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Systems and Process Development for Co-Axial Additive Fabrication Adam Taylor a, Stephen Beirne a, Gursel Alici a,b, and Gordon Wallace a a

ARC Centre for Excellence in Electromaterials Science (ACES), Intelligent Polymer Research Institute (IPRI), Australian Institute for Innovative Materials (AIIM), Innovation Campus, University of Wollongong b School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong

Introduction

Fluid Flow Profile

With the increase in popularity of additive fabrication, by process of fused deposition modelling, comes a demand to further progress this technology. This work aims to develop a co-axial fused deposition modeling system, to allow for two materials to be extruded simultaneously. In doing so, each material will be individually controlled for both deposition speed and heat exchange. The finished prototype will produce a core-sheath type extrusion, with the aim of printing biocompatible conductive pathways to a high resolution, thereby providing a means to introduce higher levels of complexity into scaffold structures for bionic development.

A crucial concept in obtaining uniform extrusion relies on the flow profile of the nozzle. The design must accommodate a highly viscous fluid input while maintaining an equal mass flow rate across its cross section. Three profiles have been created and have been theoretically tested. All nozzles performed uniquely and shall also be tested empirically.

Planned Research – Objectives

Figure 4 – Potential tip geometries

Objectives: • Develop a print nozzle which will produce a symmetric co-axial extrusion. • Independent mechanisms.

control

of

heating

chambers

and

feed

The co-axial nozzle will be created using the SLM 50 – Realizer. It offers the many advantages, ideal for this project. •Capable of printing titanium – selected nozzle material

• Obtain symmetrical 600µm print resolution.

•Acceptable print volume.

• Print materials with melting points up to 260ᵒC.

•20µm print resolution.

• Sensory feedback from heat chamber temperatures.

Figure 1 – Concept of final print. 600µm resolution

Tip Fabrication Technique

•Software compatibility with CAD/CAE applications.

Figure2 – Proposed co-axial nozzle. Figure 6 – SLM 50 print capabilities

Figure 5 – SLM 50

Existing Hardware and Proposed Modifications Existing Hardware: •Many printers modification.

Target Materials considered

for Table 1 – Target materials for co-axial additive fabrication

•The BFB Touch is a mid-tier Fused Deposition Modelling printer and is a potential candidate for this project. •Selected for its excellent control systems and ample space to allow for ease of various modifications.

Melting Material Temperature (ᵒC ) Polycaprolactone 60 Graphene ? Composites

?

Figure 2 - BFB Touch

PLA

180

60

Proposed Modifications:

ABS

-

104

• Nozzle to coaxially extrude two materials. • Direct system.

drive

extrusion

• Electrical modifications to heat chambers and sensors. Figure 3 – Modified Extruder Design

Glass Transition Temperature Desired Quality (ᵒC ) -60 Biodegradable

• Coding to alter printing process.

Conductive Prototyping / Biodegradable Prototyping

Future Research and Potential Uses • Higher levels of complexity for scaffold structures. • Print biocompatible material with conductive pathways. • Print hollow structures. • Test platform for custom extruded materials.

References

Acknowledgements

1. Cornock, R., S. Beirne, and G.G. Wallace. Development of a Coaxial Melt Extrusion Printing process for specialised composite bioscaffold fabrication. in Advanced Intelligent Mechatronics (AIM), 2013 IEEE/ASME International Conference on. 2013: IEEE.

To my supervisors Stephen Beirne, Gursel Alici, and Gordon Wallace who have guided me throughout this process. To the team at IPRI who have provided the facilities and equipment necessary to research and develop this project.


Adam taylor