Review on additive manufacturing and non-destructive testing

Additive manufacturing is based on high-precision material deposition to build a final part or component by using various techniques. It is being one of the main advances in the fourth industrial revolution. This type of manufacturing is not new, although it is growing. There are many types of additive manufacturing techniques, and the use of efficient inspection methods to ensure a certain level of quality, and to detect faults, porosities, etc., are required in the industry. Nondestructive Testing is widely applied, and particularly in additive manufacturing, to ensure efficient quality control and preventive/predictive maintenance without changing the characteristics and initial state of the material. Each Nondestructive Testing technique is based on different physical principles; therefore, the selection and correct use of each technique depends on the application, the manufacturing process, the type of material and the possible discontinuities, among many others. This article develops a complete, exhaustive, and updated review and analysis of the state of the art of Nondestructive Testing applied in additive manufacturing. The main characteristics of the processes are analyzed, highlighting the most relevant works and the challenges that each technique should face. An analysis of techniques necessary for the development of Nondestructive Evaluation has been carried out, mainly Machine Learning techniques used for the quantification, detection and analysis of defects detected by Nondestructive Testing techniques.