Materials and processes used for 3D Printing

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2.  Fused Deposition Modelling
 Stereolithography (SLA)
 Photopolymer Phase Change Inkjets
 Selective Laser Sintering (SLS)
 Plaster-based 3D Printing
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A filament is fed through heating element
Material is extruded in molten state, it fuses with the material around it that
has already been deposited
J. Brock, M. Montero, FDM Material Properties
Characterization, May 2000

4.  Properties of Interest
 Melting temperature (Tm) –
It will affect the temperature of the extruder
 Glass transition temperature (Tg) – The materials stretch while shrinking slightly
until they stiffen at their Tg
 Coefficient of thermal expansion (CTE)–
Tg and CTE relate to how much thermal stresses are generated which affects bed
adhesion
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J. Brock, M. Montero, FDM Material Properties
Characterization, May 2000

5.  Filaments are made of thermoplastic materials
 Poly Lactic Acid (PLA)
 Made of biological material like cornstarch or sugarcane
 Tg – 65 °C (Material stretches while shrinking slightly until it reaches Tg)
 Can be repaired easily due to low Tg
 No toxic gases
 PLA parts can be printed in unheated atmosphere with no build plate heating
 Reduced stresses, retains cooling shrinkage
 Low impact strength and temperature stability
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J. Brock, M. Montero, FDM Material Properties
Characterization, May 2000

6.  Acrylonitrile Butadiene Styrene
(ABS)
 Tg – 110 °C,
 Relatively smooth surfaces in FDM
 More material warping due high
internal stresses than PLA – requires
rafts and supports, maintain
atmospheric temperature
 High crystallization, crack rapidly
compared to PLA
 ABS can be strongly attacked by
solvents like acetone, benzene and
petrochemicals – ABS parts can be
manipulated during post processing
 Generation of toxic fumes –
ventilation mandatory
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J. Brock, M. Montero, FDM Material Properties
Characterization, May 2000
B.Green,Howle, Materials for 3D Printing by Fused
Deposition, TEAMM, 2017

7.  Polyvinyl alcohol (PVA)
 Used to make supports
 Water soluble
 Can release toxic vapours of heated
 Printing with PLA or ABS
 Nylon
 Synthetic polymers
 Non toxic
 Tough and resistant to damage
 Higher temperatures approx. 250 °C require to print
 Requires heated print bed and white glue to stick while printing
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J. Brock, M. Montero, FDM Material Properties
Characterization, May 2000

8.  High-density polyethylene (HDPE)
 Often used instead of ABS
 Lighter and stronger than ABS
 Higher print temperatures and release unpleasant fumes
 Mostly chemical resistant but can be dissolved in limonene (used in industrial
cleaners) – can be used as supporters
 Warping takes place
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J. Brock, M. Montero, FDM Material Properties
Characterization, May 2000

9.  MakerBot
 Delta 3D Printer
 Ultimaker
 Cube from 3D Systems
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SLA uses liquid photo-reactive
resin
Laser beam traces one layer on
the surface of the resin
Laser light cures and solidifies
parts it hits
The platform descends by one
layer

11.  Photopolymer materials - A photopolymer is a type of polymer that changes its
physical properties when exposed to light.
 Basic constituents for photopolymer processes
 Commonly used photopolymer – ester of cinnamic acid (C9H8O2)
 Produced by reacting cinnamic acid with alcohol in the presence of light
 A typical photopholymer – 50-80% Binders + 10-40% monomers + Photoinitiator
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https://www.theseus.fi/bitstream/handle/10024/80083/pa
ndey_ramji.pdf?sequence=1

12.  Binders
 Vinylalcohol family: Vinyl Alcohol Trimer, Vinylacetate Trimer, Vinylacetate Oli-
gomer.
 Olefine family: Poly Isobutylene
 Glycerol family: Triglycerol
 Monomers – diluents and cross linkers/ diluents or cross linkers
 Acrylic acid, Isodecyl acrylate etc
 Photoinitiators – convert light energy intochemical energy by forming free radicals
upon UV exposure
 Isopropylthioxanthone, Benzophenone, Diaryliodonium salts
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https://www.theseus.fi/bitstream/handle/10024/80083/pa
ndey_ramji.pdf?sequence=1

13.  Inkjet printhead jets liquid
photopolymer and support
material
 UV light cures
photopolymer and support
material
 Excess material is removed
using a roller
 The platform descends by
one layer
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https://www.theseus.fi/bitstream/handle/10024/80083/pa
ndey_ramji.pdf?sequence=1

14.  Polyjet digital material – different photopolymers to enhance properties, eg
VeroWhitePlus RGD835
 Digital ABS - designed to stimulate high impact resistance and shock absorption
- phone casings, engine cover parts, etc, eg - RGD5160-DM
 High temperature – for hot water flow in pipes
 Transparent – for artistic modeling, eg – VeroBlackPlus RGD875
 Polypropylene like – better thermal resistance, toughness, flexibility
- Loudspeakers, eg – VeroClear RGD810
 Rubber like – stimulate elastomers
- gaskets, footwear, eg - TangoBlack FLX973
 Bio compatible – surgical guides, dental, implants, etc, eg - MED 610
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https://www.theseus.fi/bitstream/handle/10024/80083/pa
ndey_ramji.pdf?sequence=1

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https://engineering.coletek.org/3d_printing/nsw/northern_rivers/ashby/?lipi=urn%3Ali%3Apage%3A
d_flagship3_feed%3B3pQzGNfAQW%2BfZy04YzvFIA%3D%3D

16.  Ceramic photopolymers – photopolymer (binder) filled with ceramic powder
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Figure - Prints made from biocompatible
ceramic material for implantation.

17.  SLS and DMLS use a bed of small
particles (made of plastic, metal, ceramic,
or glass)
 High-power laser traces one layer on the
surface of the powder bed melting/fusing
the particles
 The platform descends by one layer and
more material is added
 Material can be preheated
 One material at a time – glass, polymers,
metals (steel, titanium, etc), cermics
 Does not require supports
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Other processes where metal
powders are used– Laser metal
deposition, electron beam melting

18.  Powder paricle size and size
distribution
- Affects flowability
- Fine Particles (ø: 0.1-5µm) tend
to form clusters and prevent
uniform recoating
- Large particles (ø: 90-120µm)
reduces layer packaging density
- Mixture of fine and larger
particles is best suit – fine
particles fill the void to achieve
higher density
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19.  Can be used for decreasing the cost
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http://www.sciaky.com/additive-manufacturing/wire-am-vs-powder-am

20.  This method uses a bed of small plaster particles
 Inkjet printhead prints with liquid adhesive (possibly colored), one layer on the
surface of the powder bed fusing the particles
 The platform descends by one layer and more material is added
 Glues particles instead of melting
Source: Zhou and Lu, 2011 20

21.  Material – plaster only (silica sand)
 Core and mould making
 Post processing required
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http://www.exone.com/Portals/0/ResourceCenter/C
aseStudies/X1_CaseStudies_All%207.pdf

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