Heat treatment of FDM and SLS delicate additive manufacturing products: mechanical properties enhancement and dimensional accuracy

Improving mechanical properties of additive manufacturing (3D printing) products has always been interesting. It has always been tried to choose the optimal annealing temperature and time to perform the optimal heat treatment. In addition to improving mechanical properties, dimensional changes during the treatment should be considered. In this research, in order to measure procedure dimensional deviation and to achieve the maximum mechanical properties of the printed samples after heat treatment, samples in the form of tensile test dumbbell shape, compressive test cylindrical shape and porous scaffolds produced with Fused Deposition Modeling (FDM) and Selective Laser Sintering (SLS) 3D printers. Polylactic acid (PLA) and poly amid 12 (PA12) was selected for FDM and SLS respectively as the most used materials for these printers. Finite element thermal analysis was performed to determine the samples heat treatment duration. Heat treatment at temperatures of 85, 100 and 115 ℃ for 25 min on PLA samples and at temperatures of 160 and 175 ℃ for 12 min on PA12 samples were determined via simulations. The results show that the tensile elastic modulus of FDM PLA samples enhanced about 30% at 100 ℃ for 25 min and for SLS PA12 samples increased about 9% at 160 ℃ for 12 min by heat treatment. Differential Scanning Calorimetry (DSC) tests were conducted on the specimens before and after heat treatment to analyze changes in crystallinity and their impacts on mechanical properties.