eng165-good material aspects

7/24/2019 ENG165-Good Material Aspects

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ENG 165-265

Spring 2015, Class 5 AdditiveManufacturing Tecni!ues

Advanced Manufacturing Choices


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Table of Contents

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1.Introduction: What is Additive Manufacturing2.Historical development

3.From Rapid Prototyping to Additive Manufacturing (AM) Where are we today?

4.Overview of current AM technologies

1.Laminated Object Manufacturing (LOM)

2.Fused Deposition Modeling (FDM)

3.3D Printing (3DP)

4.Selected Laser Sintering (SLS)

5.Electron Beam Melting (EBM)

6.Multijet Modeling (MJM)7.Stereolithography (SLA)

5.Modeling challenges in AM

6.Additive manufacturing of architected materials

7.Conclusions


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From Rapid Prototyping to Additive Manufacturing

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What is Rapid Prototyping

- From 3D model to physical object, with a click

- The part is produced by printing multiple slices (cros

s

sections) of the object and fusing them togetherin situ

- A variety of technologies exists, employing different

physical principles and working on different materials

- The object is manufactured in its final shape, with no

need for subtractive processing

How is Rapid Prototyping different from Additive Manufacturing?

The difference is in the use and scalability, not in the technology itself:

Rapid Prototyping: used to generate non-structural and non-functional demo pieces or

batch-of-one components for proof of concept.

Additive Manufacturing: used as a real, scalable manufacturing process, to generate fully

functional final components in high-tech materials for low-batch, high-value manufacturing.


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Why is Additive Manufacturing the Next Frontier

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EBF3= Electron Beam Freeform Fabrication (Developed by NASA LaRC)


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Rapid Prototyping vs Additive

Manufacturing today

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AM breakdown by industry today

Wohlers Report 2011 ~ ISBN 0-9754429-6-1


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From Rapid Prototyping to Additive Manufacturing

Rapid Prototyping in a nutshell1. 3D CAD model of the desired object is generated

2. The CAD file is typically translated into STL* format

3. The object described by the STL file is sliced alongone direction the !"# or !printing# direction$

%. &ach slice is man'fact'red and layers are f'sedtogether a (ariety of techni)'es eist$. The materialcan be deposited by dots +D$, lines 1D$ or sheets2D$

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A voxel (volumetric pixel or, morecorrectly, Volumetric PictureElement) is a volume element,representing a value on a regulargrid in three dimensional space.This is analogous to a pixel,which represents 2D image datain a bitmap.

*The STL (stereo lithography) file format issupported by most CAD packages, and is is

widely used in most rapid prototyping / additivemanufacturing technologies.STL files describe only the surface geometry ofa three dimensional object without anyrepresentation of color, texture or other commonCAD model attributes. The STL file describes adiscretized triangulated surface by the unitnormal and vertices coordinates for eachtriangle (ordered by the right-hand rule).

A li

mitation or an opportunity?


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Compromises in Additive ManufacturingAnother -ey compromise is among process speed, volumeand tolerances.

" Laminated bject /odeling L/$

" 0'sed Deposition /odeling 0D/$

" 3D rinting 3D$

" Selecti(e Laser Sintering SLS$

" &lectron eam /elting &/$

" /'ltijet /odeling //$

" Stereolithography SLA, STL$

" /icro4stereolithography

serial and projected$

" T5o photon lithography

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!aminated "b#ect Manufacturing $!"M%

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1.Sheets of material (paper, plastic,

ceramic, or composite) are either precutor rolled.

2.A new sheet is loaded on the buildplatform and glued to the layerunderneath.

3.A laser beam is used to cut the desired

contour on the top layer.4.The sections to be removed are dicedin cross-hatched squares; the dicedscrap remains in place to support thebuild.

5.The platform is lowered and anothersheet is loaded. The process is

repeated.6. The prod'ct comes o't as a rectang'lar

bloc- of laminated material containingthe prototype and the scrap c'bes. Thescrap7s'pport material is separatedfrom the prototype part.


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Laminated bject /an'fact'ring L/$5as de(eloped by 8elisys of Torrance, CA,in the 199+s. 8elisys 5ent o't of b'sinessin 2+++ and their L/ e)'ipment is no5ser(iced by C'bic Technologies.

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Equipment picture

Current market leaders- Mcor Technologies (Ireland)- Solido (Israel)- Strataconception (France)- Kira Corporation (Japan)

Mcor Technologies Matrix 300+(uses A4 paper and water-based adhesive)

Courtesy, Cubic Technologies

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KEY APPLICATION AREAS

/aim'm b'ild si"e %+in %+in 2+in

:esol'tion in ,y$ ;74 .++% in

:esol'tion in " o additional s'pport str'ct're isre)'ired the part is self4s'pported$

= :emo(al of the scrap material is laborio's= The !"# resol'tion is not as high as for other

technologies= Limited material set= >eed for sealing step to -eep moist're o't

= attern /a-ing= Decorati(e bjects

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Fused &eposition Modeling $F&M%

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1.A spool of themoplastic wire (typically

acrylonitrile butadiene styrene (ABS)) witha 0.012 in (300 m) diameter iscontinuously supplied to a nozzle

2.The nozzle heats up the wire and extrudesa hot, viscos strand (like squeezingtoothpaste of of a tube).

3.A computer controls the nozzle movementalong the x- and y-axes, and each cross-section of the prototype is produced bymelting the plastic wire that solidifies oncooling.

4.In the newest models,a second no""lecarries a s'pport 5a that can easily beremo(ed after5ard, allo5ing constr'ctionof more comple parts. The most commons'pport material is mar-eted by Stratasys'nder the name ?ater?or-s

5.The sacrificial support material (if available)is dissol(ed in a heated sodi'm hydroide

>a8$ sol'tion 5ith the assistance of'ltrasonic agitation.

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The fused deposition modeling (FDM)technology was developed by S. Scott Crump inthe late 1980s and was commercialized in 1990.The double material approach was developedby Stratasys in 1999.

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Current market leaders- Stratasys, Inc.

Stratasys Dimension SST 1200

"Ribbon Tetrus" (Carlo Squin)

Courtesy, Dr. Robin Richards,University College London, UK

www.nybro.com.au

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/aim'm b'ild si"e 2+@ 2+@ 2+@

:esol'tion in ,y$ ;74 +.++2@ 4 +.++@$

:esol'tion in " ;74 +.++2@ 4 +.+1@$

Speed Slo5

Cost /edi'm

A(ailable materials ThermoplasticsAS, C,BLT&/$

KEY METRICSADVANTAGES

DISADVANTAGES

= &conomical inepensi(e materials$= &nables m'ltiple colors= &asy to b'ild DE -its one of the most

common technologies for home 3Dprinting$

= A 5ide range of materials possible by

loading the polymer

= /aterials s'ite c'rrently limited tothermoplastics may be resol(ed by loading$

= Concept'al /odels= &ngineering /odels= 0'nctional Testing rototypes

www.redeyeondemand.com

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FAB@Home

" 0irst m'lti4material printer a(ailable to the p'blic

" pen4so'rce system

" roject goalF open4so'rce mass4collaboration de(elopingpersonal fabrication technology aimed at bringing personalfabrication to yo'r home project started by 8. Lipson and &./alone at Cornell in 2++6$.

" op'lar /echanics rea-thro'gh A5ard 2++G

RepRap" pen4so'rce system

" 0o'nded in 2++ by Dr. A. o5yer atthe Bni(ersity of ath BH$

" roject goalF Deli(er a 3D printer thatcan print itselfI

" 1stmachine in 2++G Dar5in$

" :eplication achie(ed in 2++J

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Do it Yourself FDM rapid prototyping systems

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Do it Yourself FDM rapid prototyping systems

Cubify Cube= Commercially available fully built for $1,200= Resolution 0.2mm= 16 colors= Prints in ABS and PLA= Awarded 2012 Popular Mechanics Breakthrough Award

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'& Printing $'&P%

1.A layer of po5der plaster,ceramic$ is spread across theb'ild area

2. n-jet4li-e printing of binder o(erthe top layer densifies and

compacts the po5der locally3. The platform is lo5ered and the

net layer of dry po5der isspread on top of the pre(io'slayer

%. Bpon etraction from themachine, the dry po5der isbr'shed off and recycled

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'& Printing $'&P%

K Corporation first introd'ced high4resol'tion, 2%4color, 3D 8D3D$ in2++ 6++ dpi$. K Corp 5as later bo'ght by3D Systems.

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Current market leaders- Z Corporation

- Exone- Voxeljet

Zcorp Z510

Olaf Diegel Atom 3D printed guitar

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'& Printing $'&P%

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= Widely used to print colorful and complexparts for demonstration purposes

= Molds for sand casting of metals

/aim'm b'ild si"e 1% in 1+ in J in

:esol'tion in ,y$ 6%+ dpi

:esol'tion in "


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(elective !aser (intering $(!(%

1.A contin'o's layer of po5der isdeposited on the fabricationplatform

2.A foc'sed laser beam is 'sed tof'se7sinter po5der particles in asmall (ol'me 5ithin the layer

3. The laser beam is scanned todefine a 2D slice of the object5ithin the layer

%. The fabrication piston islo5ered, the po5der deli(erypiston is raised and a ne5 layer

is deposited.After remo(al from the machine,

the 'nsintered dry po5der isbr'shed off and recycled

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" SLS technology in(ented at BT A'stin in the !J+sby oe eaman, Carl Dec-ard and Da(e o'rell.

" 0irst s'ccessf'l machineF DT/ Sinterstation2+++, in late 199+s

" DT/ later ac)'ired by 3D Systems

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Current market leaders- 3D Systems

3D Systems Sinterstation

Important note:SLS patent runs out in Feb 2014!A huge influx of players andtechnologies is anticipated.Metal Technology Co.

3D Systems

Bulatov Abstract Creations

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= Structural components

/aim'm b'ild si"e G++ mm 3J+ mm 6+mm

:esol'tion in ,y$ 8igh Spot Dependant$

:esol'tion in " +.++@

Speed /edi'm

Cost /edi'm

A(ailable materials o5dered plasticsnylon$, metals steel,titani'm, t'ngsten$,ceramics siliconcarbide$ and fiber4

reinforced /Cs


DISADVANTAGES

= ?ide array of str'ct'ral materials beyondpolymers

= >o need for s'pport materials= Cheaper than &/= ne of t5o technologies that allo5

comple parts in metals

= &pensi(e relati(e to 0D/, 3D= The )'ality of metal parts is not as high as

5ith &/

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)lectron *eam Melting $)*M%

1. The fabrication chamber ismaintained at high (ac''m and hightemperat're

2.A layer of metal po5der is depositedon the fabrication platform

3.A foc'sed electron beam is 'sed to

melt the po5der particles in a small(ol'me 5ithin the layer

%. The electron beam is scanned todefine a 2D slice of the object 5ithinthe layer

. The b'ild table is lo5ered, and a

ne5 layer of dry po5der is depositedon top of the pre(io's layer

6.After remo(al from the machine, the'nmelted po5der is br'shed off andrecycled

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Current market leaders- Arcam AB (Sweden)

Arcam A2 machine

EBM process developed by

Arcam AB (Sweden) in 1997

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= Structural components for aerospace(Ti6Al4V, gammaTiAl, Ni superalloys)

= Custom-made bio-implants (Ti6Al4V)

/aim'm b'ildsi"e

2++mm 2++mm 3+mm

:esol'tion in ,y$ ;74 +.2mm

:esol'tion in " +.++2@ +.+ mm$

Speed /edi'm

Cost 8igh

A(ailable materials /etalsF titani'm,t'ngsten, stainlesssteel, cobalt chrome,>i4based s'peralloys.


DISADVANTAGES

= /ethod of choice for high4)'ality metal parts= ?ide range of metals= 0'lly dense parts 5ith (ery homogeneo's

microstr'ct'res=


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Multi#et Modeling $M+M%1.A pie"oelectric print head 5ith

tho'sands of no""les is 'sed to jet 16micron droplets of photopolymer onthe printing str'ct're. An additional setof no""les deposits a sacrificials'pport material to fill the rest of thelayer.

2.A B< c'ring lamp is scanned acrossthe b'ild to immediately cross4lin- thephotopolymer droplets.

3. The ele(ator is lo5ered by one layerthic-ness and the process is repeatedlayer4by4layer 'ntil the model is b'ilt.

%. The sacrificial material is remo(edF# The bjet system 'ses a photopolymer as

s'pport materialM the s'pport material isdesigned to crosslin- less than the modelmaterial and is 5ashed a5ay 5ith press'ri"ed5ater.

# The 3D Systems n


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Multi#et Modeling $M+M%

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Current market leaders- Objet

-3D Systems

/'ltijet modeling //$ 5as

introd'ced by 3D Systems in 1996 as acheaper alternati(e to ind'strial4gradeStereolithography machines.

Objet Desktop 30 Pro

3D SystemsThermojet

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Multi#et Modeling $M+M%

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= Automotive= Defense= Aerospace= Consumer goods= Household appliances= Medical applications

/aim'm b'ild si"e 1+++mm J++mm ++mm

:esol'tion in ,y$ %+ dpi

:esol'tion in " 16 microns

Speed 0ast

Cost 8igh

A(ailable materials Acrylate4basedphotopolymer

KEY METRICS

ADVANTAGES

DISADVANTAGES

= 0ast process= Comple parts (ia sacrificial s'pport

materials

= Acc'racy is not as good as SLA

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(tereolithography $(!A%

1.A str'ct're s'pport base is positionedon an ele(ator str'ct're and immersedin a tan- of li)'id photosensiti(emonomer, 5ith only a thin li)'id filmabo(e it

2.A B< laser locally cross4lin-s the

monomer on the thin li)'id film abo(ethe str'ct're s'pport base

3. The ele(ator plate is lo5ered by a smallprescribed step, eposing a fresh layerof li)'id monomer, and the process is

repeated%.At the end of the job, the 5hole part isc'red once more after ecess resin ands'pport str'ct'res are remo(ed

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A suitable photosensitive polymermust be very transparent to UV lightin uncured liquid form and very

absorbent in cured solid form, toavoid bleeding solid features intothe layers underneath the currentone being printed.

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(tereolithography $(!A%Solidification of the monomer can occ'r in

t5o different modalitiesF

Free surface modeF Solidification occ'rs atthe resin7air interface. n this mode, carem'st be ta-en to a(oid 5a(es or a slant ofthe li)'id s'rface, 5hich 5o'ld compromise

the final dimensional resol'tion. The ele(atormo(es do5n at each step top4do5n b'ild$.

Fixed surface mode: The resin is stored in acontainer 5ith a transparent 5indo5 plate for

epos're, and solidification occ'rs at thestable 5indo57resin interface. n this mode,the ele(ator mo(es 'p at each step bottom4'p b'ild$.

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H-W Kanget al2012J. Micromech. Microeng.22115021

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T5o f'ndamental process (ariationseistF

# Scanning stereolithography. The laserbeam is rastered onto the s'rface. arts areconstr'cted in a point4by4point and line4by4

line fashion, 5ith the sliced shapes 5rittendirectly from a comp'teri"ed design of thecross4sectional shapes.

# Proection stereolithography. A parallelfabrication process in 5hich all the (oels ina layer are eposed at the same timeM thetopology to be printed on each layer isdefined by 2D shapes mas-s$. These 2Dshapes are either a set of real photomas-sor digital mas-s defined on a DL projector.

3

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SLA 5as pioneered by Ch'c- 8'll in

the mid419J+s see pict're belo5$. 8'llfo'nded 3D Systems to commerciali"eits ne5 man'fact'ring process.

Current market leaders-

3D Systems- Sony

3D Systems iPro 9000 XL

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= Patterns for metal processing (e.g.,molding)

= Prototypes for demonstrational purposes

/aim'm b'ild si"e 1++mm G+mm +mm

:esol'tion in ,y$ Spot Dependent

:esol'tion in " +.++%@

Speed /edi'm

Cost 8igh

A(ailable materials ThermosetpolymersFphotosensiti(eresins

KEY METRICS

ADVANTAGES

DISADVANTAGES

= 0ast= Nood resol'tion= >o need for s'pport material= hotosensiti(e polymers ha(e acceptable

mechanical properties

= &pensi(e e)'ipment O1++4O++H$= &pensi(e materials photosensiti(e resins

are PO1++42++ 7-g$= /aterial s'ite limited to resins

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" The application of rapid prototyping :$techni)'es to /&/S and >&/S re)'ireshigher acc'racy than 5hat is normallyachie(able 5ith commercial : e)'ipment.

" Laminated object man'fact'ring L/$,

f'sed deposition modeling 0D/$, andselecti(e laser sintering SLS$ all m'st beecl'ded as microfabrication candidates onthat basis.

" nly stereolithography has the potential toachie(e the fabrication tolerances re)'iredto )'alify as a /&/S or >&/S tool.

" Latest enhancements that ha(e made it anattracti(e option are high(resolution micro(and nanofabrication methods!

APPLICATION TO MEMS AND NEMS

EPFL, Lausanne, Switzerland

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" /icrostereolithography, deri(ed from con(entionalstereolithography, 5as introd'ced by -'ta in 1993.

" ?hereas in con(entional stereolithography the laserspot si"e and layer thic-ness are both in the 1++4Qmrange, in microstereolithography a B< laser beam is

foc'sed to a 1R24Qm spot si"e to solidify material ina thin layer of 1R1+ Qm.

" The monomers 'sed in : and micro4stereolithography are both B


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" T5o4photon lithography pro(ides a f'rtherenhancement of the SLA resol'tion.

" Special initiator molec'les in the monomer only startthe polymeri"ation reactions if acti(ated by t5o photonssim'ltaneo'sly. The laser intensity field can be t'ned

so that this e(ent only happens in a (ery small regionnear the foc's. The res'lt is etremely localpolymeri"ation, 5ith resol'tions in the tens ofnanometers range.

" T5o4photon polymeri"ation can occ'r e(ery5here inthe monomer bath, as opposed to only at the top layer,

simplifying the hard5are re)'irements considerably.

TWO-PHOTON LITHOGRAPHY

www.laser-zentrum-hannover.de

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Current materials in Additive Manufacturing

Materials in !M today

- Thermoplastics 0D/, SLS$

- Thermosets SLA$

- o5der based composites 3D$

-

/etals &/, SLS$- Sealant tapes, paper L/$

- Starch and s'gar 3D$

" Functional"structural parts# 0D/ AS and >ylon$

# SLS thermoplastics, metals$

# &/ high strength alloys, Ti, stainless steel, CoCr$

" #on$functional"structural parts

# SLA resins$F smoothest s'rface, good for casting# L/ paper$, 3D rinting plaster, sand$F mar-eting and concept prototypes, sand casting molds

" As ne5 materials are introd'ced, more f'nctional components 5ill be man'fact'red perhaps 3+4%+ by 2+2+$.

" mportantly A/ is one of the best approaches for comple architected materials.

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Challenges in AM materials properties

predictions

" Most AM processes introduce anisotropy in mechanical properties (z different from x,y)

" Local differences in laser/EB power (e.g., perimeter vs center) introduce heterogeneity inmechanical properties

" Laser fluctuations might result in embedded defects that are difficult to identify

" All existing machines are open-loop: temperature sensors have been introduced in someprocesses, but the readings are not used to optimize the processing parameters on the fly.

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Micro,Architected Materials"verarching vision

How can we fill unclaimed regions?

- Optimal topology

- Optimal geometry

-Base material optimization (nm-features)

- Hierarchical design

What do we need?

- Understand multi-scale mechanical behavior (deformation and failure modes)

- Understand processing -> microstructure -> mechanical properties (including size effects)

-Developing new models for FE analysis and optimal design

Superior MacroscaleBehavior by Topological

Control of the Microstructure

IMPROVED STRENGTHAT THE FILM LEVEL

SIZE EFFECTSIN PLASTICITYAND FRACTURE

UNIQUEDEFORMATIONMECHANISMS

IMPROVED STRENGTHAT THE MACROSCALE

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A -ord of caution

Tech Cons'ltancy 'ts 3D rinting at ea- of 8ype Cycle

eng165-good material aspects

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