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2014-09-11 - Colloque/Article dans les actes avec comité de lecture - Anglais - 7 page(s)

Demarbaix Anthonin , Ducobu François , Rivière Edouard , Filippi Enrico , Petit Fabrice, Preux Nicolas, "TRAJECTORIES IN LASER MACHINING CERAMICS: THERMAL MODEL TO CONTROL MATERIAL REMOVE RATE" in Eleventh International Conference on High Speed Machining, Prague, Czech Republic, 2014

  • Codes CREF : Sciences de l'ingénieur (DI2000), Mécanique (DI1240), Lasers (DI125A), Usinage (DI2131), Conception assistée par ordinateur (DI1247), Connaissance des matériaux (DI2111)
  • Unités de recherche UMONS : Génie Mécanique (F707)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
Texte intégral :

Abstract(s) :

(Anglais) Ceramic machining faces a lot of practical problems due to its mechanical properties leading to high cutting fortes (yield strength), fast tool wear (hardness) and problems to achieve given tolerances (brittle behavior). Laser machining is an attractive alternative to conventional machining techniques because this technology is a non-contact, non-abrasive one which eliminates tool wear, cutting forces, vibration… The machining of the Yttria-stabilized tetragonal zirconia polycrtistalline (Y-TZP) ceramics which is commonly used in the dental restoration was studied. Laser machining is a method allowing building of a ceramic piece layer by layer by removing material. However, the problem of this method is to master material removal rate. In fact, the thermal effects plays an important role during laser machining because of appearance of hot spot that could cause an uncontrolled material removal rate. Results of these investigations have compared several paths to predict the better trajectory allowed for a steady rate. To do this, a first step of the laser machining process is modeled with the finite elements method. A thermal model of a moving heat source is developed with the software ABAQUS v6.11. The power output of the YAG laser, the repetition rate, its spot diameter and the scanning speed are implemented in this model. Several paths were studied (Zig-Zag and Contour parallel) and compared with the reference laser machining strategy (unidirectional-Zig). A method based on the heating time and the temperature map on a path has been developed to compare these different trajectories. Our simulations show that when heating a pocket, hot spots with contour parallel trajectory are lower than the maximum of reference strategy. By contrast, the Zig-Zag strategy is avoided due to the apparition of a hot spot. Considering heating time, contour parallel strategy is better than the reference strategy (Zig) because the laser beam must be stopped to be again on one new trajectory. But this trajectory would be preferable for machining of pocket without island. Finally, an island of different sizes was implemented in pocket model. The contour parallel strategy remains more interesting than the Zig strategy. Indeed, the hot spots are again lower than hot spots of Zig trajectory. The heating time of the Zig strategy is more important than the contour parallel strategy. This modeling approach could be used to others techniques as cladding technique and selective laser melting of metals.