Optimal offline compensation of shape shrinkage for three-dimensional printing processes

Dimensional accuracy is a key control issue in direct three-dimensional (3D) printing. Part shrinkage due to material phase changes often leads to deviations in the final shape, requiring extra post-machining steps for correction. Shrinkage has traditionally been analyzed through finite element simulation and experimental investigations. Systematic models for accuracy control through shrinkage compensation are rarely available, particularly for complete control of all local features. To fill the gap for direct printing and compensate for shape shrinkage, this article develops a new approach to (i) model and predict part shrinkage and (ii) derive an optimal shrinkage compensation plan to achieve dimensional accuracy. The developed approach is demonstrated both analytically and experimentally in a stereolithography process, one of the most widely employed 3D printing techniques. Experimental results demonstrate the ability of the proposed compensation approach to achieve an improvement of an order of magnitude in the reduction of geometric errors for cylindrical products.