Closing The Loop - Towards defect free additive manufacture

制造业对革命并不陌生，从18世纪末的第一次工业革命，手工生产的机械化，一直到20世纪的计算机化，制造和生产技术不断发展。我们所处的最新工业革命--工业4.0--是由机器变得“智能”推动的。机器和系统现在都增加了传感器和人工智能，以做出自己的决定。3D打印或附加制造(AM)是这场革命的关键部分，因为它使生产以前不可能实现的部件以及更高效的设计、灵活的生产和更少的浪费成为可能。与从一大块材料开始并去除材料直到产生所需形状的减法制造相反，AM的工作原理是以高度自动化的方式逐层构建对象。然而，与许多传统的制造工艺相比，AM仍然不成熟，需要进一步的改进才能被认为是“智能”的。当用金属制造零件时，可能会出现缺陷。这些缺陷可能由裂纹、内部气孔或杂质组成，这些缺陷会显著影响制造部件的性能。这些缺陷的后果可能是组件过早或甚至更糟糕的意外故障。经过几个世纪的广泛研究，焊接、锻造和铸造等金属的制造工艺比AM要成熟得多。因此，人们对这些缺陷产生的原因以及如何优化这些过程以将其降至最低有了更好的理解。目前，AM正在进行同样的知识获取之旅；我们相信，通过采用“智能”方法可以加快这一旅程。这项工作将把创新的过程监控设备集成到AM机器中，以在构建过程中检测缺陷，使我们能够就地修复它们，并增强我们对它们发生原因的理解。这将有助于实现和加快金属AM部件的使用，用于结构最终用途和高精度应用。这种方法将使我们对新建AM组件的质量和安全性充满信心，减少对缓慢且昂贵的后处理过程的需求，并加速AM作为制造技术的采用。

The manufacturing industry is no stranger to revolutions, from the first industrial revolution in the late 18th century which saw the mechanisation of hand production, all the way to computerisation in the 20th century, manufacturing and production technology continues to evolve. The latest industrial revolution, Industry 4.0, which we find ourselves amidst, is driven by machines becoming "smart." Machines and systems are now augmented with sensors and artificial intelligence to make their own decisions. 3D printing or additive manufacturing (AM) is a key part in this revolution as it enables production of components not previously possible as well as more efficient designs, flexible production and less waste. As opposed to subtractive manufacturing which starts from a large block of material and removes material until it produces the desired shape, AM works by building (additively) an object layer-by-layer in a highly automated way. However, AM is still immature compared to many traditional manufacturing processes and requires further advancements before it can be considered "smart".When producing parts in metals, defects can occur. These defects may consist of cracks, internal pores or impurities, and these defects can significantly impact the performance of a manufactured component. The consequence of these defects can be premature, or even worse, unexpected, failure of the component. Manufacturing processes for metals such as welding, forging and casting are far more mature than AM, having been studied extensively for centuries. Consequently, there is a far better understanding of why these defects occur and how to optimise these processes to minimise them. Currently, AM is on the same journey of knowledge acquisition; a journey we believe can be accelerated by embracing a "smart" approach.This work will integrate innovative process monitoring equipment into AM machines to detect defects as they form during the build process, allowing us to fix them in-situ as well as enhancing our understanding of why they occur. This will help enable and accelerate the use of metal AM parts for structural end-use and high precision applications. This approach will give us confidence in the quality and safety of newly built AM components, reducing the need for slow and costly post-processing processes, and accelerate the adoption of AM as a manufacturing technology.