Biomedical Engineering Reference
In-Depth Information
C
O
Ca
P
Ca
0.50
0.90
1.30
1.70
2.10
2.50
2.90
3.30
3.70
4.10
4.50
Fig. 6.19
EDAX pro fi le of the b -TCP particle from the biocomposite materials (70% PDLLA + 30%
b -TCP)
the model using a second extrusion nozzle and a different material. These water
soluble structures are removed after building the prototype.
In building a prototype with FDM the process takes different steps as listed
below:
•
STL fi le creation.
After obtaining the 3D CAD model of the part, data are con-
verted to STL file format and read by the QuickSlice software. Process planning
(part building orientation, support structure design, sectioning, path planning,
and process parameter selection) is also made using the same software.
•
Sectioning
. The prototype is cut in cross sections (used values for layer thick-
ness: 0.1778, 0.2540, 0.3556 mm) and contour curves (perimeter) are determined
for each layer. Data resulting from sectioning (stored in a .SSL file) are the cross
sections of the prototype.
•
Building support structures
. Depending on the geometric shape of the prototype,
supports are built for sustaining the parts' structures in console and for prevent-
ing building the part directly on the platform (base support).
•
Determining FDM head path
. FDM heads move in XY plane following the
planned paths. Extruded material paths have certain features, called attributes,
defined by the user for each particular group of curves. After defining the neces-
sary attributes of each set (curves having the same attributes), data is stored in a
file, .SML (Stratasys Machine Language), which controls the drive wheels and
motors of the FDM head and platform.
•
Prototype construction
. SML data are transmitted to the Modeler (FDM machine)
and the physical prototype is built.
•
Elimination of support structure and finishing the prototype
. A cleaning system
is used for eliminating the water soluble support structures after the building
process is fi nished.
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