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  • 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%)

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

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

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

  • 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

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

  • Introduction to CAD/CAM/CAE

    Contents Overview

    D fi iti f CAD CAM d CAE

    Contents

    Definitions of CAD, CAM, and CAE Integrating the Design and Manufacturing Process

    h h C D bthrough a Common Database Using CAD/CAE/CAM Systems for

    d l i l lProduct Development- Practical Example

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

  • 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

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

  • Analysis Sub-Processes

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

  • 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 plants 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

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

  • 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 integrating Developments 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

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

  • 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

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

    y

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

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

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

    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

    CAD

    CAM

    Mold Design

    Mold FlowCAM

    Mold Assembly

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

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

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

  • 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

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

  • 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 t Model - 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.

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

  • 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.

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

  • 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)

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

  • Step 3Modify the design geometry (CAD again)

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

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

    (An Example)(An Example)

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

  • 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.

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

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

  • What is made of CAD/CAM/CAE

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

  • Computer science: algorithms

    Your program:

    My program:

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

  • Math: geometry

    v2

    p2v1

    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 (0u1), and2 its meets the boundary conditions2. its meets the boundary conditions

    S(0) = p1 and dS(u)/du|u=0 = v1S(1) = p2 and dS(u)/du|u 1 = v2

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

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

  • Design the profile using a drafting software

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

  • Modeling the part using a 3D geometric modeling software

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

    ric modeling software

  • Basic 3D mesh elements

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

  • The triangular mesh of the model

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

  • 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

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

  • Property analysis

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

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

    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.

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

  • Before (without NC)

    Now (with NC)

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

  • 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?

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

  • Rapid Prototyping

    Fi 1 A h ti d i f LOM

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

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