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          Dr. HABEEB HATTAB HABEEB

       Office: BN-Block, Level-3,
       Room-088
       Email: hbuni61@yahoo.com
       Ext. No.: 7292
Lecturer: Dr. HABEEB ALANI   University TENAGA Nasional
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                 University TENAGA National


             College Of Engineering
             Mechanical Department
            Academic Year – 2008-2009
  Lecture Note


Lecturer: Dr. HABEEB ALANI          University TENAGA Nasional
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                CAM
Lecturer: Dr. HABEEB ALANI   University TENAGA Nasional
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 Design Modeling Requirements

   The purposes of design modeling / / is to capture the
   design concept in a sharable medium.

   Traditionally this medium has been a piece of paper.
   Since engineering objects are mostly three dimensional,
   the model in the form of a drawing must be capture all
   the    details    of      the   design   on   this   two-dimensional
   medium.



Lecturer: Dr. HABEEB ALANI                        University TENAGA Nasional
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Design Modeling Requirements


   Engineering drafting standardizes the following:
• Symbols
• Formats
• Conventions used in drawing engineering objects.


  Drafting geometry:              Drafting functions:

      Line                          Add
                                     Delete
      Circle
                                     Modify
      Curve
                                     ---etc.----
      ---etc.----



Lecturer: Dr. HABEEB ALANI                 University TENAGA Nasional
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Design Modeling Requirements



  The importance results for using of CAD system:



 • More flexible than a manual drafting system.

 • Can produce more precise conventional engineering drawing.

 • CAD replace paper-and-pencil based drafting with higher

   efficiency.

 • CAD opens other possibilities in design modeling.




Lecturer: Dr. HABEEB ALANI                 University TENAGA Nasional
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Design Modeling Requirements


    Modeling objects features:

   • Enhance to generation of multiple views.

   • All geometric entities are modeled in the 3D space (X, Y,

      and Z).

   • 3D CAD model can be rotated and viewed from any angle.

   • NC part programming requires can be taken directly from

      the model.

   • 3D CAD model contain richer information than a 2D

      drafting model.


Lecturer: Dr. HABEEB ALANI                 University TENAGA Nasional
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Design Modeling Requirements

     Disadvantages of 3D CAD model:
    • Dimensions and tolerances are so difficult to present with
       3D model.
    • 3D wire frame model lacks face information and does not
       have the volume property.
    • 3D wire frame not complete and unambiguous model.
    • No correct section views can be generated.


  3D solid model:

 • 3D solid model revealed all details for the objects inside,

    outside, edges and others.
 Lecturer: Dr. HABEEB ALANI                  University TENAGA Nasional
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Design Modeling Requirements




    Design model information:



   • Geometry
   • Tolerances
   • Volume (for some applications and available only in solid
      models)
   • Annotation




Lecturer: Dr. HABEEB ALANI                University TENAGA Nasional
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Classification of geometric modeling techniques

                       Geometric Models


          2-D                              3-D


  Wire frame


 Finite Element Mesh


                                            Hybrid
Lecturer: Dr. HABEEB ALANI            University TENAGA Nasional
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The Age of Computers
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What is the Computers-Aided Design?



                       CAD
    The    use   of   computer   to   assist   for   creation    and
    manipulation- design model represented as a digital data or
    computer image to assist engineering the design process




Lecturer: Dr. HABEEB ALANI                      University TENAGA Nasional
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Computers-Aided Design?

 A CAD system usually consists of:

1. hardware: the computer and associated peripheral equipment.

2. Software: the computer program(s) running on the hardware.

3. Data or model created and manipulated by the software.

4.Human knowledge and activities.




Lecturer: Dr. HABEEB ALANI                University TENAGA Nasional
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Computers-Aided Design?

 Hardware :
Input Devices
– Keyboard, Mouse
– Light pens, Data Tablets




Lecturer: Dr. HABEEB ALANI   University TENAGA Nasional
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Hardware

 Output Devices
- CRT Monitors, Flat Panel Displays
– Plotters, Printers




Lecturer: Dr. HABEEB ALANI            University TENAGA Nasional
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 CAD systems

 The First 2D Software – SKETCHPAD…

 • Developed at MIT by Ivan Sutherland in 1963.
 • Allowed the user to interact with a computer graphically.
    – CRT monitor, Light Pen, Graphical Interface




Lecturer: Dr. HABEEB ALANI                  University TENAGA Nasional
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 CAD systems

 The historical evolution of CAD system

 --Business system required large computer connecting to
 many terminals

  1st CAD project, MIT in 1959 - 1960, by Ivan Sutherland,
 developed SKETCHED system, which was an early drawing
 processing system that used computers, the system included
 most of the concepts of today's interactive 2D CAD system.
  General Motors DAC-1
  Lockheed Corp. CADAM for business application in 1967

Lecturer: Dr. HABEEB ALANI                University TENAGA Nasional
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 CAD systems

 --Mini-computer to dedicated graphics terminal
 Applicon Corp. introduced AGS in 1968
 • Computer Vision Corp. introduced CADDS in 1969


 --Personal Computer (PC) AutoDESK (for low-end user)
  AutoDESK Corp. introduced AutoCAD for 2D CAD system in
 later 1970's
  AutoCAD R 12, and R13 C4 in 1996
  AutoDESK Collection, AutoCAD, AutoVision, Desiger, 3D studio
  Mechanical Desktop – parameter based system
Lecturer: Dr. HABEEB ALANI                University TENAGA Nasional
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   CAD systems


 --Integrated and knowledge-based CAD/CAE/CAM
 System (for high-end user)
  I-DEAS/Pro-E/UG/CATIA


 --Mid-range solid modeler
 • SolidWorks, Solid Edge




Lecturer: Dr. HABEEB ALANI        University TENAGA Nasional
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 CAD Used as a Design Assistant Tool


 Basic level - to assist in drafting
 - Produce 2D engineering drawing and diagram
 - CAD is only used for Computer-Aided Drafting


 Advantages:
       Productivity - short period of design and lower cost of
                       design work.
      Accuracy - improvements of product quality.
      Consistency - national standards, in-house standards.

Lecturer: Dr. HABEEB ALANI                  University TENAGA Nasional
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Advanced level - to assist in design by 3D modeling
o wireframe model, began to link with CAM and CAE
o 3D surface model, shading for image
o 3D solid model, completed information and real-photo image
o 3D CAD modeling for visualization - CAD/Design Vision
o 3D CAD modeling for analysis - CAD/CAE and FEA
o 3D CAD modeling for prototyping - CAD/RP&M
o 3D CAD modeling for manufacturing - CAD/CAM/CNC, CAD/CAPP
o 3D CAD modeling for simulation - CAD/Real Physical Model
o 3D CAD modeling for animation - CAD/Real Physical Model

Lecturer: Dr. HABEEB ALANI                 University TENAGA Nasional
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Example of CAD system-AutoCAD

Icons (Tool Palette) - Composite
set of most frequently used commands
Pull-Down Menu(Menu Bar) - Listed on the
menu bar, contain all the commands.
Screen Menu - Containing almost all the commands.
Graphics Window - the place used to build up model.
Status Line - Give you information about the current status of your
model
Command Window - A place you and AutoCAD can talk to each other

Lecturer: Dr. HABEEB ALANI                     University TENAGA Nasional
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Example of CAD system-AutoCAD




Lecturer: Dr. HABEEB ALANI      University TENAGA Nasional
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Example of CAD system-AutoCAD




Lecturer: Dr. HABEEB ALANI      University TENAGA Nasional
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 Features of AutoCAD Systems

 - Command Entry Styles

 o Keyboard entry
 o Pull-down menus
 o Screen Menus
 o Table Menu and Icons

 - Geometric Entities and Entry Coordinates

 - Three parts of AutoCAD Commands

 Draw - entities (line, arc, circle, pline etc.)
 Construct- manipulate of entities (copy, array, chamfer, fillet, mirror, etc.)
 Modify - edit of entities (erase, trim, move, etc.)
University TEAGA Nasional                                   Lecturer: Habeeb Al-Ani
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                       Tooling and Fixturing




Lecturer: Dr. HABEEB ALANI              University TENAGA Nasional
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 Tooling and Fixturing
A           is a tool of the manufacturing industry used in mass
production. Fixtures are used to hold objects in place and clamp
them to machines or operating surfaces, so that the object can be
machined or assembled.




Lecturer: Dr. HABEEB ALANI                University TENAGA Nasional
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 Fixtures differ from        , in that the fixture holds the workpiece
in one place while a tool or cutter is moved in relation to it. A
guides the tool along a path defined by the shape of the jig. The
jig may also hold the tool during this operation.



                                   Jigs




Lecturer: Dr. HABEEB ALANI                    University TENAGA Nasional
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Lecturer: Dr. HABEEB ALANI   University TENAGA Nasional
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Tooling and Fixturing



  The purposes of jigs and fixtures are widespread however
when used in mass production they have five key aspects:


oReduce the cost of production
oMaintain consistent quality
oSpeed production
oPrevent or reduce improper techniques
oImprove the overall safety to the part, operator, and machine.




Lecturer: Dr. HABEEB ALANI                University TENAGA Nasional
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Tooling characteristics
   In metal cutting, a proper tool must be identified for any
operation.
   The technical aspect of the decision increases with the
increasing number of possible tool selections and W/P
materials.


Selection of tool material factors:
oGeometry and construction include setup characteristics.
oThe material itself.
oThe shape and size of the W/P.
Lecturer: Dr. HABEEB ALANI                University TENAGA Nasional
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Tooling characteristics .. Cont..

oThe design requirement.
oThe type of operation

  -For given setup-and-tool combination machining
   parameters Feed, Speed, and cutting depth must
   be selected

-Selection of cutting parameters still no easy task. Why?.
   Because the suggested data in handbooks are based on
isolated laboratory tests using standard specimens. Many
restrictive factors such as rigidity of the setup, quality of machine
tool, force and power are carefully controlled.
Lecturer: Dr. HABEEB ALANI                   University TENAGA Nasional
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Tooling characteristics .. Cont..




    - Cutting environment determined by the site..
      (machine tool, and fixtures on the factory floor is
        often different from the environments encountered
        in laboratory tests). Whereas the performance is
        strongly dependent on environment variables.




Lecturer: Dr. HABEEB ALANI              University TENAGA Nasional
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  Machinability

1. ASM, defined the machinability / The relative ease for
    material to be machined. To the people engaged in a
    particular set of operations, Machinability has a clear
    meaning such as, number of components produced per
    hour or per tool.

 Or
2. The relative ease in achieving surface or dimensional
    specifications.


Lecturer: Dr. HABEEB ALANI              University TENAGA Nasional
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Machinability.. Cont..

     To determine the Mchinability of any product, the
researchers and manufacturers are applied evaluation
criteria in practice as follows:


   1. Tool life

   2. Limiting material-removal rate

   3. Surface finish achieved

   4. Chip control

   5. Force and power consumption

Lecturer: Dr. HABEEB ALANI             University TENAGA Nasional
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Machinability.. Cont..



     ASM, and many industry reports are indexes the results
of machinability tests.
-Long-term        absolute    machinability       standard      became
available in 1977 (ISO 3685-1977).
-The ISO standard test indicates the relative merit of two or
more     work-tool       combinations   for   a   range    of   cutting
conditions.




Lecturer: Dr. HABEEB ALANI                    University TENAGA Nasional
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Machinability.. Cont..

  Machinability test requirements


  1. Mounted the specimen between two centers or
     chuck ad center.
  2. Length to diameter ratio less than 10 / 1.
  3. Tool material HSS, P30, P10, K20, OR K10.
  4. Four sets of machining conditions, intended to cover
     everything from light to heavy roughing operations.
  5. At least four speed should be used that ideally result
     in a tool life of 5, 10, 20, or 40 min.

Lecturer: Dr. HABEEB ALANI                 University TENAGA Nasional
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Machinability.. Cont..


  Tool failure criteria for HSS



  1. Catastrophic tool failure (i. e., breakage)
  2. 0.3mm average flank-wear land width if flank wear
     is even.
  3. 0.6mm maximum flank wear if flank wear is
     irregular, scratched, chipped, or badly grooved.




Lecturer: Dr. HABEEB ALANI               University TENAGA Nasional
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Machinability.. Cont..

Influence of physical & mechanical properties of materials
on machinability

  1. Material with high yield strength and work-hardening
       ability requires more power input, exerts higher
       compression stress and in general generates higher
       temperature on the tool surface.

  2.    In   addition        to   requiring   a   high-energy       input
       machining ductile material results in a poor surface
       finish.
Lecturer: Dr. HABEEB ALANI                        University TENAGA Nasional
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Machinability.. Cont..

Influence of physical & mechanical properties of materials
on machinability

  3. Material       with     high-fracture   toughness     tends    to
      generate long chips that are hard to break.
  4. Material       with     a   high   work-hardening     capability
      requires more energy on the share plane.

  5. Good thermal conductivity can reduce the temp. on
      the tool surface.

  6. Material that tends to react chemically with the tool
      material at high temperature can destroyed tools.
Lecturer: Dr. HABEEB ALANI                    University TENAGA Nasional
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Machinability.. Cont..

Machinability of :


  Steels/ with very low carbon (0.15%C), have poor
       machinability by all criteria such as:
  1. ductile.
  2.   chips trend to adhere to the tool surface.
  3.   high strain generates more heat.
  4. More energy required.
  5. Surface finish not good.


Lecturer: Dr. HABEEB ALANI                University TENAGA Nasional
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Machinability of .. Cont..

  Free-machining steels/ are typically alloys of steel and
      sulfur, lead, or some other suitable alloying agent.
      The addition of 0.1 to 0.3 % S or 0.1 to 0.35% Pb or
      a small amount of Bi (bismuth), Se (selenium), Te
      (tellurium), and P (phosphorus) can generally reduce
      the following:
     1. Force.                      5. surface finish and
     2. Power input.                chip control improved.
     3. Tool-surface temperature.
     4. Tool wear rate.
Lecturer: Dr. HABEEB ALANI               University TENAGA Nasional
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Machinability of .. Cont..


  Stainless Steels/ stainless steels have three major types
      of microstructure:
     1. Austenitic.
     2. Ferritic.
     3. Martensitic.


  All these materials have higher tensile strength and
      greater spread between yield and fracture strength
      than low alloy steels.

Lecturer: Dr. HABEEB ALANI             University TENAGA Nasional
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Machinability of .. Cont..

  The energy input and the temperature on the tool
      surface are also higher than in ordinary steels. Due
      their high alloy content, the stainless steel containt
      abrasive        carbide   phases.   Both      of     these
      characteristics produce faster tool wear.
  Stainless steel have several reducing the machinability
      because:
     1. Strong work-hardening capability.
     2. Low thermal conductivity.
     3. Chips tend to bond to the tool surface.
Lecturer: Dr. HABEEB ALANI                University TENAGA Nasional
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Machinability of .. Cont..

  Cast iron / Flake graphite and spheroidal graphite cast
      irons have good machinability with respect to all
      criteria. The graphite flakes and spheres initiate
      fracture on the shear plane at frequent intervals.
  Machining of flake graphite and spheroidal graphite cast
      irons has the following properties:
   1. Low tool wear rate.          5. Good surface finish.
   2. High MRR.
   3. Low force.
   4. Low power consumption.
Lecturer: Dr. HABEEB ALANI               University TENAGA Nasional
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Machinability of .. Cont..

  Nickel-based alloys/ Nickel based alloys are among the
      most difficult materials to machine, because of their
      very strong work-hardening capability and hard
      abrasive-carbide phases. At much lower speeds than
      cutting steels, the tool temperature can reach the
      point at which plastic deformation and diffusion can
      take place. Because of this work hardening, the feed
      rate is very important ( when the feedrate too low,
      machining through the work-hardened material will
      continue long time.
Lecturer: Dr. HABEEB ALANI              University TENAGA Nasional
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Machinability of .. Cont..

  Aluminum Alloys/ pure aluminum is highly ductile. The
      chip ends adhere to the tool surface, where it
      becomes stringy and can be hard to break. It is
      difficult to achieve a good surface finish, espacially
      at low cutting speed. Aluminum alloys have a good
      machinability in almost all criteria.
  Cast-aluminum alloys with silicon can reduce the tool
      life and also more economically machined at lower
      cutting    speeds      and   feeds   than   other    types     of
      aluminum       alloys   abrasive     particles   causes      this
      reasons.
Lecturer: Dr. HABEEB ALANI                     University TENAGA Nasional
Machinability of .. Cont..


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  Copper and its Alloys/ pure copper is similar to other
      pure metals and has poor machinability. Unlike other
      pure metals, however, copper with a very low alloy
      content is widely used in electronic components and
      fittings.    The       cutting   speed   of   these   small-size
      components are usually limited by the spindle speed
      (up to 140-220 m/min).
  Tool forces are very high due to the large contact area
      on the rake face and the low shear angle. Surface
      finish & chip control can become a problem. For this
      reason high conductivity coppers regarded as one of
      most difficult materials to machine
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Lecturer: Dr. HABEEB ALANI   University TENAGA Nasional

				
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