Lecture Week1

MT 21_CAD/CAM 3(1-2)

Lecture: Week 1

Than Lin, Ph.D.Instructor, Undergraduate Program

Asian Institute of Technology

CAD/CAM 3(1-2), AIT-UG (January’ 2013)

Grading: Quizzes (10%) Mid Term Exam (30%)

Grading: Quizzes (10%) Mid-Term Exam (30%) Laboratory Exercises (10%) & Project (10%) and Final Exam (40%)

Textbook:

Kunwoo Lee “Principles of CAD/CAM/CAE Systems.

ReferencesReferences:

Farid M. Amirouche, Principles of Computer Aided Design and Manufacturing, 2nd Edition Prentice Hall 20042nd Edition, Prentice-Hall, 2004.

P N Rao “CAD/CAM Principles and Applications”

Introduction to CAD/CAM/CAE

ContentsOverviewD fi iti f CAD CAM d CAE

Contents

Definitions of CAD, CAM, and CAE Integrating the Design and Manufacturing Processh h C D bthrough a Common Database

Using CAD/CAE/CAM Systems for d l i l lProduct Development- Practical Example

Overview

CAD/CAM 3(1-2), AIT-UG (January’ 2013)Figure: Product Cycle

Result of Synthesis

• A conceptual design of the prospective product in the form of sketch (layout drawing)that shows the relationships among the various product components

• The major financial commitments needed to realize the product idea are made• The functionality of the product is determined• Most of the information generated and handled is qualitative and consequently is hard

to capture in the computer system

Analysis Sub-Processes

Definitions of CAD/CAM/CAE

Computer Aided Design (CAD) –The technology concerned with the use of t t t i t i th ti difi ti l i dcomputer systems to assist in the creation, modification, analysis, and

optimization of a design [Groover and Zimmers 1984]

Computer Aided Manufacturing (CAM)- the technology concerned with the use of computer systems to plan, manage, and control manufacturing operations through either direct or indirect computer interface with the plant’s production resources

Computer Aided Engineering (CAE)- The technology concerned with the use of computer systems to analyze CAD geometry, allowing the designer to simulate and study how the product will behave so that the design can be refined and optimized

Definitions of CAD/CAM/CAE

CAD,CAM, and CAE- Concerned with automating specific functions of the product cycle and making more efficient

Developments done separately not fully realized the potential of integratingDevelopments done separately, not fully realized the potential of integrating the design and manufacturing activities of the product cycle

CIM has been introduced to solve this problem, aimed at trying the separate “islands of automation” together into a smoothly running, efficient system.

CIM-concerned with using the computer database as a way to run an entire enterprise more efficiently, having an impact on accounting, scheduling,enterprise more efficiently, having an impact on accounting, scheduling, shipping, and other management functions

Integrating the Design & Manufacturing Process through a common database-A Scenario

To show how CAD/CAM/CAE are overlaid on the product cycle to

common database A Scenario

id on the product cycle to realize the goals of better quality(Q), lower Cost©, and Quick delivery(D)

Assume [Design specification calls for the cabinet to have four spaces]

Fi A di tp ]

-Disc player-Cassette playerReceiver

Figure: Audio system cabinet to be

designed-Receiver-Storage compartment

Designer to determine Dimensions of Cabinet, Material, thickness and considers assembly

Integration of CAD/CAM/CAE through the data-base

Figure: Integration of CAD,CAM and CAE through the database

the database

Using CAD/CAM/CAE Systems for Product Development-A Practical Example

-Task To design & Manufacture

the front piece of cellular phonethe front piece of cellular phone

-Assume that Styling and

conceptual design carried outp g

Mold Design

Mold FlowCAM

Mold Assembly

A case study of CAD/CAE/CAM

Four steps in the product cycle of this arm lift weightFour steps in the product cycle of this arm lift weight

Step 1Conceptual and geometric design (CAD)

Design - Using drafting software to draw the outline curve

M d l U i 3D d li ft t d l th tModel - Using 3D modeling software to model the part as a revolution surface

Database - Store the design as a file in computer

Computer-aided drafting system and geometric modeling system are the two most important components of CAD.system are the two most important components of CAD.

Step 2Analysis of CAD geometry and optimization (CAE)

SimulationSimulation

Analyses of stress, strain, deformation, heat transfer, kinemay , , , ,tics, linkage, dynamics, fluid flow, etc.

Optimization

Fi it l t th d (FEM) i th t id l d th d iFinite-element method (FEM) is the most widely used method in CAE.

Finite-Element Method

Finite-element modelingFinite element modeling Divide the CAD geometry into small pieces of required shaperequired shapeto approximate the design by a meshmesh.pp g y

Finite-element analysisFinite element analysisCalculate stress, strain, displacement etc. at any place in the model by solving a set of system equations and shape functioy g y q pns on the mesh.

(An Example)

Step 3Modify the design geometry (CAD again)

G t f d b k f th Fi it l t l iGet feed back from the Finite-element analysis

Modify the design geometry and other design data accModify the design geometry and other design data accordingly

(An Example)(An Example)

Step 4Make it, that is, manufacture it (CAM)

Manufacturing process planning Use computer technology to plan, manage, and control manufacturing process.

Numerical control (NC) machiningTh t h i f i d i t ti t t lThe technique of using programmed instructions to control a machine tool that grinds, cuts, mills, punches, bends, or turns raw stock into the finished partraw stock into the finished part.

Rapid prototypingRapid prototyping Build a prototype of the part directly from the CAD model as a stack of layers by means of laser or other techniques.

s c o ye s by e s o se o o e ec ques.

What is made of CAD/CAM/CAE

Computer science: algorithms

Your program:

My program:

Math: geometry

Gi t i t d d t t d

S(u) = ???p1y

Given two points p1 and p2, and two vectors v1 and v2,

find four vectors a0, a1, a2, and a3, such that the vector

function S(u) = a + a u + a u2 + a u3 satisfies:x function S(u) = a0 + a1u + a2u2 + a3u3 satisfies:

1. it is a smooth function in (0≤u≤1), and

2 its meets the boundary conditions2. its meets the boundary conditions

S(0) = p1 and dS(u)/du|u=0 = v1

S(1) = p2 and dS(u)/du|u 1 = v2

S(1) p2 and dS(u)/du|u=1 v2

Design the profile using a drafting software

Modeling the part using a 3D geometric modeling software

ric modeling software

Basic 3D mesh elements

The triangular mesh of the model

Property analysis

Finite element method (FEM) e e e e e od ( )or Finite difference method (FDM) or Finite volume method– For static and dynamics responses– Meshing boundary condition i

terationteration

Property analysis

Illustration of an FEM process

New design: one arc of radius 25 now should be a curve of height 25 and width 45 that is required to smoothly connect to its two adjoining lines.

Before (without NC)

Now (with NC)

NC Machining ProgrammingTo program the NC machine tool to correctly cut the part

Given the CAD data:

1. How to compute the correct tool pathcorrect tool path (dotted)?

2. How to identify and determine the twodetermine the two phases of machining?

Rapid Prototyping

Fi 1 A h ti d i f LOM

Figure 1. A schematic drawing of a LOM process.Laminated Object Manufacturing

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