Experimental Investigations into the Effects of Process Parameters and UV Curing on the Tensile Strength of Projection Based Stereolithography

Projection stereolithography (SLA) is a layer-by-layer 3D printing technique used to create complex structures and intricate geometries with high accuracy and surface finish. The final mechanical properties of any SLA printed parts are highly dependent on the process parameters and post-cure process. Proper post-curing helps cross-linking the unreacted double bond remaining after the printing and thereby enhance the mechanical strength. In this study, the impact of process parameters such as infill density, exposure time, and layer height on the tensile strength of Phrozen Beige low-irritation resin was investigated first. Maximum tensile strength of 25.792 MPa was attained at 100% infill volume of a layer thickness of 30 μm for an exposure time of 8 s. The effect of post-curing time and temperature on the ultimate tensile strength was evaluated. Phrozen Beige resin demonstrated an increase of 33.56% after 1 hour of post-curing at 25°C. Phrozen Aqua-Gray 4K resin exhibited an improvement of 44.57% after 2 h of post-curing at 25°C. Maximum tensile strength and faster achievement of completely cured state occurred at a higher post-curing temperature at the heat deflection temperature due to the acceleration of cross-linking of uncured photopolymers.