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Joined: Feb 2011
23-02-2011, 11:29 AM
lec9.ppt (Size: 682.5 KB / Downloads: 93)
More on kinematics and IK.
Some concepts from dynamics.
This time: Manufacturing & Materials
Manufacturing is undergoing a revolution:
Casting, molding, fusing, slumping
Milling, lathing (non CNC-versions)
Shape is “write-once” (not programmable) in these methods
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.
Milling involves a moving XYZ head that cuts into the workpiece:
Bits can achieve different finishes.
Lathes cut circularly symmetric parts.
Shafts, furniture, fasteners,… lenses.
Can also do grinding and polishing.
CNC milling example (Deskproto web site)
Finish is quite smooth
ballnose cutting tool.
Lots of waste, but can be recycled!
Created with CAD tools.
• Low cost in volume.
• High complexity possible.
Multi-step process, BUT:
Web-based services have 24-hour turnaround, low cost.
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.
Thin shapes in a variety of metals.
Torchmate 3 machine is $10,000 for 4x8’ workspace.
Similar idea to plasma but based on high-pressure waterjet.
Cleaner method: water plus metal can be collected.
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.