Design Realization lecture 9

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Design Realization lecture 9

• John Canny
• 9/23/03

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Last Time

• More on kinematics and IK.
• Some concepts from dynamics.

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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.

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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
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Milling

• Milling involves a moving XYZ head that cuts into
  the workpiece
• Bits can achieve differentfinishes.

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Lathing

• Lathes cut circularly symmetric parts.
• Shafts, furniture, fasteners, lenses.
• Can also do grinding and polishing.

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Milling Example

• CNC milling example (Deskproto web site)
• Finish is quite smooth
• ballnose cutting tool.
• Lots of waste, but can be recycled!

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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.

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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 cost10,000 Versalaser 16x12
  workspace.

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Laser Cutter Capabilities

• Precision is good enough to make smooth sliding
  surfaces (gears).
• Layering can be used to make3D surfaces (very
  popular for architectural models).
• Can even make PCBsby etching metalfrom clear
  plastic!

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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.

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Plasma Cutters

• Thin shapes in a variety of metals.
• Torchmate 3 machine is 10,000 for
  4x8workspace.

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Water Cutters

• Similar idea to plasma but based on high-pressure
  waterjet.
• Cleaner method water plus metal can be
  collected.
• Cost??

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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.

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Stereolithography SLA

• Earliest 3D method, based on UV-set polymers.
• Resolution quite good 0.002 layers.
• Curing needed before part can be used.

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LOM Laminated Object Modelling
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FDM Fused Deposition Modelling

• FDM is one of the most versatile 3D methods
• Many materials can be usedsolvent-based or
  thermo-plastics.
• Requires X-Y-X motion (like a CNC machine).
• Stratasys machines start at 30,000

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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.

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Roll-your-own 3D Printers

• Polymer electronics is printable with microfab
  heads, working on actuators.
• Potential for printing complete
  electro-mechanical systems.
• Two prototype printersat Berkeley.

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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.

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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.

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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.