1. IPE-409 CAD/CAM
Dr. Nafis Ahmad
Professor
Department of IPE, BUET
Email:nafis@ipe.buet.ac.bd

2. Ch#1.
Introduction to CAD/CAM
2

3. IPE-409 CAD/CAM
Reference books:
• CADCAM Principles, practice and manufacturing
management-
• Chris McMohan and Jimmie Browne
• CAD/CAM Theory and Practice
• Ibrahim Zeid

4. Topics
• Introduction
• The design process and the role of CAD-Ch#1
• Design process, role of modelling and communication,
design models, concurrent engineering, modelling using
CAD, CAD system architecture
• Defining the model-Ch#2
• Techniques for geometric modelling-Ch#3
• Elements of Interactive computer graphics-Ch#4
• Entity manipulation and data storage-Ch#5
• Standards for CAD-Ch#6
• Industrial Robotics

5. Introduction to CAD/CAM
• Airbus380 The world's largest passenger airliner,
$0.5B, 853 passenger Max, 16K Km range..
• 1988-Concept
• 1990 Project announcement
• 1994 Product announcement
• 2000 Restructured after recession ‘97~2k
• 2001 Design completed
• 2002 Component production
• 2005 Test flight
• September 2006, the first full passenger-carrying
• October 2007 delivered to Singapore Airlines

6. Introduction to CAD/CAM

7. Introduction to CAD/CAM
• Major structural sections of the A380 are built in France,
Germany, Spain, and the United Kingdom
• Delays attributed to the 530 km (330 mi) of wiring,
complexity of the cabin wiring (98,000 wires and 40,000
connectors)
• Concurrent design and production,
• High degree of customisation for each airline, and
• failures of configuration management and change control.
The German and Spanish Airbus facilities continued to use
CATIA version 4, while British and French sites migrated to
version 5. This caused overall configuration management
problems,
• Lost revenue $5B and penalties from airliners

8. CAD/CAM Introduction
Design Process
• We see the touch of engineers everywhere-building,
equipments, vehicles, rails, etc
• Now many products are very complex, need large
team to collaborate the product development and
manufacturing. Increased performance, quality and
sophistication.
• Need to shorten time and cost due to competition.
• So need computer help i.e. CAD

9. Process for bringing a product to
market
Design brief
|
Designer-explore ways
|
Design analyst-Analysis and Simulation
|
Development/research engineers-carry expt. work on
prototypes and refine design
|
Process planner-identify process and operations required
|
Production planner and controller-schedule of production

10. Models of Design Process
Formal description of the stages or elements
of design process. Though there are
variation in terminology and in detail, they
agreed a step-by stem manner
• Phal and Beitz Model
• Oshuga Model

11. PhalandBeitzModel

12. Ohsuga
Model

13. Role of Modelling and communication
Design model and models of design process?
Design is abstract until manufactured.
So we need models to evaluate, manipulate and
refine. Models are used for recording and
manipulating ideas and provide a basis for
evaluation of the design.
Models have a major role in the communication of
design between participants in the process

14. Types of design
• Varity of representation is required from
preliminary layout to complete design.
• Models depend on what design property to be
modelled, who or what is target or receiver
• Model the function of a design, structure, form,
shape, surface condition, dimension, material etc.
• It may be mathematical model

16. Applications of design Models
• Evaluating Action-to
assess the properties and
merits of design
• Generative Action-
Generate information from
model for use downstream
of the design process,
usually in order to
progress its manufacture
• In both case extraction of
information from model is
necessary

17. Applications of design Models
• Design Analyst do-
• A visual assessment
• Mass of the
component
• Evaluation of stresses
• Manufacturing engs.
• Extract info for tooling
• For control of
production machine.

18. Traditional design process and
Concurrent Engineering
• Traditional: design descriptions are produced in the form of
engineering drawing..etc. by design department, then design is
sent for analytical evaluation, and for preparation of plans and
instructions for manufacture.
• If manufacturing specialist and design analyst find issues, they
send it back to design department which is than reissue the
design. In aerospace manuf. Avg. drawing change is 4.5 times.
• Designer concentrate on functional aspects at the expense of
ease of manufacturing, maintainability etc.
• Concurrent Engineering aims to overcome all these issues by
bringing together a design team with appropriate combination of
specialist expertise. Where CE is not suitable

19. Concurrent Engineering
• Both Phal & Beitz Model and Ohsuga Model are traditional
view (sequential models)-sequence of design stages,
followed by manufacturing.
• However pressure to reduce product design and
development time-scales leading companies to conduct
design, development, analysis and the preparation of
manufacturing information in parallel.
• This concept is know as Concurrent Engineering.
• Mainly used by those companies which have established
products and where ew models are required at regular
intervals.

20. Over the wall vs. CE

21. CAD in Modelling
• Design progressively refined in the abstract, until it is
completely defined for manufacture
• A series of models of various aspects of the design are
prepared
• Sequencially/Concurrently others extract info from these
models and forms new models to assist them
• Parallally developed
• Models of functional and other custormer requirement s for the
design
• Models of constraints on design, imposed by available mat.,
manuf. Process etc.
• Models of loads imposed on design
• Models to evaluate performance of the design..stress, thermal etc..

22. Use of Models in Design

23. CAD System Architecture
• CAD System consists of –Hardware, Software, data
and human knowledge and activities
• Software-comprises of different elements or process
data stored in the database in different ways. These
are
• Model definition
• Model manipulation
• Picture generation
• User interaction
• Database management
• Application-
• Utilities-color to display

24. CAD System Architecture

25. CAD System Architecture

26. New design concept

27. CAD Projects
Infusion pump

28. CAD Projects
Robot arm

29. Assignment
1. Take a sheet of paper, write your student ID, name,
sketch different components of the pen you are using.
Submit the paper. Draw 3D models of each
components(1:1 scale), assemble them and submit
through https://tl.ahmadn.info
2. Make a list of top 10 CAD Software(5-open source/free
and 5-non-opensource/commercial) and compare their
features.
3. 3D models of Assignment 1 must be created by at least
1 Open source/Free and 1 non-open
source/commercial CAD software.