Inside3DPrinting_BrentStuckerWorkshop

Additive Manufacturing

Reshaping Manufacturing: Understanding 3D Printing Processes

Prof. Brent StuckerFounder & CEO, 3DSIM, LLC

Edward R. Clark Chair of Computer Aided EngineeringDepartment of Industrial Engineering, University of Louisville

Inaugural Chairman, ASTM F42 Committee on Additive Manufacturing


AM has the potential to enable anyone to make many things they

require, anywhere!


AM enables…

…an advanced manufacturing facility to be set up using only electricity, some raw materials, and a computer.


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.


AM is used for the…

…automatedmanufacture 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.


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


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


Typical AM Process Chain

1. Create CAD Solid Model

2. Generate STL File3. Verify File & Repair4. Create Build File

1. Orientation, Location2. Slicing3. Support Material

Generation5. Build part layer-by-

layer6. Post-processing

Click for Movie


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


New Additive Manufacturing File Format

• AMF– Additive Manufacturing Format– Additive Manufacturing File


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

<?xml version="1.0" encoding="UTF-8"?><amf units="mm">

<object id="0"><mesh>

<vertices><vertex>

<coordinates><x>0</x><y>1.32</y><z>3.715</z>

</coordinates></vertex><vertex>

<coordinates><x>0</x><y>1.269</y><z>2.45354</z>

</coordinates></vertex>...

</vertices><region>

<triangle><v1>0</v1><v2>1</v2><v3>3</v3>

</triangle><triangle>

<v1>1</v1><v2>0</v2><v3>4</v3>

</triangle>...

</region></mesh>

</object></amf>

Basic AMF Structure

Addresses vertex duplication, leaks of STL & UNITS


Compressibility

Comparison for 32‐bit Floats; need to look at double precision

CURVED PATCH(Curved using vertex normals)

PLANNAR PATCH

Optionally add normal/tangent vectors to some triangle mesh vertices

to allow for more accurate geometry.

CURVED PATCH(or curved using edge tangents)

Curved patches


Multiple Materials

Micro-structureGradient

Materials


Print Constellation

• Print orientation• Duplicated objects• Sets of different objects• Efficient packing• Hierarchical


Metadata

<metadata type=“Author”>John Doe”></metadata><metadata type=“Software”>SolidX 2.3”></metadata><metadata type=“Name”>Product 1></metadata><metadata type=“Revision”>12A”></metadata>

<object id=“1”><metadata type=“Name”>Part A ></metadata>

</object id=“1”>


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?


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– …


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


Envisiontec Perfactory

www.ajm-magazine.com www.crdm.co.uk


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


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.


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


What is VP best for?

• High accuracy parts that don’t have stringent structural requirements

• Patterns– Investment casting– RTV molding– …


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…


Single-Droplet

• Solidscape Modelmakers– 0.0005” layers – small, accurate parts made slowly


Multi-Droplet

• Thermojet and Actua from 3D Systems– Prints waxy-like materials

• No longer in production, but still serviced


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


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


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


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– …


Binder Jetting

• An additive manufacturing process in which a liquid bonding agent is selectively deposited to join powder materials. – Zcorp– Voxeljet– ProMetal/ExOne– …


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


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)


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


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


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– …


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


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


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


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


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

CO2 LaserX-Y Scanning

Mirrors

FeedCartridges

PartCylinder

Counter-RotatingPowder LevelingRoller Laser Beam

SelectivelyMelts Powder

SELECTIVE LASER SINTERING

45

Loose Powder

46

Energy is Applied – Laser or Electron Beam Energy

Radiation/Heat from

Energy Source

47

The Powder Begins to Heat Due to Incident Radiation

48

The Outside of the Particles Heat More Quickly than the Inside

49

Smaller Particles Begin to Melt

50

Larger Particles May or May Not Melt Depending Upon Dwell Time of Radiation

51

Melted Portions of the Material Begin to Coalesce (Sinter) Resulting in a Physical Bond and Shrinkage

52

When the Heat is Removed, the Part Cools as a Porous Solid

53

Melting within a Powder Bed Can Lead to Curl

54


55


56


57

Undesirable Shrinkage Controllable Shrinkage Heater Scanning System

Comparison of Shrinkage With and Without Heaters

58

Undesirable Shrinkage Controllable Shrinkage Scanning SystemHeaterHeater


59

Undesirable Shrinkage Controllable Shrinkage Scanning SystemHeater

Index


60

Undesirable Shrinkage Controllable Shrinkage Scanning SystemHeater



Metal Laser Sintering Methods for Controlling Shrinkage

Complex Scan Patterns Supports


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!


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


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


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


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


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


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.


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


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…


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.


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/


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


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


– 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


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


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


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)


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


General Comments

• Powder Materials• Modeling• Implications of AM


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


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


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.


• 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 leveldetails 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….


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


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


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


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”


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


Questions & Comments?

[email protected]+1-502-852-2509

Technology

Inside3DPrinting_BrentStuckerWorkshop