Production and characterisation of filament-based Material Extrusion (MEX) additively manufactured copper parts
Fankai Meng, Margherita Beretta, Ahmed Selema, Peter Sergeant, Jef Vleugels, Frederik Desplentere, Eleonora Ferraris
Abstract
Material Extrusion (MEX) Additive Manufacturing of metal components is increasingly applied in recent years due to its low cost and potential for multi-material printing, with filament-based MEX being widely developed among all subdivisions of MEX. This technology utilises a compounded filament of polymeric binders and metal powder. The printing process involves hot extrusion of the compounded filament, which acts as a carrier of the metal powder and is deposited along a programmed print path to construct a 3D part. The as-printed parts are debound in several steps to ensure complete binder removal and pressureless sintered, targeting high densification levels. In this work, a copper-based filament was utilised as feedstock material and a full factorial design of experiments was performed to study the effect of layer height, volumetric speed and flowrate multiplier on the density of the as-printed part. Selected specimens from the DoE were debound and sintered and characterised. Various tests including density measurements, SEM, optical microscopy, micro-CT, etc., were applied at different stages to evaluate the porosity in the filament and printed parts. As a result, a relative density of 94% and an electrical conductivity of 63 %IACS (international annealed copper standard) were achieved for the sintered copper, which could be directly linked to the purity of the feedstock material.