Design and performance assessment of custom static intermixers in extrusion 3D printing using machine learning-driven...

Area of Science:

• Materials Science
• Additive Manufacturing
• Polymer Processing

Background:

• Uniform blending is critical for consistent material properties in multi-material extrusion additive manufacturing.
• Static intermixers are employed to enhance the homogeneity of polymer melts during extrusion.

Purpose of the Study:

• To evaluate the performance of five different static intermixer designs (Split Path, Helix Array, Full Turn Helix, Half Moon, Cross Bars) in a coaxial extruder.
• To determine the most effective mixer geometry for achieving uniform blending of multi-colored polylactic acid (PLA) pellets.

Main Methods:

• Tested five static intermixer designs with a 50/50 mixture of red and blue PLA pellets at 210 °C.
• Assessed mixing performance using microscopic imaging and machine learning analysis (histogram evaluation, clustering, color uniformity indices).

Main Results:

• The Split Path and Full Turn Helix mixers yielded the most uniform color distribution with minimal segregation.
• Helix Array, Half Moon, and Cross Bars designs showed moderate to inconsistent mixing with visible streaking.
• All tested mixer configurations significantly improved blending compared to the control (no mixer).

Conclusions:

• Static intermixer geometry significantly impacts blending uniformity in multi-material extrusion.
• Split Path and Full Turn Helix designs are recommended for optimizing mixing in coaxial extrusion systems.
• This research provides quantitative data for developing improved extrusion systems for applications like functionally graded materials and advanced polymer composites.