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

背景：低压粉末注射成型（LPIM）是一种先进的制造工艺，用于具有类似金属铸造形状复杂性的低成本和小批量制造净形状部件。该技术利用低粘度原料（蜡基粘结剂与粉末混合）在注射步骤中实现高成型性。在随后的脱脂和烧结处理中，粘结剂从生坯部分完全去除，以获得致密的金属部分。根据金属粉末工业联合会的数据，2009年至2017年，北美金属注射成型粉末市场增长了510%。***最初用于陶瓷成型，LPIM工艺迅速成为汽车，航空航天和医疗行业金属零件快速制造的吸引力。然而，机械性能的优化已经进行了原料的最佳成型性尚未证明。因此，由于缺乏对这些混合物流变行为的基本知识，对低粘度原料可塑性机制的理解不足，限制了LPIM工艺的全部潜力的实现。目前，由于粘结剂之间的复杂相互作用和这种混合物的剪切变薄行为，对LPIM原料流变行为的建模面临许多挑战。******目标：这项发现资助提案的总体目标是提高对低粘度原料可塑性的基础知识，并开发新的实验和模拟工具来预测LPIM原料在注射过程中的流动行为。这将通过开发一种实验方法来研究蜡基原料的可塑性（目标#1），然后用于开发和验证模拟注射过程的数值模型（目标#2）来实现。最后，将利用新的数值模型来确定候选原料，这些原料将被加工（脱脂和烧结），以评估LPIM制造零件的机械性能（目标#3）。******成果：通过提供一种创新的制造方法，这些LPIM研究工作有可能改变和影响一些工艺工程实践，这种方法可能会在使用具有适当尺寸公差的硬金属材料生产复杂形状零件方面取得真正的突破，这是加拿大制造业的主要目标之一。这项研究计划的影响还将体现在培训高素质人才、在开放获取知识库中传播成果以及在竞争性关键领域（如航空航天、石油、卫生技术和许多其他部门）进行技术转让等方面

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.**