Meccanica Magazine n. 4

ENG
LIS4.0 project: interview with Francesco Braghin, head of WP2
1. What is the WP2 of the LIS4.0 project about? Which are the
challenges it must face?
WP2 of LIS4.0 has dealt with the design and production of sensorised
extruders capable of impregnating the long carbon (or glass) fibres
with a thermoplastic matrix in an optimised way and of depositing
the impregnated fibres on the component being produced at optimal
temperature and pressure to maximise adhesion and mechanical
performance of the final piece. The design brought up many
challenges: if the fibre isn’t correctly “wettened”, the performance of
the ultimate manufactured piece will be worst than expected; if the
printing head doesn’t apply the expected pressure or temperature,
it will not properly stick to the underlying surface; if the extrusion
speed isn’t in sync with the speed of the end-effector of the robotic
arm, not only the components will not be shaped as desired but also
the risk of having a wrinkled component will increase or fibres will
break during the deposition process.
2. Which are the innovative solutions explored for composite
material structures, both in terms of design and management of
the product lifecycle?
To tackle the challenges mentioned above, it is necessary to
implement an integrated approach: the extruder must take into
account the material to be extruded as well as the manufactured
product on which to deposit the fibre in order to optimize the speed
profiles and the trajectory of the extruder itself. Therefore, the
adopted approach was holistic, meaning that it took into account the
starting material, the technological extrusion – pultrusion process,
the mechanical structure of the extruder as well as its control, and
the robotic arm used. Moreover, considering that the long fibre
could also be made of glass, monitoring of the manufactured object
can easily be implemented (for example, through a technology called
Optical Backscatter Reflectometer – OBR). Thus, the final result
is a 3D-printed carbon structure with an integrated distributed
monitoring system capable of assessing mechanical and thermal
stresses. This improves the safety and reliability of the component.
3. Which applications can be activated by sensor integration or the
development of materials with self-healing features?
Monitoring critical (and even non-critical) components is currently
of increasing interest since it allows to change the maintenance
approach: from programmed to predictive.
For mission-critical components, this perspective change is
crucial. Nowadays, to maintain the required safety standards, it is
mandatory to frequently carry out non-destructive inspections,
which are money and time-consuming. On the contrary, by adopting
an integrated monitoring system, it would be possible to foresee the
component’s remaining life and intervene when necessary.
4. Which prototype developments were carried out in BAAM 3D
moldless?
At the time being, simple samples were created, which enabled us
to test the quality of the developed system and the implemented
process. The desired outcome remains producing mechanical
components for automotive
meccanica magazine
101