Investigating the effect of fused deposition modelling on the tribology of PETG thermoplastic

Abstract

A widely recognized consequence of the additive manufacturing process is the deterioration of mechanical properties through the development of macrodefects, microdefects, and chemical changes. This has particularly negative impacts on fatigue and wear resistance of components produced by additive manufacturing, which limits the utility of the technology for engineering applications. In this investigation, we find that glycol-modified polyethylene terepthalate processed via Fused Deposition Modelling (FDM) exhibits a significantly lower wear rate as compared to virgin material when subjected to slow-speed dry sliding contact, which is a rare case of an additively-manufactured material with improved bulk properties. Using pin-on-disk testing, we demonstrate favorable wear resistance for additively-manufactured pins against a surface ground 440c stainless steel counterface, which reflects potential utility of the material in light-duty, low-maintenance linear and rotary motion applications. The wear behavior observed under these test conditions corresponds to an order of magnitude decrease in wear relative to existing literature. Annealing the samples results in a further decrease in wear rate, while samples produced in a dry nitrogen atmosphere exhibit increased wear and a change in morphology and thickness of the transfer film. X-ray photoelectron spectroscopy testing validates that FDM printing results in material oxidation, that this oxidation corresponds with an improvement in wear performance, and that printing in a dry nitrogen environment inhibits this change.