Analysis and simulations on molding experiments of 3D thin shell parts have been conducted. Moldings with POM having three different thicknesses were carried out, to see their effect on warpage on the part. The moldings were conducted with a thermal and three pressure sensors along the part, in order to compare the process with simulations. The warpage on the parts were characterized by measuring distances, at four different locations in the part, using a CMM. Molding simulations have been executed taking into account actual processing conditions implementation in the software. Various aspects of the simulation set-up have been considered in order to improve the simulation accuracy: machine barrel geometry, injection speed profiles, cavity injection pressure, melt and mold temperatures, material rheological and pvT characterization. Quality factors investigated for the quantitative comparisons were: injection pressure profile, short shots length, flow pattern, temperature profile and warpage. The importance of a calibrated molding process monitoring for an accurate implementation strategy of the simulation and its validation has been demonstrated for thin shell parts. Furthermore, the effects of venting conditions in the mold on the process repeatability and on cavity injection pressure were investigated. A reliable molding experimental database was obtained, accurate simulations were conducted and a number of conclusions concerning improvements to simulation accuracy are presented regarding: ultra cooling effect on pvT data, finite volume mesh size, application of the short shots method in thin-wall injection molding, the use of cavity pressure for process control validation, the role of IM machine geometry (nozzle, injection chamber) on simulation accuracy, and finally the sensitivity of simulation results depending on the quality of material data characterization, hereunder pressure dependent viscosity. Eventually, simulations of thin wall thickness sub-gram molded parts have been optimized and a methodology for improved molding simulations of cavity injection pressure, filling pattern and warpage was established.