Oxygen Saturation as a Strategy to Mitigate User-Induced Variation in Tomographic Volumetric Additive Manufacturing

Tomographic Volumetric Additive Manufacturing (TVAM), also known as Computed Axial Lithography (CAL), offers unparalleled geometric freedom and speed but faces challenges with inconsistency caused by user-induced variation. This paper presents novel insights into mitigating user-induced variation by addressing manual preparation of the photopolymer and print vials. Two different methods of preparing the print vials are employed to investigate the oxygen concentration within a batch of photopolymer, each followed by ten consecutive prints of the same geometry and subsequent analysis of the polymerization progressions captured through in-situ monitoring. Results show that the oxygen concentration of the photopolymer is highly dependent on the method of preparation, and that promoting oxygen diffusion directly in the print vial to saturate the photopolymer before printing significantly increases the consistency of
the printing process. Using this methodology, print vials exhibited a curing onset variation of only a few seconds, significantly enhancing the uniformity of the printed parts.