FDM PRINTABILITY OF RECYCLED MATERIAL: INVESTIGATION OF MECHANICAL PROPERTIES & SURFACE CHARACTERISTICS

Abstract

The main objectives of this study are to investigate the effect FDM 3D printing with different parameters on mechanical properties of the material and to investigate the effect of recycling and reuse of the material on its mechanical characteristics. The project consists of cyclical experimental testing and recycling, the results of which are analyzed using the Taguchi method. The material for the research is a polylactic acid, also known as PLA, and the focused printing parameters are infill pattern, infill density and extrusion temperature. For infill pattern triangular, tri-hexagonal and octet shapes were investigated and for infill density and printing temperature 40,60,80 percent and 190,200,210°C were taken correspondingly. For design of the experiment the L9orthogonal array Taguchi method was used, resulting in total of 9 samples. After printing, specimens underwent through tensile, hardness and bending tests on the corresponding equipment. After, the material was recycled - the tested specimen were then shredded, palletized and then extruded as a new filament. The recycled PLA went through the same tests and after that the material was recycled and tested again. All in all, 3 runs of experiment were conducted for virgin PLA and for 2 iterations of recycling. Overall, according to results, the optimal printing parameters for the virgin material were 80 percent infill density, 200°C extrusion temperature and tri-hexagonal shape infill pattern. After recycling, tensile and bending properties of the PLA decreased and the effect of the parameters changed. However, with proper printing parameters such as 80 percent infill density, 190°C extrusion temperature and tri-hexagonal shape infill pattern, recycled PLA can give close to the virgin material results of tensile, hardness and bending tests.