Support-Free Low-Temperature Laser-Based Powder Bed Fusion of Polymers Using a Semi-Sintering Process

In conventional laser-based powder bed fusion of polymers (PBF-LB/P), aging of the powder due to preheating of the powder bed is a significant issue. This paper proposes a method for low-temperature PBF-LB/P using a semi-sintering process that minimizes powder aging caused by preheating. By partially semi-sintering the low-temperature powder bed, it was possible to execute the PBF-LB/P while avoiding the aging of most of the powder. Furthermore, the suppression of curling by the semi-sintered body eliminated the need to connect the base plate to the parts, which was necessary in previously reported low-temperature PBF-LB/P. Using the semi-sintering process, we successfully built cuboid and tensile test specimens in a polyamide 11 powder bed maintained below the crystallization temperature, where the powder hardly aged. The apparent densities of the built specimens were comparable to those produced using high-temperature PBF-LB/P. However, the elongation in the building direction of the built parts by the semi-sintering process should be improved. This study represents the first step toward the practical application of low-temperature PBF-LB/P using semi-sintering.