Hollow-Core 3D Printing (HC3DP) is a novel concept for material extrusion (ME) 3D printing, It overcomes shortcomings of state-of-the-art ME systems by introducing large-scale, tubular beads instead of solid ones.

ME has become a popular 3D printing method for large-scale applications such as in the automotive, naval, aerospace, and architecture sectors. It allows the production of complex, customized parts without the need of labor-intensive molds. The increasing need to produce larger and larger parts has been addressed with the introduction of large pellet extrusion systems to increase the extrusion rate. With these extruders the production time is not limited by the extrusion rate of the extruder (kg/h) but by the time the material needs to cool down before the next layer can be printed consecutively. Furthermore, larger bead dimensions result in increased material usage and, therefore, might affect the environmental impact of the printed element. 

To address these challenges, we investigate a method for large extrusion 3D printing based on hollow beads. This novel approach addresses the limitations of speed, cooldown and maximises the extrusion rate of thermoplastic 3D printing while only using a fraction of material. By addressing these limitations of traditional 3DP approaches, HC3DP pushes polymer 3D printing into a scale relevant for architecture and construction, offering similar extrusion rates as concrete 3DP. 

As part of ongoing interdisciplinary research of NCCR DFAB, at ETH Zurich,  Hollow Core 3D printing contributes to the NCCR research stream Performance-Integrated 3D printing, by providing a radically new fabrication method for large-scale, highly insulating 3D printed components.