The present paper presents a heat transfer model to a new polishing process that smoothens the surface of products manufactured by fused deposition modeling (FDM) technology. FDM is one of the most common additive manufacturing techniques which, unfortunately, results in very rough surfaces when compared to similar technologies. This high roughness results from the stepped surface (stair like surface) caused by the technology nature of depositing several 2D layers to form the final 3D product. To smooth the surface, it is heated up till melting which trigger surface tension force to smooth the surface. To achieve surface melting, the surface is exposed to a localized hot air jet with certain temperature and velocity from a moving nozzle with appropriate translational velocity; this introduces three main process parameters: air jet temperature, air jet velocity and air nozzle translational velocity over the product surface. Two analytical heat transfer models were derived using different process parameters and proved to be in agreement with each other. Also, a part of the obtained experimental results verifies model results. Moreover, the effect of entrained air on the heated jet was considered in the model. It can be concluded that we have an analytical model fits the experimental one and represents the modeled process.