Intro Cad 1

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CAD/CAMComputer Aided Design and

Computer Aided Manufacturing

Introduction to CAD/CAM


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CAD/CAM

CAD/CAM = Computer Aided Design and

Computer Aided Manufacturing. It is the

technology concerned with the use ofcomputers to perform design and

manufacturing functions.


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Introduction

In general, a Computer Aided Design (CAD)

package has three components:

a) Design,

b) Analysis and

c) Visualization, as shown in the sketch. A

brief description of these components

follows.

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a) Design: Design refers to geometric

modeling, i.e., 2-D and 3-D modeling,

including, drafting, part creation, creation ofdrawings with various views of the part,

assemblies of the parts, etc.

b) Analysis: Analysis refers to finite elementanalysis, optimization, and other number

crunching engineering analyses

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c) Visualization:

Visualization refers to

computer graphics,

which includes:

rendering a model,

creation of pie charts,contour plots, shading

a model, sizing,

animation, etc. 5


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Each of these three areas has been

extensively developed in the last 30 years.

Several books are written on each of thesesubjects and courses are available through

the academic institutions and the industry.


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Most commercial CAD packages (software)

consist of only a single component: design

or analysis or visualization. However, a few

of the vendors have developed an integrated

package that includes not only these three

areas, but also includes the manufacturing

software (CAM).

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Due to the large storage requirement,

integrated packages use either an UNIX

workstation or a mainframe platform, andnot the popular PC platform.

With the improvement in PC computing

speed, its only a matter of time before wesee an integrated package running on pc.

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Computer Aided Manufacturing

(CAM) CAM is the next stage of CAD. A part

created in CAD can be downloaded and

manufactured, without a human handtouching the part.

The process is called CAM, and involves

CAD, Networking, and NC programming,as shown below.

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Throughout the history of our industrial

society, many inventions have been

patented and whole new technologies haveevolved . Perhaps the single development

that has impacted manufacturing more

quickly and significantly than any previoustechnology is the digital computer .

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Computer-aided design(CAD) is defined as

the application of computers and graphics

software to aid or enhance the productdesign from conceptualization to

documentation .

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CAD. is most commonly associated with the

use of an interactive computer graphics

system , referred to as a CAD system .Computer-aided design systems are

powerful tools and in the mechanical design

and geometric modeling of products andcomponents .

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CAD can be defined as the use of computer

systems to perform certain functions in the

design process.

CAM is the use of computer systems to

plan, manage and control the operations of

manufacturing plant through either direct or

indirect computer interface with the plants

production resources.


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From CAM definition, the application of

CAM falls into two broad categories:1. Computer monitoring and control .

Computer ProcessProcessdata

Control signals

Computer ProcessProcess data


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2. Manufacturing support application .

Control signalsComputer Mfg

operations

Process data


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The Product Cycle and

CAD/CAMIn order to establish the scope and definition

ofCAD/CAM in an engineering environment

and identify existing and future related tools,a study of a typical product cycle is

necessary. The following Figure shows a

flowchart of such a cycle.

i l d if l


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The Manufacturing Process

The Design Process

SynthesisAnalysis The CAD Process

The CAM Process

Design

needs

Design

definitions,

specifications,

and requirements

Collecting

relevant design

information and

feasibility study

Design

conceptualization

Design

modeling and

simulation

Design

analysis

Design

optimization

Design

evaluation

Design

documentation and

communication

Process

planning

Ordermaterials

Design and

procurement of

new tools

Production

planning

NC, CNC, DNC

programming

ProductionQuality

control

Packaging

Marketing

Shipping

Typical Product Life Cycle


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The product begins with a need which is identified

based on customers' and markets' demands.

The product goes through two main processes from

the idea conceptualization to the finished product:

1. The design process.

2. The manufacturing process.

The main sub-processes that constitute the design process

are:1. Synthesis.

2. Analysis.


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Implementation of a Typical CAD Process on

a CAD/CAM systemDelineation of

geometric model

Definition

translator

Geometric model

Design and

Analysis algorithms

Drafting and

detailing

Documentation

To CAM Process

Interface

algorithms

Design changes


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CAD Tools Required to Support the Design Process

Design phase Required CAD tools

Design conceptualization Geometric modeling techniques;Graphics aids; manipulations; and

visualization

Design modeling and simulation Same as above; animation; assemblies;

special modeling packages.

Design analysis Analysis packages; customized

programs and packages.

Design optimization Customized applications; structural

optimization.

Design evaluation Dimensioning; tolerances; BOM; NC.

Design communication and

documentation

Drafting and detailing


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Implementation of a Typical CAM Process on

a CAD/CAM systemGeometric model

Interfacealgorithms

Process planning

Inspection

Assembly

Packaging

To shipping and marketing

NC programs


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Manufacturing phase Required CAM tools

Process planning CAPP techniques; cost

analysis; material and

tooling specification.

Part programming NC programming

Inspection CAQ; and Inspection

software

Assembly Robotics simulation and

programming

CAM Tools Required to Support the Design Process


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Definitions of CAD Tools Based on Their

Constituents

Computer

graphics

concepts

Design toolsGeometric

modeling

CAD

tools


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Definition of CAD Tools Based on Their Implementation

in a Design Environment

Design tools + Computer

Hardware

(control unit; display

terminals;I/O devices

Software (graphics;modeling; applications

programs

= CAD tools


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Definitions of CAM Tools Based on Their

Constituents

Networking

concepts

Mfg toolsCAD

CAM

tools


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Definition of CAM Tools Based on Their Implementation

in a Manufacturing Environment

Mfg tools + Computer

Hardware

(control unit; display

terminals;

I/O devices

Software (CAD; NC;

MRP; CAPP)= CAM tools

Networking


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Definitions of CAD/CAM Tools Based on

Their Constituents

Mfg tools

Networking

Design tools

Geometric

modeling

Computer

graphics

concepts

CAD/CAM

tools


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Definition of CAD/CAM Tools Based on Their

Implementation in an Engineering Environment

Design and

Mfg tools

Hardware

Software = CAD/CAM tools

Networking

+ Computer

ypical Utilization of CAD/CAM Systems in an Industrial Environme


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Geometric modeling

of conceptual design

Is design evaluation

Possible with available

Standard software?

Design testing

And evaluation

Is final design

Applicable?

Drafting

Documentation

Process planning

Are there

manufacturing

discrepancies in CAD

databases?

NC

programming

Machining

Inspection

Assembly

Develop customized

programs and

packages

No

Yes

Yes

Yes

Geometric modeling and graphics package

Design

package

Programming

package

No

No

CAPP package

NC

package

Inspection

And Robotics

package

ypical Utilization of CAD/CAM Systems in an Industrial Environme


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Automation and CAD/CAM

Automation can be defined as the

technology concerned with the application

of complex mechanical, electronic, andcomputer-based systems in the operation

and control ofmanufacturing systems.

TT pes of Man fact ring S stems


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TTypes of Manufacturing Systems

1. Continuous-flow processes. Continuous dedicated production of

large amount of bulk product. Continuous manufacturing is

represented by chemicals, plastics, petroleum, and food industries.

2. Mass production of discrete products. Dedicated production of

large quantities of one product (with perhaps limited model

variations). Examples include automobiles, appliances and engine

blocks.3. Batch production. Production of medium lot sizes of the same

product. The lot may be produced once or repeated periodically.

Examples: books, clothing and certain industrial machinery.

4. Job-shop production. Production of low quantities, often one of akind, of specialized products. The products are often customized

and technologically complex. Examples: prototypes, aircraft,

machine tools and other equipment.


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Productionquantity

Continuous-

flow

production Mass

production

Batchproduction

Job shop

production

Product variety


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Category Automation achievements

Continuous-flow process Flow process from beginning to end

Sensors technology available to measureimportant process variables

Use of sophisticated control and optimization

strategies

Fully computer automated lines

Mass production of discrete products Automated transfer machines

Dial indexing machines

Partially and fully automated assembly lines

Industrial robots for spot welding, part handling,

machine loading, spray painting, etc.

Automated material handling systems

Computer production monitoring

Batch production Numerical control (NC), direct numerical

control (DNC), computer numerical control(CNC).

Adaptive control machining

Robots for arc welding, parts handling, etc.

CIM systems.

Job shop production Numerical control, computer numerical control


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Most of the automated production systems implemented today

make use of computers. CAD/CAM in addition to its particular

emphasis on the use of computer technology, is also

distinguished by the fact that it includes not only the

manufacturing operations but also the design and planning

functions that precede manufacturing.

To emphasize the differences in scope between automation and

CAD/CAM, consider the following mathematical model:

Computer Technology in Automation


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321 TBTBQTTTlc

BQ

T

Q

TT

Tlc

321cyclelifeitsduring

productofuniteachonspenttimeaverageThe

.productdifferenteachforonceedaccomplisharethatactivities

othertheallforandproductthedesigningforrequiredtimeThe3 T

.productionofbatcheachforupsettingandplanningwithassociatedtimeThe2 T

cycle.lifeproductt thethroughouproducedbatchesofnumberTheB

product.ofunitoneproducetorequiredtimeThe1 T

batch.eachinproducedunitsofnumberTheQ

cyclelifeproducttheduringtimetotalclTT


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Automation technology is concerned with reducing

the with emphasis on the unit production

time

CAD/CAM concerned with reducing all three

terms, but is perhaps focused on terms.The emphasis in CAD/CAM includes the design

and planning function of the product life cycle.

1T

32 &TT

The most important term in mass production

and batch production

become very important in job shopmanufacturing.

1T

32 &TT

21

&TT


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Advantages of CAD/CAM

systems Greater flexibility.

Reduced lead times.

Reduced inventories. Increased Productivity.

Improved customerservice.

Improved quality. Improved communications

with suppliers.

Better product design.

Greater manufacturingcontrol.

Supported integration.

Reduced costs.

Increased utilization.

Reduction of machinetools.

Less floor space.


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Computer-aided manufacturing(CAM) is

defined as the effective use computer

technology in manufacturing planning andcontrol .

CAM is most closely associated with

functions in manufacturing engineering ,such as process and production planning ,

machining , scheduling, management,

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quality control, and numerical control (NC)

part programming.

Computer-aided design and computer-aidedmanufacturing are often combined

CAD/CAM systems

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This combination allows the transfer of

information from the design into the stage

of planning for the manufacturing of aproduct, without the need to reenter the data

on part geometry manually.

The database developed during CAD isstored; then it is processed further, by

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CAM, into the necessary data and

instructions for operating and controlling

production machinery, material- handlingequipment, and automated testing and

inspection for product quality

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Rationale for CAD/CAM

The rationale for CAD/CAM is similar to

that used to justify any technology-based

improvement in manufacturing. It grows ourof a need to continually improve

productivity, quality and competitiveness.

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There are also other reasons why a company

might make conversion from manual processes

to CAD/CAM: Increased productivity and Better quality

Better communication

Common database with manufacturing

Reduced prototype construction casts

Faster response to customers44


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Applications of CAD/CAM

The emergence of CAD/CAM has had a

major impact on manufacturing, by

standardizing product development and byreducing design effort, tryout, and prototype

work; it has made possible significantly

reduced costs and improved productivity.

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Some typical applications of CAD/CAM are

as follows:

Programming for NC, CNC, and industrialrobots;

Design of dies and molds for casting, in

which, for example, shrinkage

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CAD Platform In general, we can run CAD software on three

different CAD platforms: Mainframe,

Workstation, and PC. When the CAD

programs first became available, they couldonly be run on a mainframe computer.

However, as the PCs have become faster and

cheaper, almost all the CAD vendors haveintroduced a version of their CAD software

that will effectively run on a Pentium or

higher computer.47


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CAD Evaluation Criteria In the current CAD market, ProE and

AutoCAD are arguably the most dominating

CAD software. AutoCAD is basically a 2-D

program, with some capability to create 3-Dmodels, where as, ProE is a truly 3-D CAD

package.

Following is a brief description of thegeneral criteria for evaluating a CAD

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Hardware: Most desirable features in a good

hardware are:

Open architecture

High speed, large storage

Compact size

Inexpensive components

Inexpensive upgrading

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Software: In general, the most comprehensive

software are written to satisfy almost all the

modeling needs of a modeler, consequently,the software tend to be very complex and hard

to learn.

To create a simple model, we go throughseveral unnecessary steps, and lack the

intuitiveness of a simple, straightforward

program. 51


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There are several other factors that we

should consider when evaluating software.

Following is a brief description of thesefactors.

Operating System: Unix or Windows/NT.

PCs in general use Microsoft Windows,where as, operating system for Workstations

is Unix.52


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User Interface: Most popular CAD software

have menu driven commands, which is

preferable to the old system of non-menudriven, where user interface was completely

by responding to software commands.

Documentation and Support: Learning asoftware can be very difficult if the software

lacks good documentation.

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Maintenance: Cost of the hardware and

software upgrades can significantly impact

the small and medium size companiesdecision to choose one software over the

others.

Modeling Capabilities: In, general, a CADsoftware can be classified as either a 2-D or

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Ease of Modeling: As a rule-of-thumb, a

general, all-purpose type CAD software is

much more complex and difficult to learnthan a special purpose CAD package.

Interface with other CAD Packages and

Data Transferability: A CAD package isused to create models that will be used for

analysis, manufacturing, or some other

applications. 55


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Design Documentation: Besides creating a

model, the software should be capable of

creating drawings, assemblies,dimensioning, various views (isometric,

orthogonal, etc.), labels and attributes, etc.

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Documents

Intro Cad 1