Additive Manufacturing (AM) techniques create 3D objects by adding successively 2D cross-sections in the vertical direction. Fused Deposition Modelling (FDM), also known as Free Form Extrusion (FFE), is one of the most popular variants. Here, each 2D slice is built by an extruded filament that is quickly deposited onto the previously layer. The quality of parts produced by FDM is often unsatisfactory for engineering applications, namely with respect to dimensional accuracy, surface quality and mechanical performance. The latter is related to the strength of the adhesion between contiguous filaments. These attributes are strongly influenced by the processing conditions during deposition and cooling. With the aim of understanding better the effect of FDM process parameters on cooling and adhesion, a computer code was developed to predict the evolution of filament temperature and of the resulting adhesion [1]. The code contains a solution to the transient heat conduction problem that is coupled to an algorithm that activates the relevant boundary conditions for each specific deposition sequence (taking into consideration the geometry being built), and to an adhesion quality criterion [1,2]. This work studies the effect of major operating parameters on the evolution of cooling and consequent adhesion quality for a few representative parts. The thermal phenomena influencing adhesion problems are also discussed. [1] S.F. Costa, F.M. Duarte, J.A. Covas, J. Mat. Proc. Technol. 245 (2017) 167 [2] S.F. Costa, F.M. Duarte, J.A. Covas, Virtual Phys. Prototyp. 10 (2015) 35 Keywords: Additive Manufacturing (AM), Fused Deposition Modelling (FDM), Free Form Extrusion (FFE), Modelling, Heat transfer, Computer-aided engineering.