Manufacture of soles for footwear using digitized designs with flexible filaments for 3D printers

The purpose of the research is to develop shoe soles by digitized designs with flexible filaments in 3D printers. The motivation to conduct the research was the conceptualization of the process of transferring digitized and simulated data to 3D objects that meet the needs of the customer. For the digitization process of the sole through software design and 3D scanning, the sole of a women's shoe size 36 (24.6 cm.) in the Peruvian standard was replicated. In addition, some variants were made using Rhinoceros 6.0 software, allowing to make meshes to generate the piece which was later exported in STL file format. On the other hand, the shoe sole was produced with Thermoplastic Polyurethane (TPU) and Thermoplastic Elastomer (TPE) filaments, with 5% and 12% infill variants printed on an Anet A8 and M3D Crane Quad printer. A total of 16 samples were printed as a result of one piece per combination. Moreover, the software "Voxelizer 2.1" was used to generate the GCODE which allows 3D reading and printing. Finally, two tests were performed on the printed sole patterns: elongation and tensile strength: The tensile test applies a variable vertical force to each pattern to determine how it will behave under pressure. The elongation test consists of applying a variable force to each pattern in order to measure the material’s ability to resist changes in shape until finding its point of fracture. The results show that the sole designs do not have significant variations in the elongation test, but the software design digitizing process has higher performance versus 3D scanning. In the tensile strength test, the design digitization process has also a higher performance versus 3D scanning; however, as it is not significant, both processes can be used for the manufacture of footwear soles. Thus, there is no interaction or average dependence between the filler percentages and the type of filament (TPU, TPE). Finally, the elaboration of footwear soles by digitized designs with flexible filaments does not present a significant difference among the means of factors involved in this study: Infill density, type of filament, printer.