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. Suitable binder was obtained from different characterization
and printing test. 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
finish surface of the sintered parts is highlighted.