High-speed material jetting additive manufacturing of silicone structures: mechanical characterization

The rapid additive manufacturing (AM) of highly viscous elastomers such as silicone has recently become possible due to the advancements in the fluid dispensing mechanism of material jetting systems leading to jetting of inks with a viscosity of 106 mPa.s under the shear stress of the nozzle. The drop-on-demand material delivery, which is the key to rapid AM of silicone prepolymers in these systems, can be the source of an inferior mechanical performance of AM-made parts compared to the bulk material because of their increased level of porosity as a result of jet printing. In this paper, the rheological properties of silicone have been tuned to maximize the density of AM-made silicone parts (99.6%) and reduce the difference between the mechanical properties of AM-made and cast parts. Parts that were printed and molded using the optimized ink demonstrate statistically insignificant differences between their ultimate tensile strength and strain, tearing resistance, and hardness.