Porosity formation in high pressure die casting (HPDC) impacts mechanical properties and casting quality. Much is published regarding micro porosity and its impact on mechanical properties, but there is limited research on the actual formation of macro porosity. In production applications, macro porosity plays a critically important role in casting quality and acceptance by the customer. This paper argues that the most useful definition of macro porosity is the limits of visual detectability. With this definition, it will be shown macro porosity presents stochastically within a controlled HPDC process. This means macro porosity has a random probability distribution or pattern that should be analyzed statistically and cannot be predicted precisely. The general region where macro porosity forms is predictable with simulation, but its actual size and distribution of the voids are random. These results challenge the industry accepted practices for inspections and process controls. This also underscores the importance of up-front design for manufacturability to avoid macro porosity-related quality issues.

高压压铸（HPDC）中的孔隙形成会影响机械性能和铸件质量。关于微孔隙及其对机械性能的影响，已经发表了很多文章，但是关于宏观孔隙的实际形成的研究很少。在生产应用中，宏观孔隙率对铸件质量和客户接受度起着至关重要的作用。本文认为宏观孔隙度最有用的定义是视觉可检测性的极限。有了这个定义，就可以看出在受控的HPDC过程中宏观孔隙是随机出现的。这意味着宏观孔隙度具有随机概率分布或模式，应进行统计分析，无法准确预测。通过模拟可以预测宏观孔隙形成的一般区域，但其实际大小和空隙分布是随机的。这些结果挑战了行业认可的检查和过程控制实践。这也强调了可制造性的前期设计的重要性，以避免与孔隙率相关的质量问题。