Selective Laser Melting versus Electron Beam Melting

“État actuel des fabrications additives pour les
applications métalliques”
Atelier CNES – 18/19 Novembre 2013, Toulouse, France
Olivier RIGO
Carsten ENGEL
25.11.13 1© sirris | www.sirris.be | info@sirris.be |

Special thanks …
Le Fonds Européen de Développement Régional
et la Région Wallonne investissent dans votre avenir.

Sirris | Metal Additive Manufacturing
25.11.13 3
 Index
 Sirris – short overview
 Generalities:
 Metal Additive Manufacturing
 Technology comparison: LBM vs EBM
 Metallurgical aspects
 Mechanical aspects
 Case studies
 Contact
© sirris | www.sirris.be | info@sirris.be |

Sirris | Driving industry by technology
130 experts & hight-tech infrastructure
Collective centre
of the technology industry
• Non profit organization
• Industry owned
4,700 industrial interventions
(advice, projects, services)
•within 1,700 different companies
•whose 75% are SME’s
•24M EUR turnover
Mission: “Increase the competitiveness of
companies of the Agoria sectors through
technological innovations”

Sirris | 23 years of Additive Manufacturing
AM centre – Leading position in EU
16 engineers and technicians
17 high-tech additive technologies in house
Most complete installed base in EU
Driving technology companies in applications
Technologies:
• Stereolithography (normal & hi-res)
• Paste polymerisation for ceramics and metals (Optoform)
• 3D Printing of plaster and metal powder
• Laser sintering of polymeric powder (PA,…): P360 – P390
• Objet Connex 500: bi-material
• Laser sintering of metal powder (parts and mould inserts)
• Electron Beam Melting (Arcam A2)
• 3D Printing of wax (Thermojet)
• Vacuum Casting of Alu, Bronze, Zamak
• Laser Cladding (EasyClad)
• Laser Beam Melting (MTT)
• Bi-material FDM system
• Fab@home system (for students)
• MCOR technology (color 3Dprinter)

25.11.13 6
 Index
 Generalities:
 Case studies
 Contact

Generalities: Metal Additive Manufacturing
Direct
Fabrication
system
Laser
E-Beam
Print head
Nozzle
Post-
processing
Indirect
Binder
Debinding
+ sintering
Post-
processing

 Electron Beam
Melting (EBM)
 Laser Beam Melting
(LBM)
• Metallic powder deposited in a
powder bed
• Electron Beam
• Vacuum
• Build temperature: 680-720°C
• Metallic powder deposited in
a powder bed
• Laser Beam
• Argon flow along Ox direction
• Build temperature: 200°C

 Electron Beam Melting

Benefits and drawbacks - EBM
Benefits Drawbacks
 Few developed materials, only
conductive materials possible
 Tricky to work with fine powder
 Powder is sintered -> tricky to
remove (e.g. interior channels)
 Long dead time between 2
productions (8 hours for cooling –
A2, A2X, A2XX systems)
 Sintered powder = good for
thermal conductivity = less supports
 Suitable for very massive parts
 Less supports are needed for
manufacturing of parts
 Possibility to stack parts on top of
each other (mass production)
 Process under vacuum (no gaz
contaminations)
 High productivity
 No residual internal stress (constant
680-720°C build temperature)
 Very fine microstructures (Ti6Al4V),
very good mechanical and fatigue
results (Ti6Al4V)
 Expensive maintenance contract

 Electron Beam
Melting (EBM)
(LBM)
powder bed
• Electron Beam
• Vacuum
a powder bed
• Laser Beam

25/11/2013
© Sirris | www.sirris.be | info@sirris.be |
13
Spread powder
Recoater
Laser beam
Melted
zones
Previous layers
Initial plate
Argon
Main tank
The building steps

Laser Beam Melting – SLM Solutions 250HL

Benefits and drawbacks - LBM
Benefits Drawbacks
• Flexibility for new material
developments
• Possibility to work with fine
powders 10µm (d50)
• Easy powder removing from the
parts (the parts are not embedded in
pre-sintered cake)
• Short dead time between 2
productions (2 hours for cooling)
• Possibility of restarting an
interrupted job
• Easy visual inspection of building
process during the manufacturing
(either with unaided eye or with
optical camera)
• Process is wall thickness dependent.
(not suitable for massive parts)
• Process involving internal stresses
in the parts need additional
annealing
• Process requiring strong supports
for parts fasten during the
manufacturing (not only for heat
transfer)
• Need to use build plates of the
same material than the powder used
in the machine (e.g.: more expensive
for titanium powder)
• Cutting tool necessary (eg: a saw) in
order to release the parts from the
build plate

Technology comparison – EBM – LBM
LBM EBM
Size (mm) 250 x 250 x 350*¹ 210 x 210 x 350*²
Layer thickness (µm) 30 - 60 50
Min wall thickness (mm) 0.2 0.6
Accuracy (mm) +/- 0.1 +/- 0.3
Build rate (cm³/h) 5 - 20 80
Surface roughness (µm) 5 - 15 20 - 30
Geometry limitations Supports needed
everywhere (thermal,
anchorage)
Less supports but powder
is sintered
Materials Stainless steel, tool steel,
titanium, aluminum,…
Only conductive materials
(Ti6Al4V, CrCo,…)
CENG 25/11/2013© sirris 2013 | www.sirris.be | info@sirris.be |
16
*1 SLM Solutions 250HL
*2 Arcam A2

0
2
4
6
8
10
productivity
3D complexity
maximum size
AccuracySurface finish
mech prop -
density
material range
EBM (Arcam)
LBM (SLM Solutions
Technology comparison – EBM – LBM
CENG 25/11/2013© sirris 2013 | www.sirris.be | info@sirris.be |
17
*1 SLM Solutions 250HL
*2 Arcam A2

25.11.13 18
 Index
 Generalities:
 Case studies
 Contact

Metallurgical aspects – LBM & EBM
 Electron Beam
Melting (EBM)
(LBM)
powder bed
• Electron Beam
• Vacuum
a powder bed
• Laser Beam
25/11/2013
© sirris 2013 | www.sirris.be | info@sirris.be | 19

Experimental procedures
 Electron Beam
Melting (EBM)
(LBM)
• Random scanning strategy
• Vacuum
• Pre-heating of the subtrate:
680-720°C
• Complex lasing strategy:
79° rotation between two
successive layers
• Pre-heating of the subtrate:
200°C
Characteristics of theTi6Al4V ELI powders
Process Ti (wt%) Al(wt%) V(wt%)
LBM Bal 5,9 4,2
EBM Bal 3,3 4,4
Reference axis for EBM
and LBM

Results and discussion
Perpendicular to the building direction
• Equiaxed morphology (around 50μm
of diameter)
• Width does NOT significantly change
along the height
No evolution of the thermal gradient
intensity, no evolution of the grain
width

Parallel to the building direction
• Elongated grains characteristic of an
epitaxial growth aligned with the heat
flow
• No epitaxial growth apparent
Explanation: Tilt of the primary β grains
Suggestion: combined effect of part geometry
and a modification of the direction of the
maximum heat flow that had possibly been
brought about by the Argon flow

Perpendicular to the
building direction
• Equiaxed morphology as for LBM
 Electron Beam Melting (EBM)
Parallel to the building direction
Explanation:
• Random scanning trategy
• Thermal homogeneity due to
substrate preheating (680-720°C)
• No argon flow
Hoped this would allow a significant reduction of
internal stresses and then improve mechanical
properties
• Epitaxial growth:
• No Tilt (≠LBM)

• Typical morphology of a
Widmanstätten microstructure
• Pre-heating of the substrate
induces slower cooling rates
thus favouring a diffusive
transformation to α
Cooling rate is directly influenced by the preheating of the
substrate: the lower the preheating, the faster the cooling
rates and the finer the resulting microstructure
Characteristics:
• Uniform, Fine Grain
• Columnar
• Lamellar Alpha Phase
• Larger Beta Grains

Two types of porosities (spherical and non- spherical) due to entrapped
argon in powder particles (amount porosity in GA is about 0.2-0.1%) or un-
melted areas can be observed.

25.11.13 26
 Index
 Generalities:
 Case studies
 Contact

Mechanichal comparison
 Electron Beam
Melting (EBM)
(LBM)
• Layer Thickness: 70µm
• Job 130503a
• As built sample without
additional post treatment
• Job 130423a
• Laser Beam

 Tensile test:
 According to standard ASTM E111-04 and
NF EN 10002 standards

 Mechanical properties comparison (Tensile testing)
1126
1202
1029
1094
Rp0.2 (Mpa) Rm (Mpa)
Yield strenght/UTS
(Oy samples)
LBM (50µm anealed) EBM (70µm)
3,1
9,9
LBM EBM
A (%)

 Mechanical properties comparison (Tensile testing)
1079
1120
974
1032
Rp0.2 (Mpa) Rm (Mpa)
Yield strenght/UTS
(Oz samples)
LBM (50µm anealed) EBM (70µm)
4,1
10,8
LBM EBM
A (%)

Mechanichal comparison
 Electron Beam
Melting (EBM)
(LBM)
• Job 120124a
• As built sample without
additional post treatment
• Job 121214b
• Laser Beam

Whöler fatigue curve with a stress ratio
of 0.1 and 4 different levels tensile test
probes (3 each) :
 10-50 kcycles (level 1)
 1-2 exp 6 kcycles (level 4)
Mode: strain-strain
Control: force
Form: sinusoidal
R: 0.1
End process criteria: break or 10^7 cycles
 Fatigue test:
 According to standard ASTM E466-07

 Mechanical properties comparison (Fatigue testing)
EBM Oz
Post-machined
samples
LBM Oz
Post-machined
samples

 Mechanical properties comparison (Fatigue testing)
EBM Oz
Post-machined
samples
LBM Oz
Post-machined
samples
Ref 2
Roll formed
TiAl6V4

 Hip treatement in order to improve fatigue properties
EBM Oz
Post-machined
samples
Ref 2
Roll formed
TiAl6V4
EBM Oz
Post-machined
samples + HIP

 Orientation impact?
EBM Ox
Post-machined
samples + HIP
Ref 2
Roll formed
TiAl6V4
EBM Oz
Post-machined
samples + HIP

 Surface roughness impact
EBM Oz
Post-machined
samples
EBM Oz
As-Built sample
Ref 2
Roll formed
TiAl6V4

25.11.13 38
 Index
 Generalities:
 Case studies
 Contact

Case study 01: Massive ESA-CSL part
EBM
 Dimensions:
208*175*38mm (L*W*H)
Machining

Case study 02: ESA-CSL-AlmaSpace
LBM
Machining
Machining EBW

Case study 03: Design of an “improved”
support geometry for an antenna
Support mass : 223 g 57.5% mass reductionInitial mass ~ 400 g
LBM

25.11.13 42
 Index
 Generalities:
 Case studies
 Contact

http://www.sirris.be
#sirris
http://www.linkedin.com/company/sirris
25.11.13
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Selective Laser Melting versus Electron Beam Melting

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