SYSTEMATIC DIMENSIONAL CALIBRATION PROCESS FOR 3D PRINTED PARTS IN SELECTIVE LASER SINTERING (SLS)

摘要

The selective laser sintering (SLS) processes, known for enhancing engineering properties and durability of products, are widely used in auto part development processes. The dimensional displacements of the 3D printed parts, however, hinder utilizing the technology directly to enhance their development process. In general, the SLS process causes curved shapes (convex) due to thermal deformation (thermal expansion and thermal contraction) in the powder sintering and cooling processes, which accompanies multi-phase changes of the raw materials (polymer powders). In this research, we aim to present a systematic dimensional calibration process by investigating and analyzing the dimensional deformation patterns of 3D printed samples in SLS platform (using 3D Systems 'sPro60 SD). Firstly, the test samples with complex features are produced to check the reference dimensional deviation of the SLS process. Secondly, the deformation patterns are measured and analyzed as a form of a 2nd order polynomial regression model in the global Cartesian coordinates of the platform. Lastly, the dimensional calibration methods to minimize the process errors are presented by the pre-processing of the original CAD file (stl) with inverse transformation of the features using the 2nd order polynomial regression model. At the end of the paper, we will propose an algorithm that predicts the deformation and calibrates point-based 3D CAD STL files of samples in order to mitigate the dimensional deformation, along with test samples for illustrative purposes.