the communications tool is graphics.
Design is used for two primary purposes: personal
expression, and product or process development (Figure
1.1). Design for personal expression, usually associated
with art, is divided into concrete (realistic) and abstract
design and is often a source of beauty and interest.
When a design serves some useful purpose, such as the
shape of a new automobile wheel, it is classified as a
design for product or process development.

Figure 1.1.Design is grouped as artistic and technical

1.1.1. Aesthetic Design
There are certain aesthetic design concepts that
are useful for engineers. Function means that a
product possesses a form related directly to the
purpose of that product. For example, a sports car
marketed because of its power and speed should
have a body design that “radiates” speed (Figure
1.2). The architect Louis Sullivan used the phrase
“form follows function,” meaning that the form of a
design is joined to its function. Form is the overall
physical appearance of a product and consists of
many elements, the arrangement of which is
critical to the aesthetics and function of the
product. These elements are unity, style, line,
space, mass, proportion, balance, contrast, and
color.

Cont.
Unity: is the use of similar elements throughout the design or
product line. The engineer accomplishes unity by thinking of the
product as a whole instead of as individual parts or components.
Style: is the addition of decoration to a product and is closely linked
to marketing. For example, the basic functional components of an
automobile do not change every year, but the style usually does.
New styles are created each year to generate consumer interest and
increase the product life cycle.
Line: is another characteristic of a product. Lines can be thin, thick,
straight, or curved and can be used to emphasize the intended
function. For example, thin, curved lines on a sports car emphasize
the function of speed.
Space: is the relationship of a product to its background, as well as
to its negative elements (holes, slots, voids).

Cont.
Mass: is the design element that provides a sense of weight or heaviness.
The physical space that an object occupies has a bearing on the perceived
function of that product. For example, the sports car should appear to have
little mass. This can be accomplished by designing the chassis and body so
that the car is close to the ground.
Proportion: is the relationship of the smaller elements to the whole
design. For example, if the sports car had very large wheel wells, they
would look disproportionate compared with the rest of the vehicle.
Balance: is the design element that gives the product equilibrium. There
are two types of balance: symmetrical and asymmetrical. For example, the
sports car displays asymmetrical balance between the front and rear halves
and symmetrical balance between the left and right sides.
Contrast: is the feature used to emphasize or deemphasize certain
elements in a design. For example, the sports car uses a single color and
material for the body, eliminating contrast to give the feeling of wholeness.
Contrast can be provided by decorations, such as chrome bumpers.
Color: is the element used to evoke emotions, give sensations of weight,
and enhance a design form. For example, a red-colored sports car tends to
evoke feelings of excitement and quickness.

1.1.2. Functional Design
Functional design focuses on the function of the product or
process instead of its appearance. Many products are a mix
of function and aesthetics, but some are almost exclusively
functionally designed. A pair of crutches is designed with
little regard for aesthetics, to function as an aid to a person
with a leg injury. An automobile radiator used to cool an
internal combustion engine is totally designed so that its
functional requirements are met with little regard to
aesthetics.

Figure 1.2.Aesthetic and functional design

1.1.3. Engineering Design
Engineering design is a problem-solving process that uses
knowledge, resources, and existing products to create new
goods and processes. Engineering design has both aesthetic
and functional elements and can be broken into two broad
categories: product design and system or process design
(Figure 1.1). The design process, as implemented by industry,
varies between companies; some use a linear or step-by-step
approach, while others use a more integrated team approach.
Product Design
Product design is the process used to create new products,
such as a new automobile model (Figure 1.2), a new
appliance, or a new type of wheelchair. Product design is a
complex activity that includes market, production, sales,
service, function, and profit analyses. The goal of product
design is to produce a product that meets the wants and
needs of the consumer, is economically produced, is safe for
the consumer and the environment, and is profitable to the
company.

Cont.
System Design
System design is the process used to create a new system or process. A
systems engineer or industrial engineer is an engineer who specializes in
designing systems. A system is an orderly arrangement of parts that are
combined to serve one general function. Examples of system designs
include the arrangement of the assembly process in a factory; the heating,
ventilation, and air-conditioning (HVAC) system in a structure; and the
electrical system in the automobile in Figure 1.2. The objective is to
produce a system that serves a specific function economically, is safe for
the consumer and the environment, and is profitable for the company.
Traditional Engineering Design
Traditional engineering design is a linear approach divided into a number
of steps. For example, a six-step process might be divided into problem
identification; preliminary ideas, refinement, analysis, optimization, and
documentation (see Figure 1.3). The design process moves through each
step in a sequential manner; however, if problems are encountered, the
process may return to a previous step. This repetitive action is called
iteration or looping. Many industries use the traditional engineering design
process; however, a new process has developed that combines some
features of the traditional process with a team approach that involves all
segments of a business.

Cont.
Figure 1.3.Traditional engineering design sequence

Cont.
Concurrent engineering
The production process executes the final results of the design process
to produce a product or system. In the past, the creative design process
was separated from the production process. With the advent of
computer modeling and product data management systems, this
separation is no longer necessary, and the modern engineering design
approach brings both processes together.
Concurrent engineering is a nonlinear team approach to design that
brings together the input, processes, and output elements necessary to
produce a product. The people and processes are brought together at
the very beginning, which is not normally done in the linear approach.
The team consists of design and production engineers, technicians,
marketing and finance personnel, planners, and managers, who work
together to solve a problem and produce a product. Many companies
are finding that concurrent engineering practices result in a better,
higher-quality product, more satisfied customers, fewer manufacturing
problems, and a shorter cycle time between design initiation and final
production.

Cont.
Figure 1.4.Concurrent engineering design

1.2. Customer Ideas
1.2.1. Collaborating
Collaboration is perhaps the most popular way to
involve customers in the design process. Here,
customers are given an opening to contribute their
ideas and suggestions and the company then takes
those into account when the next round of product
development takes place.
1.3. Design Concepts
Concept design simply refers to a phase of the design
process. It’s the point within the development cycle that
typically sits between the product requirements and
detailed design.

Cont.
Here’s where it usually sits within manufacturing:
Idea > requirements > concept design > detailed design > prototyping > manufacturing
Concept design plays a vital role; it can’t start without the initial product requirements
having been scoped out, yet the detailed design process is highly ineffectual without it.
The difference between concept and detailed
The design process for most products splits into two disciplines:
 Concept design
This phase is ‘big picture’ thinking without getting bogged down in technical detail. This
stage of the process confirms the product requirements. The designers know what problems
need to be solved, and they’re subsequently able to brainstorm how the product will address
them.
This stage is an intensely creative stage of product development. Think white boards full of
Post-It notes, mind mapping and long brainstorming sessions. It calls on designers to
consider all possibilities and be unafraid to think big.
During the concept design process, the more ideas and the less constrained one is by
perceived technical limitations, the better - it is innovation without limits.
 Detailed design
This phase tightens the reigns on the design scope. It’s also the point which explores the
cold, hard truths of what is and isn’t possible.
During the detailed design process, clearances, manufacturability, tolerances and customer
perception are all taken into account. The big thinking of the concept phase is dealt a far
more critical eye with only the most practical and market-appealing ideas making it to the
prototype stage.

1.4. Sketches and Preliminary Layouts
1.4.1. Sketches
Sketches are drawings, often freehand, that are
used by designers such as architects, engineers
and interior designers as a quick and simple way
of exploring initial ideas for designs. They are not
intended to be accurate or definitive, merely a way
of investigating and communicating design
principles and aesthetic concepts.

Cont.
Sketches can also be used to explore more technical
aspects of a design, providing an initial response and
possible solutions to problems, constraints and
opportunities such as services layout, structure, method
of construction , solar paths and shading, prevailing
wind , patterns of circulation , relationships between
aspects of the site and so on.
Much is made of the architect’s ‘back of a cigarette
packet/napkin’ sketches that then becomes the basis for
a building design. Indeed, this is reportedly how Renzo
Piano came up with the design for The Shard, and Mike
Davies from RSHP developed the initial idea for the
Millennium Dome.

Cont.
Figure 1.6.Initial idea for the Millennium Dome.

Cont.
Preliminary sketches capture and communicate the essence of an idea,
focusing on its driving features, and in the same way that an artist sketch is
often more evocative than a finished painting, concept drawings can
sometimes capture the sense of an idea more clearly than later drawings or
even the completed building.
1.4.2. Preliminary Drawings are the initial plans for projects prepared by the
designer or architect's and engineer's (A/E) firm during the early planning or
promotional stage of the building development. They provide a means of
communication between the designer and the user (customer). These drawings
are NOT intended to be used for construction, but they are used for exploring
design concepts, material selection, preliminary cost estimates, and approval
by the customer, and a basis for the preparation of finished working drawings.
Notice that most of the
design work incorporated into the preliminary drawings at the 35 percent stage
of completion contain, as a minimum, the following information: site plans,
architectural floor plans, elevations, building sections, preliminary finish
schedule and furniture layouts, interior and exterior mechanical and electrical
data, and civil and structural details.

Basic Engineering Graphics unit 1.pdf

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