ADVANCED PHOTO-FABRICATION SYSTEM FOR THERMOSETTING MATERIALS
Paulo Bártolo, Geoffrey Mitchell
Polytechnic Institute of Leiria
Portugal

Keywords: Photo-fabrication, curing, stereolithography

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Optical and thermal effects are simultaneously used, in a new fabrication process for rapid prototyping, to locally induce a phase change in a liquid resin. This process involves two distinct chemical reactions occurring simultaneously, the thermal-initiated curing reaction initiated by heat and the photo-initiated curing reaction initiated by UV irradiation. The resin samples used have small concentration of thermal and photo-initiators, showing a very low reaction rate when they occur separately. However, when the two effects intersect each other, the population of radicals produced will be sufficiently high to initiate the curing reaction with a higher reaction rate. On the other hand, the coupling of temperature and UV radiation induces an increase in the temperature, in the regions where both effects are present, with advantages in terms of reaction rate and fractional conversions, improving the process in terms of a better localised curing reaction.
The proposed photo-fabrication process is described in detail in this paper from a chemical and physical point of view, and its major advantages with respect to conventional stereolithography are outlined in terms of accuracy, cost and time.