Rapid Prototyping Operations

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Rapid Prototyping Operations
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Rapid prototyping

• Introduction
• Subtractive processes
• Additive process
• Virtual Prototyping
• Applications

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Rapid prototyping

• Technology which considerably speeds the
  iterative product development process

Fig a) Examples of parts made by rapid
prototyping b) Stereolithography model of
cellular phone
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Advantages

• CAD data files can be manufactured in hours.
• Tool for visualization and concept verification.
• Prototype used in subsequent manufacturing
  operations to obtain final part
• Tooling for manufacturing operations can be
  produced

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Classification of Rapid Prototyping

• Rapid prototyping is classified to 3-major groups
  
• Subtractive ( Removal of material )
• Additive ( Adding of material )
• Virtual ( Advanced computer base
  visualization)

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Subtractive Process

• Subtractive process use computer based Prototype
  technology to speed the process
• Essential Technologies for subtractive
  prototyping
• Computer based drafting packages ( 3-D
  representation of parts)
• Interpretation software (Translation of cad file
  to manufacturing software)
• Manufacturing Software (Planning Machining
  operations)
• Computer-Numerical Control Machinery

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Additive Process

• Build parts in layer by layer (slice by slice as
  stacking a loaf of bread)

Fig The computational steps in producing a
stereolithography file a) Three dimensional
description of part b)The part is divides into
slices (only one in 10 is shown) c)support
material is planned d)A set of tool directions is
determined to manufacture each slice. Shown is
the extruder path at section A-A from c) For a
fused-deposition-modeling operation
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Additive Process

• Require elaborate software
• 1 Obtain cad file
• 2 Computer then constructs slices of a
  3-dimensional part
• 3 slice analyzed and compiled to provide the
  rapid prototyping machine
• 4 setup of the proper unattended and provide
  rough part after few hours
• 5 Finishing operations and sanding and painting
• 6labor intensive and production time varies from
  few minutes to few hours

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Fused Deposition Modeling

• A gantry robot controlled extruder head moves in
  two principle directions over a table
• Table can be raised or lowered as needed
• Thermo plastic or wax filament is extruded
  through the small orifice of heated die
• Initial layer placed on a foam foundation with a
  constant rate
• Extruder head follows a predetermined path from
  the file
• After first layer the table is lowered and
  subsequent layers are formed

Fig (a)Fused-deposition-modeling process.
(b)The FDM 5000, a fused-decomposition-modeling-ma
chine.
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Fused Deposition Modeling
Fig a)A part with protruding section which
requires support material b) Common support
structures used in rapid-prototyping machines
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Stereolithiography

• Works based on the principle of curing liquid
  photomer into specific shape
• A vat which can be lowered and raised filled with
  photocurable liquid acrylate polymer
• Laser generating U-V beam is focused in x-y
  directions
• The beam cures the portion of photo polymer and
  produces a solid body
• This process is repeated till the level b is
  reached as shown in the figure
• Now the plat form is lowered by distance ab
• Then another portion of the cylinder is shaped
  till the portion is reached

Fig Stereolithiography Process
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Selective laser sintering (SLS)
Fig The selective laser sintering process
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Selective laser sintering

• SLS based on sintering of nonmetallic powders
  onto a selective individual objects
• Basic elements in this process are bottom of
  processing chambers equipped with 2 cylinders
• Powder feed cylinder which is raised
  incrementally to supply powder to part-build
  cylinder through a roller mechanism
• Part-build cylinder which is lowered
  incrementally to where the sintered part is
  formed.

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Selective laser sintering

• Set of the proper computer files and the
  initiation of the production processes
• Machine operate unattended and provide rough part
  after few hours
• Finishing operations as sanding and painting
• Labor intensive production time varies from few
  minutes to few hours

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Selective laser sintering

• Layer of powder is first deposited on part build
  cylinders
• A laser beam controlled by instruction from 3-D
  file is focused on that layer tracing sintering
  a particular cross-section into a solid mass
  dust is taken off.
• Another layer of powder is now deposited this
  cycle is repeated again and dust is shaken off

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Solid Base curing

• Also called Solid ground curing
• Entire slices of part are manufactured at one
  time
• So large throughput is achieved
• Most expensive time consuming
• The entire process is shown

FigThe solid based curing process
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Ballistic Particle Manufacturing

• Ballistic particle manufacturing
• Stream of material , such as plastic ,ceramic,
  metal or wax ejected through small orifice at a
  surface
• Mechanism similar to inkjet mechanism (
  piezo-electric pump)
• Operation repeats similar to other process to
  form a part with layers of wax deposited on top
  of each other
• Ink jet heat guided by three-axis robot

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3-D Printing process
Similar to ballistic particle manufacturing
FigThree dimensional printing process
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3-D Printing process

• Print head deposits an inorganic binder material
• Binder directed onto a layer of ceramic metal
  powder
• A piston supporting the powder bed is lower
  incrementally with each step a layer is
  deposited and unified by binder
• Commonly used materials Aluminum oxide, silicon
  carbide,silica and zirconium.
• Common part produced by 3-D printing is a ceramic
  casting shall
• Curing around 150 C 300 F
• Firing 1000 C 1500 C

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Laminated object manufacturing (LOM )

• Laminated implies laying down of layers which are
  adhesively bonded to one another
• Uses layer of paper or plastic sheets with heat
  activated glue on one side of the product parts
• Excess material to be removed manually
• Simplified by preparing the laser to burn
  perforations in cross-sectional pattern
• LOM uses sheets as thin as 0.05mm
• Compressed paper has appearance and strength of
  soft wood , and often mistaken for elaborate wood
  carvings.

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Laminated Object Material (LOM)
Fig (a) Laminated object-manufacturing process
(b)Crankshaft-part example made by LOM
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Virtual prototyping

• Virtual prototyping (modeling and simulation of
  all aspects of a prototype, i.e. mechanical
  design, kinematics, dynamics, and controls
  accompanied by a realistic visualization).
• Realizing the best design in the shortest
  lead-time of complex products/processes
• Allows the exotic, unconventional designs be
  prototyped, rapidly and cost-effectively

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Applications of Rapid Prototyping

• Production of individual parts
• Production of tooling by Rapid Prototyping (Rapid
  Tooling)

Fig Manufacturing steps for investment casting
that uses rapid prototyped wax parts as blanks.
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Rapid Tooling

• The term Rapid Tooling (RT) is typically used to
  describe a process which either uses a Rapid
  Prototyping (RP) model as a pattern to create a
  mold quickly or uses the Rapid Prototyping
  process directly to fabricate a tool for a
  limited volume of prototypes .
• a)Tooling time is much shorter than for a
  conventional tool. Typically, time to first
  articles is below one-fifth that of conventional
  tooling.
• b) Tooling cost is much less than for a
  conventional tool. Cost can be below five percent
  of conventional tooling cost.
• c) Tool life is considerably less than for a
  conventional tool.
• d) Tolerances are wider than for a conventional
  tool.

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Rapid Tooling
Fig Manufacturing steps in sand casting that
causes that uses rapid-prototyped patterns
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Rapid Tooling
Fig Manufacturing steps in sand casting that
causes that uses rapid-prototyped patterns
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THE END