Evaluating the effects of selective laser sintering processing parameters on the melt pool dimensions of tungsten carbide through numerical thermal modeling

[摘要] ENGLISH ABSTRACT: The selective laser sintering (SLS) industry is a relatively novel industry within the broad spectrum of available additive manufacturing (AM) technologies. This layer wise processing technology has gained popularity over recent years, due to its ability to produce low volume, highly complex components made from difficult to process metal materials.A major driver for this industry is the development of materials for new or improved applications. However, each time manufacturers want to add a new material to their machine, a specific set of processing parameters needs to be developed for that material in order to ensure that high density, high strength components are produced. The primary aim of this developing technology is to produce high quality, low costs components, yet it still struggles to overcome inefficiencies relating to the product development phase. Currently, large quantities of raw material are wasted during the machine-material calibration stage in the SLS industry.The aim of this study was to investigate the possibility of improving or replacing the current inefficient research and development (R&D) methods of the SLS industry with numerical modeling. In this study, a numerical thermal model was developed, which manufacturers can use in their production facility, in order to predict changes in the melt pool geometry for new or unconventional materials by changing certain processing parameters. This will allow them to make decisions regarding other machine input parameters such as the scan track hatch spacing and layer thickness before performing any physical calibration tests.Tungsten carbide (WC) was selected as the main processing material for this study, as it is still a relatively novel addition to this technology field. WC has an array of unique material properties, which makes it ideal for application in industries such as the mining, tooling and oil and gas industries.A numerical thermal model was used to develop a feasible set of processing parameters specifically for processing tungsten carbide. The results from the numerical model were validated by comparing the simulated melt pool geometry to that of experimentally produced samples. The simulation was able to predict the change in the melt pool geometry with the change in processing parameters successfully. However, the result comparisons revealed that there were still deviations present between the simulated and the actual measurements. The highest deviations between the simulated and actual melt pool geometry measurements were found to be 24% and 50% for the scan track width and penetration depth, respectively. Additionally, a cost comparison revealed that the simulated calibration method was 46.5% more affordable than that of the conventional calibration techniques used in the industry.Although, the findings of this study are not enough to suggest that numerical modeling should replace traditional calibration methods completely, it rather motivates using numerical thermal modeling in addition to current techniques in order to assist with decision making and reduce the scope of the calibration process. This scope reduction may lead to cost savings and increased sustainability, which will ultimately improve the efficiency of the SLS process chain.

[发布机构] Stellenbosch University