Browsing by Author "Sacks, Natasha"

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    Improving the R&D process efficiency of the selective laser sintering industry through numerical thermal modeling
    (2019) Olivier, Carlo Martin; Oosthuizen, Gert Adriaan; Sacks, Natasha
    ENGLISH ABSTRACT: The selective laser melting (SLS) industry is a relatively novel industry within the broad spectrum of available additive manufacturing (AM) technologies. As with most developing industries, the primary aim is to develop better quality components at reduced costs, often with a disregard towards efficiency. Resource efficiency is a key component of waste management and ties directly to sustainable manufacturing. In the SLS industry, large quantities of raw material are wasted during the machine calibration stage. Each time a new material is developed for SLS manufacturing a specific set of processing parameters need to be developed in order to ensure that high density, high strength components are produced. This paper investigates the possibility of replacing the current inefficient research and development (R&D) methods with numerical modeling. The fusion process can be simulated in a numerical thermal model using a combination of temperature dependent material properties and heat transfer principles.
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    Influence of powder characteristics on the spreadability of pre-alloyed tungsten-carbide cobalt
    (Southern African Institute for Industrial Engineering, 2021) Govender, Preyin; Blaine, Deborah Clare; Sacks, Natasha
    With rising interest in additive manufacturing (AM) techniques, there is an increased focus on research that evaluates critical parameters that guide the selection of powders that are suitable for AM. One such parameter is a powder’s spreadability, described by metrics such as powder bed density and percentage coverage. This study focused on three spray-dried WC-Co powders (two 12 wt% and one 17 wt% Co) and evaluated the influence of typical powder characteristics, such as particle size and shape, apparent density, and flow rate, on their spreadability. It was found that particle size distribution influenced the powder spreadability. Larger particles hindered the even spreading of powder over the base plate, resulting in low powder bed density and percentage coverage. This also correlated with the powders’ apparent densities. The flow rate and angle of repose gave an indication of how cohesive the powders are. The more cohesive a powder, the poorer the spreadability, resulting in a lower powder bed density and percentage coverage.