Freeformer from Arburg offers a new additive manufacturing technology and gives new opportunities to manufacture parts of high quality.. The main advantage is the use of polymer pellets as raw material which offers the possibility to process any plastic commercially available. . The transformation of standard materials using the Freeformer (ABS, TPU, supporting material, PS) is as easy as the inkjet printing one. However, in the case of non-standard materials the process has to be optimized in order to gett goot quality parts.. In the same way that for regular polymer processing technologies like injection molding, optimization of the processing parameters and the choice of appropriate polymer grade is needed. Freeformer technology is based on two injection molding units enable to melt standard pellets and to feed the printing head. The discharge unit featuring a pulsed nozzle closure generates small (down to 300 μm) molten polymer « droplets » contituting, layer- by-layer, the three-dimensional part. A common approach to optimize the part structure (porosity, adhesion between layers, dimensional accuracy), is to realize a parametric study. However, this approach is time consuming and not always efficient. Thus, a better understanding of the correlations between materials and process is needed. The different steps of part building have been examined through model experiments in the case of polyolefin materials (PP and PE). The first step to optimize is adhesion of the polymer « droplets » onto the platform. Therefore, specific materials (blends of PP or PE with several contents of PA) contituting the platform has been developed . . The material choice dedicated to the platform was made based on adhesion tests and evaluation of mutual diffusion (part/platform) through rheological tests. Concerning parts construction, optimization of adhesion between the part layers was carried on thanks to the determination of coalescence, reptation and crystallization times