Modeling and Correcting Cure-Through in Continuous Stereolithographic 3D Printing

Continuous stereolithography offers significant speed improvements over traditional layer-by-layer approaches but is more susceptible to cure-through, undesired curing along the axis of exposure. Typically, cure-through is mitigated at the cost of print speed by reducing penetration depth in the photopolymer resin via the addition of nonreactive light absorbers. Here, a mathematical approach is presented to model the dose profile in a part produced using continuous stereolithography. From this model, a correction method is developed to modify the projected images and produce a chosen dose profile, thereby reducing cure-through while maintaining print speed. The method is verified experimentally on a continuous stereolithographic 3D printer, and the practicality of various dose profiles is investigated. In optimizing the critical dose parameter, the measured gelation dose D-gel is found to be insufficient for accurate reproduction of features, and an optimal value of D-c = 5D(gel) is chosen for the test resin. Using optimized parameters with a high-absorbance height resin (h(a) = 2000 mu m), feature height errors are reduced by over 85% in a test model while maintaining a high print speed (s = 750 mm h(-1)).