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									PUK


                SELECTION OF
                MATERIALS AND
                PROCESSES




DESIGN FOR                Ismet P. Ilyas
MANUFACTURING
AND ASSEMBLY
PUK   INTRODUCTION
      An integral part of design for manufacture (DFM) is the
      systematic early selection of MATERIAL and PROCESS
      combinations for the manufacture of parts
      Designers’ knowledge of manufacturing processes and materials




                                            (Based on survey carried out in Britain)
PUK   INTRODUCTION
      Designers’ knowledge about a range of polymeric materials




                                              (Based on survey carried out in Britain)
PUK
PUK
      Strategi Pemilihan
          Atribut Bahan
PUK
PUK
      Strategi Pemilihan
         Kelompok Bahan
PUK
      Strategi Pemilihan
      TAXONOMI RUMPUN Bahan
PUK
      Strategi Pemilihan
      Struktur Kelompok PROSES
PUK
PUK
         Strategi Pemilihan
      • Tahapan:
        –   Translations
        –   Screening
        –   Ranking
        –   Supporting
            Information
PUK
PUK
      Strategi Pemilihan
        Strategi (Translation)
PUK
PUK
      Implementasi Pemilihan
       Tools & Metode (Diagram Ashby)
PUK
      Implementasi Pemilihan
            Tools & Metode
PUK
      Implementasi Pemilihan
            Tools & Metode
PUK
      Implementasi Pemilihan
            Tools & Metode
PUK
      Strategi Pemilihan
          Implementasi
PUK   GENERAL REQUIREMENT FOR EARLY
      MATERIALS AND PROCESS SELECTION

      Information on which the initial selection of material /
      process combinations and their ranking should be
      available at the early concept design stage of a new
      product.

      Such information might include, for example :
       Product life volume
       Permissible tooling expenditure levels
       Possible part shape categories and complexity levels
       Service requirements or environment
       Appearance factors
       Accuracy factors
PUK   SELECTING OF MANUFACTURING PROCESSES

      The selection of appropriate processes is based upon a
      matching of the required attributes of the part and the various
      process capabilities

      Processes can be categorized as :
      A. Primary processes;
         Casting, forging and injection moulding.

      B. Secondary processes (generate the main shape of the part);
         Material removal and others processes such as machining,
         grinding and broaching.

      C. Tertiary processes (do not affect the geometry of the part);
        Finishing processes such as surface treatments and heat
         treatments.
PUK   Compatibility between processes and materials
PUK   PROCESS CAPABILITIES

      Capabilities of a range of manufacturing processes :

      A. Sand casting
      B. Investment casting
      C. Die casting
      D. Injection moulding (thermoplastic)
      E. Structural foam moulding
      F. Blow moulding (extrusion and injection)
      G. Rotational moulding
      H. Impact extrusion (forward and backward)
      I. Cold heading
      J. Hot forging (closed die)
PUK   CASTING METHODS
PUK   SAND CASTING
      Sand mold is the traditional method of casting and has been used for
      millennia.
      Sand casting consist of :
      a) Placing a pattern in sand to make an imprint
      b) Incorporating a gating system
      c) Filling the resulting cavity with molten metal
      d) Allowing the metal to cool until it solidifies
      e) Breaking away the sand mold and
      f) Removing the casting


      Schematic illustration of a sand mold
PUK   Sand casting operation
PUK    Capabilities of Sand Casting Process

            Part size                 Tolerances              Surface finish      Shapes produced
      Weight :                   General :                   500 -1000 in. *    Large part with walls
       0,2 lb – 450 ton *         0,02 (1 in.)            5 – 25 m (Ra) **   and internal
       0,05 kg – no limits **     0,1 (24 in.)                                 passages of complex
      Min. wall :                Dim. Across parting                              geometry requiring
       0,125 in *               line add :                                       good vibration
       3 mm – no limits **        0,1 (24 in.2)                                damping
                                   0,04 (200 in.2)                              characteristics
      Process limitations        Typical application                 Materials        Comments
       Secondary                 Engine blocks            Cast iron, carbon      Very flexible
        machining usually         Engine manifolds         steel, alloy steel,     manufacturing
        required                  Machine bases            stainless steel,        process in terms of
       Production rates          Gears pulleys            aluminium and           possible
        often lower then                                    alloys, cooper and      geometries,
        other casting                                       alloys, zinc and        part size, and
        processes                                           alloys (limited         possible material
       Tolerances, surface                                 basis), magnesium      Pattern is reusable
        finish coarser then                                 and alloys and          and mould
        other casting                                       nickel and alloys.      expendable
        processes
       Requires generous
       draft (approx. 3 deg.)
       and radii (approx.
       equal to thickness)
      *) Product design for manufacturing and assembly, Boothroyd.
      **) Manufacturing engineering and technology, kalpakjian.
PUK   SAND CASTING SAMPLE PRODUCT
PUK   INVESTMENT CASTING
      Investment casting is also known as the lost wax process. It can be used
      to make parts that cannot be produced by normal manufacturing
      techniques, such as turbine blades that have complex shapes, or
      airplane parts that have to withstand high temperatures.

                 Why Investment Casting ?

      DESIGN FLEXIBILITY
      Investment casting produces near-net-shape configurations, offering
      designers and engineers freedom of design in a wide range of alloys. The
      process is capable of producing precise detail and dimensional accuracy.
      WIDE CHOICE OF ALLOYS
      More than 120 ferrous and nonferrous metals are routinely cast.
      ELIMINATE TOOLING SET-UP
      By offering near-net-shape configuration, fixturing costs are substantially
      reduced or eliminated.
      REDUCE PRODUCTION COSTS
      Costly machining operations are reduced and often eliminated.
      CUT ASSEMBLY OPERATIONS
      Several parts can be made as one casting, reducing handling, assembly and
      inspection costs.
PUK   The Basics of the Investment Casting Process
PUK   The Basics of the Investment Casting Process
      1. WAX INJECTION

                      Wax replicas of the desired
                      castings are produced by
                      injection molding. These
                      replicas are called patterns.


      2. ASSEMBLY
                    The patterns are attached to a
                    central wax stick, called a
                    sprue, to form a casting cluster
                    or assembly.

      3. SHELL BUILDING
                    The shell is built by immersing
                    the assembly in a liquid ceramic
                    slurry and then into a bed of
                    extremely fine sand. Up to eight
                    layers may be applied in this
                    manner.
PUK   The Basics of the Investment Casting Process
      5. CONVENTIONAL CASTING            7. CUT OFF

              In the conventional                     The parts are cut
              process, the shell is                   away      from   the
              filled with molten metal                central sprue using
              by gravity pouring. As                  a      high    speed
              the metal cools, the                    friction saw
              parts and gates, sprue
              and       pouring   cup
              become       one   solid
              casting.                   8. FINISHED CASTINGS

                                                      After        minor
      6. KNOCKOUT                                     finishing
                                                      operations,    the
              When the metal                          metal castings--
              has cooled and                          identical to the
              solidified,     the                     original      wax
              ceramic shell is                        patterns--are
              broken      off  by                     ready           for
              vibration or water                      shipment to the
              blasting.                               customer.
PUK   Capabilities of Investment Casting Process

            Part size               Tolerances            Surface finish         Shapes produced
      Weight :                 General :                 63 -25 in.            Small intricate parts
       1oz – 110 lb             0,02 (1 in.)                                  requiring good finish,
      Major dimention :          0,004 (6 in.)                                 good dimensional
       to 50 in.                                                                control, and hight
      Min. wall :                                                                strength
       0,025 (ferrous)
       0,060 (nonferrous)
      Process limitations      Typical application           Materials               Comments
       Most investment         Turbine blades         Carbon steel, alloy       Expendable
        casting are less        Burner nozzles         steel, stainless steel     pattern and mold
        than 12 in. and less    Armament               (limited basis),          Greater flexibility in
        than 10 lbs              components             aluminium and              material choice or
       L/D ratio of through    Lock components        alloys, cooper and         part geometry than
        or blind holes less     Sewing machine         alloys, magnesium          die casting, but
        than 4:1 and 1:1         components             and alloys and             much higher
        respectively            Industrial handtools   nickel and alloys.         production costs
       Tooling cost and         bodies                                           Less susceptible to
        lead time generally                                                        porosity than most
        greater than for                                                           casting processes
        others casting                                                            Multiple parts may
        process except die                                                         be cast
        casting                                                                    simultaneously
                                                                                   around central
                                                                                   sprue
PUK   INVESTMENT CASTING SAMPLE PRODUCT

      Castings of propeller, disc, fitting   Castings of valves body   Machine component
PUK   DIE CASTING




      The pressure die-casting particularly suitable for high volume runs, faster production
      rates, and cheaper component cost than other methods. Tighter tolerances, thinner walls
      and better surface can also be achieved.
PUK   Cold-Chamber Casting
PUK   Hot-Chamber Casting
PUK   DIE CASTING SAMPLE PRODUCT

      Cylinder Head Cover    Mobile Phone




      Notebook               Video Camera
MS6015
PUK          INJECTION MOULDING
 Injection molding is the most common and versatile method of forming
  plastic into products.
 It is a fast process and is used to produce large numbers of identical items
  from high precision engineering components to disposable consumer goods.
 This process allows for part designs with great deal of intricacy, including
  fine small parts, decorative designs and surface finishes, extremely high
  gloss surface finish, and highly complex contours and shape.
 Small to medium sized part with intricate detail and good surface finish
 Tooling is costly and requires greater lead time than most alternative process
 Tolerances : - General 0,003 (1 in.); 0,008 (6 in.)
                  - Hole dia. 0,001 (1); 0,002 (1 dia.)
 Surface finish : 8 – 25 in.
MS6015
PUK               Injection Molding Machine




       The injection molding process depends on the injection pressure, injection
       velocity, melt temperature, mold temperature, and holding time.

  There are two type of injection molding machine:
  1. Horizontal                                    2. Vertical
MS6015
PUK         Injection Mold


                         Closed mold                     Opened mold




    The mold consist of two halves each attached to the stationary platen
     and the moving platen of the molding machine.
    The mold halves each contains the core and cavity to form the part
     geometry.
MS6015
PUK      Types of injection mold
MS6015
PUK      Design Considerations
MS6015
PUK      Design Considerations
          Part complexity
           - The part complexity will increase the cost of the mold, not only in
             terms of mold finishing, but may incur sliding cores and other mechanics
           - The trade off is between mold cost and the additional cost of
             having more parts.
          Material selection
           - Viscosity (at processing temperature and pressure
           - Coefficient of thermal expansion (shrinkage factor)
           - Strength and stiffness
           - Impact resistance
           - Service temperature
           - Degradation

          Wall and rib thickness - even thickness is molded part is important.
          Corner radii and fillets - avoid sharp corners which leads to poor
            melt flow and stress concentration.
          Holes - Careful treatment in design to avoid obstruction of mold
           opening.
          Drafts - thermosets 1/2 to 1
                   - thermoplastics 1/8 to 1/2
          Poor design can result in high levels of molded in stress, resulting
           in warpage or failure
MS6015
PUK      STRUCTURAL FOAM MOULDING
          Structural foam molding is a derivative of the injection molding
           process. Large structural parts often require thicker walls than
           standard injection molding can produce.
          Structural foam molding allows for the injection molding of thick
           wall parts through the addition of a foam agent, thus the term
           structural foam molding.
          Structural foam molding is intended to produce very large, thick
           plastic parts.
          Typical products are large trash containers, freeway sand safety
           containers, and in-ground housing for water systems.
         Typical Materials Used
         Acrylonitrile-Butadiene-Styrene (ABS)
         Polystyrene (PS)
         Polycarbonate (PC)
         Polypropylene (PP)
         Polyvinyl chloride (PVC)
MS6015
PUK      Methods of Producing Structural Foam
         The Low Pressure Process
         To achieve consistent quality moldings, it is recommended to use
         dedicated special purpose injection molding machines. The
         machines introduce a gas into the melted plastic which when
         injected into the closed mould tool subsequently foams the plastic
         material of the component being produced.

         Conventional Molding Machines
         Another widely used method is the use of standard injection molding
         machines with added "blowing agents" incorporated into the material.
         Using dry chemical blowing agents mixed in with the granules of
         plastic, the plastic is melted in the barrel of the machine.
         Typical Moldings Produced
         The use of the more controlled Low Pressure Process enables larger
         moldings to be produced. Almost all thermoplastic materials can be
         foamed and wall sections at 5 -- 15 mm, are thicker than compact
         (normal) injection moldings. Limited only by the size of molding
         machines, moldings of up to 40 kgs and in excess of one meter have
         been produced.
MS6015
PUK      Capabilities of Structural Foam Molding

               Part size           Tolerances          Surface finish    Shapes produced
         Weight :               Approximately that    Poor             Large, somewhat
          25 – 50 lb           of injection         Paint generally   intricate parts,
         Min. wall :            moulding              required          requiring high stiffness
          0,09 – 2,0 in.                                               and/or thermal or
                                                                        acoustical insulating
                                                                        properties
         Process limitations         Typical             Materials           Comments
                                   application
          Detail as sharp as    Pallets            Thermoplastic       Tooling
           those of injection    Housing                                 approximately
           moulding not          Drawers                                 20% les then
           possible              TV cabinets                             injection moulding
          Cycle time is long   Fan shrouds                             Solid
           (2 – 3 mi.)                                                    approximately 0,03
                                                                           – 0.8 in thick
                                                                         Entire wall cross
                                                                          section has
                                                                          densities between
                                                                          50% and 90% of
                                                                          solid weight
                                                                         Process generates
                                                                          a low level
                                                                          internal stress.
MS6015
PUK      SAMPLE PRODUCT
MS6015
PUK      BLOW MOULDING
          Plastic Blow Mold is a process used to produce hollow
           component parts.
          Thermoplastic type resin can be use are polyethylene(PE),
           polyvinychloride(PVC), polyethylene terephthalate(PET),
           and engineering plastic such as polycarbonate(PC).
         Blow moulding type :
         a) Extrusion
         b) Injection blow mould
         c) Stretch blow mould
MS6015
PUK      BLOW MOULDING
           Blow Mold process consist of three stage
             – Melting and plasticizing
             – Parison formation
             – Blowing and molding
MS6015
PUK         BLOW MOULDING

Extrusion Blow Molding Process
 For making hollow, seamless part out of thermoplastic polymers. Blow
 molding uses air to inflate the softened plastic to solidify on the wall
MS6015
PUK             BLOW MOULDING

Injection Blow Molding Process
•   Typical material used : LDPE, LLDPE, PP, PET,
    PVC
•   Three-phase process injection blow molding are:
     – Injection mloding of a preform shaped as a
        test tube
     – The expansion of the preform, with air
        pressure, into the bottle/form shape
     – Removal of the part
MS6015
PUK           BLOW MOULDING

Stretch Blow Molding Process
• It involves the parison / preform being conditioned to a specific temperature and
  then very quickly stretched in two (biaxial) directions.
• The process is divided into four: Injection, conditioning, stretching & blowing,
  discharge
• Stretch blow molding is
  basically a modification of
  either injection blow
  molding or extrusion blow
  molding
• Injection stretch blow
  moulding is used for the
  production of high quality
  containers.
• Typical material used: PET
• Common used product:
  Carbonated and soft drink
  bottles, Agrochemical                                                         Preform
  containers, Cooking oil
  containers
MS6015
PUK             BLOW MOULDING
Capabilities of Blow Moulding Process
       Part size               Tolerances            Surface finish    Shapes produced
 Envelope ::             General :                    250 -500 in.   Hollow, well-rounded
  Up to 800 gal           0,02 (1 in.)                              thin walled part with
   container (105 ft3)     0,04 (6 in.)                              low degree of
 Min. wall :             Wall :                                        asymmetry
  0,015 -0,125 in.        50% of nominal wall
                         Neck :
                           0,04 (injection only)
       Process            Typical application           Materials          Comments
     limitations
  With extrusion         Most polymer              Thermoplastics     Injection blow
   blow moulding,          containers to 5 galons                        moulding: smaller
   some geometries        Toys                                          parts, more
   produce a high         Auto heater ducting                           accurate neck
   level of material                                                    Extrusion blow
   scrap                                                                 moulding: more
  Integral handles                                                      asymmetrical parts,
   possible with                                                         less costly tooling
   extrusion blow                                                       High production
   moulding only                                                         rate, particular for
  Poor control of                                                       injection blow
   wall thickness                                                        moulding (as low
                                                                         as 19 s per cycle)
MS6015
PUK      ROTATIONAL MOULDING
MS6015
PUK               ROTATIONAL MOULDING
Capabilities of Rotational Moulding Process


        Part size                Tolerances         Surface finish       Shapes produced
 Envelope :                  General :              Poor              Large containers with
  Up to 5000 gal              0,025 (1 in.)      Parts generally   minimal detail
   container (670 ft3)         0,05 (6 in.)        textured
 Min. wall :                   0,01 (24 in.)
  0,06 -0,40 in.            Wall :
                               0,015
                             Neck :
                               0,04 (injection
                               only)
  Process limitations        Typical application       Materials             Comments
  Abrupt wall change,        Containers          Thermoplastics       Cycle time 8 – 20 min
   long, thin projections,    Toys                                     Insert for securing or
   and small                                                             stiffening are possible
   separations between                                                  Less detail possible
   opposing part                                                         than with blow
   surfaces not possible                                                 moulding
MS6015
PUK          IMPACT EXTRUSION

 Impact Extrusion is commonly used to make collapsible tubes such as toothpaste
 tubes, cans usually using soft materials such as aluminum, lead, tin. Usually a
 small shot of solid material is placed in the die and is impacted by a ram, which
 causes cold flow in the material.
MS6015
PUK             IMPACT EXTRUSION

 Capabilities of Impact Extrusion Process

        Part size               Tolerances           Surface finish          Shapes produced
 Dia. :                    O.D:  0,002 (0,5 in.)    20 -63 in.          • Approx. 1 – 2 in. dia.
  0,075 – 2,5 in.         I.D :  0,003 (5 in.)                             Part with a close end
 Length :                  Bottom dia. :  0,005                             thicker than side walls
  3 - 24 in.              (5in)                                             (backward extrusion)
                           Tolerances                                      • Combination of
                           approximately 50%                                 forward/backward
                           for rectangular parts                             common
  Process limitations      Typical application          Materials                Comments
  Flat inner bottom        Fasteners              Carbon steel,           Generally chosen over
   requires additional      Sockets for socket     alloys steel,            screw machine part if
   operation                 wrench                 aluminium and            material savings is
  Tooling cost are high    Gear blank with        alloys, copper and       significant (25% or
  Max. L/D ratio for k      shank                  alloys, zinc and         more)
   extrusion is 10 (in                              alloys, magnesium       Significant
   some aluminium                                   and alloys, titanium     improvement in
   alloys)                                          and nickel and           mechanical properties
  L/D ratio almost                                 alloys                   due to cold working,
   unlimited in forward                                                      allowing further
   extrusion                                                                 material reduction
  Tolerance not as                                                         Limited asymmetry
   good as machining                                                         possible.
MS6015
PUK          FORGING

Forgings are consistent from piece to piece, without any of the porosity, voids,
inclusions and other defects.
A Forged metal can result in the following
 • Increase length, decrease cross-section, called drawing out the metal.
 • Decrease length, increase cross-section, called upsetting the metal.
 • Change length, change cross-section, by squeezing in closed impression dies.
   This results in favorable grain flow for strong parts
MS6015
PUK            FORGING

  Capabilities of Forging Process
        Part size               Tolerances             Surface finish          Shapes produced
  Weight :                 Perpendicular to die        125 -250 in.        • Part of moderate
   0,1 – 500 lb           motion:  0,7 % of                                  complexity, in a wide
                           dimension.                                          range of sizes, whose
                           Parallel to die motion:                             failure in service would
                            0,3 (10 in.2 area) ,                             be catastrophic
                           0,12 (100 in.2 area)
  Process limitations      Typical application            Materials                 Comments
   Hol may not be          Crankshafts              Carbon steel,           By controlling material
    produced directly       Airframe                 alloys steel,            flow, grain structure
   Flash must be            components               stainless steel,         may be aligned with
    removed and             Tools                    aluminium and            the direction of
    secondary machining     Nuclear components       alloys, copper and       principal stress
    is often required       Agricultural             alloys, magnesium       Close die forging
   Die wear and die         component                and alloys, titanium     nearly always pass
    mismatch can be                                   and nickel and           through series of
    significant                                       alloys                   impressions before
   Generous draft                                                             completing
    angles and radii are                                                      In decreasing order of
    suggested                                                                  forgability: Al, Mg,
                                                                               steel, St steel, titanium,
                                                                               high temperature alloys
PUK
MS6015
PUK      TUGAS 1: GRUP PRESENTASI (Literatur)

         RAPID PROTOTYPING SYSTEM?
            •Deskripsi?
            •Jenis Teknologi?
            •Kemampuan Proses:
            Part size    Tolerances    Surface finish   Shapes produced



             ?             ?               ?                 ?
             Process       Typical       Materials        Comments
           limitations   application



             ?             ?               ?                 ?
         Jadual: Minggu/11 November 2
         Grup: 2 Orang

								
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