Numerically evaluating the effect of extrusion angle on material flow and thermal behaviour during additive friction extrusion deposition (AFED)

Abstract Additive Friction Extrusion Deposition (AFED), also known as “SoftTouch”, is an emerging friction-based Additive Manufacturing (AM) technology allowing material to soften before the deposition, increasing the printing speed and reducing cost [1]. However, high power is required during the process, as excessive force is needed to extrude enough material through the printing head. This study investigates how extrusion angle and tool rotational speed affect thermal distribution and material flow in AFED to minimise power consumption. A three-dimensional computational fluid dynamics (CFD) model is proposed, and ANSYS ® Workbench CFD code (Fluent) is used to discretise the CFD model. A User-Defined File (UDF) is developed and compiled to calculate the viscosity of aluminium alloy 6061 using a temperature- and strain-rate-dependent non-Newtonian viscosity model. Extrusion angles between 0 º and 45 º , tool rotational speed between 75 and 1050, and a constant mass flow rate of 0.9 kg/hr are considered during numerical simulation. The study found that a printing head without an extrusion angle requires a higher force, averaging 29 kN, to extrude material. However, increasing the extrusion angle from 5 º to 45 º significantly reduces the force by an average of 17.17%. Additionally, increasing the printing head’s rotational speed has a significant impact on the extrusion force. Increasing the RPM from 75 to 1050 reduces the extrusion force by an average of 43.11%. Analysing the temperature, viscosity, and strain rate contours revealed that a printing head with 840 RPM and an extrusion angle of 40 degrees consumes significantly less power (2.6 kW) and produces sufficient heat and strain in the processing zone to soften the material before extrusion.