Dimensional accuracy, surface roughness and morphology of desktop stereolithography 3D printing materials

Stereolithography (SLA) is a type of additive manufacturing (AM) technology used to create 3D printed objects. This process uses an ultraviolet (UV) laser to cure a photosensitive resin into a solid object. Information on material characteristics is an important aspect for designers especially in relation to critical engineering applications. In this study, high temp (HT) and clear (CL) resins were used to make the test specimens. HT is categorised as an engineering material while CL is categorised as a standard material based on the Formlabs materials library. Both materials were used to make specimens for dimensional accuracy, surface roughness and surface morphology using different layer thicknesses. Measurements for dimensional accuracy were performed using a coordinate measuring machine (CMM) and analysis was performed on respective geometry shapes. Meanwhile, surface roughness and surface morphology measurements were performed using a surface roughness tester and a scanning electron microscope (SEM) respectively. Based on the results obtained, HT resin and CL resin show good dimensional accuracy where the published measurement dimensions were less than 5% deviation compared to the nominal dimensions except for certain cylindrical holes made of CL resin. From the surface roughness test results, it was found that the roughness value in the y-direction was better than the roughness value in the x-direction for both HT and CL resins. The surface roughness readings for HT resin in the y-direction were 1.0846 µm for 100 µm layer thickness (LT) and 1.1446 µm for 25 µm LT while for CL resins were 1.3870 µm for 100 µm LT and 1.5020 µm for 25 µm LT. Furthermore, the layer formation results for CL resins on SEM micrographs were found to be better than those of HT resins for layer thickness of 25 µm and 100 µm. Based on these findings, HT resins and CL resins can be considered for rapid tooling (RT) applications with further justification in terms of design and other requirements.