Optimizing mechanical properties of HIPS fabricated with low-cost desktop 3D printers: investigating the impact of process parameters

Recently, low-cost desktop three-dimensional (3D) printers, employing the fused deposition modeling (FDM) technique, have gained widespread popularity. However, most users cannot test the strength of printed parts, and little information is available about the mechanical properties of printed high-impact polystyrene (HIPS) parts using desktop 3D printers. In this study, the user-adjustable parameters of desktop 3D printers, such as crisscross raster orientation, layer thickness, and infill density, were tested. The experimental plans were designed using the Box-Behnken method, and tensile, 3-point bending, and compression tests were carried out to determine the mechanical responses of the printed HIPS. The prediction models of the process parameters were regressed to produce the optimal combination of process parameters. The experimental results showcase that the crisscross raster orientation has significant effects on the flexural and compression strengths, but not on the tensile strength. With an increase in the layer thickness, the tensile, flexural, and compression strengths first decreased and then increased, reaching their minimum values at approximately 0.16 mm layer thickness. In addition, they all increased with an increase of infill density. It was demonstrated that when the raster orientation, layer thickness, and infill density were 13.08 degrees/-76.92 degrees, 0.09 mm, and 80%, respectively, the comprehensive mechanical properties of the printed HIPS were optimal. Our results can help end-users of desktop 3D printers understand the effects of process parameters on the mechanical properties, and offer practical suggestions for setting proper printing parameters for fabricating HIPS parts.