In this thesis a new efficient model has been developed in the thermal analysis of Laser Powder Bed Fusion, an Additive Manufacturing (or: 3D-printing) method that is used to manufacture metal products. During this process, a laser is used as a heat source to melt metal powder grains to each other, that are solidified when cooled down. In Laser Powder Bed Fusion high temperatures changes arise at the laser spot, that are in a scale smaller than the scale of the manufactured product. This requires a very fine spatial discretization (or: mesh) if the thermal analysis is done purely numerical. A fine mesh leads to high computational cost. Various methods have been previously developed to reduce this costs, like the semi-analytic method. The new model in this thesis is ased on a the previously developed thermal model that uses the semi-analytic method....