A Normalized Trace Geometry Modeling Method with Bulge-Free Analysis for Direct Ink Writing Process Planning

Abstract Direct ink writing (DIW) is an additive manufacturing technology that has been widely used in many fields, including soft electronics, ceramic structures, and flexible biomedical applications. In DIW process, writing a trace with desired geometry is of fundamental importance to fabricate a three-dimensional model. In this article, a normalized geometry modeling method with bulge-free analysis for process planning in DIW is presented. The geometry prediction model is developed by converting conventional dispensing parameters to a dimensionless variable, speed ratio v* . The developed model is independent of tip gauge and feeding mechanism. To address the common bulge issue in DIW of low-viscosity fluids, the critical bulge-free printing range has been identified by characterizing the bulge formation process. The developed geometry prediction model and the identified bulge-free printing range are validated by experimental data of several different tips and inks. Finally, a DIW process planning method based on the developed geometry prediction model is demonstrated.