Effects of Visible and UV Illumination on Dimensional Accuracy and Surface Roughness in Dual-Color Volumetric Additive Manufacturing (VAM)

Volumetric additive manufacturing (VAM) enables layerless and fast printing within seconds. However, print quality remains highly sensitive to the delivered energy. In this study, the effects of visible (460 nm) and ultraviolet (385 nm) projector power were evaluated in a dual-color VAM setup with a CQ/EDAB initiated TEGDMA/BisGMA resin with an o-Cl-HABI inhibitor. Cubes (6×6×6.7 mm3) were printed under controlled visible and ultraviolet power and exposure times, then evaluated using in situ shadowgraphy, three-dimensional metrology, and confocal microscopy. Higher visible power reduced the polymerization initiation time, but increasing the visible dose rapidly led to over-polymerization, resulting in dimensional growth, corner rounding, and increased surface roughness (Ra). The lowest lateral variation was observed at the shortest exposure times, with a maximum error of 1.8%. Ultraviolet illumination did not significantly change initiation time or reduce over-polymerization within the tested intensities and inhibitor concentration ranges. Surface evaluations revealed a periodic line texture with a pattern pitch of approximately 25 μm. By shifting the focal plane and using a low-resolution projector, the pattern pitch increased to about 150 μm. These values were aligned with the MTF50 spatial frequencies of each projector at different defocus positions. This study provides useful guidelines for adjusting intensity to achieve high-fidelity VAM printed parts.