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Bishop and Leigh
for the thermoplastic component was 3DFilaPrint
Premium polylactic acid (PLA) 2.85 mm
(3DFilaPrint, UK). All print parameters were
previously determined empirically through an
iterative process. The key print parameters used
were: 1.8 mm extrusion width; 1 mm layer height;
0% infill; 230°C extrusion temperature; and
50 mm/s default printing speed.

3 Results and discussion

A typical face shield for use during the COVID-19
pandemic comprises several key components
(Figure 1): A headband (1), clear lens/visor Figure 1. Typical components that make up an
(2), a strap (3), top protection (4), and a bottom emergency face shield.
support piece (5). Other crowdsourcing projects
have sought to produce the headband and bottom
support pieces using desktop 3D printers. Within
this study, LSAM was applied in the same way
but with the goal of speeding up the production of
these parts by approximately ×20.
The design requirements dictated by the
functionality of the 3D printed parts were as follows
(key function analysis, Figure 2). The headband is
needed to easily conform to the user’s head and
hold a lens/visor with sufficient splash protection
to meet the required regulations. The headband also
needed to have a way to be held onto the head of the
user using some form of strap and be lightweight
as it would need to be worn for extended periods
of time. The parts of the face shield should also
be entirely free from sharp regions or defects that
are likely to cause injury or discomfort to a user.
To aid clarity for this paper, the production of the Figure 2. InVision Freehand schematic showing
largest component, the headband will be the focus. the design methodology employed in optimizing a
As the target production time for the headband was design for large-scale additive manufacturing.
sub-10 min, the design needed to be fully optimized To print effectively, the minimum feature size
for production with LSAM, leveraging the key of the printed design needs to be specifically
advantages of the process. The material used for
the thermoplastic component was 3DFilaPrint selected as it is determined by the nozzle diameter
Premium PLA 2.85 mm (3DFilaPrint, UK). of the LSAM system (tool diameter analysis). For
To optimize the design, the obvious strategy to example, the minimum horizontal width of any
adopt first in designing a part for LSAM is reducing section which protrudes from the main headband
the amount of material required (dematerialization) must be at least ×2 nozzle diameter, but no larger
which dictates that all material must contribute to than ×2.5 nozzle diameter, or else, the printed
the critical function of the device, with no excess, extrusions will not bond together (parametric
unrequired material present. design based on tool diameter). To reduce overall

International Journal of Bioprinting (2020)–Volume 6, Issue 4 53