The morphology of high-density polyethylene (HDPE)/polyamide-6 (PA-6) blends with different melt-shear-viscosity ratios (VRs), prepared by combining a single-screw extruder with a convergent die was studied. Two different screw geometries, metering and mixing screws, and three screw speeds, 20, 40 and 60 rpm, were evaluated to investigate their effects on the morphology of extruded ribbons. Two mixing screws with low and high shear intensity, respectively, were used. Both the geometry and speed of screw were found to have an important role in the morphological changes of the blends. In contrast to previous studies, the results shown in this work reveal that it is possible to develop a laminar structure of PA-6 in an HDPE matrix with a VR larger than one by controlling the flow fields, through appropriately combining the type and shear intensity of the screw with its speed. A well-developed laminar PA-6 phase with an aspect ratio of about 100 was obtained under the optimum combination.