Rapid Prototyping RP

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Rapid Prototyping (RP)

• Introduction of RP
• Generate a prototyping by Laying Manufacturing
  Technology - composite material layer by layer
• Build in one step - directly from model to
  manufacturing

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Rapid Prototyping (RP)

• Development of RP
• First Phase Manual (or Hard) Prototyping
• Age-old practice for many centuries
• Prototyping as a skilled craft is traditional and
  manual and based on material of prototype
• Natural prototyping technique

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Rapid Prototyping (RP)

• Development of RP
• Second Phase Soft (or Virtual) Prototyping
• Mid 1970s
• Increasing complexity
• Can be stressed, simulated and tested with exact
  mechanical and other properties

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Rapid Prototyping (RP)

• Development of RP
• Third Phase Rapid Prototyping
• Mid 1980s
• Hard prototype made in a very short turnaround
  time (relies on CAD modelling)
• Prototype can be used for limited testing
• prototype can consist in the manufacturing of the
  products
• 3 times complex as soft prototyping

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Rapid Prototyping (RP)

• Fundamentals of RP
• Building computer model
• Model is building by CAD/CAM system
• Model must be defined as enclosed volume or solid
• Converting model into STL file format
• STereoLithography (STL) file is a standard format
  to describe CAD geometry used in RP system
• STL file file approximates the surfaces of the
  model by polygons

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Rapid Prototyping (RP)

• Fundamentals of RP
• Fabricating the model
• Building model layer by layer
• Forming a 3D model by solidification of
  liquid/powder

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Rapid Prototyping (RP)

• Applications of RP
• For design evaluation
• Touch and holding a physical prototype
• For function verification
• e.g. assembly, kinematics performance, and
  aerodynamic performance
• Models for further manufacturing processes
• e.g. Vacuum casting, spray metal moulding,
  investment casting, etc.

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Rapid Prototyping (RP)

• Advantages and Disadvantages
• No planning of process sequences
• No specific equipment for handling materials
• No transportation between machining
• Features-based design and feature recognition are
  unnecessary
• Defining a blank geometry is unnecessary
• Defining different setups or complex sequences of
  handling material is unnecessary

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Rapid Prototyping (RP)

• Advantages and Disadvantages
• No need to consider jigs and fixtures
• Designing and manufacturing moulds and dies
• Specific materials are restricted

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Rapid Prototyping (RP)

• Role of RP in Product Development Cycle
• Product design
• Increase part complexity and diversity with
  little effect on lead time and cost
• Minimise time-consuming discussion and
  evaluations of manufacturing possibilities
• Tool design and manufacturing
• Minimise design, manufacturing and verification
  of tooling
• Reduce parts count and eliminate tool wear

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Rapid Prototyping (RP)

• Role of RP in Product Development Cycle
• Assembly and test
• Reduce labour content of manufacturing (e.g.
  machining, casting, inspection and assembly,
  etc.)
• Reduce material costs (e.g. handling, waste,
  transportation, spare and inventory, etc.)
• Function testing
• Avoid design misinterpretations, i.e. what you
  design is what get)

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Rapid Prototyping (RP)

• Due to the newness of the technology, there are
  already so many words for RP used today
• RP( most commonly used) - Rapid Prototyping
• RPTM(inc. new development trends) - Rapid
  Prototyping, Tooling and Manufacture
• Direct CAD Manufacturing/Desktop
  Manufacturing/Instant Manufacturing/CAD Oriented
  Manufacturing RP

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Rapid Prototyping (RP)

• Layer Manufacturing/Material Addition
  Manufacturing/Material Deposit Manufacturing/
  Material Increase Manufacturing/Solid Freedom
  Manufacturing - Emphasis the unique
  characteristic of RP

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Rapid Prototyping (RP)

• Classification of RP Systems
• By the initial form of its material, RP systems
  can be categorised into
• Liquid-based
• Liquid-based material ? Curing Process ? Solid
• (e.g. SLA, SGC, SOUP, etc.)

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Rapid Prototyping (RP)

• Classification of RP Systems
• Solid-based
• Encompass all forms of material in the solid
  form, such as in the form of wire, a roll,
  laminates and pellets.
• (e.g. LOM and FDM, etc.)
• Powder-based
• Grain-like material ? Joining/Binding ? Solid
• (e.g. SLS and 3DP, etc.)

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Rapid Prototyping (RP)

• Features of RP Systems
• The features of some commercially available RP
  systems can be summarised into
• Process type - Stereo lithography, Laminating,
  Fused deposition modelling, Sintering of powder,
  Solid ground curing, etc.
• Work space(mm) - depends on the models
• Material - photopolymer resin, coated paper, ABS,
  wax, metal alloy, etc.

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Rapid Prototyping (RP)

• Features of RP Systems
• Layer thickness(mm) - 0.05 - 0.3(SLA) 0.1 -
  1(LOM.) 0.05(FDM) 0.08(SLS) 0.01 - 0.15(SGC)
• Accuracy(mm) - 0.01- 0.2(SLA) 0.1 - 0.2(LOM)
  0.127 - 0.254(FDM) 0.03 - 0.38(SLS) 0.05 -
  0.5(SGC)
• Manufacturer - 3D System, Stratasys, Helisys,
  DTM, EOS, etc.

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Rapid Prototyping (RP)

• Pre-Processing Tasks
• Prepare geometric model in STL file format
• Solid or surface CAD model to be built is next
  converted into format dubbed the .STL file format
  because it is a standard input data to any RP
  process. STL originates from 3D Systems, which
  pioneers the Stereolithography system in 1987.
  The format approximates the surfaces of the model
  using tiny triangles. Since 1990, almost all
  major CAD/CAM vendor supply the CAD-STL
  interface.

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Rapid Prototyping (RP)

• Pre-Processing Tasks
• Building up direction
• The direction affects many key aspects of RP
  process, quality of the surface finish, build
  time, amount of support structures needed, and
  amount of trapped volume. For experience,
  minimising the height of the geometry will reduce
  the no. of layers required, thereby decreasing
  build time, but also sacrifice part resolution or
  accuracy.

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Rapid Prototyping (RP)

• Pre-Processing Tasks
• Trapped volume
• It is the amount of liquid resin in the RP
  process (e.g. SLA) that was entrapped by the
  processed or solidified region. Thus trapped
  volumes can exist in concave regions that as
  containers. It may be eliminated by either
  building a part with a drain hole and fill the
  hole after solidification or modifying the
  orientation of the part.

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Rapid Prototyping (RP)

• Pre-Processing Tasks
• Part placement
• In RP, the time spent building a prototype does
  not depend on the no. of parts but on the total
  no. of slices required. By closely packing
  multiple parts into feasible volume, several
  parts can be built at the same time.

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Rapid Prototyping (RP)

• Pre-Processing Tasks
• Support structure
• The support structure in RP process has the
  following functions
• ensure the recoater blade will not strike the
  platform when the first layer is swept
• improve uniformity of layer thickness
• provide a simple means of removing the part from
  the platform upon its completion

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Rapid Prototyping (RP)

• Pre-Processing Tasks
• Support structure
• However, overdesign of support structures
  results in added design and manufacturing time,
  as well as finishing operations

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Rapid Prototyping (RP)

• Post-Processing Tasks
• Part removal and cleaning
• After a part is built, drain excess liquid resin
  at the platform and the part back into the vat.
  Next, the part and the platform are placed in a
  cleaning apparatus with solvent (e.g. TPM). It
  will produce little swelling distortion on a
  part. Once the part has been thoroughly cleaned
  of excess resin, both platform and part are
  rinsed with water to remove TPM film. The last
  step is to remove the part from the platform by
  flat-bladed knife.

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Rapid Prototyping (RP)

• Post-Processing Tasks
• Post curing
• During some RP processes, such as SLA, the laser
  scans each layer along the boundary and hatching
  lines only. This means that inside portions of
  the layers may not be completely solidified. Thus
  the part is post-cured to complete the
  polymerisation process by exploring with UV
  radiation in a specially designed apparatus.

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Rapid Prototyping (RP)

• Post-Processing Tasks
• Part finishing
• This process is to remove the supports by using
  a dull edged blade or putty knife. Care must be
  taken to avoid damaging a part that contains
  fragile sections. Once the supports have been
  removed, minor sanding is applied to eliminate
  residual traces of the supports.

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Rapid Prototyping (RP)

• Principle of Stereolithography Apparatus (SLA)
• SLA was developed in 1986 by 3D Systems. The
  process is based on the following principles
• Parts are built from a photo-curable liquid resin
  that solidifies when sufficiently exposed to a
  laser beam which scans across the surface of the
  resin
• The building is done layer by layer, each layer
  being scanned by the optical scanning system and
  controlled by an elevation mechanism which lowers
  at the completion of each layer

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Rapid Prototyping (RP)

• Process of SLA
• Step 1 - A liquid state photosensitive polymer
  that solidifies when exposed to a lighting
  source
• Step 2 - A platform that can be elevated is
  located just one layer of thickness below the
  surface
• Step 3 - According to the cross section of the
  part (starting with bottom layer). The laser
  scans the polymer layer above the platform to
  solidify the polymer

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Rapid Prototyping (RP)

• Process of SLA
• Step 4 - The Platform is lowered into the
  polymer bath to the layer thickness
• Step 5 - Repeat 3 and 4 until the top layer of
  the part is generated
• Step 6 - Post-curing and part finishing will
  then be performed

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Rapid Prototyping (RP)

• Applications of SLA
• Models for conceptualisation,packaging and
  presentation
• Prototypes for design, analysis, verification and
  functional testing
• Masters for prototype tooling and low volume
  production tooling
• Patterns for investment casting, sand casting and
  moulding
• Tools for fixture and tooling design and
  production tooling

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Rapid Prototyping (RP)

• Principle of Selective Laser Sintering (SLS)
• SLS was developed by DTM Corporation in 1992.
  The process is based on the following principles
• Parts are built by sintering when a CO2 laser
  beam hit a thin layer a powdered material. The
  interaction of the laser beam with the powder
  raises the temperature, resulting in particle
  melting and bonding together

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Rapid Prototyping (RP)

• Principle of Selective Laser Sintering (SLS)
• The building of the part is done layer by layer.
  Each layer of the building process contains the
  cross sections of one or many parts. The next
  layer built directly on the top of the sintered
  layer after an additional layer of powder is
  deposited via a roller mechanism on the top of
  the previously formed layer

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Rapid Prototyping (RP)

• Process of SLS
• Step 1 - A part cylinder is located at the
  height necessary for a layer of powdered
  material to be deposited on the cylinder to
  the desired thickness. The powder is applied
  from the feed cylinder by the levelling roller

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Rapid Prototyping (RP)

• Process of SLS
• Step 2 - The layer of powder is selectively
  raster- scanned and heated with a laser,
  causing particles to adhere to each other. The
  laser scan forms the powder into the required
  cross section shape. Again this step starts
  with the bottom cross section
• Step 3 - The part cylinder is lowered by the
  layer thickness to permit a new layer of
  powder to be deposited

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Rapid Prototyping (RP)

• Process of SLS
• Step 4 - The new layer is scanned, conforming it
  to the shape of the next upper cross-section
  and adhering it to the previous layer
• Step 5 - Repeat 3 and 4 until the top layer of
  the part is generated
• Step 6 - Post-curing may be required for some
  material

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Rapid Prototyping (RP)

• Applications of SLS
• Concept models
• Functional models and working prototypes
• Wax casting pattern
• Polycarbonate patterns. These build faster than
  wax patterns and are ideally suited for design
  with thin walls and fine features. These pattern
  are also durable and heat resistant
• Metal Tools. Direct rapid prototype of tools of
  moulds for small or short production runs.

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Rapid Prototyping (RP)

• Process of FDM
• The process of FDM is relatively simple and fast
  but its use is limited to thermoplastic materials
• Step 1 - The thermoplastic material in the form
  of filament is heated to just above its
  solidification temperature
• Step 2 - The extrusion head is heated and moves
  according to the pattern of the cross section
  of each layer of the part

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Rapid Prototyping (RP)

• Process of FDM
• Step 3 - The material is extruded on the
  foundation or previously built layer. As it is
  extruded, it is cooled and thus solidifies to
  form the required pattern of part
• Step 4 - Repeat 2 and 3 until the top layer of
  the part is generated
• Step 5 - Part finishing may be required

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Rapid Prototyping (RP)

• Applications of FDM
• Models for conceptualisation and presentation
• Prototypes for design, analysis and functional
  testing
• Patterns and masters for tooling. Models can be
  used as patterns for investment casting, sand
  casting and moulding

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Rapid Prototyping (RP)

• Principle of Laminated Object Manufacturing (LOM)
• LOM was developed by Helisys Inc. in 1991. The
  process is based on the following principles
• Parts are built, layer by layer, by laminating
  and laser-trimming materials that are delivered
  in sheet form. The sheets are laminated into
  block by a thermal adhesive coating

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Rapid Prototyping (RP)

• Process of LOM
• The accuracy of the process of LOM is high. The
  most popular laminated material is paper sheet.
• Step 1 - Sheet material is supplied from a
  continuous roll form. Each sheet attached to
  the block, using heat and pressure to form a
  new layer
• Step 2 - The platform is lowered by the
  thickness of the sheet whenever a sheet is
  attached to the stack

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Rapid Prototyping (RP)

• Process of LOM
• Step 3 - After a layer is deposited, a CO2 laser
  is traced on the layer along the contours
  corresponding to the current cross section
• Step 4 - Areas of the layer outside the contours
  are cross-hatched by the laser (i.e. cut into
  small pieces for removal afterwards)

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Rapid Prototyping (RP)

• Process of LOM
• Step 5 - After the part is built, the result is
  imbedded within a block of supporting material.
  This material is then broken into chunks along
  the cross-hatching lines
• Step 6 - The resulting part may then be coated
  with a sealant to keep out moisture

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Rapid Prototyping (RP)

• Applications of LOM
• Applicable for a wide range of product, equipment
  for aerospace or automotive, consumer products,
  and medical devices
• Prototypes for design, analysis and functional
  testing
• Tools for production
• Small volume of finished goods

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Rapid Prototyping (RP)

• Principle of 3D Printing (3DP)
• 3DP was invented by MIT in 1994
• Parts are created by a layered printing process
  and adhesive bonding, based on sliced cross
  section data. A layer is created by adding
  another layer of powder. The powder layer is
  selectively joined, where the part is to be form,
  by ink-jet printing of a blinder material

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Rapid Prototyping (RP)

• Process of 3DP
• The process of 3DP is more efficient and
  relatively cheaper than sintering types.
• Step 1 - Platform is located at the height
  necessary for a layer of ceramic powder to be
  deposited
• Step 2 - The layer of ceramic powder is
  selectively raster-scanned with a print head
  that delivers a liquid binder, causing
  particles to adhere to each other

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Rapid Prototyping (RP)

• Process of 3DP
• Step 3 - The platform is lowered by the
  layer thickness to permit a new layer of
  powder to be deposited
• Step 4 - The new layer is scanned, conforming it
  to the shape of the next upper cross section
  and adhering it to the previous layer

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Rapid Prototyping (RP)

• Process of 3DP
• Step 5 - Repeat 3 and 4 until the top layer of
  the part is generated
• Step 6 - A post-process heat treatment is
  applied to solidify the part

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Rapid Prototyping (RP)

• Applications of 3DP
• CAD-Casting metal parts. A ceramic shell with
  integral cores can be fabricated directly from
  the CAD model
• Direct metal parts. It is adaptable to a variety
  of material systems, allowing the production of
  metallic/ceramic parts with novel composition
• Prototypes with colours and elastic feature