The development of a conical screw-based extrusion deposition system and its application in fused deposition modeling with thermoplastic polyurethane

This paper aims to develop an integrated and portable desktop 3D printer using direct extruding technology to expand applied material field. Different from conventional fused deposition modeling (FDM) which uses polymer filaments as feedstock, the developed system can fabricate products directly using polymer pellets. And its printing properties are also investigated.

A conical screw-based extrusion deposition (CSBED) system was developed with a large taper conical screw to plasticize and extrude fed materials. The 3D printer was developed with assistance of precision positioning and controlling system. Biocompatible thermoplastic polyurethane (TPU) pellets were selected as raw materials for experiments. The influences of four processing parameters: nozzle temperature, fill vector orientation, layer thickness and infill density on the product’s internal structure and tensile properties were investigated.

It is concluded that the customized system has a high manufacturing accuracy with a diminutive global size and is suitable for printing soft materials such as TPU. Theoretical calculation shows the developed conical screw is more effective in plasticizing and extruding compared with conventional screw. Printed samples can achieve applicable tensile properties under harmonious parameter cooperation. Deposited materials are found to have voids among adjacent roads under unbefitting parameters.

The developed system efficiently improves material limitations compared to commercial FDM systems and exhibits great potential in medical field because soft materials such as biocompatible TPU pellets can be directly used.