laser powder bed fusion: model validation under various … · 2019. 6. 27. · a. staub –inspire...
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A. Staub – inspire AG 11
Laser Powder Bed Fusion: model validation under various processing
condition
CADFEM Simulation Conference Rapperswil
19.06.2019
Alexandre StaubScientific Assistant R&D SLM
Doctoral Student at ETH Zurich
Inspire AG – innovation centre for additive manufacturing Switzerland
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is strictly forbidden.
A. Staub – inspire AG 2
Who is inspire?
facts & figures
Non-profit technology transfer institute
Focus on production technology
10 MM CHF turnover
60 Employees, 20 working on AM-topics
Inspire-icams (St.Gallen)
12 people
1.5 MM CHF turnover
> 20 running R&D projects with industry
Continuously several BA / MA projects
Inspire-icams – AM since 1996 in metals & plastic
A. Staub – inspire AG 3
Who is inspire? Research focus in SLS & SLM
Materials
• Powder requirements
• Materials for AM • AM-adapted alloys (Al)
• Hybrid materials
• Material characterization• Microstructure
• Mechanical properties
• …
AM-Processes
• Processing windows for materials
• SLM- / SLS-Process Simulation• Residual stresses
• Process effects
• …
• Process monitoring
• 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)
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Context
LPBF = SLM = DMLS
Laser Powder Bed Fusion
Machine main characteristics:
– Build volume: 250*250*250mm, increasing
– Laser Type: Nd:YAG 1064nm
– Laser Power: up to 4 x 500W
– Laser sport diameter: [80; 500] µm
– Layer thickness: [30; 200] µm
Part main characteristics:
– From tenths of mm to tenths of centimetres
– Accuracy: +/-0.1mm
– Small to Medium batch size
– High added value products
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Context
LPBF processes : shown outstanding production capabilities for
various sectors in the last decades:
– Reduction of the assemblies
– Reduction of the lead and development time
– Realisation of complex geometries
– Realisation of individual products
But… Facing productivity and scaling up issues
– Limited build volume
– Limited build rates
– Residual stresses and part distortions
And further …
– Repeatability – Trial and Error
– Cost per parts
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Context
Images courtesy of inspire AG and Ansys Inc.
Success rate:
6 out of 18
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Why use a simulation in AM ?
Dudai, et al.
Simulation: originate from “similis” (Lat.), meaning “alike”
Reduce the trials and errors costs
– Less trials / Less material / Less machine time
Simulation is good when:
– Complex problems
– Lots of variables
– Systematic experimentation
– Expand the domain of
understanding
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Why use a simulation in AM ?
Simulation = a way to optimise
– Optimisation of the process
– Find the best parameter set
– Optimise the productivity
– Optimise the end results: reduce deformation, reach better tolerances on the
geometry
– Optimise the performance of the parts
– Optimise supporting structures
– Optimisation of the geometry
– Full use of the AM capabilities
– Reduction of the weight
– Insuring best performance
– Optimise supporting structures
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LPBF: man ways to get to the same results!
Consistent processing windows development:
– Material: 17-4PH
– Layer thickness: 40 µm
– Hatch: 90µm
– Variation of Power and Speed up to 350W
Fix a target for the comparison:
95.00%
95.50%
96.00%
96.50%
97.00%
97.50%
98.00%
98.50%
99.00%
99.50%
100.00%
30 35 40 45 50 55 60 65 70 75 80 85
Re
lati
ve m
ate
rial
de
nsi
ty
Energy Density [J/mm3]
100W
150W
200W
250W
300W
350W
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Calibration of the model
Thermal strain model
Calculation time for a 40mm
high cross: ~5 days!
Anisotropy in X – Y direction not
observed on the build cross
Other process effect not
simulated
Results of the calibration:
Laser Power Max distortion
(height 14.8mm)
150W 0.161
200W 0.158
250W 0.144
300W 0.134
350W 0.1310.12
0.125
0.13
0.135
0.14
0.145
0.15
0.155
0.16
0.165
100 200 300 400
Calibration trend
A. Staub – inspire AG 11
Geometry to be tested
Is a cantilever enough to test
simulation capabilities?
Add of AM features:
– Lattice structure
– 45° overhang
– Horizontal hole Ø3mm
Easy to remove Cantilever
(without EDM)
Conclusion at this point of the
study:
– Geometry might be to complex
– Simulation is unstable and time
consuming
– Measurement is relatively difficult
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A case for industrial applications
From a complex part to a full material body
– Support redesign to full material
– Insert design
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Displacement on the outer ring in magnitude of 0.4-0.5 mm
Displacement of the blades in magnitude of 0.2-0.3mm
A case for industrial applications
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It is time to simulate more!
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M.Sc.Eng. Alexandre Staub
Scientific Assistant R&D SLM
Doctoral student at ETH Zurich
+41 71 274 73 14
Get in touch with us today!
AM-experienced young scientist
• 2014: First steps in Selective Laser Melting
• 2015: Fraunhofer UMSICHT (Germany)
• 2016: Innovation Center for AM Switzerland (inspire AG - icams)
• Q1 2017: M.Sc.Eng. with emphasis on AM (UTBM, France)
• Q2 2017: Current position (ETHZ + icams)