Digital image processing: advances in research and applications in additive manufacturing

Additive Manufacturing is a layer-by-layer process that permits the fabrication of very complex geometries without the limitations of traditional processes. However, defects originated during the layer-by-layer material processing, can affect the final parts. In fact, the quality of the produced component can be impacted by anomalies on a single layer, therefore interactions between layers need to be evaluated from a wider perspective. These issues introduce typical quality problems like layer misalignment, dimensional inaccuracies, and the generation of residual stress. The layerwise manufacturing approach can yield a lot of data during the Additive Manufacturing process. This data can be employed to assess the process stability and spot the beginning of errors while the part is being manufactured. Layer-by-layer real time process monitoring development has become more necessary in recent years. The quality and stability of the process throughout the layer-by-layer fabrication of the part can be ascertained by in-situ monitoring of Additive Manufacturing techniques. The measurements that can be made using in-situ sensing are known as "process signatures," and they can serve as a source of data to identify potential flaws. Digital Image Processing is a quick and low-cost monitoring method for quality control in Additive Manufacturing. This technique can provide methods for offline and online monitoring and provides access to various types of information about anomalies across build plate by processing thousands of images from the layers fabrication. It is possible to generate two and three-dimensional spatial models using objects extracted through Digital Image Processing, that can be used in statistical reconstruction modeling within a numerical procedure, such as Finite Element Analysis. This paper reviews the capability of monitoring methods based on Digital Image Processing and their application in quality control of parts fabricated via Additive Manufacturing.