thermal and facture characterization of welding zones
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Thermal and facture characterization of welding zones produced by polymer
extrusion 3D printingJonathan E. Seppala, Kaitlyn E. Hillgartner, Chelsea S. Davis, and Kalman B. Migler
Polymer & Complex Fluids GroupNational Institute of Standards and Technology (NIST)
Polymers & Complex Fluids GroupNIST Adhesion Soc.
Feb 23rd, 2016
reprap.org
FDM/FFF Process
Fused deposition modeling (FDM)™aka Fused filament fabrication (FFF)aka Material extrusion
Weld Zone
Nozzle
Printing Layer LP
First Sub-Layer LP-1
Polymers & Complex Fluids GroupNIST Adhesion Soc.
Feb 23rd, 2016
Outline
II. Rheology
I. Thermography III. Fracture Strength
𝜎𝜎 =2𝐹𝐹𝐻𝐻
III. Comparison to Classical Weld Theory
Wool Poly. Eng. And Sci. 1988 28
Polymers & Complex Fluids GroupNIST Adhesion Soc.
Feb 23rd, 2016
Materials
ButadieneSpheres
TEM micrograph ABS
Styrene Acrylonitrile Matrix
J. Mater. Sci. Lett. 19 (2000) 73-75
Acrylonitrile butadiene styrene (ABS)Butadiene-g-Styrene Acrylonitrile/Styrene Acrylonitrile (BgSAN/SAN)
Polymers & Complex Fluids GroupNIST Adhesion Soc.
Feb 23rd, 2016
Process Characterization: Thermography
Extruder
Polymers & Complex Fluids GroupNIST Adhesion Soc.
Feb 23rd, 2016
IR Intensity Profiles
Reflection + Emission Intensity
LP
LP-1
LP-2
Polymers & Complex Fluids GroupNIST Adhesion Soc.
Feb 23rd, 2016
Temperature Profiles
Weld zone:Average of layer above and below.
Polymers & Complex Fluids GroupNIST Adhesion Soc.
Feb 23rd, 2016
Weld Temperature
Print Speed Extrusion Temperature
To be published in Additive Manufacturing
Polymers & Complex Fluids GroupNIST Adhesion Soc.
Feb 23rd, 2016
ABS Rheology
• Shift factors from time-temperature superposition• Provides comparison in molecular mobility between
different temperatures
1 s at 230 °C
1200 s at 150 °C
Polymers & Complex Fluids GroupNIST Adhesion Soc.
Feb 23rd, 2016
Spectroscopic Monitoring of Fused Deposition Modeling
acrylonitrile peak (A) butadiene peak (B) styrene peak (S)
Blue: Crystalline ABS in starting strand
Red: Molten ABS just below nozzle
Raman Spectrometer
Light Source
Fiber optics
v
Polymers & Complex Fluids GroupNIST Adhesion Soc.
Feb 23rd, 2016
Conclusion
Temperature measurement / thermal imaging is 1st step towards development of physics based model of FDM.
Weld formation in material extrusion occurs over ~1 s; most of the interdiffusion occurs over time scale much less that 1s.
Temperature kinetics, rheology and weld theory provide foundation for understanding fracture strength as a function of temperature and feed rate.
In-situ monitoring is achievable. Linking back to real time control is a challenge.
Polymers & Complex Fluids GroupNIST Adhesion Soc.
Feb 23rd, 2016
Contact info:
Seppala:http://www.nist.gov/mml/msed/polymers/jonathan-e-seppala.cfm
Migler:http://www.nist.gov/mml/msed/polymers/kalman-migler.cfm
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