Additive manufacturing (AM) can produce three-dimensional parts from a wide range of materials like polymers, metals, and ceramics. High speed sintering (HSS) process is a developing polymer powder bed fusion process that has a high potential to be commercialised for high volume productions. The drawbacks of the HSS process are the low part quality and process repeatability. This is caused by a lack of understanding of the relationship between process parameters. In this thesis, cost analysis was performed to measure the commercial viability of the HSS process. A systematic study of the HSS process chain was performed to reveal areas that can affect the process output. An experimental investigation on the effect of two key build parameters (lamp and ink) and a post-processing technique (PUSh process) on the dimensional accuracy and tensile strength of parts was conducted. A novel non-destructive characterisation technique using reflectance spectroscopy was introduced to monitor process repeatability and reproducibility. A novel analytical model was developed to quantify the energy density of a part and predict its future performance. The cost analysis for potential commercial HSS machines showed that the cost per part was half the laser-sintering equivalent. An elastomeric material, ALM TPE210-S was successfully processed using HSS. The PUSh process enhanced the mechanical properties of parts by 50-225% at the expense of size reduction (~-5 %). The lamp irradiance and ink volume had significant effect on parts made from EOS PA2200 material. The results showed a positive correlation between reflectance and tensile strength, which suggested the suitability of visible spectroscopy as a quality assessment tool. The constructed energy density model (HSSED model) was validated using input data collected from the characterisations of material/equipment/part. A positive correlation was found between energy density and part properties. The research had developed an increased understanding of the HSS process and helped it move forward towards its commercialisation.