The powder bed fusion additive manufacturing (PBF-AM) technique fabricates intricate shapes with high mechanical strength. The PBF-AM comprises two steps - powder spreading and powder fusion. Powder spreading is the fundamental and most important process, as the homogeneity of the powder bed produced by spreading determines the quality of the final parts. The sizes of powders in PBF-AM are in the order of microns and are composed of spherical and non-spherical shapes. At such a scale, particles experience forces like van der Waals and electrostatic in addition to elastic, gravitational, and frictional forces. Besides the above-mentioned force fields, other significant parameters that affect the quality of the bed are layer thickness, particle sizes and shapes, and the speed of recoater. A simulation-assisted optimization of the process parameters plays a vital role in developing PBF AM products of high quality. It is essential to consider an accurate contact model in the Discrete Element Method (DEM) to simulate the dynamic behaviour of cohesive powder particles. The present work analyses the cohesive contact models like Johnson-Kendall-Roberts (JKR) and Derjaguin-Muller-Toporov (DMT) that consider non-contact van der Waals forces for the powder spreading process. The influence of cohesive parameters and particle size distribution on the powder bed generated by the spreading process is analysed. In addition, the Tabor parameter that establishes the models' suitability range is investigated. The accuracy of the contact models will help analyse the realistic behaviour of powder flow under relevant powder compositions and operational conditions. In the present talk, the results of the detailed Discrete Element Simulation study will be presented.