A deep learning-based approach for defect detection in powder bed fusion additive manufacturing using transfer learning

Although powder bed fusion joining (TYB) metal additive manufacturing is frequently preferred in the production of complex geometry parts today, real-time monitoring of part manufacturing processes is insufficient. Therefore, the machine control system remains largely open loop. While some metal additive manufacturing machines present the powder bed monitoring with images, it has not been found that they can automatically detect the defects that may occur in the powder bed layer and stimulate the control system. In the study, an exemplary machine learning-based approach is presented for on-site monitoring and defect detection of powder bed images, which can be a component of a real-time control system in any TYB metal additive manufacturing machine. Using the deep learning method, which is one of the subfields of machine learning, a classification was made to detect the defects that may occur in creating a layer of the process. Detection and classification of defects were carried out using the convolutional neural networks model. The data set for training and performance of the model was created with photographs of a three-dimensional sample structure manufactured on the EOS M290 machine. The best performance was obtained in the VGG16 model with 88.3% accuracy by performing transfer learning from VGG-16, Inception V3, and DenseNet pre-learning models.