Improvement of the spatial resolution of prototypes using infrared laser stereolithography on thermosensitive resins

In this paper, the use of infrared laser radiation to achieve localized curing in thermosensitive materials, is presented. In stereolithography, the objective is to cure a localized region in a material by precisely confining the laser energy to the area that is to be cured. In the experiment, a CO2 laser beam at 10.6 μm (infrared radiation) was focused onto a sample with a composition of epoxy resin, diethylene triamine (curing agent) and silica powder (filler). Using a differential scanning calorimeter (DSC) we were able to determine reaction rates as a function of temperature as well as the enthalpy involved in the phase transition and activation energy of the curing process. This paper presents a numerical model for the two-dimensional curing problem with infrared radiation laser by using a Finite Element Technique in Ansys program. The solution of the heat equation simulating this process was in general agreement with our previous observations of the stereolithographic results. Results and discussion about prototypes of different geometries and sizes were performed and presented as well as discussion about width and depth of the layer cured in the prototype construction.