Injection moulding is a strategically important process for thin-wall components in the high volume, rigid plastics packaging sector. Component function is critically dependent on flow-induced micromorphology, especially in thin-sections where flow and heat transfer effects are very complex. Polymer characteristics and processing conditions therefore have an important influence on the physical properties obtained. Research objectives are aimed at obtaining in-depth understanding of different stages in the injection moulding process using real-time data acquisition. In-cavity pressures and temperatures were recorded in critical locations within the mould cavity using high performance piezoelectric transducers, subsequently analysed using a data acquisition system (Kistler Instruments AG). Virgin and modified grades of polypropylene (PP) have been investigated; parallel injection moulding simulation was also carried out using Autodesk Moldflow (AMI) software. An extensive ‘Design of Experiments’ (DoE) approach was used to understand the effect of various processing conditions on component structure / properties, using five process condition ‘factors’ (Design Expert software). Process windows were defined for each polymer type; in-cavity pressure data were obtained and interpreted. Practical pressure-time and predicted data during the mould filling cycles are similar, indicating that process simulation is fairly accurate. Some unusual flow effects were observed including melt-front hesitation, and this has been analysed using in-cavity data. Results have been interpreted in terms of the developed microstructures within thin-wall sections, including skin-core morphology and crystalline texture, obtained using optical microscopy and DSC. Concepts from the study can be utilised in materials selection, to optimise process control and to help formulate design rules for thin-wall moulded components, based upon target mechanical properties.