Rapid Prototyping Guide for Designers and Engineers

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Rapid Prototyping

• The designers' guide to choosing the right 3D
  printing approach

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• Who this guide is for
• Industrial designers and design engineers who
  need help selecting a 3D printing approach for
  rapid prototyping their 3D CAD designs
• What this guide contains
• Considerations for comparing different3D
  printing materials technologies
• How to select an appropriate material and 3D
  printing process for your prototyping project
• Steps to narrow down your choices to one or two
  different 3D print technologies

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Design Geometry Considerations
Taking these factors into account will help you
to find a 3D print process that will meet the
geometric needs of your design
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• Will your design fit into the build volume of a
  3D printer?
• Issue 3D printers come in all shapes and sizes,
  but there are constraints on how big a single
  part can be
• Impact large part sizes constrain your choice of
  3D printers unless you can split your design into
  multiple 3D parts and print them separately

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• Does your design have any features that are too
  small to 3D print?
• Issue Each 3D print technology and material has
  a minimum threshold for the size of details it
  can print
• Impact If you require a very fine level of
  detail, or very thin walls, this will constrain
  your choice of materials and 3D print processes

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• Does your part need to be 3D printed as a solid
  object?
• Issue Since 3D printing is an additive process,
  cost is driven primarily by the amount of
  material used
• Impact If your rapid prototype doesnt require
  solid parts, you can save money by adjusting your
  design to be a hollow shell prior to 3D printing

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• Will your part need support material for
  overhanging areas?
• Issue Many 3D printing technologies require
  support material to be printed for parts that
  have overhanging regions, adding cost for support
  material and post-production support removal
• Impact For highly complex geometries, consider a
  process that does not require support material to
  be generated, or if other considerations are more
  important, then orient your 3D file for minimum
  overhangs in order to minimize cost

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Material Considerations
Selecting the right material for your rapid
prototype is critical to achieving your testing,
demonstration, or presentation objectives
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• What is the purpose of your rapid prototyping
  project?
• Issue its critical to understand why youre
  building a rapid prototype because materials that
  are acceptable for some applications can be
  inappropriate for others
• Impact many materials are appropriate for
  visualization or form and fit purposes, whereas
  various aspects of functional testing have more
  demanding requirements leading to material
  selection trade-offs

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• How will your rapid prototype be used?
• Issue how the rapid prototype will be used is an
  important consideration when comparing material
  mechanical, thermal, or optical properties
• Impact for aesthetic models, the look and feel
  factors such as color and surface finish are the
  primary selection criteria, whereas functional
  prototypes may require materials with specific
  mechanical, thermal, or optical properties, or
  resistance to specific environmental factors

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• Are there aesthetic considerations for your rapid
  prototype?
• Issue will your rapid prototype be used to
  communicate your design to customers, senior
  management or other stakeholders, or is it
  intended solely for internal testing uses?
• Impact communicating your design ideas to others
  requires accurately modeling the color,
  appearance, and surface texture of the prototype
  parts in order to secure their buy-in

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• How will environmental factors impact the choice
  of materials?
• Issue prototype testing environments can cause
  certain materials to fail or perform poorly, such
  as high temperatures, UV light or exposure to
  corrosive chemicals
• Impact Your environmental requirements will
  constrain your material choices. For example,
  photopolymers are inappropriate for outdoor
  texting because they cannot be exposed to
  sunlight for long periods. Other materials are
  sensitive to high or low temperatures, react with
  certain chemicals, or absorb moisture.

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• What are your prototypes mechanical
  requirements?
• Issue What aspects of your prototype are you
  testing? Does it have snap-fit or hinging
  requirements? Does it need strength to withstand
  loads and forces? Will it be subject to impacts?
  Does it have fatigue requirements?
• Impact depending on which of these properties
  you wish to test with the rapid prototype, and
  the final manufacturing material, you may
  consider 3D printing with the same material, or
  with another 3D printing material that
  approximates the same key mechanical properties

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3D Printing Technologies
The relationship between material selection and
3D printing technology selection is not always
straightforward. The next slides will help
clarify which 3D printingtechnologies are best
for different types of prototypes.
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• Fused Deposition Modeling (FDM)
• Process extrudes filament of molten
  thermoplastic material from a heated nozzle to
  deposit thin layers successively on the part
  requires support material for some part
  geometries
• Surface Finish visible print lines may require
  sanding for smooth surface surface
  accuracy/tolerance not quite as high as CNC
  machined part
• Best For functional prototypes and end use parts
  made of common mass production plastics, as well
  as low-cost form and fit models

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• Stereolithography (SLA)
• Process focuses a UV laser on a tank of liquid
  plastic resin to trace out and solidify thin
  layers of material into 3D objects, layer by
  layer requires support material for some part
  geometries
• Surface Finish SLA parts have no porosity,
  therefore look and behave very similarly to
  molded parts relatively high level of surface
  accuracy and finish, second only to Material
  Jetting
• Best For functional testing of molded parts or
  production of tooling when FDM or SLS is not an
  option due to insufficient accuracy or detail
  different SLA materials can simulate different
  mass production materials

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• Material Jetting (PolyJet / MJP)
• Process jets thin layers of liquid photopolymer
  resin onto a build surface, where they are
  solidified using a UV laser, creating a solid
  part requires support material for some part
  geometries
• Surface Finish produces parts with the highest
  surface finishes and details, and is suitable
  when a very high level of detail and surface
  accuracy are paramount
• Best For parts where highest achievable level of
  detail and accuracy is paramount, or where more
  than one material needed in the same part

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• Selective Laser Sintering (SLS)
• Process uses a laser to sinter plastic powder
  layer by layer into a final part, creating a
  solid but slightly porous part does not require
  support material
• Surface Finish after surface blasting, SLS parts
  have a surface finish that is slightly grainy,
  like fine sandpaper print lines may be visible
• Best For complex geometries where supporting
  material is difficult to remove and parts where
  toughness and durability of nylon is desirable

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• Powder-Binder Printing (Zcorp)
• Process uses a printer jet to deposit colored
  liquid binder onto a bed of powder to fuse the
  material layer by layer into a solid object,
  creating full color parts does not require
  support material
• Surface Finish Raw powder-binder printed parts
  are powdery and slightly rough to the touch,
  fragile, and the colors are muted. After treating
  with an infiltration treatment, the part has a
  grainy surface texture, is more robust, but
  fragile, and has vibrant colors.
• Best For aesthetic and display models where
  accurate visual representation of the parts is
  the key consideration

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• Direct Metal Laser Sintering (DMLS)
• Process uses a laser to sinter metal powder
  layer by layer into a final metal part, which has
  similar density and strength as a CNC machined
  part requires support material for most part
  geometries
• Surface Finish DMLS parts have surface finish
  and mechanical properties equivalent to a fine
  investment cast part can be further machined to
  produce very accurate, complex, high performance
  parts
• Best For near net shape metal parts

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• Electron Beam Melting (EBM)
• Process uses an electron beam to melt metal
  powder layer by layer into a solid metal part
  faster build times than DMLS requires support
  material for most part geometries
• Surface Finish EBM surface finish is rougher
  than DMLS since additional particles adjacent to
  the electron beam melt and connect to the part
  surface finish similar to very rough casting can
  be further machined to produce very accurate,
  complex, high performance parts
• Best For near net shape metal parts with surface
  finish somewhat rougher than DMLS

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• Selective Laser Melting (SLM)
• Process uses high power lasers to melt metal
  powder layer by layer into a solid metal part
  requires support material for most part
  geometries
• Surface Finish SLM parts have slightly lower
  porosity than DMLS parts since the material has
  been fully melted can be further machined to
  produce very accurate, complex, high performance
  parts
• Best For near net shape metal parts with higher
  density than DMLS, and similar surface finish

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To Learn More

• Read the full guide for
• Relationship between design, 3D print
  manufacturability, and cost
• In-depth discussion of 3D print material
  considerations
• Side-by-side comparison of 3D printing
  technologies

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