Design and fabrication of internal mixer and filament extruder for extraction of hybrid filament composite for FDM applications

Additive manufacturing is an advanced manufacturing technology to produce components with superior quality, aesthetic shape, less wastage and reduced production time. Fused deposition modeling (FDM) is one of the additive manufacturing techniques adopted by small scale industries as it is most economical and produces compact sized components. Even though, the lack of feedstock (i.e., filament) material leads to increase in overall manufacturing cost. This paper explores design and fabrication of internal mixer (IM) and filament extruder for blending of composite materials, production of polymer filaments and hybrid composite filaments (i.e., polymer filaments with reinforcement of natural fibers) for FDM applications. The polylactic acid polymer, bamboo natural fibers and maleic anhydride compatibilizer are taken as a raw material. The internal mixer has been fabricated successfully is the most economical approach as compared to commercially available IM. The result shows that, the developed IM produces 250 g of blended mixture (i.e., combination of polymers, natural fibers and plasticizers) in a duration of 30 min. Also, the designed and fabricated portable filament extruder tested and extracted continuous polymer and hybrid filaments with a diameter ranging from 1.6 to 2 mm and mass flow rate of 15.6 mm³/s respectively. In addition, the obtained filament having no warping, without clogging, no under and over extrusion, more precise and most economical as compared to existing filament extruders. The developed IM and filament extruder are adequate to small scale vendors and industries.