1. Additive Manufacturing
Reshaping Manufacturing:
Understanding 3D Printing Processes
Prof. Brent Stucker
Founder & CEO, 3DSIM, LLC
Edward R. Clark Chair of Computer Aided Engineering
Department of Industrial Engineering, University of Louisville
Inaugural Chairman, ASTM F42 Committee on Additive Manufacturing
4. Additive Manufacturing
AM enables…
…an entrepreneur to
start selling a new
product without ever
needing to buy a
machine, purchase a
tool or prove out a mold;
and start shipping
products the day after
the design is finalized.
5. Additive Manufacturing
AM is used for the…
…automated
manufacture of hearing
aids so that you simply
scan the ear, print out a
custom-fitted hearing
aid, insert electronics,
and ship them by the
millions.
6. Additive Manufacturing
What is Additive Manufacturing?
(3D Printing)
• The process of joining materials to make objects from
3D model data, usually layer upon layer, as opposed to
subtractive manufacturing methodologies
7. Additive Manufacturing
University of Louisville’s
Involvement in AM
• One of the best equipped additive manufacturing
(AM) facilities in the world
• Performing Basic and Applied Research, since
starting with SLS in 1993
• Over 20 people focused on AM
• Close partner of leading AM users
– Boeing, GE, DoD, service bureaus, etc.
• Over 70 member organizations in our RP Center
– Includes Haas Technical Education Center
8. Additive Manufacturing
Typical AM Process Chain
1. Create CAD Solid
Model
2. Generate STL File
3. Verify File & Repair
4. Create Build File
1. Orientation, Location
2. Slicing
3. Support Material
Generation
5. Build part layer-by-
layer
6. Post-processing
Click for Movie
9. Additive Manufacturing
What is an STL Model File?
• Represents 3D solid models using
groups of planar triangles
– Describe each triangle by
• 3 vertices & unit normal vector
– No topological information
• Enumerate all triangles
• No special order
– Better accuracy = smaller triangles
= larger files
• Set triangle accuracy relative to
accuracy of machine used
• Holes between triangles, overlapping
triangles, and inverted vectors can be
problems
• No knowledge of dimensions (mm or
inches)
Facet 1
Facet 2
Facet 3
11. Additive Manufacturing
General Concept
(XML)
• Parts (objects) defined by volumes and materials
– Volumes defined by triangular mesh
– Materials defined by properties/names
• Color properties can be specified
– Color
– Texture mapping
• Materials can be combined
– Graded materials
– Lattice/Mesostructure
• Objects can be combined into constellations
– Repeated instances, packing, orientation
18. Additive Manufacturing
How do we build parts
using AM?
• 7 Process Categories
– ASTM/ISO Standard terminology, categories &
definitions will be used
• What are the secret limitations you might not be
aware of?
• What types of materials can you use?
• What is each process good for?
19. Additive Manufacturing
Vat Photopolymerization
• An additive manufacturing process in which liquid
photopolymer in a vat is selectively cured by light-
activated polymerization.
– Stereolithography
– Envisiontec DLP
– Micro-SLA
– 2-photon lithography
– …
20. Additive Manufacturing
Projection Systems
• Use a projector (LED
or DLP) to illuminate
the cross-section
– Resolution limited by
pixels of projector
– Typically faster per
layer
– Common for micro-
stereolithography
http://www.cmf.rl.ac.uk/latest/msl.html
22. Additive Manufacturing
Developments in Vat
Photopolymerization
• Increased proliferation of DLP/LCD/LED
technology to cure entire layers at once.
• New photopolymer materials which mimic
engineering photopolymers
• Expiration of initial stereolithography patents are
opening up the marketplace
• Renewed interest in 2-photon polymerization for
nano-scale components
23. Additive Manufacturing
Secrets of Vat
Photopolymerization
• Always need supports
– Thus, we must remove them
– Downward facing surfaces are inferior
• Photopolymers do not have long-term stability in
the presence of light
– They continue to react and degrade over time.
24. Additive Manufacturing
Materials in VP
• Over 20 years of photopolymer research,
including by major chemical companies, has led to
many resins which you can buy
• No materials are “standard engineering-grade”
polymers
– Specially-formulated to mimic engineering polymers
25. Additive Manufacturing
What is VP best for?
• High accuracy parts that don’t have stringent
structural requirements
• Patterns
– Investment casting
– RTV molding
– …
26. Additive Manufacturing
Material Jetting
• An additive manufacturing process in which droplets
of build material are selectively deposited
– Wax or Photopolymers
– Multiple nozzles
– Single nozzles
– Includes
• Objet
• 3D Systems Projet
• Stratasys Solidscape machines
• Several Direct Write machines
• Etc…
29. Additive Manufacturing
Developments in Material
Jetting
• New Stratasys/Objet Connex 500
– Multi-material & Multi-color
• Many traditional “2D printing” companies are
investigating 3D printing
– Thermoplastics are difficult
• Viscosity issues
– Metals are starting to be publically discussed
• Significant interest in printed electronics
– Major industry interest at the intersection between 2½D
& 3D geometries
30. Additive Manufacturing
Secrets of Material Jetting
• Always need supports
– Thus, we must remove them
– Downward facing surfaces are inferior (particularly true
if secondary support materials are not used)
• Secondary support materials make support
removal easier
– Water Soluble
– Different Strength
– Different Melting Temp
31. Additive Manufacturing
Material Jetting Materials
• Only commercial materials are wax-like materials
or photopolymers
– Need low viscosity
– Waxes melt at low temperature, but solidify quickly
– Photopolymers are cured using light just after
deposition
• No materials are “standard engineering-grade”
polymers
– Specially-formulated to mimic engineering polymers
32. Additive Manufacturing
What is Material Jetting
best for?
• Smooth, accurate parts that don’t have stringent
structural requirements
• Mixing of stiff and flexible materials/colors gives
tremendous variability in design
– Artwork
– Full-color mock-ups
– Gradient material assemblies
– …
33. Additive Manufacturing
Binder Jetting
• An additive
manufacturing process
in which a liquid
bonding agent is
selectively deposited to
join powder materials.
– Zcorp
– Voxeljet
– ProMetal/ExOne
– …
34. Additive Manufacturing
Developments in Binder
Jetting
• 3D Systems purchased Zcorp and has changed
marketing to “Colorjet”
– Printing sugary food and ceramics (pottery & art)
– Announced a color personal 3D printer
• ExOne is pushing “sand printing” and builds metal
parts for Shapeways
• Voxeljet, fcubic, etc. make marketplace dynamic
– Continuous build platform design has major
ramifications
35. Additive Manufacturing
Secrets of Binder Jetting
• Parts from starch/plaster look pretty but are quite
brittle
– Post-process infiltration of these materials by
cyanoacrylate or another material is needed for strength
• Infiltration makes these parts very heavy
• Metal parts are not engineering-grade
– Mostly applicable to art
– Need infiltrated (highest accuracy)
or sintered (shrinks)
36. Additive Manufacturing
Binder Jetting Materials
• Majority of the build material is the powder
– Makes the process very, very fast
• Materials are by nature “composite”
• Gradients in color/properties possible by printing
different binders
• Any powder which can be spread and then glued,
reacted, catalyzed, or otherwise fused using a
binder is a candidate
• Living tissue and dental ceramics are promising
37. Additive Manufacturing
What is Binder Jetting best
for?
• Color parts used for marketing or proof-of-
concept.
• Metal parts for artistic purposes or with limited
engineering functionality.
• Powder metal green parts
• Sand casting molds
38. Additive Manufacturing
Material Extrusion
• An additive
manufacturing process in
which material is
selectively dispensed
through a nozzle or orifice
– Based on Stratasys FDM
machines
– Office friendly
– DIY community
– Best selling platform
– …
39. Additive Manufacturing
Developments in Material
Extrusion
• Expiration of initial FDM patents has led to a vast
proliferation of personal 3D printers
– More “personal” machines sold @$1k-$2k than “industrial”
machines for $10k-$200k
– Lots of new materials, competitors, etc.
– Many ways for consumers to access & buy these machines
• 3D Systems & Stratasys offer personal 3D printers in
addition to their industrial offerings
• Renewed interest in “manufacturing” parts via extrusion
– High-temp materials, concrete, fiber-reinforced composites, etc.
– People seem to be taking it more seriously than a few years ago
40. Additive Manufacturing
Secrets of Material
Extrusion
• Always need supports
– Thus, we must remove them
– Downward facing surfaces are inferior
• Secondary support materials make support
removal easier
– Water soluble, easier to remove, etc.
• Fundamental tradeoffs in build style mean you can
NEVER be fully dense & simultaneously achieve
maximum accuracy without post-processing
41. Additive Manufacturing
Material Extrusion
Materials
• Commercial materials include easy to extrude
engineering polymers
– ABS, PC, PC/ABS, PPSF, etc.
– Chocolate and meltable food products
– Many DIY materials being explored
• Syringe & pumped nozzles also available
– Pastes, glue, cement
– Frosting & other food products
• Need materials which soften under shear load and
maintain their shape after deposition
42. Additive Manufacturing
What is Material Extrusion
best for?
• Inexpensive prototypes
• Functional parts without
stringent engineering
constraints
– Limited fatigue strength
• Great platform on which
to try lots of things
– Living tissue
– Food
– Toys
43. Additive Manufacturing
Powder Bed Fusion
• An additive manufacturing process in which thermal
energy selectively fuses regions of a powder bed
– SLS, SLM, DMLS, EBM, BluePrinter, etc.
– Polymers, metals & ceramics
62. Additive Manufacturing
Electron Beam Melting
(EBM) Arcam
• Electrons are emitted from a
heated filament >2500° C
• Electrons accelerated through
the anode to half the speed of
light
• A magnetic lens focuses the
beam
• Another magnetic field
controls deflection
• When the electrons hit the
powder, kinetic energy is
transformed to heat.
• The heat melts the metal
powder
No moving parts!
63. Additive Manufacturing
EBM versus Laser
Processes
• EBM Benefits
– Energy efficiency
– High power (4 kW) in a narrow
beam
– Incredibly fast beam speeds
• No galvanometers
– Fewer supports
• EBM Drawbacks
– Only works in a vacuum
• Gases (even inert) deflect the
beam
– Does not work well with
polymers or ceramics
• Needs electrical conductivity
– Needs larger powder particles
64. Additive Manufacturing
Developments in Powder
Bed Fusion
• The most-used platform for “functional parts”
• Significant R&D investments
• Many metal laser sintering machine manufacturers
– SLM Solutions, ConceptLaser, EOS, Phenix, Renishaw, Realizer
• Starting to see new polymer machine manufacturers
– Several companies entering the marketplace to compete with 3D
Systems & EOS
• Open versus Closed machine architecture battles
• GE’s purchase of Morris Technologies (2012) is still
having major ramifications on the metal laser sintering
marketplace
65. Additive Manufacturing
Secrets of Powder Bed
Fusion
• An Expert User is the most critical aspect of
getting a good part
– User-selected trade-offs between speed, accuracy and
strength in polymer laser sintering
– Takes about a year to learn enough to consistently make
good parts in metal processes
• Polymers are not 100% recyclable
• Metal supports are a huge pain
– $50k-$100k/year per machine waste is common
• Blade crashes and/or over-supporting
66. Additive Manufacturing
Polymer Materials in
Powder Bed Fusion
• You can use any
material you want, as
long as it’s nylon
– Or if it meets the
cooling curve
• Opposite of injection
molding
– Fast heating, slow
cooling
67. Additive Manufacturing
Metal Materials in Powder
Bed Fusion
• Most casting and welding alloys can be processed
using metal laser sintering
– Very fast melting & solidification times gives unique
properties & challenges
– High reflectivity, high thermal conductivity materials
are difficult to process (copper, gold, aluminum, etc.)
• Titanium is the “sweet spot” for EBM
68. Additive Manufacturing
Other Materials in Powder
Bed Fusion
• Ceramics are difficult, but possible
to directly process
• Green parts are easy to process
– Powder metallurgy, sand casting, etc.
69. Additive Manufacturing
What is Powder Bed Fusion
best for?
• Manufacturing end-use products
– Polymer parts from Nylon 11 or 12 (including glass-
filled nylons)
– Metal parts from Titanium, Stainless Steel, Inconel
super alloys, tool steels and more
• Prototyping components where functional testing
is required on the prototype
70. Additive Manufacturing
Sheet Lamination
• An additive manufacturing
process in which sheets of
material are bonded to form an
object.
– Paper (LOM)
• Using glue
– Plastic
• Using glue or heat
– Metal
• Using welding or bolts
• Ultrasonic AM…
71. Additive Manufacturing
Developments in Sheet
Lamination
• Renewed interest in paper-based machines at the
low-end by Mcor and others
• Fabrisonics sells 3 platforms based upon metal
ultrasonic additive manufacturing
• Other solid state AM methods are being
investigated
– Friction stir AM, etc.
72. Additive Manufacturing
Secrets of Sheet Lamination
• Getting rid of excess
material is difficult
– Cut then Stack – versus –
Stack then Cut
– Mechanical properties are
typically quite poor
http://www.cubictechnologies.com/
73. Additive Manufacturing
Materials in Sheet
Lamination
• Paper is used for proof of concept parts
– Color printing on the paper gives color parts
• Metal sheets can be cut and stacked for tooling
and other applications
• Ceramic tapes can be cut and stacked and then
fired for ceramic parts
• Polymer sheets (such as by Solido) can be bonded
and cut to form prototypes
74. Additive Manufacturing
What is Sheet Lamination
best for?
• Paper machines make cheap physical
representations of your design
• Original LOM-like machines can be used like
wood as patterns for sand casting, or as
topographical maps, etc.
• Metal laminated tooling reduces the time to build
large molds such as for stamping
• Micro-fluidic ceramic parts can be made using
ceramic tapes
75. Additive Manufacturing
– Wire & Powder Materials
– Lasers & Electron Beams
– Great for feature addition & repair
Directed Energy Deposition
• An additive manufacturing
process in which focused
thermal energy is used to
fuse materials by melting as
they are being deposited
76. Additive Manufacturing
Developments in Directed
Energy Deposition
• Electron Beam with wire
seems to be leading for part
production currently
• DoD is interested in laser
powder deposition for repair
(America Makes project)
– Manufacturers are marketing
laser deposition heads as add-
ons to existing machine tools
77. Additive Manufacturing
Secrets of Directed Energy
Deposition
• Material needs something to land on (supports)
– We don’t typically make 3D complex parts, just
complex parts with mostly upward-facing features
• There is a direct correlation between feature size
and build speed.
– Accurate processes are painfully slow
– Fast process are very inaccurate
• Surface finish & accuracy requirements almost
always require finish machining
78. Additive Manufacturing
Materials in Directed
Energy Deposition
• Most metal alloys
can be deposited
with some success
– Rapid cooling
affects properties
• Polymers and
ceramics rarely
used, but possible
Optical Absorption vs Wavelength
Wavelength (microns)
79. Additive Manufacturing
What is Direct Energy
Deposition best used for?
• Adding features to existing structures
– Replace complex forgings with sheet structures that we
build up near-net shape parts on
• Repair & refurbishment of existing components
– Qualified for many high-performance applications
81. Additive Manufacturing
Powders
• Small powder particles
– Give better feature resolution, surface finish,
accuracy and layer thicknesses
– Are difficult to spread and/or feed
– Become airborne easily (repel in EBM)
– React with oxygen easily
• Spherical powders with a tight PSD are best
• Powder morphology, packing density, fines, etc.
make a HUGE difference in some processes
82. Additive Manufacturing
AM can now enable us to…
…control the overall geometry of a part, which could be
made up of a truss network, where each truss has an
optimized thickness and could have an individually
controllable microstructure or material.
• But we don’t know how to:
• Efficiently represent this type of multi-scale
geometry in a CAD environment, or
• Efficiently optimize these multi-scale features, or
• Efficiently simulate the link between AM
process parameters and microstructure, or
• Efficiently compute the effects of changes in
microstructure on part performance
Courtesy David Rosen, Georgia Tech
83. Additive Manufacturing
Simulation Needs
• We need improved computational design tools for additive
manufacturing
• Like those used for injection molding and casting/forging
• But, physics-based tools are inefficient when applied to AM
• Requires dramatic simplification of the process and/or geometry
• Instead, AM-industry software focuses primarily on
geometry and not process control or performance/quality
• Forces the AM industry to continue the Build/Test/ Redesign cycle
of traditional manufacturing.
84. Additive Manufacturing
• Process simulations that are faster than an AM machine
builds a part
– Predict residual stress and distortion so we know how to place
supports and how to pre-distort our CAD model
• Material simulations which can predict crystal level
details and the resulting mechanical properties
• Lightning fast solutions on GPU-based platforms
• We simulate only what we need to get a practical
answer as FAST as possible
• Come tomorrow morning to hear more….
85. Additive Manufacturing
Engineering Implications
• More Complex Geometries
– Internal Features
– Parts Consolidation
– Designed internal structures
• No Tools, Molds or Dies
– Direct production from CAD
• Unique materials
– Controllable microstructures
– Multi-materials and gradients
– Embedded electronics
86. Additive Manufacturing
Business Implications
• Enables business models used for 2D printing,
such as for photographs, to be applied in 3D
– Print your parts at home, at a local “FedEx Kinkos,”
through “Shapeways” or at a local store
• Removes the low-
cost labor advantage
• Entrepreneurship
– Patents expiring
• New Machines
– Software tools
– Service providers Pharmaceutical Manufacturing in China
87. Additive Manufacturing
Web 2.0 + AM =
Factory 2.0
• User-changeable web content plus a network of
AM producers is already enabling new
entrepreneurial opportunities
– Shapeways.com
– Freedom of Creation
– FigurePrints
– Spore
– …and more
87
88. Additive Manufacturing
Impact on Logistics
• Eliminates drivers to
concentrate production
• “Design Anywhere /
Manufacture Anywhere” is
now possible
– Manufacture at the point of
need rather than at lowest
labor location
– Changing “Just-in-Time
Delivery” to “Manufactured-
on-Location Just-in-Time”
89. Additive Manufacturing
Big Picture Possibilities
• Additive Manufacturing has the potential to:
– Make local manufacturing of products normative
• Small businesses can successfully compete with multi-national
corporations to produce goods for local consumption
• Parts produced closer to home cost the same as those made
elsewhere, so minimizing shipping drives regional production
– Reverse increasing urbanization of society
• No need to move to the “big city” if I can design my product
and produce it anywhere
– Make jobs resistant to outsourcing
• Creativity in design becomes more important than labor costs
for companies to be successful
89