Influence of Post-Processing by Annealing on Additive Manufacturing Productivity and Mechanical Properties in Three-Point Bending of Additively Manufactured Specimens from PETG and Recycled PETG

Additive manufacturing technologies using extrusion of plastic material (MEX) stand out due to the accessibility of equipment and raw materials (filaments, granular materials), the variety of equipment and materials, low operating costs and the potential for use in non-industrial environments. However, additive manufacturing using extrusion of plastic material (MEX) faces a number of factors that reduce the mechanical characteristics of parts and the productivity of the manufacturing process, preventing the adoption of this manufacturing technology on a large scale. Post-processing is a crucial step in additive manufacturing using plastic extrusion, which has a significant impact on the finished product. In this sense, in this paper, the influence of the annealing heat treatment (temperature, t = 75 °C and duration, d = 180 min) on the mechanical characteristics during three-point bending of the specimens manufactured additively by extrusion of filaments made of PETG and recycled PETG 100 (rPETG 100, where 100 represents the amount of recycled material) is studied using the layer height deposited in one pass, Lh = (0.10/0.15/0.20) mm, and the percentage fill density, Id = (50/75/100)%. The annealing heat treatment generated a 14.24% increase in flexural strength of the additively manufactured PETG specimens and a 2.48% increase in the flexural strength of the additively manufactured rPETG specimens.