Biomedical Engineering Reference
In-Depth Information
models are sliced and transferred to instructional parameters. Most research
laboratories rely on a script known as G-code. In all cases, the slices are
formed on the x, y plane, with the z axis presenting a variable layer spacing
or thickness. An AM machine follows tool path directions in the x, y axes to
generate a deposition layer. Once the layer is complete, the z axis is incre-
mented by one slice thickness and the process is repeated until the three
dimensional model is generated. Deposited microfilaments are deposited as
a raster (a grid of filaments) and sometimes a contour is used to better de-
fine the edge of the structure. Laying down of patterns of filaments can be
controlled and can be specified anywhere between 01 and 1801 (with respect
to the x-axis). This angle of deposition is known as the raster angle (RA).
FDM is a particular type of AM process, which uses spools of polymer
filament (Figure 9.1a). Many spool systems contain two spools for the build
and support materials. The support material is used to maintain the scaffold
d
n
3
r
4
n
g
|
1
.
Figure 9.1
Schematic of the extrusion elements of spool (a) and chamber (b) FDM
machines. Cross-section of a typical FDM fabricated scaffold (c). Three-
dimensional image of an FDM fabricated scaffold (d).
Adapted from Zein et al.
13
and Domingos et al.
12
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