Hybrid additive/subtractive manufacturing system to prepare dense and complicated ceramic parts
Résumé
As the conventional binder jetting method is limited in terms of
achievable density and finish surface, a new concept of hybrid
subtractive/additive manufacturing system has been recently
developed. The system relies on a modified binder jetting machine
which integrates a slurry-based deposition system and a pulsed
laser. The slurry-based deposition system is a spray device which
can be an alternative to the recoating blade traditionally used to
spread layers of coarse powder. By using slurry containing fine
ceramic grains, thin layers of highly packed powder can be obtained
which is highly beneficial to improve the sintered density of printed
parts. The other limitation of binder jetting is the rough finish
surface. Thanks to the smallness of the spot size, a pulsed laser is
a good option to refine the contour of each printed layers thus
enhancing the overall part resolution and smoothness.
The present work exhibits some preliminary results obtained
using this new concept of hybrid machine. Parts made in alumina
have been produced demonstrating the advantages and current
limitations of the new approach. Alumina powders have been
processed to change the particle size, distribution and morphology
in order to assess the influence of these characteristics on printing
behavior. Furthermore, process parameters were studied such
as layer thickness, deposited amounts of binder on each layer,
spreading speed of recoater. This work also reports the results of
the first tests using the laser to refine the borders of each printed
layer. The influence of this treatment on the finished surface of the
sintered parts is highlighted.