Selective Laser Melting Opportunities and limitations · Selective Laser Melting / Laser Powder Bed...
Transcript of Selective Laser Melting Opportunities and limitations · Selective Laser Melting / Laser Powder Bed...
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A.B. SpieringsDr.-Ing. ETHZ, Head R&D SLM
Inspire AG – innovation centre for additive manufacturing Switzerland
16th int. Bhurban Conference on Applied Sciences and Technology
Selective Laser Melting –
Opportunities and limitations
8. – 12. January 2019
Islamabad, Pakistan
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Who’s inspire?
Introduction to additive manufacturing
Opportunities with Selective Laser Melting (SLM)
Limitations of & R&D needs for SLM
Trends & Conclusions
Agenda
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Who’s inspire?
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… the national (Swiss) non-profit R&D centre for advanced manufacturing technologies
Who’s inspire?
Inspire
is a competence centre for the swiss machine manufacturing industry, with close relations to ETH in
Zurich.
is a common initiative of Swissmem, the Swiss Federal Institute of Technology ETH, and the State
Secretariat for Education, Research and Innovation (SERI).
Who’s inspire?
Spierings, Adriaan © 2019 inspire AG 5
… the national (Swiss) non-profit R&D centre for advanced manufacturing technologies
Who’s inspire? Who’s inspire?
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facts & figures
Non-profit technology transfer institute
Focus on production technology
> 80 Employees, 20 working on AM-topics
Inspire-icams (St.Gallen)
12 people
> 20 running R&D projects
Continuously Bachelor / Master projects (ETH, Europe)
Who’s inspire? Who’s inspire?
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Who’s inspire? Who’s inspire?
Inspire AM lab in St.Gallen
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Industrial AM-
applications
Research goals Who’s inspire?
Applications
AM-Machines
AM-Processes
AM-Materials
Industry
requirements
Sources: Intenet
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Materials
• Powder requirements
• Materials for AM • Alloys for additive
manufacturing (e.g. Al)
• Hybrid materials
• Material characterization• Material integrity
(cracks, pores, …)
• Microstructure
• Static / dynamic mechanical properties
• …
AM-Processes
• Processing window for various materials
• SLM- / SLS- Process Simulation• Internal stresses
• Process effects
• Monitoring solutions
• Process productivity & performance
• Process chain view
Machine
• Future machine concepts
• Optimization of machine components
• Interconnectivity, machine lines
• Quality management systems
Applications
Space / Aerospace / Industry
Lightweight structures
Structurally optimised parts
Tooling, mould & die
Pre-serial AM-Development
Large structures & coating
Embedded functions
Standardisation (ASTM-ISO, VDI)
Research topics Who’s inspire?
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International network Who’s inspire?
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Introduction to additive manufacturing
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Definition
Principle
Additive Introduction to additive manufacturing
“Additive manufacturing (AM), n – processes of joining materials to make objects from 3D
model data, usually layer upon layer, as opposed to subtractive manufacturing fabrication
methodologies.”
Energy
Melt-pool
CAD model Slice-process Layer information Build process
ASTM
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Selective Laser Melting / Laser Powder Bed Fusion
Metal additive manufacturing Introduction to additive manufacturing
Electron Beam Melting
Direct Metal Deposition
Laser Powder Bed Fusion - LPBF
Electron Beam Powder Bed Fusioon - EBM
Powder feed additive manufacturing - DMD
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Introduction to additive manufacturingAdvantages & disadvantages
[inspire, 1 - 8]
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Advantages
− No undercuts – “all” geometries are possible
− New optimized design are possible
- bionic / lightweight
− Production of lot-size ONE
− “Customised” design
− Different geometries in the
same build process
− Complex structure already assembled
− Functional integration
Disadvantages
− Limited number & process-specific materials, esp. for plastic materials
− Finishing required (support structures, surface quality)
− Lot-sizes: from 1 to 100 / 1000 - not for big series!
Introduction to additive manufacturingAdvantages & disadvantages
Redesign for Additive
Manufacturing
“Complexity for free” [Source: A.Spierings]
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Industrial opportunities
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Tooling
– Conformal cooling / heating
channels
– Internal channels
OpportunitiesFields of application of LPBF
Source : Concept Laser
Source : inspire, Hufenus et al. 2012
Source : inspire Source : inspire
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Functional integration
– Assembled parts
– Integration of added value,
and new functions
– Integration of sensors into
metallic parts
OpportunitiesFields of application of LPBF
Source : inspireSource : inspire
Lubrication supply
CFD-optimized channels
Lightweight structure &
Gas ionization delivery & suction
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Machinery
– Turbine industry
– Blades / vanes
– Injection nozzles
– …
– Machine industry
– …
OpportunitiesFields of application of LPBF
Source : Morris Technologgy / GESource : www.shining3dscanner.com)
Source : inspire & Burckhardt Compression
Jet engine
combustor
Source: EOS
Injection
nozzle
Source : inspire
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Lightweight structures
– Lattice lightweight structures
Weight savings up to 60%
– Topology optimization
OpportunitiesFields of application of LPBF
Source : inspire Source : RUAG Space
Source : inspire Source : inspireSource : inspire
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Lightweight structures
– Lattice lightweight structures
– Outer shell load bearing structure
– Innter lattice structure Stabilization of the outer shel
OpportunitiesFields of application of LPBF
Source: inspire
Core-shell strucutreSingle lattice structure
“3-dimensional double T-beam”
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Lightweight structures – Bionic counterpart
OpportunitiesFields of application of LPBF
Bamboo core shell strucutre Bone core shell strucutre
Source: Internet
Mechanical engineering
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Space & Aerospace
– Structural parts
– Lightweight components
– …
OpportunitiesFields of application of LPBF
Insert structures for space composite panels
Source: inspireSource: inspire
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Space & Aerospace
– Structural parts
– Lightweight components
– Brackets
– …
OpportunitiesFields of application of LPBF
Source: RUAG Space
Source: GE-Additive
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Space & Aerospace: Examples
OpportunitiesFields of application of LPBF
3D Printing in space:
The «MELT project»(Manufacturing of Experimental
Layer Technology)
FDM-printer on the ISS
https://3druck.com
Airbus To 3-D-Print Airframe Structures
The EBAM 110 e-beam AMsystem from Sciaky,
to print large m-sized Ti aircraft structural parts.NASA's additive test program included
a hydrogen-oxygen rocket injector
What began as a unit with over 150 individual
pieces requiring months to manufacture was
transformed by AM into a two-part, 3D printed
unit built in 10 days.
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Space & Aerospace
– A recent study found that aircraft weight could be reduced by 7% just by replacing conventional
means of manufacturing with additive manufacturing.
OpportunitiesFields of application of LPBF
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Limitations & R&D needs
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Limitations
Huge expectations
… only realistic if industrial requirements
are met:
- Part quality
- Process stability
Need for quality & reliability !
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Part- costs
Production technology
Prototyping
Niche technology
Low-tec technology
Fields of application of LPBF
!
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From powder to the final part
The SLM-process chain Limitations
Spierings (2018)
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LimitationsPart quality
[Spierings 2018]
Question: What is “AM-part quality” ?
Which parameter affects quality?
What are the (really)
relevant parameters?
What are their specific
level of influence ?
How do we measure
them (correctely)?
Metrology
How is their variation
reduced?
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LimitationsPart quality
[Spierings 2018]
Material Integrity– Pores, Irregulare defects, cracks, …
– Mechanical properties– Anisotropy in static / dynamic mech. properties
– Fracture toughness, …
Mikrostructure– Grain size distribution
– Solidification principles
– …
Surface properties– Dependent on powder properties
– Dependent on part orientation
– Dependent on process parametes
– …
Accuracy– Dependent on powder, process window etc.
– 0.1 bis 0.2mm
AlSi12: Side surface «smooth»
AlSi12: Side surface «rough»
EBSD of a AlSi12 alloy, inspire-icams
Typic pore distribution in AM-parts . Source:
inpsire
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LimitationsInfluencing parameters
Estimation:
Up to 150 influencing
parameters exist
along the process
chain. (Rehme et al.)
Expected
≥ 50 parameters
directly affect the
quality of the process,
and the final part.
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Example powder: Varying powder properties
Parameters Particle size distribution Particle shape
Powder flowability
Essential influence on the resulting process- & material properties
Spierings, A.B., et.al, Powder flowability characterisation methodology for powder-bed-based metal
additive manufacturing. 2015, Progress in Additive Manufacturing: p. 1-12.
Influencing parameters: Challenges Limitations
«coarse» powder «fine» powder
Good powder layer quality Bad layer quality
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LimitationsInfluencing parameters: Challenges
Example powder: Varying powder properties
Variations in powder properties affect
the process quality & efficiency.
Speed 1 Speed 2 > 1 Speed 3 > 2
[Spierings 2018]
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Process characteristics
Influencing parameters
LimitationsInfluencing parameters: Challenges
LPBF
Very smallmelt-pool
Very shortlaser
interactiontime
Very high temperature
gradients
Very high cooling
rates
Ion J (2005)
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Process characteristics
Melt pool sizes
Characteristic size 1/10 mm
Dependent on
laser parameters
physical material parameters
(e.g. conductivity)
Marangoni convection
…
LimitationsInfluencing parameters: Challenges
LPBF
Very smallmelt-pool
Very shortlaser
interactiontime
Very high temperature
gradients
Very high cooling
rates
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Process characteristics
Laser interaction time @ high intensity
Characteristic interaction time 1/100 - 1/1000 s(high scan speeds)
LimitationsInfluencing parameters: Challenges
LPBF
Very smallmelt-pool
Very shortlaser
interactiontime
Very high temperature
gradients
Very high cooling
rates
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Process characteristics
Cooling rates and gradients
Very high cooling rates𝑑𝑇
𝑑𝑡= 𝐺 ⋅ 𝑅 up to 103 to 105 Ks-1
Solidification front stabilityΔ𝑇0
𝐷𝑙=
𝐺
𝑅instable if
Δ𝑇0
𝐷𝑙>
𝐺
𝑅
LimitationsInfluencing parameters: Challenges
LPBF
Very smallmelt-pool
Very shortlaser
interactiontime
Very high temperature
gradients
Very high cooling
rates
G… temperature gradient in the melt-pool
R… solidification front growth rate
T0… equilibrium solidification temperature range
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Result:
Non-equilibrium solidification
Impact on precipitation
behavior,phases etc.
Fine microstructures Long elongated grains parallel to the build
direction (BD), …
Often > 100 m, hence much
longer than a layer thickness
with a comparably small
diameter
Typical range
5m to 20m
LimitationsInfluencing parameters: Challenges
Anisotropic mechanical behaviour
(Hall Petch)
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Examples
Limitations
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Example alloy composition / non-equilibrium solidification (IN738LC)
Traditional alloy compositions do not need to fit to the AM-processing conditions.
Defects (cracks etc) can be the result!
LimitationsInfluencing parameters: Challenges
[Cloots et al., inspire] Typical defects in AM-materials Grain boundary cracking & crack surface analysis
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LimitationsInfluencing parameters: Challenges
[Cloots et al., inspire]
Example alloy composition / non-equilibrium solidification (IN738LC)
For AM-processes, the alloy compositions may require narrower tolerances.
APT analysis of a grain boundaryNon-equilibrium solidification simulation
(Scheil)
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LimitationsInfluencing parameters: Challenges
Example alloy composition: Aluminium
For AM-processes, alloy design is required to overcome typical problems:
Increased defect formation (Cracks / porosity)
Columnar grains & preferential grain orientation Anisotropic mechanical properties
AlSi10Mg microstructure (Thijs et al. 2013)Young’s modulus in dependence of sample orientation during SLM
of AlSi10Mg alloy (Hitzler 2017)
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LimitationsInfluencing parameters: Challenges
[Spierings et al. 2018]
Example alloy composition: 5xxx Aluminium alloy design
Alloy design for AM can overcome some of these bottle necks
Example: Al-Mg-Sc-Zr alloy
almost no anisotropic mechanical properties
Grain size stabilization
Advanced microstructure control in Al-Mg-Sc-Zr alloysAnisotropy-free mechanical properties
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LimitationsQuality management for AM-processes
[Spierings 2018]
Quality considerations along the AM-process chain
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Trends & conclusions in metal AM
Trends
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Productionmachines
•Not prototpying
•New machineconcepts /application specific
•Processchainautomation
• Increase in productivity
Processfeedbackcontrol
• In-line process-and part qualitycontrol
•Neuronal networks
Quality managementSystems
•Process quality
•Part quality
Materials
•Alloys for AM
•New materials
Standardization
•Processes
•Materials
•Quality measures
•…
Development needs
DMG-Mori: Lasertec 65
Trends & conclusionsTrends in metal AM
5 m long Ti wing beams
for the C919 plane
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Laser Powder Bed Fusion
2000
LPBF
Binder Jetting
Powder feed
Wire feed
Electron Beam Melting
Part sizes Lot sizes
mm to dm
mm to dm
mm to dm
cm to dm
dm to m
Low to medium
Medium to high
low
low
medium
Trends in metal AM Trends & conclusions
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(Metal) additive manufacturing
– …has achieved important industrial perspectives for improved part performances
– Lightweight
– Structural optimization
– Functional integration
– …is still facing significant R&D needs in terms of
– Missing quality management systems accross the process chain
– Improved process (feedback) control
– Alloy design for AM
– Standardization
– …LPBF will face competition with alternative AM-technologies
– Binder Jetting (HP)
– Powder / wire feed systems
Conclusions Trends & conclusions
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A.B. SpieringsDr.-Ing. ETH ZurichHead R&D SLM
Lerchenfeldstrasse 3
9014 St.Gallen
[email protected]+41 71 274 73 19
www.inspire.ethz.ch
Springer Journal «Progress in Additive Manufacturing»ISSN: 2363-9512 (print version)
ISSN: 2363-9520
• Reduced peer-review time for short
communications.
• Double-blinded peer-review system for all
submitted papers.
• Interdisciplinary topics ranging from data
processing to simulation, new and hybrid
process, to materials and microstructural
analysis.