Development of low-pressure powder injection molding feedstocks to increase the moldability of metallic complex shape parts

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CONTEXT: Low-pressure powder injection molding (LPIM) is an advanced manufacturing process used for the cost-effective and small series fabrication of net-shape components with similar metal casting shape complexity. The technology takes advantage of low-viscosity feedstocks (wax-based binder mixed with powder) to achieve high moldability during the injection step. During the subsequent debinding and sintering treatments, the binder is completely removed from the green part to obtain a dense metallic part. According to the Metal Powder Industries Federation, the market for metal injection molding powders in North America grew by an impressive 510% between 2009 and 2017.Initially used in ceramics shaping, the LPIM process rapidly became attractive for the rapid manufacture of metallic parts in the automotive, aerospace and medical industries. However, the optimization of mechanical properties has been performed with feedstocks whose optimal moldability has not been demonstrated. Therefore, realizing the full potential of the LPIM process is limited by a poor understanding of the mechanisms underlying the moldability of low-viscosity feedstocks, resulting directly from a lack of fundamental knowledge on the rheological behavior of these mixtures. Today, modeling the rheological behavior of the LPIM feedstocks poses many challenges due to the complex interactions between binders and shear thinning behavior of such mixtures.OBJECTIVES: The general objectives of this Discovery Grant proposal are to improve fundamental knowledge on the moldability of low-viscosity feedstocks, and to develop new experimental and simulation tools for predicting the flow behavior of LPIM feedstocks during the injection process. This will be achieved by developing an experimental method to study the moldability of wax-based feedstocks (objective #1), which will then be used to develop and validate a numerical model simulating the injection process (objective #2). Finally, the new numerical model will be exploited to identify the candidate feedstocks demonstrating the best moldability properties which will be then processed (debinding and sintering) in order to evaluate the mechanical properties of LPIM manufactured parts (objective #3).OUTCOMES: These LPIM research efforts have the potential to change and influence some process engineering practices by offering an innovative manufacturing method that could lead to real breakthroughs for producing complex shape parts from hard metallic materials with the proper dimensional tolerances, which is one of the main goals of the Canadian manufacturing industry. The impact of this research program will also be felt in the form of training of highly qualified people, results dissemination in open access repositories, and technology transfer in competitive key areas, such as the aerospace, petroleum, health technologies, and many more sectors.