In modern engineering process, designers, engineers, and technicians commonly use several computer assisted technologies to design and to evaluate their products at each stage in the product development cycle. Computer assisted technologies for product design usually comprise among their tools Computer Aided Design (CAD), Computer Aided Engineering (CAE) and Computer Aided Manufacturing (CAM). CAE systems are those ones capable to solve, based on any numerical method, a set of algebraic equations to obtain desired results in function of loading and the boundary conditions of process. CAE programs are used to calculate tensions, shifts, vibration, heat transfer, fluid flow, and other process parameters. In this work, in order to analyze a type of Rapid Prototyping technique, it has been developed a numerical model able to simulate the heat transfer at thermosensitive polymeric material during cure by laser irradiation. The analysis has been carried out as a transient thermal problem using the general-purpose finite element software ANSYS. The technique considered in this work is the Infrared Thermolithography (IRTL) that is a Rapid Prototyping (RP) process that makes use of a CO2 laser beam to cure, or solidify, thermosensitive polymeric materials producing three-dimensional parts. To improve the process of localized cure, it is necessary an effective control of the parameters involved. In order to study the process and optimize the localized cure, a numerical model was developed to simulate the thermal behavior of samples during cure by CO2 laser irradiation. The numerical model is able to simulate the heat transfer during a repetition of laser pulses over a polymeric material. The obtained numerical results agree with previous experimental observations, and the numerical model developed shows to be an important tool to continue the investigation of process parameters influence in order to optimize the Thermal Stereolithography process. In this work, numerical results obtained applying two different approaches of heat diffusion during simulations are compared in order to analyze the developed numerical model. ANDRADE, S.R, JARDIM, A.L., SOUZA, E.N, MACIEL FILHO R, Proceedings of the 2nd International Conference on Advanced Research in Virtual and Rapid Prototyping, vol2, pp. 519-525, 2005ANDRADE, S.R., Simulação Numérica do Processo de Solidificação de Placas Finas com Redução da Espessura com Núcleo Líquido (2003), Phd Thesis, Faculty of Mechanical Engineering, UNICAMP, Campinas, SPBARROS, M.L., SCARPARO, M.A.F., GERCK, E., KIEL, A., HURTACK, J.J., (1994) J. of Appl Pol. Sci, 54BARTOLO, P.J., MITCHEL, G., (2003) Rapid Prototyping J, 9 (3), pp. 150-156BEAMAN, J.J., MARCUS, H.L., BOUREL, D.L., BARLOW, J.W., CRAWFORD, R.H., (1997) Solid Freeform Fabrication: A New Direction in Manufacturing, , Dordrecht London: Kluwer Academic PublishersBELFORE, D.A., (1993) Laser Focus World, 126BIRD,B.R., STEWART, W.E., LIGHTFOOT, E.N.,Transport Phenomena, John Wiley & Sons Ed., New York, 1960CERVERA, G.B.M., LOMBERA, G., (1999) Rapid Prototyping J, 5 (1), pp. 21-26FLANDIN, L., VOUYOVITCH, L., BEROUAU, A., BESSEDE, J.L., ALBEROLAU, N., (2005) J of Phys D, Appl Phys, 38 (1), pp. 144-155GARCIA, A., (2001) Solidificação: Fundamentos e aplicações, , Campinas, SP: Ed. UNICAMPINCROPERA, F.P., DEWIT, D.P., (1998) Fundamentos de Transferência de Calor e de Massa, Ed, , Livros Técnicos e Científicos, Rio de JaneiroJACOBS, P.F., (1996) Stereolithography and Other RP&M Technologies: From Rapid Prototyping to Rapid Tooling, , SMEJARDINI, A.L., MACIEL FILHO, R., SCARPARO, M.A.F., ANDRADE, S.R., MOURA, L.F.M., (2004) J. of Mat. and Prod. Tech, 21, pp. 241-245. , 4JARDINI, A.L., ANDRADE, S.R., MOURA, L.F.M., SCARPARO, M.A.F., (2006) J. of Mat. Tech.Proces, 102, pp. 104-109JARDINI, A.L.M., SCARPARO, M.A.F., WAGNER, P.R.S., IERARDI, M.C.F., KIEL, A.E., (1998) J. of the Brazil. Soc. Mech. Sci, 20 (2), pp. 146-154JARDINI, A.L.M., SCARPARO, M.A.F., MARINHO, G., SALLES, D.S., ALLEN, S.D., (2000) Proceedings of Laser Application in Microelectronic and Optoelectronic Manufacturing, USAKAPLAN, R., (1990) Stereolitography: A Marriage of Technologies, , JuneLADOUCE-STELANDRE, L., BOMAL, Y., FLANDIN, L., LABARRE, D., (2003) Rubber Chem and Technology, 76 (1), pp. 145-159LIU, G.R., LEE, J.H., PATERA, A.T., YANG, Z.L., LAM, K.Y., (2005) Comput. Methods Appl. Mech. Engrg, 194, pp. 3090-3107ROSEN, S.L., Fundamental Principles of Polymeric Materials, New York Willey Ed., 1982SANTOS, R.G., ANDRADE, S.R., PERALTA, J.L., (2003) Mater Sci Forum, 426, pp. 1499-1504ZIENKIEWICZ, O.C., PAREKH, C.J., WILLS, A.J., The Application of Finite Element Method In Heat Conduction Problems Involving Latent Heat (1676) Rock Mechanics, 5, pp. 65-76