Extra-wide deposition in extrusion additive manufacturing: A new convention for improved interlayer mechanical performance

James Allum, Amirpasha Moetazedian, Andy Gleadall, Niall Mitchell, Theodoros Marinopoulos, Isaac McAdam, Simin Li, Vadim V. Silberschmidt

Research output: Contribution to journalArticlepeer-review

Abstract

Recent studies have contested long-standing assumptions that mechanical anisotropy is caused by weak interlayer bonding and demonstrated that microscale geometry (the groove between extruded filaments) is the major cause of anisotropy in extrusion additive manufacturing (AM). Inspired by those finding, this study investigates the potential for a new convention for print-path design to improve mechanical properties by setting extrusion width to be at least 250 % of nozzle diameter. The new convention enabled an almost 50 % improvement in mechanical performance, which was supported by finite element analysis data, whilst simultaneously reducing the printing time by 67 %. Whereas a typical extrusion AM part uses several side-by-side extrusions, here, three 0.4-mm-wide extrusions are replaced with a single extra-wide 1.2-mm extrusion; two 0.6-mm-wide extrusions are also studied. The contact area between layers of the extra-wide extrusion was 90 % as opposed to 63 % for the conventional approach. The improved contact area led to a 40–48 % enhancement of strength, strain-at-fracture and toughness. This study presents a compelling case for a methodological shift to extra-wide extruded-filament deposition and explains the underlying cause of anisotropic strength observed in previous studies. Two case studies demonstrate practical applicability for a print run of 1000 nylon visors and lower-limb polylactide prosthetic sockets, for which extra-wide filaments more than doubled load-bearing capabilities. Polylactide material was used for most of the study; potential for translation to other materials is discussed.

Original languageEnglish
Article number103334
Number of pages12
JournalAdditive Manufacturing
Volume61
Early online date5 Dec 2022
DOIs
Publication statusPublished - 5 Jan 2023
Externally publishedYes

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