Dedusting of metal powders for additive manufacturing (3D ... · 3-D Printing Metal powders for 3-D...
Transcript of Dedusting of metal powders for additive manufacturing (3D ... · 3-D Printing Metal powders for 3-D...
Grinding & Dispersing
Dedusting of metal powders for additive manufacturing
InPrint 2017 | 15.11.2017 | Christian Höfels3-D Printing
Agenda
1. Introduction
2. Basics of Classification
3. NETZSCH Classifier
4. Application Examples
Introduction – 3-D Printing
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Source: https://en.wikipedia.org/wiki/Selective_laser_sintering
Process Group Example Abbreviation Working Principle
Sintering
Selective Laser Sintering SLSLocal melting of
Polymer powders (SLS)OrMetal powders (SLM)
Selective Laser Melting SLM
Laser Metal Deposition LMD
Electron Beam Sintering EBS
Extruding Fused Deposition Modeling FDMExtrusion of fused/molten polymers using a nozzle
UV-Curing
Stereolithography SLA
Local inducedCo-polymerization
Multi-Jet-Modeling MJM
Continuous Liquid Interface Production
CLIP
LCM LCMLocal inducedCo-polymerization+ Sintering process
3-D Printing
Metal powders for 3-D printing (additive manufacturing) are produced from molten, atomized metals. The manufacturing process prohibits the achievement of an exact particle distribution.
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Source: https://en.wikipedia.org/wiki/Selective_laser_sintering
3-D Printing
Various and wide PSD is created
Small Particles:
influence the flow ability and dust behavior
Sinter too fast/are melted
Large Particles:
Destroying the surface of the layer
Are not heated/melted enough
Grading and classification is necessary
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Source: http://advancedpowders.com/plasma-atomization-technology/our-technology/
3-D Printing
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Benefits Limits
• Increased design freedom• Non weldable metals cannot be
processed
• Light weight structures• Material properties: tend to show
anisotropy in construction direction
• New functions such as complex internal channels
• Part size: standard powder bed system are 250 x 250 x 250 mm
• Less raw material consumption• Part design: overhang angles < 45° need
removable supports
• No tools needed
• Complex parts can be produced
• Recommended for small series
Introduction – A real exampleCGS 10 classifier wheel
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Material 1.4404
3-D printed
Material 1.4571
Conventional 3 parts soldered
Agenda
1. Introduction
2. Basics of Classification
3. NETZSCH Classifier
4. Application Examples
Definition of Classification
An air classifier uses the aerodynamic differences of particles in a two-phase flow (gas and solid substances) in order to separate them according to their rate of descent.
Two different types of force have an effect during air classifying:
Drag force (FW)
Gravity (FG) and centrifugal forces respectively
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v
FW
FG
FW
FG
FW
FG
Fine Fraction
Coarse Fraction
Process Fundamentals
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Drag force: ∗ ∗ ∗ Gravity force: ∗ ∗
Area of circle: A ∗ Volume of sphere: V ∗
~ ~ ~ ~
Particle Size A-Factor d2 V-Factor d3
0.01 10-4 > 10-6
0.1 10-2 > 10-3
1 1 ~ 1
10 102 < 103
Separation Forces in Centrifugal Classifiers
In a dynamic classifier the particles experience the following two types of force within the flow:
The drag force caused by the radial components of the flow
The centrifugal force caused by the tangential components of the flow
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[1] Prof. Dr. Matthias Stieß: Mechanische Verfahrenstechnik-Partikeltechnologie 1, 3. Auflage 2009
[1]
Standard Classifier Wheel vs. CONVOR® Classifier Wheel
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HF = constant
vr constant
HF constant
vr = constant
Agenda
1. Introduction
2. Basics of Classification
3. NETZSCH Classifiers
4. Application Examples
NETZSCH Fine Classifier CFS
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1 Product inlet2 Air inlet3 Guide vane4 Classifier wheel5 Fines outlet6 Coarse outlet
NETZSCH Fine Classifier CFS – Design
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NETZSCH High-efficiency Fine Classifier CFS/HD-S
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1 Product inlet2 Air inlet3 Classifier wheel4 Guide vanes5 Separating wall6 Coarse outlet
NETZSCH High-efficiency Fine Classifier CFS/HD-S –Design
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NETZSCH High-efficiency Fine Classifier CFS/HD-S –Plant Example
Classifying plant for inert gas operation
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Agenda
1. Introduction
2. Basics of Classification
3. NETZSCH Classifier
4. Application Examples
Application
Stainless steel (AISI 316L)
Particle size distribution of:
d10 ~ 17 µm
d50 ~ 37 µm
d90 ~ 63 µm
Bulk density = 4520 g/l
The goal is the limitation of the fine fraction to < 5 % < 15 µm in the coarse
actual: d5 ~ 11 µm
The d50 is not indicated, it results after classification
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Test Results
A pilot test carried out on a CFS 8 HD-S.
Due to the relatively high density of the stainless steel, the rotational speed of the classifier was low: 2000 rpm (max: 12000 rpm)
The load was kept constant at 0.1 kg/m³
d5 of the coarse material ~ 21.2 µm
Yield: 98.7 % coarse material
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Feed PSD
Coarse material PSD
Fine material PSD
SEM Pictures
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FEED FINE COARSE
Magnification
500x
1000x
Raw Material
Examples of applied materials:
Stainless steel
Tool-steel
Aluminum and aluminum alloys
Titanium and titanium alloys
Chrome-Cobalt-Molybdenum alloys
Bronze alloys
Nickel-based alloys
Copper alloys
Ceramics
Plastics (Procedure: Laser Sintering)
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Source: https://de.wikipedia.org/wiki/Selektives_Laserschmelzen
Summary
3-D Printing is a rising technology with a huge industrial potential
Dynamic air classifiers are used to grade the 3-D printing raw materials
High dispersion classifier dedust sharply CFS HD-S
High efficiency and yield
Standard classifier can operate in the coarser range
Improvement of the productivity
Replacing sieves
CFS Standard
CONVOR®-wheel for finest products and HF-wheel for coarser products
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Thank you for your attention!
Christian HöfelsProcess Technology Development
NETZSCH Trockenmahltechnik GmbHTel.: +49 6181 506 277Fax: +49 6181 571 270