Polymer Powders for Laser Sintering

Transcription

1 Polymer Powders for Laser Sintering Manfred Schmid, inspire icams

2 Agenda - Additive Manufacturing and Laser Sintering (LS) - Market for Polymer Powders - Essential Powder Properties - Polyamide 12 (PA12) for LS - Processing of PA12 (commercial materials) - Properties influencing process and parts

3 Introduction inspire AG Competence centre for the Swiss Industry regarding production technique and tooling. Founded on an initiative of ETH-Zürich and machine building industry. Approved as ETH-research annex institute (non-profit foundation). ETH inspire Industry SME Universities of applied science Basic R&D Application driven R&D Technology Development Product development Inspire, icams is working with Additive Manufacturing since 20 years

4 Introduction Additive Manufacturing

5 Additive Manufacturing state of the art Source: Gartner

6 Introduction Laser Sintering (LS) Invented from Carl Deckard (1986 Univ. Austin (TX))

7 Introduction LS powders

8 Introduction LS powders PA11 PA12 filled 10% others PA12 unfilled 85%

9 Introduction LS powders Polymer Powders for Laser Sintering Duraform PA / Orgasol invent smooth

10 Introduction LS process A n : Energy per unit area (or volume considering layer thickness) A N Scan Laser Power Space Scan Speed ( Layer Thickness) PA 12 Used range: 100 ~ 200 J/cm3

11 LS process building parts work on DTM 2500 plus for best processing, part details and good productivity part bed temp: 175 C laser power: 38 W hatch distance: 0.25 mm Laser speed: 10 m/s A n = 15 x 10-3 J/mm 2 > < > = part bed temp: 164 C laser power: 48 W hatch distance: 0.15 mm Laser speed: 10 m/s A n = 32 x 10-3 J/mm 2

12 Polymer powders for Laser Sintering Duraform PA / Orgasol invent smooth

13 LS process mechanical properties Duraform PA 175 C / 38 W / 0.25 mm A n = 15 x 10-3 J/mm 2 Orgasol invent smooth 164 C / 48 W / 0.15 mm A n = 32 x 10-3 J/mm 2 Tensile tests with parts in X-, Z-direction Charpy tests with parts in X-, Z-direction

14 ISO 197 1eA ISO 197 1eU ISO-527 LS process mechanical properties Duraform PA Orgasol invent smooth values from MDS 3DS inspire values MDS - Arkema inspire values build direction X Z X Z X Z X Z Young s modulus MPa ± ± ± ± 21 max. Tensile Strength MPa ± ± ± ± 3.6 Elongation at Break % ± ± ± ± 0.3 Charpy unnotched kj/m ± ± ± ± 0.7 Charpy notched kj/m ± ± ± ± 0.2 pronounced loss of mechanical properties in Z-direction for Orgasol invent

15 LS process surface characterisation GelSight for fast and reliable surface characterisation in mm- and µm-range Duraform PA Orgasol invent smooth

16 oxes oxes oxes Orgasol inv smooth Number of enclosing boxes Number of enclosing boxes Number of enclosing boxes Duraform PA LS process PA12 Lying Topface surface characterisation Surface Investigation Gelsight Magnification 3x Primary surface; S1-nesting index (ni) = mm mm top surface bottom I SO surface upright I SO surface µm % mm % Parameters Value Unit Isotropy 88.7 % First Direction 63.5 Second Direction Third Direction µm MountainsMap 0 Imaging 5 Topography % Sdar I SO mm² Spar 37.8 mm² Height Parameters µm mm Sq 16.7 µm Flatness 5.0 Ssk Parameters I SO FLTt 4.5 Sku µm FLTp 24.2 µm Sz 148 µm 4.0 FLTv 23.9 µm Sa 13.0 µm FLTq 8.48 µm µm 0 Spatial 5Parameters % 3.0 Sal mm 2.5 Str Std Hybrid Parameters Sdq Sdr 10.6 % Feature Parameters Spd /mm² mm S10z 113 µm Other 20 3D 40 Parameters % S 180 Miscellaneous q = 7.7 μm 1 mm Sdar 41.8 mm² Scale of analysis S Spar a = 6.0 μm 37.8 mm² Parameters Value Unit I nformation I SO Isotropy 86.6 % Method Enclosing boxes Flatness Parameters First Direction 90.0 Parameters FLTt Second Value Direction µm Fractal dimension Third Direction 2.26 FLTp µm FLTv 16.4 µm µm 0 FLTq µm % MountainsMap Imaging Topography PA12 Lying Bottomface Surface Investigation Gelsight Magnification 3x Primary surface; S1-nesting index (ni) = mm SF surface; F-operator = poly. degree 6; S1 = SF mmsurface; F-operator = poly. degree 6; S1 = SF mm surface; F-operator = poly. degree 6; S1 = m mm mm % S q = 19.0 μm S a = 15.6 μm S q = 16.7 μm S a = 13.0 μm µm mm Hybrid Parameters Sdq Sdr 11.0 % 0.5 Feature Parameters 0.0 Spd /mm² mm S10z 147 µm 0 Other 20 3D 40 Parameters % Miscellaneous inspire AG 130 Height Parameters Sq 19.6 µm Ssk Sku 3.12 Sz 172 µm Sa 15.6 µm Spatial Parameters Sal mm Str Std S q = 17.8 μm S a = 14.2 μm 50 Sdar 42.2 mm² SF I SO surface; F-operator = poly. degree 6; S1 = m Spar 37.8 mm² Height Parameters µm Sq I SO mm 7.67 µm µm 5.0 Ssk Flatness Parameters Sku FLTt µm Sz FLTp µm µm Sa FLTv µm µm Spatial FLTq Parameters 6.60 µm µm % Sal mm Str Std Hybrid Parameters Sdq Sdr 6.47 % Feature Parameters Spd /mm² mm S10z 64.3 µm Other 20 3D 40Parameters % S Miscellaneous q = 20.1 μm Sdar mm² 1 mm Scale of analysiss 0.01 Spar a = 16.3 μm 37.8 mm² I nformation Parameters I SO Value 12781Unit Method IsotropyEnclosing boxes Flatness 4.13 Parameters % First Direction FLTt µm Parameters Value Second Direction FLTp µm Fractal dimension 2.28 Third Direction FLTv µm FLTq 3.37 µm µm % µm PA12 standing part (90deg) Surface Investigation Gelsight Magnification 3x Primary surface; S1-nesting index (ni) = mm mm x 0 20 Other 3D Parameters Primary surface; S % S1-nesting q = 24.3 index μm (ni) = mm MountainsMap Imaging Topography Height Parameters Sq 17.8 µm Ssk Sku 3.04 Sz 143 µm Sa 14.2 µm Spatial Parameters Sal mm Str Std Hybrid Parameters Sdq Sdr 11.7 % 0.5 Feature Parameters 0.0 Spd /mm² mm S10z 117 µm Miscellaneous S a = 19.4 μm S a and S q are the Average Roughness and Root Mean Square Roughness are evaluated over the complete 3D surface respectively µm I nformation Method Parameters Fractal dimension

17 Summary 1 Polymer powders for Laser Sintering Duraform PA / Orgasol invent smooth

18 Polymer powders for Laser Sintering Duraform PA / Orgasol invent smooth

19 LS Materials powder production Evonik (Vestosint ) Arkema (Orgasol ) 3D Systems Duraform PA Production: Precipitation Arkema Orgasol invent smooth Production: Polymerisation DuraForm PA Orgasol invent smooth µm µm

20 LS parts microstructure and porosity E ρ = LP / HS*v (J/mm 2 ) Orgasol i.s. Duraform PA Porosität (SLS) = 4% - 6%

21 process window LS Materials thermal behavior melting crystallisation Dt max =10ºC Dtmax =4ºC 97% area

22 LS Materials thermal behavior temperature sensitivity of Orgasol invent smooth partial curling

23 LS Materials molecular properties polymerisation of polyamide 12 (PA12) O H X n X Orgasol invent smooth C N PA 12 (blocked chain ends) + H 2 O (CH 2 ) 11 Lauryllactam H 2 N n COOH Duraform PA PA 12 (open chain ends) = reactive end groups -NH 2 and -COOH MVR values (235 C / 2.16 kg): post condensation during SLS processing increasing chain length increasing melt viscosity Orgasol IS: remain at about 15 cm 3 /10 min Duraform PA: reduction cm 3 /10 min

24 LS Materials molecular properties H H O H O N (CH 2 ) 11 C OH + H N (CH 2 ) 11 C OH n m T, t, Δp H2 O K p,t = [chain(m+n)] H 2O [chain(m)] [chain(n)] H H O N (CH 2 ) 11 C OH + n+m H 2 O Chemical equilibrium depends on Δp and T SLS provides best conditions for successful post condensation T > 100 C; dry N 2 atmosphere drying chamber!

25 LS Materials molecular properties unwanted post condensation of powder (aging) low melt viscosity at process start Laser mirror COOH top layer NH 2 CONH COOH NH 2 COOH 2 nd layer new part CONH NH 2 3 rd layer powder SLS building chamber Inter-layer bonding intra-layer bonding

26 Summary 2 Duraform PA Orgasol invent smooth production precipitation direct polymerisation Particle shape Thermal situation potato compromise regarding flowability larger Sintering window easier processing crystal size and structure! Powder distribution broad (bimodal) PA12 chain ends (termination) mechanical properties open easy flowing melt enhanced properties due to post condensation more homogenous in all directions spherical more detailed parts better part surfaces needs more stable temp. situation during processing thermal problems narrow high powder flowability better powder density blocked less powder aging (economy) pronounced drop in z- direction

27 lesson learned

28 Release in two month Thank you! Questions?