In this paper correlations between the shear strength of the polymer–metal interface and the topography of the aluminum substrate are investigated, considering also the influence of the reinforcement fibers and the main injection molding process parameters. When overmolding polymer on a metal support, three different phenomena take place, differently concurring to the final adhesion behavior: (a) infiltration of the thermoplastic melt into the micron-size roughness features of the metal substrate, which is fostered by high metal substrate temperature, (b) polymer delamination from the metal substrate, due to polymer differential shrinkage during cooling, whose in-plane component is effectively contrasted by high percentage of glass fiber reinforcement, and (c) glass fiber anchorage, which fastens the polymer plate to the polymer residues interlocked within the metal substrate.