Empirical process model for shrinkage-induced warpage in 3D printing

Purpose: The purpose of this work is to explain the emergence of warpage due to a locally and temporally inhomogeneous shrinkage in 3D printing (Binder-Jetting) of polymers. Design/methodology/approach: An analysis of shrinkage yields parameters for a one-dimensional layer model of the binding process. Based on this, residual stresses and deformation are calculated by means of a numerical simulation model. Findings: The simulation supports the assumption that the curling of specimens is created by a force transmission between layers due to inhomogeneous shrinkage. Furthermore, the layered production process might contribute to nonlinear deformations of not horizontally orientated surfaces. Research limitations/implications: The simulation allows imitating the warping during the manufacturing process qualitatively. Exact values of deformations cannot be predicted, yet. Practical implications: The results expand the knowledge about warpage effects in 3D printing caused by the layer-wise building process. Originality/value: The developed model imitates the mechanisms leading to deformations during the 3D printing process, focusing on the physical interaction of layers with each other.