Low adhesion continuous constrained-surface projection stereolithography process based on curing degree control

Abstract

In constrained-surface projection stereolithography process, significant separation force is required to separate the cured part from the bottom surface of the resin tank, which reduces the throughput and accuracy of the process. To reduce separation force and improve printing efficiency and printing accuracy, in this study, photosensitive/thermosetting resin was used as the printing material, and the relationship between the resin curing degree and separation force was investigated. On this basis, a low adhesion continuous constrained-surface projection stereolithography process based on curing degree control was proposed. By adjusting the ratio of the composite resin to control the curing degree of the resin during the printing process, thereby the Young's modulus of the cured resin layer was temporarily reduced, the separation force between the cured part and the bottom of the resin tank was weakened, which thus realized the continuous printing of resin. Then the final mechanical properties of the entire part are improved by thermal curing. The results show that compared with pure photosensitive resin, when the thermosetting resin content is 70%, the separation force can be reduced by 95.7%, the volume shrinkage can be reduced by 64.5%. The maximum tensile strength after post-curing of the printing part is 71 MPa, and the maximum tensile modulus after post-curing the printing part is 997 MPa. This process results in enhanced part printing accuracy, and the maximum speed can reach up to 1080 mm/h. The above results indicate that this new continuous 3D printing method via curing degree control provides a new avenue to fabricate part with high efficiency toward functional applications.