Hybrid heating in Fused Filament Fabrication process

Abstract Changing the heating regime of the polymer during printing by the Fused Filament Fabrication (FFF) process can produce changes in the behavior of the polymer, but also changes in the characteristics of the printed product. The work proposes to replace the traditional resistive heating system with two hybrid heating systems that bring an additional temperature of 120-160oC: resistive and hot air jet, resistive and infrared radiation. The samples printed by using the two hybrid heating systems were DSC analyzed and visual tested. The filaments used for the experimental program were commercial filaments of ABS and PLA. A model to evaluate the melting of the polymer during the printing process was proposed, and it was experimentally confirmed. The visual testing revealed that the printed lattice’s structure is characterized by lower dimension voids of the structure, being built by depositions that are not circular in section, but flattened, due to the longer time in viscous / partially molten state. The elongation viscosity and the storage modulus decreased with about 10%, being slightly lower in the case of the infrared radiation heat source. The glassy temperature remained unchanged; the mobility of the molecules being not affected by the supplementary heat. The energy consumed to form the crystals is not changed by the supplementary heat. Mechanical behavior of the printed piece, during compression tests, was also influenced by the addition of the second heat source. For both materials a decrease in deformability is recorded as the temperature of the hot air jet increases.