In injection molding, during the filling phase, the polymer in contact with the wall solidifies developing the so-called skin layer. Although the skin layer formation mechanism can be interpreted by exploiting the no-flow temperature for amorphous polymers, there is still a low understanding of what happens for the semi-crystalline. In fact, for these polymers, the high shear stresses combined with the thermal gradient at the polymer-mold interface, cause the so-called flow-induced crystallization. This work aims to experimentally investigate the skin layer formation at different injection molding processing conditions. A full factorial DOE was performed in a state-of-the-art microinjection molding machine using a commercial PET pushed into an open-cavity mold. The thermal and mechanical boundary conditions at the polymer-wall interface were varied using insulating coatings and different flow rates, respectively. The mold coatings were applied to different steel substrates to address the substrate thermal conductivity contributions. The in-line acquisition of the cavity pressure allows for the assessment of the contributions of the modified boundary conditions to the skin layer formation. The results show that the insulating mold coating succeeds in delaying the skin formation during mold filling, leading to a lower pressure gradient inside the cavity. The cavity pressure against filling time curves obtained in coated setups show different trends to the uncoated setup. Keywords: Injection molding, Skin layer formation, Coatings.