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Lecture Computer Science Division EECS at UC Berkeley (PowerPoint)

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Lecture Computer Science Division EECS at UC Berkeley (PowerPoint) Powered By Docstoc
					Design Realization
    lecture 9

    John Canny
      9/23/03
                Last Time
 More on kinematics and IK.

 Some concepts from dynamics.
This time: Manufacturing & Materials
 Manufacturing is undergoing a revolution:
 Traditional methods:
     Casting, molding, fusing, slumping
     Milling, lathing (non CNC-versions)
     Stamping
     Rolling, extrusion


 Shape is “write-once” (not programmable) in
  these methods.
       Next-wave Manufacturing
 Reprogramming shape:
   CNC machining:
    A computer outputs a path for a
    cutting tool to create a specified
    surface.

   Not new, but now inexpensive,
    PC-based.

   Plastics, wood, metal, glass.


                        Flashcut 2000, XYZ-axes, 9x7x6.5”, $2895
                    Milling
 Milling involves a moving XYZ head that cuts
  into the workpiece:

 Bits can achieve different
  finishes.
                   Lathing
 Lathes cut circularly symmetric parts.
 Shafts, furniture, fasteners,… lenses.
 Can also do grinding and polishing.
               Milling Example
 CNC milling example
  (Deskproto web site)

 Finish is quite smooth
   ballnose cutting tool.


 Lots of waste, but can
  be recycled!
       Next-wave Manufacturing
 PC-boards:
   Created with CAD tools.
   Photographic reproduction:
     • Low cost in volume.
     • High complexity possible.

   Multi-step process, BUT:
   Web-based services have 24-hour turnaround,
    low cost.
       Next-wave Manufacturing
 CNC Laser cutter:
   X-Y axes control a powerful laser.
   Fine line (0.007” or better).
   Positioning to 1000 dpi,
   Some control of depth:
     • Engraving as
       well as cutting.
   Moderate cost:
    $10,000 Versalaser
    16x12” workspace.
       Laser Cutter Capabilities
 Precision is good enough to make smooth
  sliding surfaces (gears).
 Layering can be used to make
  3D surfaces (very popular for
  architectural models).
 Can even make PCBs
  by etching metal
  from clear plastic!
     Other 2D Cutting Technologies
 Lasers can cut metal, but not
  easily
   Power limits, need to deal with
    material removal.
 Plasma cutters use an
  electrically-generated plasma
  jet to cut
   Sweeps away material.
              Plasma Cutters
 Thin shapes in a variety of metals.
 Torchmate 3 machine
  is $10,000 for 4x8’
  workspace.
              Water Cutters
 Similar idea to plasma but based on high-
  pressure waterjet.
 Cleaner method: water plus metal can be
  collected.
 Cost??
                 3D printers
 A variety of 3D printing techniques have
  appeared in the last few years.
 SLA: Stereolithography: laser curing of
  liquid plastic.
 SLS: Selective Laser Sintering: similar, laser
  fuses powder.
 LOM: Layered Object Modeling: laser cuts
  paper one layer at a time.
 FDM: Fused Deposition Modeling: a thread
  of plastic is melted through a moving head.
          Stereolithography: SLA
 Earliest 3D method, based on UV-set polymers.
 Resolution quite good: 0.002” layers.
 Curing needed before
  part can be used.
LOM: Laminated Object Modelling
  FDM: Fused Deposition Modelling
 FDM is one of the most
  versatile 3D methods
   Many materials can be used:
    solvent-based or thermo-
    plastics.
   Requires X-Y-X motion (like
    a CNC machine).
   Stratasys machines start at
    $30,000
       Roll-your-own 3D Printers
 Material feeding heads are
  commercial modules.
   Microfab makes heads for
    solvent-based and thermo-
    plastics.


 Add a CNC XYZ-stage to
  create your own printer.
        Roll-your-own 3D Printers
 Polymer electronics is printable with microfab
  heads, working on actuators.
 Potential for printing complete electro-
  mechanical systems.
 Two prototype printers
  at Berkeley.
       3D Printer Disadvantages
 Slow! Adding material is much slower than
  removing it.
 Speed scales very poorly with resolution:
  double resolution and decrease speed by 8x.
 Laser 3D methods faster (than other heads)
  for equivalent resolution, but limited
  materials.
              3D Printing Data
 The standard 3D printing format is “STL”.

 Available as an output option for most CAD
  tools, as a 3rd-party translator for Maya.

 Then process-specific CAM software
  (Computer-Aided Manufacturing) creates a
  tool control file:
   Tool path for milling and lathing.
   Slices and support structures for 3D printers.
                 Summary
 CNC machines provide shape programmability.
 Lathes and mills provide traditional shaping.
 Layered methods can create almost unlimited
  shapes, but slowly.
 2D and 3D shaping methods generally based
  on CNC motion of an active head.
 Architecture of shaping machines is open:
  movement and heads are available separately.