11 Roles of an Engineering Drawing

 

TOPICS

• Graphics language in Engineering Design Process
  
• Computer-Aided Drafting & Design (CADD)
  

Graphics Language in Engineering Design Process

Lockhartet al.

“Design is the act of creating the specifications for a product or process that best satisfies the design criteria.

Bertoline et al.

“Design is the process of conceiving or inventing ideas and communicating those ideas to others in a form that is understood easily.”

What is “Engineering Design”?

Simplified Definition

Design Process

Needs 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

 Yesterday, I went to Civil department to buy a textbook.

I saw the window panels are very dirty.

Maybe, a person responsible to this job is lazy.

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

..…

 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 ?

 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.

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

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

Visualization &

Communication

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

The glass panel

is thin, so he omits

section lines !

Um.. . I will show you the side view of this window.

 Ah.. I see. The offset distance is small, so she can not access the opposite side of the window and the

overlapped zone.

 That is right !. If we do not solve this problem, learning environment will become worse and …….

Teamwork

Individual

1. Hire a cleaning service company.
   
2. Buy a usable device.
   
3. Redesign the window construction.
   
4. Change the window to
   

   concrete wall.
   

5. Design a homemade cleaning device.
   

6. ………………………

	Criteria
	Availability	Cost	Simplicity	Aesthetic
Hire a cleaning service company. Buy a usable device. Redesign the window construction. Change the window to concrete wall. Design a homemade cleaning device. 6. ………………………

Assume you (or your team) make a decision that

“Design a homemade cleaning device”

is the best solution under listed criteria.t

1. Modify from an existing solution.
   

 

Solutions A, B …

 

1. Ad hoc solutions.
   

Major functions of a device

1. Wash & Polish (the panel)
   
2. Wipe
   

Would you like to combine both functions into a single device ?

Yes

Single device.

No 1)

Two devices: One for wash & polish

another one for wipe.

Assume you (or your team) choose this choice.

2) Single device but has a changeable part.P 2 : Generate possible solutions.

Function

Wipe

What should be an appropriate form of part(s) to do the required functions?

Hold

(by user)

What material is the part should be made of ?

Easy to use. Should not rust.

How parts are assembled ?

Not too expensive.

Not too heavy.

Can insert between the panels.

Solutions

Criteria

Cost Weight

Size Ease of operation …

Assume you (or your team) choose the solution Cis used to represent rough ideas.

If this final results are unsatisfactory,

the selected solution will be modified.

Mathematical analysis

Computer simulation

Build and test a prototype Operation

STEP 4 : Document the solutions Documentation =

Write a technical report

ComputeCAided

Drafting & Design

Definition

Computer-aided drafting and design (CADD) is the computer process of making engineering drawings and technical documents more closely related to drafting.

Evolution of Engineering Drawing

Time

Brain

Pencil & Paper

Traditional tool 2-D CADD Solid modeling

Working Drawing

Interpret

by operator

Create machine code

by operator

Translate

part information to machine code

Process

Conventional machine

(manual operate)

aCNC machine

Drafting stage

Design stage

Advantages of CADD

1. Increased accuracy
   
2. Increased drawing speed
   
3. Easy to revise
   
4. Availability of drawing libraries
   
5. Built-in several analysis tools
   
6. Better presentation (Easy to visualize)
   

   – Pan, rotate, animate, shade, texture
   

   CADD Capability
   

   1. Draw
      
   2. Modify
      
   3. Dimension
      
   4. Object snap
      
   5. Layer concept
      

2-D CADD

Draw a group of lines that

are connected and present

• Orthographic multiview
  
• Pictorial view

Concepts in Working Drawing Creation

Solid modeling Draw a closed contour and convert to surface.

Modify this surface to

solid object.

Create an orthographic

view from a solid object.

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.

To create a good engineering drawings YOU MUST

do the following tasks yourself.

• Apply a proper line weight and style.
  
• Select a necessary view.
  
• Decide the appropriate places of dimensions.
  
• Select an appropriate section techniques (if necessary)
  

(within scope of drawing interpretation)

Because they are frequently used technical document.

Therefore,YOU MUST prepare yourself for interpreting (or visualizing) them when you become ENGINEER.

No CADD software can create a pictorial view from an orthographic multiview.

 

What do you think ? Good or Poor

 

What do you think ? Good or Poor.

 

What do you think ? Good or Poor.

 

What do you think ? Good or Poor

What do you think ? Good or Poor