Roles of an Engineering Drawing-Engineering Drawing and Graphics-Lecture Slides, Slides of Engineering Drawing and Graphics

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Roles of an

Engineering Drawing

TOPICS

• Graphics language in Engineering Design

Process

• Computer-Aided Drafting & Design

(CADD)

Graphics Language in

Engineering Design Process

What is “Engineering Design”?

“ Engineering design is a systematic process by which solutions to the needs of humankind are obtained.

“ Design is the process of conceiving or inventing ideas and

communicating those ideas to others in a form that is understood easily.”

Lockhart et al.

“ Design is the act of creating the specifications for a

product or process that best satisfies the design criteria.

Eide

Bertoline et al.

Simplified Definition

Needs Design Process solutions

1. Write down the problem statement.

2. Generate possible solutions.

3. Evaluate each solution against

the criteria and select the best one.

4. Document the solution.

The Role of Graphics

Visualization

Communication

Documentation

Let’s try to think together…

Yesterday, I went to ME department to buy a textbook. I saw the window panels are very dirty.

Let’s try to think together…

Maybe, a person responsible to this job is lazy.

I don’t think so. I saw she worked diligently.

..…

Let’s try to think together…

I asked her, why don’t you clean those windows?

What did she answer you?

She said it is impossible to clean those windows.

So, what do you think?

I looked at the windows again, then I understood her answer.

What are your findings?

Let’s try to think together…

?

?

I founded that the windows have two glass panels. One is fixed to the top, another one is fixed to the

bottom of a window frame. Both panels place offset with each other and their free edge overlap about mid of the window’s height.

Let’s try to think together…

Sorry, I cannot imagine about the window you have explained.

Okay, I will show you a sketch of the windows.

Visualization

&

Communication

Let’s try to think together…

Sorry, I still do not understand why it is hard to clean the

Um...

The glass panel is thin, so he omits section lines!

I will show you the side view of this window.

window.

Let’s try to think together…

Ah.. I see. The offset distance is small, so she can not

That is right !. If we do not solve this problem,

access the opposite side of the window and the overlapped zone.

learning environment will become worse and …….

Computer-Aided

Drafting & Design

(CADD)

Computer-aided drafting and design (CADD)

is the computer process of making engineering

drawings and technical documents more closely

related to drafting.

Definition

Sketch an idea

Create drawings

Manu- facturing

Parts

Traditional tool 2-D CADD Solid modeling

CNC machine

Translate part information to machine code

Pencil & Paper

Ideation (^) Brain

Conventional machine (manual operate)

Time

Process

Working Drawing Interpret by operator

Evolution of Engineering Drawing

Create machine code by operator

Advantages of CADD

1. Increased accuracy

3. Easy to revise

2. Increased drawing speed

1. Built-in several analysis tools

2. Better presentation (Easy to visualize)

• Pan, rotate, animate, shade, texture

4. Availability of drawing libraries

Drafting

stage

Design

stage

CADD Capability

1. Draw

3. Dimension

2. Modify

4. Object snap

5. Layer concept

Concepts in Working Drawing Creation

Draw a group of lines that are connected and present

• Orthographic multiview
• Pictorial view

2-D CADD

Create an orthographic view from a solid object.

Draw a closed contour and convert to surface. Modify this surface to solid object.

Solid modeling

Limitation of CADD

(within scope of drawing creation)

Good engineering drawings must have the following

characteristics.

Parts or product information is completely given.

Information is clearly presented.

Information can be used in manufacturing of part.

Always remind yourself that “Good drawing cannot be created by using CADD software alone without understanding the drawing concepts.”

 Apply a proper line weight and style.

 Select a necessary view.

 Decide the appropriate places of dimensions.

 Select an appropriate section techniques (if necessary)

Limitation of CADD

(within scope of drawing creation)

To create a good engineering drawings YOU MUST

do the following tasks yourself.