23-02-2011, 11:29 AM
presented by:
John Canny
lec9.ppt (Size: 682.5 KB / Downloads: 201)
Design Realization
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.
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.