Grinding & Dispersing. Dedusting of metal powders for additive manufacturing. 3-D Printing InPrint Christian Höfels

Transcription

1 Grinding & Dispersing Dedusting of metal powders for additive manufacturing 3-D Printing InPrint Christian Höfels

2 Agenda 1. Introduction 2. Basics of Classification 3. NETZSCH Classifier 4. Application Examples Introduction 3-D Printing Process Group Example Abbreviation Working Principle Sintering Selective Laser Sintering Selective Laser Melting Laser Metal Deposition Electron Beam Sintering SLS SLM LMD EBS Local melting of Polymer powders (SLS) Or Metal powders (SLM) Extruding Fused Deposition Modeling FDM Extrusion of fused/molten polymers using a nozzle Stereolithography SLA UV-Curing Multi-Jet-Modeling Continuous Liquid Interface Production MJM CLIP Local induced Co-polymerization LCM LCM Local induced Co-polymerization + Sintering process Source: Dedusting of metal powders Grinding & Dispersing November

3 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. Source: Dedusting of metal powders Grinding & Dispersing November 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 Source: Dedusting of metal powders Grinding & Dispersing November

4 3-D Printing Benefits Increased design freedom Light weight structures New functions such as complex internal channels Less raw material consumption Limits Non weldable metals cannot be processed Material properties: tend to show anisotropy in construction direction Part size: standard powder bed system are 250 x 250 x 250 mm Part design: overhang angles < 45 need removable supports No tools needed Complex parts can be produced Recommended for small series Dedusting of metal powders Grinding & Dispersing November Introduction A real example CGS 10 classifier wheel Material D printed Material Conventional 3 parts soldered Dedusting of metal powders Grinding & Dispersing November

5 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. Fine Fraction F W Two different types of force have an effect during air classifying: Drag force (F W ) Gravity (F G ) and centrifugal forces respectively FG F W F W FG FG Coarse Fraction v Dedusting of metal powders Grinding & Dispersing November

6 Process Fundamentals Drag force: Gravity force: Area of circle: A Volume of sphere: V ~ ~ ~ ~ Particle Size A-Factor d 2 V-Factor d > > ~ < 10 3 Dedusting of metal powders Grinding & Dispersing November 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 [1] [1] Prof. Dr. Matthias Stieß: Mechanische Verfahrenstechnik-Partikeltechnologie 1, 3. Auflage 2009 Dedusting of metal powders Grinding & Dispersing November

7 Standard Classifier Wheel vs. CONVOR Classifier Wheel H F = constant v r constant H F constant v r = constant Dedusting of metal powders Grinding & Dispersing November Agenda 1. Introduction 2. Basics of Classification 3. NETZSCH Classifiers 4. Application Examples

8 NETZSCH Fine Classifier CFS Dedusting of metal powders Grinding & Dispersing November NETZSCH Fine Classifier CFS Design 1 Product inlet 2 Air inlet 3 Guide vane 4 Classifier wheel 5 Fines outlet 6 Coarse outlet Dedusting of metal powders Grinding & Dispersing November

9 NETZSCH High-efficiency Fine Classifier CFS/HD-S Dedusting of metal powders Grinding & Dispersing November NETZSCH High-efficiency Fine Classifier CFS/HD-S Design 1 Product inlet 2 Air inlet 3 Classifier wheel 4 Guide vanes 5 Separating wall 6 Coarse outlet Dedusting of metal powders Grinding & Dispersing November

10 NETZSCH High-efficiency Fine Classifier CFS/HD-S Plant Example Classifying plant for inert gas operation Dedusting of metal powders Grinding & Dispersing November Agenda 1. Introduction 2. Basics of Classification 3. NETZSCH Classifier 4. Application Examples

11 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 Dedusting of metal powders Grinding & Dispersing November 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: rpm) The load was kept constant at 0.1 kg/m³ Feed PSD Coarse material PSD Fine material PSD d5 of the coarse material ~ 21.2 µm Yield: 98.7 % coarse material Dedusting of metal powders Grinding & Dispersing November

12 SEM Pictures Magnification FEED FINE COARSE 500x 1000x Dedusting of metal powders Grinding & Dispersing November 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) Source: Dedusting of metal powders Grinding & Dispersing November

13 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 Dedusting of metal powders Grinding & Dispersing November Thank you for your attention! Christian Höfels Process Technology Development NETZSCH Trockenmahltechnik GmbH Tel.: Fax: christian.hoefels@netzsch.com