The optimization project described in this paper was produced by
a team of experts – in materials (University of Modena and Reggio Emilia), in metal AM (Additiva Srl), and in
the virtual optimization of the AM process
The process to evaluate the best configuration
for the part to be printed was developed as
A. Printing a reference shape and measuring
the distortion to calibrate the model
B. Executing a set of rapid simulations to
identify the best orientation/positioning for
the part inside the build platform
C. Analyzing the distortion tendency (maximum and average
D. Analyzing the process time
Table I - Results of screening on part orientation
A. Model calibration
In order to configure the 3D printing machine set-up and the laser
parameters identified to melt the aerodynamic wing part, a crossshaped
sample was printed using a CONCEPT LASER M2 system. This
sample was measured to establish its deviations from the nominal
ones used by the software in order to calibrate the model’s response.
This approach is used in the preliminary stages of modelling to
accelerate computing time while ensuring that the model suitably
represents the process.
B. Orientation and positioning
Four positions were developed for the part, as shown in Fig. 2. Two of
them (2 and 3) were selected to minimize the printing time (minimum
job height), while the other two (1 and 4) were expected to result in a
minimum mass for the supports in the critical areas of the part.
The software enables the maximum displacement of the part to be
estimated, and the areas where that distortion is expected to be
identified. Table I summarizes the results of this screening phase (the
qualitative levels of distortion and the workload necessary to remove
the supports was assessed by the manufacturer based on experience).
Orientation no. 2 had the maximum expected displacement, while
Orientation no. 3 had the minimum one. Orientation no. 3, however,
would require a high mass of support structures that would be
difficult, or even impossible, to remove. While the internal support
structures could be left inside the cavities, this would unacceptably
increase the weight of the part. Consequently, Orientations no. 2 and
3 were discarded and not investigated further.
Orientation no. 1 showed a maximum displacement that was
higher than the one of Orientation no. 4, yet, Orientation no. 4 had
the maximum height in the Z axis, leading to greater printing time
and cost. This simplified model showed that neither Orientation no. 1
nor no. 4 fulfil the design requirement of a maximum distortion less
than 0.6 mm.
When considering both the manufacturing times and the distortion
tendency, however, Orientation no. 4 was the most promising
candidate for printing: the increased printing time did not cause
consistent variations in the total production cost, and the primary
purpose of the project was to reduce the number of deformations.
C. Analysis of the distortion tendency
The third step consisted of developing a compensated geometry.
ANSYS Additive Suite simulates the laser melting process, predicts
distortions, and develops a new compensated geometry by reversing
the distortion effects. The melting of this new compensated geometry
should significantly reduce the distortions, resulting in a part as close
as possible to the original 3D model.
Fig. 3 shows the new compensated geometry. A maximum
displacement of 0.70 mm was observed on the red surface. The
slight difference from the analysis described in (B) was due to the
simulation assumptions: in this case, to obtain a better estimate of
the distortion, a finer mesh was used in
addition to the actual scan pattern.
The part was printed both using the
uncompensated geometry (not shown)
and the compensated geometry for
Orientation no. 4 (Fig. 4). 3D optical
scanning was used to measure the
surface of the part in three scenarios:
after the melting process (with parts
and support structures still attached
to the build platform); after stress
reduction; and after removal of the supports. The results of the dimensional
measurements, shown in Fig. 5, are in agreement with the simulation
result in terms of position, maximum and minimum deviation from
the nominal values, as well as the tendency towards improvement by
moving the solution from four different orientations.
The comparison between the simulation results and the 3D scans
of the printed parts clearly shows how it is possible to obtain an
accurate output through simulation, which can predict the location of
the maximum distortions in the upper part of the component.
Just from the preliminary simulations,
it was possible to keep the maximum
distortion below 0.59 mm. Compensation
further improved the quality of the part,
with a maximum displacement of 0.48 mm
and a lower average and standard deviation
of the absolute value of the distortions.
These results were achieved with a single
simulation iteration; better results could be
achieved with more iterations in order to
better estimate the effects of distortion, and
thus generate a more effective compensated