Over the last few years, we carried out various studies of the micro injection molding process and micro injection molding products. In particular, our focus was on the study of the microstructure, morphology, and properties of microinjection parts using polyoxymethylene (POM) as a model semi-crystalline polymer. The work was based on experimental and simulation studies in simple rectangular cavities and in stepped cavities with abrupt changes in thickness. In continuation of this work, we considered the effect of two flow configurations, contracting and expanding, on the developed morphology of POM under the severe strain rates and high thermal gradients provided by the micro injection molding process using two three zones stepped plaque cavities. Two levels (low and high) of mold temperature and injection speed were tested. The morphology developed in each zone was examined in the flow direction using either polarized light microscopy (PLM) or scanning electron microscopy (SEM). Compared to conventional injection molding, more complex morphological structures are obtained, caused by local flow conditions and thermal gradients. The morphology depends strongly on the local thickness of the molding and thickness changes. X-ray diffraction was also used to assess the microstructure in each thickness zone. Differential scanning calorimetry (DSC) was used to evaluate locally the developed crystallinity. In the presentation, we shall compare and explain the microstructural and morphological characteristics in both the contracting and expanding flow configurations and how they can relate to those observed in micro gears.