Chemical Smoothing of 3D Printed ABS

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Abstract
This report investigates the characterization of 3D printed materials in order to improve design guidelines and material properties of this relatively new manufacturing method – focussing on the requirements of surface finish and strength. The effects of chemical exposure to parts produced through Fused Deposition Modelling is therefore examined, regarding the ability of treatments to improve the surface finish of parts as well as their effect on the tensile properties of parts. Parts were additively manufactured through the process of FDM using the filament material acrylonitrile-butadiene-styrene (ABS). Parts were printed both flat and upright so that in-plane as well as interlaminar tensile properties could be investigated. Chemical treatment methods included dipping in an acetone solution and acetone vapour smoothing. Microscopic images as well as surface roughness tests examined the effect of these smoothing methods on the surface finish of each specimen and average roughness values were compared before and after smoothing. Lastly, the tensile properties of each specimen were investigated through elongation until fracture within a Zwick tensile tester. Strain readings were obtained from an extensometer as well as Digital Image Correlation and these differing results were compared. The strength data of treated and untreated specimens, in both testing directions were also compared. Results obtained from the investigation showed that dipping was a more effective smoothing method than cold vapour smoothing, although parts were adequately smoothed using both techniques. It was also found that in-plane specimens could withstand higher stress values than interlaminar specimens – 28MPa compared with 18.8MPa, and were more ductile as they withstood greater elongation before fracturing. There was, however, no significant difference between strength data of treated and untreated specimens – for both smoothing methods. ABS parts can therefore be smoothed to improve their surface finish without altering their strength properties to a large degree.
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