Microfluidics as a Platform for the Analysis of 3D Printing Problems.

Area of Science:

• Materials Science
• Fluid Dynamics
• Additive Manufacturing

Background:

• Fused Filament Fabrication (FFF) is a key 3D printing technique.
• Accurate extrusion flow control is crucial for FFF, but challenged by upstream back-flow.
• Optical access to melting chambers for studying back-flow is limited.

Purpose of the Study:

• To investigate the back-flow phenomenon upstream of 3D printing nozzles.
• To utilize microfluidics as a platform for studying complex fluid flow in FFF.
• To develop a flow map correlating fluid elasticity and flow conditions.

Main Methods:

• Developed a microfluidic device mimicking a 3D printing nozzle using soft-lithography.
• Employed aqueous polymer solutions to replicate printing flow conditions (Elasticity number).
• Created a dimensionless flow map (De-Re) to analyze fluid behavior.

Main Results:

• Confirmed the presence of upstream vortices in the nozzle contraction.
• Demonstrated that fluid elasticity is the primary cause of these vortices.
• Established a link between fluid elasticity, vortex formation, and back-flow.

Conclusions:

• Upstream vortices, driven by fluid elasticity, are responsible for the back-flow issue in FFF.
• Microfluidic modeling provides valuable insights into FFF internal flow dynamics.
• Findings can inform strategies for improved extrusion control in 3D printing.