Optimal Offline Compensation of Shape Shrinkage for 3D Printing Processes

Dimensional accuracy is a key control issue in direct 3D printing. Part shrinkage due to material phase changes often leads to final shape deviations, requiring extra postmachining steps for correction. Shrinkage has traditionally been analyzed through finite element simulation and experimental investigations. Systematic models for accuracy control through shrinkage compensation are hardly available, particularly for complete control of all local features. To fill the gap for direct printing and compensate shape shrinkage, we develop a new approach to (1) model and predict part shrinkage, and (2) 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 one order of magnitude in reduction of geometric errors for cylindrical products.