Development and Modeling of Melt Electrohydrodynamic Jet Printing of Phase Change Inks for High Resolution Additive Manufacturing

Abstract

This paper presents the development and modeling a highresolution electrohydrodynamicjet (EHDjet) printing process using phasechange ink (i.e., wax), which is capable of producing sub10 خ¼m footprints (sub10 fL in volume) for superresolution additive manufacturing. In this study, we successfully apply EHDjet printing for phasechange ink (wax), which is widely used as modeling and supporting material for additive manufacturing, to achieve micronscale features. The resolution for single droplet on substrate is around 5 خ¼m with the thickness in the range of 1–2 خ¼m, which provides great potential in both highresolution 3D printing and 2D dropondemand microfabrication. The droplet formation in EHD printing is modeled by finite element analysis (FEA). Two important forces in EHD printing, electrostatic force and surface tension force, are modeled separately by FEA. The droplet size is obtained by balancing the electrostatic force and surface tension of the pending droplets around meniscus apex. Furthermore, to predict the droplet dimension at different process conditions, a dimensionless scaling law is identified to describe the relationship between dimensionless droplet diameter and modified nondimensional electrical bond number. Finally, the droplets inflight velocity and impact characteristics (e.g., Reynolds number and Weber number) are modeled using the results from FEA analysis.